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Wang B, Pan X, Teng IT, Li X, Kobeissy F, Wu ZY, Zhu J, Cai G, Yan H, Yan X, Liang M, Yu F, Lu J, Yang Z, Biondi E, Haskins W, Cao YC, Benner SA, Tan W, Wang KK. Functional Selection of Tau Oligomerization-Inhibiting Aptamers. Angew Chem Int Ed Engl 2024; 63:e202402007. [PMID: 38407551 DOI: 10.1002/anie.202402007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 02/19/2024] [Accepted: 02/21/2024] [Indexed: 02/27/2024]
Abstract
Pathological hyperphosphorylation and aggregation of microtubule-associated Tau protein contribute to Alzheimer's Disease (AD) and other related tauopathies. Currently, no cure exists for Alzheimer's Disease. Aptamers offer significant potential as next-generation therapeutics in biotechnology and the treatment of neurological disorders. Traditional aptamer selection methods for Tau protein focus on binding affinity rather than interference with pathological Tau. In this study, we developed a new selection strategy to enrich DNA aptamers that bind to surviving monomeric Tau protein under conditions that would typically promote Tau aggregation. Employing this approach, we identified a set of aptamer candidates. Notably, BW1c demonstrates a high binding affinity (Kd=6.6 nM) to Tau protein and effectively inhibits arachidonic acid (AA)-induced Tau protein oligomerization and aggregation. Additionally, it inhibits GSK3β-mediated Tau hyperphosphorylation in cell-free systems and okadaic acid-mediated Tau hyperphosphorylation in cellular milieu. Lastly, retro-orbital injection of BW1c tau aptamer shows the ability to cross the blood brain barrier and gain access to neuronal cell body. Through further refinement and development, these Tau aptamers may pave the way for a first-in-class neurotherapeutic to mitigate tauopathy-associated neurodegenerative disorders.
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Affiliation(s)
- Bang Wang
- Department of Chemistry and Department of Physiology and Functional Genomics, Center for Research at Bio/Nano Interface, Health Cancer Center, UF Genetics Institute and McKnight Brain Institute, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32611, USA
- Foundation for Applied Molecular Evolution, Firebird Biomolecular Sciences LLC, 13709 Progress Boulevard, No. 7, Alachua, FL 32615, USA
| | - Xiaoshu Pan
- Department of Chemistry and Department of Physiology and Functional Genomics, Center for Research at Bio/Nano Interface, Health Cancer Center, UF Genetics Institute and McKnight Brain Institute, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32611, USA
| | - I-Ting Teng
- Department of Chemistry and Department of Physiology and Functional Genomics, Center for Research at Bio/Nano Interface, Health Cancer Center, UF Genetics Institute and McKnight Brain Institute, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32611, USA
| | - Xiaowei Li
- Department of Chemistry and Department of Physiology and Functional Genomics, Center for Research at Bio/Nano Interface, Health Cancer Center, UF Genetics Institute and McKnight Brain Institute, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32611, USA
| | - Firas Kobeissy
- Center for Neurotrauma, Multiomics & Biomarkers, Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Dr. SW, Atlanta, GA 30310-1458, (USA). Department of Emergency Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - Zo-Yu Wu
- Center for Neurotrauma, Multiomics & Biomarkers, Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Dr. SW, Atlanta, GA 30310-1458, (USA). Department of Emergency Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - Jiepei Zhu
- Center for Neurotrauma, Multiomics & Biomarkers, Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Dr. SW, Atlanta, GA 30310-1458, (USA). Department of Emergency Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - Guangzheng Cai
- Center for Neurotrauma, Multiomics & Biomarkers, Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Dr. SW, Atlanta, GA 30310-1458, (USA). Department of Emergency Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - He Yan
- Department of Chemistry and Department of Physiology and Functional Genomics, Center for Research at Bio/Nano Interface, Health Cancer Center, UF Genetics Institute and McKnight Brain Institute, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32611, USA
| | - Xin Yan
- Department of Chemistry and Department of Physiology and Functional Genomics, Center for Research at Bio/Nano Interface, Health Cancer Center, UF Genetics Institute and McKnight Brain Institute, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32611, USA
| | - Mingwei Liang
- Department of Biochemistry and Molecular Biology, UF Health Cancer Center, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Fahong Yu
- Department of Chemistry and Department of Physiology and Functional Genomics, Center for Research at Bio/Nano Interface, Health Cancer Center, UF Genetics Institute and McKnight Brain Institute, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32611, USA
| | - Jianrong Lu
- Department of Biochemistry and Molecular Biology, UF Health Cancer Center, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Zunyi Yang
- Foundation for Applied Molecular Evolution, Firebird Biomolecular Sciences LLC, 13709 Progress Boulevard, No. 7, Alachua, FL 32615, USA
| | - Elisa Biondi
- Foundation for Applied Molecular Evolution, Firebird Biomolecular Sciences LLC, 13709 Progress Boulevard, No. 7, Alachua, FL 32615, USA
| | - William Haskins
- Gryphon Bio, Inc., 611 Gateway Blvd. Suite 120 #253, South San Francisco, CA 94080-7066, USA
| | - Y Charles Cao
- Department of Chemistry and Department of Physiology and Functional Genomics, Center for Research at Bio/Nano Interface, Health Cancer Center, UF Genetics Institute and McKnight Brain Institute, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32611, USA
| | - Steven A Benner
- Foundation for Applied Molecular Evolution, Firebird Biomolecular Sciences LLC, 13709 Progress Boulevard, No. 7, Alachua, FL 32615, USA
| | - Weihong Tan
- Department of Chemistry and Department of Physiology and Functional Genomics, Center for Research at Bio/Nano Interface, Health Cancer Center, UF Genetics Institute and McKnight Brain Institute, Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32611, USA
- Molecular Science and Biomedicine Laboratory (MBL), State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Aptamer Engineering Center of Hunan Province, Hunan University, Changsha, Hunan, 410082, China
- Zhejiang Cancer Hospital, Hangzhou Institute of Medicine (HIM), Chinese Academy of Sciences, Hangzhou, Zhejiang, 310022, China
| | - Kevin K Wang
- Center for Neurotrauma, Multiomics & Biomarkers, Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, 720 Westview Dr. SW, Atlanta, GA 30310-1458, (USA). Department of Emergency Medicine, McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
- Gryphon Bio, Inc., 611 Gateway Blvd. Suite 120 #253, South San Francisco, CA 94080-7066, USA
- Brain Rehabilitation Research Center, Malcom Randall VA Medical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL 32608, USA
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Narasimman V, Ramachandran S. Purification, structural characterization, and neuroprotective effect of 3,6-diisobutyl-2,5-piperazinedione from Halomonas pacifica CARE-V15 against okadaic acid-induced neurotoxicity in zebrafish model. J Biochem Mol Toxicol 2024; 38:e23708. [PMID: 38597299 DOI: 10.1002/jbt.23708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 02/26/2024] [Accepted: 03/29/2024] [Indexed: 04/11/2024]
Abstract
Halomonas pacifica CARE-V15 was isolated from the southeastern coast of India to determine its genome sequence. Secondary metabolite gene clusters were identified using an anti-SMASH server. The concentrated crude ethyl acetate extract was evaluated by GC-MS. The bioactive compound from the crude ethyl acetate extract was fractionated by gel column chromatography. HPLC was used to purify the 3,6-diisobutyl-2,5-piperazinedione (DIP), and the structure was determined using FTIR and NMR spectroscopy. Purified DIP was used in an in silico molecular docking analysis. Purified DIP exhibits a stronger affinity for antioxidant genes like glutathione peroxidase (GPx), glutathione-S-transferase (GST), and glutathione reductase (GSR). Using in silco molecular docking analysis, the protein-ligand binding affinities of GSR (-4.70 kcal/mol), GST (-5.27 kcal/mol), and GPx (-5.37 kcal/mol) were measured. The expression of antioxidant genes were investigated by qRT-PCR. The in vivo reactive oxygen species production, lipid peroxidation, and cell death levels were significantly (p ≤ 0.05) increased in OA-induced group, but all these levels were significantly (p ≤ 0.05) decreased in the purified DIP pretreated group. Purified DIP from halophilic bacteria could thus be a useful treatment for neurological disorders associated with oxidative stress.
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Affiliation(s)
- Vignesh Narasimman
- Native Medicine and Marine Pharmacology Laboratory, Faculty of Allied Health Sciences, Chettinad Hospital and Research Institute, Chettinad Academy of Research and Education (Deemed to be University), Chettinad Health City, Kelambakkam, Tamil Nadu, India
| | - Saravanan Ramachandran
- Native Medicine and Marine Pharmacology Laboratory, Faculty of Allied Health Sciences, Chettinad Hospital and Research Institute, Chettinad Academy of Research and Education (Deemed to be University), Chettinad Health City, Kelambakkam, Tamil Nadu, India
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Arribas RL, Viejo L, Bravo I, Martínez M, Ramos E, Romero A, García-Frutos EM, Janssens V, Montiel C, de Los Ríos C. C-glycosides analogues of the okadaic acid central fragment exert neuroprotection via restoration of PP2A-phosphatase activity: A rational design of potential drugs for Alzheimer's disease targeting tauopathies. Eur J Med Chem 2023; 251:115245. [PMID: 36905916 DOI: 10.1016/j.ejmech.2023.115245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 01/24/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023]
Abstract
Protein phosphatase 2A (PP2A) is an important Ser/Thr phosphatase that participates in the regulation of multiple cellular processes. This implies that any deficient activity of PP2A is the responsible of severe pathologies. For instance, one of the main histopathological features of Alzheimer's disease is neurofibrillary tangles, which are mainly comprised by hyperphosphorylated forms of tau protein. This altered rate of tau phosphorylation has been correlated with PP2A depression AD patients. With the goal of preventing PP2A inactivation in neurodegeneration scenarios, we have aimed to design, synthesize and evaluate new ligands of PP2A capable of preventing its inhibition. To achieve this goal, the new PP2A ligands present structural similarities with the central fragment C19-C27 of the well-established PP2A inhibitor okadaic acid (OA). Indeed, this central moiety of OA does not exert inhibitory actions. Hence, these compounds lack PP2A-inhibiting structural motifs but, in contrast, compete with PP2A inhibitors, thus recovering phosphatase activity. Proving this hypothesis, most compounds showed a good neuroprotective profile in neurodegeneration models related to PP2A impairment, highlighting derivative 10, named ITH12711, as the most promising one. This compound (1) restored in vitro and cellular PP2A catalytic activity, measured on a phospho-peptide substrate and by western-blot analyses, (2) proved good brain penetration measured by PAMPA, and (3) prevented LPS-induced memory impairment of mice in the object recognition test. Thus, the promising outcomes of the compound 10 validate our rational approach to design new PP2A-activating drugs based on OA central fragment.
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Affiliation(s)
- Raquel L Arribas
- Instituto-Fundación Teófilo Hernando, Universidad Autónoma de Madrid, 28029, Madrid, Spain; Departamento de Ciencias Básicas de la Salud, Universidad Rey Juan Carlos, 28922, Alcorcón, Spain
| | - Lucía Viejo
- Instituto-Fundación Teófilo Hernando, Universidad Autónoma de Madrid, 28029, Madrid, Spain; Instituto de Investigación Sanitaria, Hospital Universitario de la Princesa, C/ Diego de León, 62, 28006, Madrid, Spain
| | - Isaac Bravo
- Instituto de Investigación Sanitaria, Hospital Universitario de la Princesa, C/ Diego de León, 62, 28006, Madrid, Spain; Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, 28049, Madrid, Spain
| | - Minerva Martínez
- Instituto-Fundación Teófilo Hernando, Universidad Autónoma de Madrid, 28029, Madrid, Spain
| | - Eva Ramos
- Departamento de Farmacología y Toxicología, Facultad de Veterinaria, Universidad Complutense, 28040, Madrid, Spain
| | - Alejandro Romero
- Departamento de Farmacología y Toxicología, Facultad de Veterinaria, Universidad Complutense, 28040, Madrid, Spain
| | - Eva M García-Frutos
- Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, 28049, Madrid, Spain; Universidad de Alcalá, Departamento de Química Orgánica y Química Inorgánica, Ctra. Madrid-Barcelona Km.33,600, 28871, Alcalá de Henares, Madrid, Spain
| | - Veerle Janssens
- Department of Cellular & Molecular Medicine, Laboratory of Protein Phosphorylation and Proteomics, KU Leuven, B-3000, Leuven, Belgium; LBI (KU Leuven Brain Institute), B-3000, Leuven, Belgium
| | - Carmen Montiel
- Instituto-Fundación Teófilo Hernando, Universidad Autónoma de Madrid, 28029, Madrid, Spain
| | - Cristóbal de Los Ríos
- Instituto-Fundación Teófilo Hernando, Universidad Autónoma de Madrid, 28029, Madrid, Spain; Departamento de Ciencias Básicas de la Salud, Universidad Rey Juan Carlos, 28922, Alcorcón, Spain; Instituto de Investigación Sanitaria, Hospital Universitario de la Princesa, C/ Diego de León, 62, 28006, Madrid, Spain.
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Sitosari H, Morimoto I, Weng Y, Zheng Y, Fukuhara Y, Ikegame M, Okamura H. Inhibition of protein phosphatase 2A by okadaic acid induces translocation of nucleocytoplasmic O-GlcNAc transferase. Biochem Biophys Res Commun 2023; 646:50-55. [PMID: 36706705 DOI: 10.1016/j.bbrc.2023.01.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/09/2023] [Accepted: 01/12/2023] [Indexed: 01/15/2023]
Abstract
Post-translational modification (PTM) is crucial for many biological events, such as the modulation of bone metabolism. Phosphorylation and O-GlcNAcylation are two examples of PTMs that can occur at the same site in the protein: serine and threonine residues. This phenomenon may cause crosstalk and possible interactions between the molecules involved. Protein phosphatase 2 A (PP2A) is widely expressed throughout the body and plays a major role in dephosphorylation. At the same location where PP2A acts, O-GlcNAc transferase (OGT) can introduce uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) molecules and mediates O-GlcNAc modifications. To examine the effects of PP2A inhibition on OGT localization and expression, osteoblastic MC3T3-E1 cells were treated with Okadaic Acid (OA), a potent PP2A inhibitor. In the control cells, OGT was strictly localized in the nucleus. However, OGT was observed diffusely in the cytoplasm of the OA-treated cells. This change in localization from the nucleus to the cytoplasm resulted from an increase in mitochondrial OGT expression and translocation of the nucleocytoplasmic isoform. Furthermore, knockdown of PP2A catalytic subunit α isoform (PP2A Cα) significantly affected OGT expression (p < 0.05), and there was a correlation between PP2A Cα and OGT expression (r = 0.93). These results suggested a possible interaction between PP2A and OGT, which strengthens the notion of an interaction between phosphorylation and O-GlcNAcylation.
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Affiliation(s)
- Heriati Sitosari
- Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 770-8525, Japan; Department of Oral Biology, Faculty of Dentistry, Universitas Gadjah Mada, Yogyakarta, 55281, Indonesia
| | - Ikkei Morimoto
- Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 770-8525, Japan
| | - Yao Weng
- Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 770-8525, Japan; Department of Oral Rehabilitation and Implantology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 770-8525, Japan
| | - Yilin Zheng
- Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 770-8525, Japan
| | - Yoko Fukuhara
- Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 770-8525, Japan
| | - Mika Ikegame
- Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 770-8525, Japan
| | - Hirohiko Okamura
- Department of Oral Morphology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 770-8525, Japan.
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Maltsev AV, Nikiforova AB, Bal NV, Balaban PM. Amyloid Aβ25-35 Aggregates Say ‘NO’ to Long-Term Potentiation in the Hippocampus through Activation of Stress-Induced Phosphatase 1 and Mitochondrial Na+/Ca2+ Exchanger. Int J Mol Sci 2022; 23:ijms231911848. [PMID: 36233148 PMCID: PMC9570122 DOI: 10.3390/ijms231911848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 10/02/2022] [Accepted: 10/04/2022] [Indexed: 11/16/2022] Open
Abstract
The search for strategies for strengthening the synaptic efficiency in Aβ25-35-treated slices is a challenge for the compensation of amyloidosis-related pathologies. Here, we used the recording of field excitatory postsynaptic potentials (fEPSPs), nitric oxide (NO) imaging, measurements of serine/threonine protein phosphatase (STPP) activity, and the detection of the functional mitochondrial parameters in suspension of brain mitochondria to study the Aβ25-35-associated signaling in the hippocampus. Aβ25-35 aggregates shifted the kinase–phosphatase balance during the long-term potentiation (LTP) induction in the enhancement of STPP activity. The PP1/PP2A inhibitor, okadaic acid, but not the PP2B blocker, cyclosporin A, prevented Aβ25-35-dependent LTP suppression for both simultaneous and delayed enzyme blockade protocols. STPP activity in the Aβ25-35-treated slices was upregulated, which is reverted relative to the control values in the presence of PP1/PP2A but not in the presence of the PP2B blocker. A selective inhibitor of stress-induced PP1α, sephin1, but not of the PP2A blocker, cantharidin, is crucial for Aβ25-35-mediated LTP suppression prevention. A mitochondrial Na+/Ca2+ exchanger (mNCX) blocker, CGP37157, also attenuated the Aβ25-35-induced LTP decline. Aβ25-35 aggregates did not change the mitochondrial transmembrane potential or reactive oxygen species (ROS) production but affected the ion transport and Ca2+-dependent swelling of organelles. The staining of hippocampal slices with NO-sensitive fluorescence dye, DAF-FM, showed stimulation of the NO production in the Aβ25-35-pretreated slices at the dendrite-containing regions of CA1 and CA3, in the dentate gyrus (DG), and in the CA1/DG somata. NO scavenger, PTIO, or nNOS blockade by selective inhibitor 3Br-7NI partly restored the Aβ25-35-induced LTP decline. Thus, hippocampal NO production could be another marker for the impairment of synaptic plasticity in amyloidosis-related states, and kinase–phosphatase balance management could be a promising strategy for the compensation of Aβ25-35-driven deteriorations.
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Affiliation(s)
- Alexander V. Maltsev
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Butlerova 5A, 117485 Moscow, Russia
- Correspondence:
| | - Anna B. Nikiforova
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Institutskaya 3, Pushchino, 142290 Moscow, Russia
| | - Natalia V. Bal
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Butlerova 5A, 117485 Moscow, Russia
| | - Pavel M. Balaban
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Butlerova 5A, 117485 Moscow, Russia
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Schiavi-Ehrenhaus LJ, Romarowski A, Jabloñski M, Krapf D, Luque GM, Buffone MG. The early molecular events leading to COFILIN phosphorylation during mouse sperm capacitation are essential for acrosomal exocytosis. J Biol Chem 2022; 298:101988. [PMID: 35487245 PMCID: PMC9142561 DOI: 10.1016/j.jbc.2022.101988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 04/18/2022] [Accepted: 04/20/2022] [Indexed: 12/03/2022] Open
Abstract
The actin cytoskeleton reorganization during sperm capacitation is essential for the occurrence of acrosomal exocytosis (AR) in several mammalian species. Here, we demonstrate that in mouse sperm, within the first minutes of exposure upon capacitating conditions, the activity of RHOA/C and RAC1 is essential for LIMK1 and COFILIN phosphorylation. However, we observed that the signaling pathway involving RAC1 and PAK4 is the main player in controlling actin polymerization in the sperm head necessary for the occurrence of AR. Moreover, we show that the transient phosphorylation of COFILIN is also influenced by the Slingshot family of protein phosphatases (SSH1). The activity of SSH1 is regulated by the dual action of two pathways. On one hand, RHOA/C and RAC1 activity promotes SSH1 phosphorylation (inactivation). On the other hand, the activating dephosphorylation is driven by okadaic acid-sensitive phosphatases. This regulatory mechanism is independent of the commonly observed activating mechanisms involving PP2B and emerges as a new finely tuned modulation that is, so far, exclusively observed in mouse sperm. However, persistent phosphorylation of COFILIN by SSH1 inhibition or okadaic acid did not altered actin polymerization and the AR. Altogether, our results highlight the role of small GTPases in modulating actin dynamics required for AR.
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Affiliation(s)
- Liza J Schiavi-Ehrenhaus
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas (IBYME-CONICET), Buenos Aires, Argentina
| | - Ana Romarowski
- Department of Veterinary and Animal Science, University of Massachusetts, Amherst, Massachusetts, USA
| | - Martina Jabloñski
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas (IBYME-CONICET), Buenos Aires, Argentina
| | - Darío Krapf
- Instituto de Biología Molecular y Celular de Rosario (IBR), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Rosario (UNR), Rosario, Argentina
| | - Guillermina M Luque
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas (IBYME-CONICET), Buenos Aires, Argentina.
| | - Mariano G Buffone
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas (IBYME-CONICET), Buenos Aires, Argentina.
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Solís-Chagoyán H, Domínguez-Alonso A, Valdés-Tovar M, Argueta J, Sánchez-Florentino ZA, Calixto E, Benítez-King G. Melatonin Rescues the Dendrite Collapse Induced by the Pro-Oxidant Toxin Okadaic Acid in Organotypic Cultures of Rat Hilar Hippocampus. Molecules 2020; 25:molecules25235508. [PMID: 33255515 PMCID: PMC7727803 DOI: 10.3390/molecules25235508] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/02/2020] [Accepted: 11/06/2020] [Indexed: 02/06/2023] Open
Abstract
The pro-oxidant compound okadaic acid (OKA) mimics alterations found in Alzheimer's disease (AD) as oxidative stress and tau hyperphosphorylation, leading to neurodegeneration and cognitive decline. Although loss of dendrite complexity occurs in AD, the study of this post-synaptic domain in chemical-induced models remains unexplored. Moreover, there is a growing expectation for therapeutic adjuvants to counteract these brain dysfunctions. Melatonin, a free-radical scavenger, inhibits tau hyperphosphorylation, modulates phosphatases, and strengthens dendritic arbors. Thus, we determined if OKA alters the dendritic arbors of hilar hippocampal neurons and whether melatonin prevents, counteracts, or reverses these damages. Rat organotypic cultures were incubated with vehicle, OKA, melatonin, and combined treatments with melatonin either before, simultaneously, or after OKA. DNA breaks were assessed by TUNEL assay and nuclei were counterstained with DAPI. Additionally, MAP2 was immunostained to assess the dendritic arbor properties by the Sholl method. In hippocampal hilus, OKA increased DNA fragmentation and reduced the number of MAP2(+) cells, whereas melatonin protected against oxidation and apoptosis. Additionally, OKA decreased the dendritic arbor complexity and melatonin not only counteracted, but also prevented and reversed the dendritic arbor retraction, highlighting its role in post-synaptic domain integrity preservation against neurodegenerative events in hippocampal neurons.
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Affiliation(s)
- Héctor Solís-Chagoyán
- Laboratorio de Neurofarmacología, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City 14370, Mexico; (H.S.-C.); (A.D.-A.); (M.V.-T.); (J.A.); (Z.A.S.-F.)
| | - Aline Domínguez-Alonso
- Laboratorio de Neurofarmacología, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City 14370, Mexico; (H.S.-C.); (A.D.-A.); (M.V.-T.); (J.A.); (Z.A.S.-F.)
| | - Marcela Valdés-Tovar
- Laboratorio de Neurofarmacología, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City 14370, Mexico; (H.S.-C.); (A.D.-A.); (M.V.-T.); (J.A.); (Z.A.S.-F.)
- Departamento de Farmacogenética (current affiliation), Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City 14370, Mexico
| | - Jesús Argueta
- Laboratorio de Neurofarmacología, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City 14370, Mexico; (H.S.-C.); (A.D.-A.); (M.V.-T.); (J.A.); (Z.A.S.-F.)
| | - Zuly A. Sánchez-Florentino
- Laboratorio de Neurofarmacología, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City 14370, Mexico; (H.S.-C.); (A.D.-A.); (M.V.-T.); (J.A.); (Z.A.S.-F.)
| | - Eduardo Calixto
- Departamento de Neurobiología, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City 14370, Mexico;
| | - Gloria Benítez-King
- Laboratorio de Neurofarmacología, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City 14370, Mexico; (H.S.-C.); (A.D.-A.); (M.V.-T.); (J.A.); (Z.A.S.-F.)
- Correspondence: ; Tel.: +52-55-4160-5097
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Yadikar H, Torres I, Aiello G, Kurup M, Yang Z, Lin F, Kobeissy F, Yost R, Wang KK. Screening of tau protein kinase inhibitors in a tauopathy-relevant cell-based model of tau hyperphosphorylation and oligomerization. PLoS One 2020; 15:e0224952. [PMID: 32692785 PMCID: PMC7373298 DOI: 10.1371/journal.pone.0224952] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 06/15/2020] [Indexed: 12/15/2022] Open
Abstract
Tauopathies are a class of neurodegenerative disorders characterized by abnormal deposition of post-translationally modified tau protein in the human brain. Tauopathies are associated with Alzheimer's disease (AD), chronic traumatic encephalopathy (CTE), and other diseases. Hyperphosphorylation increases tau tendency to aggregate and form neurofibrillary tangles (NFT), a pathological hallmark of AD. In this study, okadaic acid (OA, 100 nM), a protein phosphatase 1/2A inhibitor, was treated for 24h in mouse neuroblastoma (N2a) and differentiated rat primary neuronal cortical cell cultures (CTX) to induce tau-hyperphosphorylation and oligomerization as a cell-based tauopathy model. Following the treatments, the effectiveness of different kinase inhibitors was assessed using the tauopathy-relevant tau antibodies through tau-immunoblotting, including the sites: pSer202/pThr205 (AT8), pThr181 (AT270), pSer202 (CP13), pSer396/pSer404 (PHF-1), and pThr231 (RZ3). OA-treated samples induced tau phosphorylation and oligomerization at all tested epitopes, forming a monomeric band (46-67 kDa) and oligomeric bands (170 kDa and 240 kDa). We found that TBB (a casein kinase II inhibitor), AR and LiCl (GSK-3 inhibitors), cyclosporin A (calcineurin inhibitor), and Saracatinib (Fyn kinase inhibitor) caused robust inhibition of OA-induced monomeric and oligomeric p-tau in both N2a and CTX culture. Additionally, a cyclin-dependent kinase 5 inhibitor (Roscovitine) and a calcium chelator (EGTA) showed contrasting results between the two neuronal cultures. This study provides a comprehensive view of potential drug candidates (TBB, CsA, AR, and Saracatinib), and their efficacy against tau hyperphosphorylation and oligomerization processes. These findings warrant further experimentation, possibly including animal models of tauopathies, which may provide a putative Neurotherapy for AD, CTE, and other forms of tauopathy-induced neurodegenerative diseases.
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Affiliation(s)
- Hamad Yadikar
- Program for Neurotrauma, Neuroproteomics & Biomarkers Research, Departments of Emergency Medicine, Psychiatry, Neuroscience and Chemistry, University of Florida, Gainesville, Florida, United States of America
- Department of Biological Sciences, Faculty of Science, Kuwait University, Safat, Kuwait
- Department of Chemistry, Chemistry Laboratory Building, University of Florida, Gainesville, FL, United States of America
- * E-mail:
| | - Isabel Torres
- Program for Neurotrauma, Neuroproteomics & Biomarkers Research, Departments of Emergency Medicine, Psychiatry, Neuroscience and Chemistry, University of Florida, Gainesville, Florida, United States of America
| | - Gabrielle Aiello
- Program for Neurotrauma, Neuroproteomics & Biomarkers Research, Departments of Emergency Medicine, Psychiatry, Neuroscience and Chemistry, University of Florida, Gainesville, Florida, United States of America
| | - Milin Kurup
- Program for Neurotrauma, Neuroproteomics & Biomarkers Research, Departments of Emergency Medicine, Psychiatry, Neuroscience and Chemistry, University of Florida, Gainesville, Florida, United States of America
| | - Zhihui Yang
- Program for Neurotrauma, Neuroproteomics & Biomarkers Research, Departments of Emergency Medicine, Psychiatry, Neuroscience and Chemistry, University of Florida, Gainesville, Florida, United States of America
| | - Fan Lin
- Program for Neurotrauma, Neuroproteomics & Biomarkers Research, Departments of Emergency Medicine, Psychiatry, Neuroscience and Chemistry, University of Florida, Gainesville, Florida, United States of America
| | - Firas Kobeissy
- Program for Neurotrauma, Neuroproteomics & Biomarkers Research, Departments of Emergency Medicine, Psychiatry, Neuroscience and Chemistry, University of Florida, Gainesville, Florida, United States of America
- Faculty of Medicine, American University of Beirut Medical Center, Beirut, Lebanon
| | - Richard Yost
- Department of Chemistry, Chemistry Laboratory Building, University of Florida, Gainesville, FL, United States of America
| | - Kevin K. Wang
- Program for Neurotrauma, Neuroproteomics & Biomarkers Research, Departments of Emergency Medicine, Psychiatry, Neuroscience and Chemistry, University of Florida, Gainesville, Florida, United States of America
- Brain Rehabilitation Research Center, Malcom Randall VA Medical Center, Gainesville, FL, United States of America
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9
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Cheng G, Li L. High-glucose-induced apoptosis, ROS production and pro-inflammatory response in cardiomyocytes is attenuated by metformin treatment via PP2A activation. J Biosci 2020; 45:126. [PMID: 33184242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Metformin has been shown to ameliorate diabetic cardiomyopathy. In the present research we investigated whether metformin would reduce cardiomyocyte apoptosis that was induced by high-glucose stimulation in vitro via activation of PP2A. Primary human and rat cardiomyocytes were subject to high-glucose stimulation. Okadaic acid was used to inhibit PP2A activity. Cell viability and apoptosis was assessed using CCK-8 and by flow cytometry, respectively. Release of HMGB1, TNFα or IL-6 was analyzed by ELISA. Oxidative stress was evaluated by measuring cellular ROS and mitochondrial superoxide level. PP2A activity was evaluated by Serine/ Threonine phosphatase assay system or analyzing Y307 phosphorylation level of PP2A catalytic domain (PP2Ac) by Western blot and the association between PP2Ac and α4 by co-immunoprecipitation. Activation of the NF-κB signaling pathway was assessed by detecting Ser32 phosphorylation level of IκBα as well as nuclear entry of p65 protein by Western blot. Activation of the GSK3β/MCL1 signaling pathway was assessed by detecting Ser9 phosphorylation level of GSK3 β and protein level of MCL1. We found Metformin pre-treatment attenuated human and rat cardiomyocytes apoptosis, HMGB1, TNFα and IL-6 release and ROS production that were induced by high-glucose stimulation, and these effects of metformin could be blocked by okadaic acid treatment. Metformin reduced the upregulation of PP2Ac pY307 and the PP2Ac-a4 association, which was not affected by okadaic acid treatment. Metformin pre-treatment reduced NF-κB activation in human and rat cardiomyocytes apoptosis that was elicited by high-glucose stimulation, and this effect of metformin could be blocked by okadaic acid treatment. GSK3 β/MCL1 is not part of metformin activating PP2A induced myocardial cell death inhibition. In conclusion, metformin reduced apoptosis, ROS production and inflammatory response in primary human and rat cardiomyocytes in vitro in a PP2A dependent manner.
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Affiliation(s)
- Gang Cheng
- Department of Anesthesiology, Fuwai Cardiovascular Hospital (State Key Laboratory of Cardiovascular Disease, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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10
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Xu J, Zhang L, Xu Y, Zhang H, Gao J, Wang Q, Tian Z, Xuan L, Chen H, Wang Y. PP2A Facilitates Porcine Reproductive and Respiratory Syndrome Virus Replication by Deactivating irf3 and Limiting Type I Interferon Production. Viruses 2019; 11:v11100948. [PMID: 31618847 PMCID: PMC6832233 DOI: 10.3390/v11100948] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 10/11/2019] [Accepted: 10/11/2019] [Indexed: 12/12/2022] Open
Abstract
Protein phosphatase 2A (PP2A), a major serine/threonine phosphatase in mammalian cells, is known to regulate the kinase-driven intracellular signaling pathways. Emerging evidences have shown that the PP2A phosphatase functions as a bona-fide therapeutic target for anticancer therapy, but it is unclear whether PP2A affects a porcine reproductive and respiratory syndrome virus infection. In the present study, we demonstrated for the first time that inhibition of PP2A activity by either inhibitor or small interfering RNA duplexes in target cells significantly reduced their susceptibility to porcine reproductive and respiratory syndrome virus (PRRSV) infection. Further analysis revealed that inhibition of PP2A function resulted in augmented production of type I interferon (IFN). The mechanism is that inhibition of PP2A activity enhances the levels of phosphorylated interferon regulatory factor 3, which activates the transcription of IFN-stimulated genes. Moreover, inhibition of PP2A activity mainly blocked PRRSV replication in the early stage of viral life cycle, after virus entry but before virus release. Using type I IFN receptor 2 specific siRNA in combination with PP2A inhibitor, we confirmed that the effect of PP2A on viral replication within target cells was an interferon-dependent manner. Taken together, these findings demonstrate that PP2A serves as a negative regulator of host cells antiviral responses and provides a novel therapeutic target for virus infection.
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Affiliation(s)
- Jiayu Xu
- State Key Laboratory of Veterinary Biotechnology, Heilongjiang Provincial Key Laboratory of Laboratory Animal and Comparative Medicine, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Lu Zhang
- State Key Laboratory of Veterinary Biotechnology, Heilongjiang Provincial Key Laboratory of Laboratory Animal and Comparative Medicine, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Yunfei Xu
- State Key Laboratory of Veterinary Biotechnology, Heilongjiang Provincial Key Laboratory of Laboratory Animal and Comparative Medicine, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - He Zhang
- State Key Laboratory of Veterinary Biotechnology, Heilongjiang Provincial Key Laboratory of Laboratory Animal and Comparative Medicine, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Junxin Gao
- State Key Laboratory of Veterinary Biotechnology, Heilongjiang Provincial Key Laboratory of Laboratory Animal and Comparative Medicine, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Qian Wang
- State Key Laboratory of Veterinary Biotechnology, Heilongjiang Provincial Key Laboratory of Laboratory Animal and Comparative Medicine, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Zhijun Tian
- State Key Laboratory of Veterinary Biotechnology, Heilongjiang Provincial Key Laboratory of Laboratory Animal and Comparative Medicine, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China
| | - Lv Xuan
- Department of public health policy, University of California, Irvine, CA 92697, USA
| | - Hongyan Chen
- State Key Laboratory of Veterinary Biotechnology, Heilongjiang Provincial Key Laboratory of Laboratory Animal and Comparative Medicine, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China.
| | - Yue Wang
- State Key Laboratory of Veterinary Biotechnology, Heilongjiang Provincial Key Laboratory of Laboratory Animal and Comparative Medicine, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China.
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11
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Alarcan J, Barbé S, Kopp B, Hessel-Pras S, Braeuning A, Lampen A, Le Hégarat L, Fessard V. Combined effects of okadaic acid and pectenotoxin-2, 13-desmethylspirolide C or yessotoxin in human intestinal Caco-2 cells. Chemosphere 2019; 228:139-148. [PMID: 31029959 DOI: 10.1016/j.chemosphere.2019.04.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 03/27/2019] [Accepted: 04/03/2019] [Indexed: 06/09/2023]
Abstract
Lipophilic phycotoxins are secondary metabolites produced by phytoplanktonic species. They accumulate in filtering shellfish and can cause human intoxications. Humans can be exposed to combinations of several phycotoxins. The toxicological effects of phycotoxin mixtures on human health are largely unknown. Published data on phycotoxin co-exposure show that okadaic acid (OA) is simultaneously found with pectenetoxin-2 (PTX-2), 13-desmethylspirolide C (also known as SPX-1), or yessotoxin (YTX). Therefore, the aim of this study was to examine the effects of three binary mixtures, OA/PTX-2, OA/SPX-1 and OA/YTX on human intestinal Caco-2 cells. A multi-parametric approach for cytotoxicity determination was applied using a high-content analysis platform, including markers for cell viability, oxidative stress, inflammation, and DNA damage. Mixtures effects were analyzed using two additivity mathematical models. Our assays revealed that OA induced cytotoxicity, DNA strand breaks and interleukin 8 release. PTX-2 slightly induced DNA strand breaks, whereas SPX-1 and YTX did not affect the investigated endpoints. The combination of OA with another toxin resulted in reduced toxicity at low concentrations, suggesting antagonistic effects, but in increased effects at higher concentrations, suggesting additive or synergistic effects. Taken together, our results demonstrated that the cytotoxic effects of binary mixtures of lipophilic phycotoxins could not be predicted by additivity mathematical models. In conclusion, the present data suggest that combined effects of phycotoxins may occur which might have the potential to impact on risk assessment of these compounds.
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Affiliation(s)
- Jimmy Alarcan
- ANSES, French Agency for Food, Environmental and Occupational Health & Safety, Fougeres-Laboratory, Toxicology of Contaminants Unit, 10B Rue Claude Bourgelat, 35306, Fougères, France; German Federal Institute for Risk Assessment, Department of Food Safety, Max-Dohrn-Straße 8-10, 10589, Berlin, Germany.
| | - Sabrina Barbé
- ANSES, French Agency for Food, Environmental and Occupational Health & Safety, Fougeres-Laboratory, Toxicology of Contaminants Unit, 10B Rue Claude Bourgelat, 35306, Fougères, France.
| | - Benjamin Kopp
- ANSES, French Agency for Food, Environmental and Occupational Health & Safety, Fougeres-Laboratory, Toxicology of Contaminants Unit, 10B Rue Claude Bourgelat, 35306, Fougères, France.
| | - Stefanie Hessel-Pras
- German Federal Institute for Risk Assessment, Department of Food Safety, Max-Dohrn-Straße 8-10, 10589, Berlin, Germany.
| | - Albert Braeuning
- German Federal Institute for Risk Assessment, Department of Food Safety, Max-Dohrn-Straße 8-10, 10589, Berlin, Germany.
| | - Alfonso Lampen
- German Federal Institute for Risk Assessment, Department of Food Safety, Max-Dohrn-Straße 8-10, 10589, Berlin, Germany.
| | - Ludovic Le Hégarat
- ANSES, French Agency for Food, Environmental and Occupational Health & Safety, Fougeres-Laboratory, Toxicology of Contaminants Unit, 10B Rue Claude Bourgelat, 35306, Fougères, France.
| | - Valérie Fessard
- ANSES, French Agency for Food, Environmental and Occupational Health & Safety, Fougeres-Laboratory, Toxicology of Contaminants Unit, 10B Rue Claude Bourgelat, 35306, Fougères, France.
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12
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Doherty DF, Nath S, Poon J, Foronjy RF, Ohlmeyer M, Dabo AJ, Salathe M, Birrell M, Belvisi M, Baumlin N, Kim MD, Weldon S, Taggart C, Geraghty P. Protein Phosphatase 2A Reduces Cigarette Smoke-induced Cathepsin S and Loss of Lung Function. Am J Respir Crit Care Med 2019; 200:51-62. [PMID: 30641028 PMCID: PMC6603057 DOI: 10.1164/rccm.201808-1518oc] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 01/14/2019] [Indexed: 12/18/2022] Open
Abstract
Rationale: CTSS (cathepsin S) is a cysteine protease that is observed at higher concentrations in BAL fluid and plasma of subjects with chronic obstructive pulmonary disease (COPD). Objectives: To investigate whether CTSS is involved in the pathogenesis of cigarette smoke-induced COPD and determine whether targeting upstream signaling could prevent the disease. Methods: CTSS expression was investigated in animal and human tissue and cell models of COPD. Ctss-/- mice were exposed to long-term cigarette smoke and forced oscillation and expiratory measurements were recorded. Animals were administered chemical modulators of PP2A (protein phosphatase 2A) activity. Measurements and Main Results: Here we observed enhanced CTSS expression and activity in mouse lungs after exposure to cigarette smoke. Ctss-/- mice were resistant to cigarette smoke-induced inflammation, airway hyperresponsiveness, airspace enlargements, and loss of lung function. CTSS expression was negatively regulated by PP2A in human bronchial epithelial cells isolated from healthy nonsmokers and COPD donors and in monocyte-derived macrophages. Modulating PP2A expression or activity, with silencer siRNA or a chemical inhibitor or activator, during acute smoke exposure in mice altered inflammatory responses and CTSS expression and activity in the lung. Enhancement of PP2A activity prevented chronic smoke-induced COPD in mice. Conclusions: Our study indicates that the decrease in PP2A activity that occurs in COPD contributes to elevated CTSS expression in the lungs and results in impaired lung function. Enhancing PP2A activity represents a feasible therapeutic approach to reduce CTSS activity and counter smoke-induced lung disease.
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Affiliation(s)
- Declan F. Doherty
- Airway Innate Immunity Research Group, Centre for Experimental Medicine, Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen’s University Belfast, Belfast, United Kingdom
| | - Sridesh Nath
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, and
| | - Justin Poon
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, and
| | - Robert F. Foronjy
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, and
- Department of Cell Biology, State University of New York Downstate Medical Centre, Brooklyn, New York
| | - Michael Ohlmeyer
- Icahn School of Medicine at Mount Sinai, New York, New York
- Atux Iskay LLC, Plainsboro, New Jersey
| | - Abdoulaye J. Dabo
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, and
- Department of Cell Biology, State University of New York Downstate Medical Centre, Brooklyn, New York
| | - Matthias Salathe
- Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Miami, Miami, Florida
| | - Mark Birrell
- Respiratory Pharmacology Group, Airway Disease Section, National Heart and Lung Institute, Imperial College, London, United Kingdom; and
- Respiratory, Inflammation and Autoimmunity, Innovative Medicines and Early Development Biotech Unit, AstraZeneca, London, United Kingdom
| | - Maria Belvisi
- Respiratory Pharmacology Group, Airway Disease Section, National Heart and Lung Institute, Imperial College, London, United Kingdom; and
- Respiratory, Inflammation and Autoimmunity, Innovative Medicines and Early Development Biotech Unit, AstraZeneca, London, United Kingdom
| | - Nathalie Baumlin
- Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Miami, Miami, Florida
| | - Michael D. Kim
- Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Miami, Miami, Florida
| | - Sinéad Weldon
- Airway Innate Immunity Research Group, Centre for Experimental Medicine, Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen’s University Belfast, Belfast, United Kingdom
| | - Clifford Taggart
- Airway Innate Immunity Research Group, Centre for Experimental Medicine, Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen’s University Belfast, Belfast, United Kingdom
| | - Patrick Geraghty
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, and
- Department of Cell Biology, State University of New York Downstate Medical Centre, Brooklyn, New York
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13
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Lee SH, Zwiazek JJ. Regulation of water transport in Arabidopsis by methyl jasmonate. Plant Physiol Biochem 2019; 139:540-547. [PMID: 31029027 DOI: 10.1016/j.plaphy.2019.04.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 03/19/2019] [Accepted: 04/17/2019] [Indexed: 06/09/2023]
Abstract
Following a stress event, jasmonate-dependent signaling pathway triggers a shift from growth to defense responses that are accompanied by the cessation of growth in many plants. However, the processes leading to this growth inhibition remain obscure. In this study, we provide evidence for a rapid inhibition of cell hydraulic conductivity (Lp) by methyl jasmonate (MeJA) in the roots of wild-type Arabidopsis within 0.5 h of 20 and 50 μM MeJA treatments. We also demonstrate that MeJA did not affect Lp in fad3-2 and fad7-2 Arabidopsis mutants that are deficient in jasmonate precursor, linolenic acid. The reductions of Lp in wild-type plants were accompanied by the down-regulation of several plasma membrane intrinsic protein (PIP) isoforms, and dephosphorylation. Treatments with HgCl2 did not further reduce Lp in the wild-type plants, but significantly reduced Lp in the fad3-2 and fad7-2 that had been first treated with MeJA. Continuous prolonged exposure to exogenous 50 μM MeJA inhibited the relative growth rates (RGR) of shoots and net photosynthesis (Pn) in the Arabidopsis wild-type and fad7-2 plants, but had no effect on the RGR of roots. The results demonstrated that a reduction of aquaporin (AQP)-mediated water transport was the initial target of MeJA exposure, and may contribute to the processes of growth inhibition by MeJA.
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Affiliation(s)
- Seong Hee Lee
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Bldg., T6G 2E3, Edmonton, AB, Canada
| | - Janusz J Zwiazek
- Department of Renewable Resources, University of Alberta, 442 Earth Sciences Bldg., T6G 2E3, Edmonton, AB, Canada.
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14
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Lin HH, King YC, Li YC, Lin CC, Chen YC, Lin JS, Jeng ST. The p38-like MAP kinase modulated H 2O 2 accumulation in wounding signaling pathways of sweet potato. Plant Sci 2019; 280:305-313. [PMID: 30824008 DOI: 10.1016/j.plantsci.2018.12.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 12/11/2018] [Accepted: 12/13/2018] [Indexed: 06/09/2023]
Abstract
In sweet potato (Ipomoea batatas cv Tainung 57), MAPK cascades are involved in the regulation of Ipomoelin (IPO) expression upon wounding. p38 MAPK plays an important role in plant's responses to various environmental stresses. However, the role of p38-like MAPK in wounding response is still unknown. In this study, the levels of phosphorylated-p38-like MAPK (pp38-like MAPK) in sweet potato were noticeably reduced after wounding. In addition, SB203580 (SB), a specific inhibitor blocking p38 MAPK phosphorylation, considerably decreased the accumulation of pp38-like MAPK. Expression of a wound-inducible gene IPO was elevated by SB. Moreover, it stimulated hydrogen peroxide (H2O2) production rather than cytosolic Ca2+ elevation in sweet potato leaves. However, NADPH oxidase (NOX) inhibitor diphenyleneiodonium could not inhibit IPO induction stimulated by SB. These results indicated a p38-like MAPK mechanism was involved in the regulation of IPO expression through NOX-independent H2O2 generation. In addition, the presence of the protein phosphatase inhibitor okadaic acid or the MEK1/ERK inhibitor PD98059 repressed the H2O2- or SB-induced IPO expression, demonstrating phosphatase(s) and MEK1/ERK functioning in the downstream of H2O2 and pp38-like MAPK in the signal transduction pathway stimulating IPO. Conclusively, wounding decreased the amount of pp38-like MAPK, stimulated H2O2 production, and then induced IPO expression.
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Affiliation(s)
- Hsin-Hung Lin
- Institute of Plant Biology and Department of Life Science, National Taiwan University, Taipei, 10617, Taiwan; Department of Horticulture and Biotechnology, Chinese Culture University, Taipei, 11114, Taiwan
| | - Yu-Chi King
- Institute of Plant Biology and Department of Life Science, National Taiwan University, Taipei, 10617, Taiwan
| | - Yu-Chi Li
- Institute of Plant Biology and Department of Life Science, National Taiwan University, Taipei, 10617, Taiwan
| | - Chih-Ching Lin
- Institute of Plant Biology and Department of Life Science, National Taiwan University, Taipei, 10617, Taiwan; Institute of Plant and Microbial Biology, Academia Sinica, Taipei, 11529, Taiwan
| | - Yu-Chi Chen
- Department of Biotechnology, National Kaohsiung Normal University, Kaohsiung, 82444, Taiwan
| | - Jeng-Shane Lin
- Institute of Plant Biology and Department of Life Science, National Taiwan University, Taipei, 10617, Taiwan; Department of life sciences, National Chung Hsing University, Taichung, 40227, Taiwan.
| | - Shih-Tong Jeng
- Institute of Plant Biology and Department of Life Science, National Taiwan University, Taipei, 10617, Taiwan.
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15
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Hu J, Yang Y, Wang M, Yao Y, Chang Y, He Q, Ma R, Li G. Complement C3a receptor antagonist attenuates tau hyperphosphorylation via glycogen synthase kinase 3β signaling pathways. Eur J Pharmacol 2019; 850:135-140. [PMID: 30771350 DOI: 10.1016/j.ejphar.2019.02.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 02/04/2019] [Accepted: 02/13/2019] [Indexed: 12/19/2022]
Abstract
Neurofibrillary tangles aggregated from hyperphosphorylated tau protein are the main pathological feature of Alzheimer's disease (AD). Complement C3 (or C3a) is the core component of the complement system and is associated with AD pathological processes. However, it remains unclear whether C3a or the C3a receptor has any effect on tau phosphorylation. In this study, we found that exposure of SH-SY5Y cells to okadaic acid (OA) decreased cell viabilities and induced tau hyperphosphorylation. These effects were alleviated by C3a receptor antagonist SB290157 and were further validated by C3a receptor siRNA in OA-treated SH-SY5Y cells. In addition, our results demonstrated that SB290157 markedly inhibited the activities of glycogen synthase kinase 3β (GSK3β), but had no effect on protein phosphatase 2A C subunit (PP2Ac) and cyclin-dependent kinases 5 (CDK5). Our findings here indicate the unique role of the C3a receptor in regulating tau phosphorylation via GSK3β signaling pathways and suggest that the C3a receptor may be a viable target for treating AD.
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Affiliation(s)
- Junjie Hu
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yang Yang
- Department of Geriatrics, Affiliated Hospital of Binzhou Medical University, Binzhou 256603, China
| | - Minli Wang
- Department of Neurology, The People's Hospital of Guangxi Zhuang-Autonomous Region, Nanning 530021, China
| | - Yi Yao
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yanmin Chang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Quanwei He
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Rong Ma
- Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Gang Li
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
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16
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Hamidi N, Nozad A, Sheikhkanloui Milan H, Amani M. Okadaic acid attenuates short-term and long-term synaptic plasticity of hippocampal dentate gyrus neurons in rats. Neurobiol Learn Mem 2019; 158:24-31. [PMID: 30630043 DOI: 10.1016/j.nlm.2019.01.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 11/13/2018] [Accepted: 01/05/2019] [Indexed: 01/04/2023]
Abstract
Protein phosphorylation states have a pivotal role in regulation of synaptic plasticity and long-term modulation of synaptic transmission. Serine/threonine protein phosphatase 1 (PP1) and 2A (PP2A) have a critical effect on various regulatory mechanisms involved in synaptic plasticity, learning and memory. Okadaic acid (OKA), a potent inhibitor of PP1 and PP2A, reportedly leads to cognitive decline and Alzheimer's disease (AD)-like pathology. The aim of this study was to examine the effect of OKA on electrophysiological characteristics of hippocampal dentate gyrus (DG) neurons in vivo. Male Wistar rats were divided into two control and OKA groups. OKA was injected intracerebroventricularly (i.c.v.) into lateral ventricles and after two weeks the long-term potentiation (LTP) and paired-pulse responses recorded from hippocampal perforant path-DG synapses in order to assess short-term and long-term synaptic plasticity. Results of this study revealed that OKA-induced inhibition of PP1 and PP2A activity drastically attenuates the field excitatory postsynaptic potential (fEPSP) slope and population spike (PS) amplitude following paired pulse and high frequency stimulation (HFS) of hippocampal DG neurons indicating pre- and post-synaptic involvement in electrical activity of these neurons. Administration of OKA impaired the short-term and long-term spatial memories conducted by Y-maze and passive avoidance tests, respectively. OKA-induced attenuation in electrophysiological activity and consequent memory deficits also provide a beneficial tool for studying neurodegenerative disorders such as AD.
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Affiliation(s)
- Nasrin Hamidi
- Department of Physiology, School of Medicine, Ardabil University of Medical Sciences, Ardabil, Iran
| | - Abdollah Nozad
- Department of Physiology, School of Medicine, Ardabil University of Medical Sciences, Ardabil, Iran
| | | | - Mohammad Amani
- Department of Physiology, School of Medicine, Ardabil University of Medical Sciences, Ardabil, Iran; Department of Anatomy and Neurobiology, University of California, Irvine, CA 92697, USA.
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17
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He S, Fu Y, Guo J, Spear M, Yang J, Trinité B, Qin C, Fu S, Jiang Y, Zhang Z, Xu J, Ding H, Levy DN, Chen W, Petricoin E, Liotta LA, Shang H, Wu Y. Cofilin hyperactivation in HIV infection and targeting the cofilin pathway using an anti-α 4β 7 integrin antibody. Sci Adv 2019; 5:eaat7911. [PMID: 30662943 PMCID: PMC6326757 DOI: 10.1126/sciadv.aat7911] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 11/30/2018] [Indexed: 06/09/2023]
Abstract
A functional HIV cure requires immune reconstitution for lasting viremia control. A major immune dysfunction persisting in HIV infection is the impairment of T helper cell migration and homing to lymphoid tissues such as GALTs (gut-associated lymphoid tissues). ART (antiretroviral therapy) does not fully restore T cell motility for tissue repopulation. The molecular mechanism dictating this persistent T cell dysfunction is not understood. Cofilin is an actin-depolymerizing factor that regulates actin dynamics for T cell migration. Here, we demonstrate that blood CD4 T cells from HIV-infected patients (n = 193), with or without ART, exhibit significantly lower levels of cofilin phosphorylation (hyperactivation) than those from healthy controls (n = 100; ratio, 1.1:2.3; P < 0.001); cofilin hyperactivation is also associated with poor CD4 T cell recovery following ART. These results suggest an HIV-mediated systemic dysregulation of T cell motility that cannot be repaired solely by ART. We further demonstrate that stimulating blood CD4 T cells with an anti-human α4β7 integrin antibody can trigger signal transduction and modulate the cofilin pathway, partially restoring T cell motility in vitro. However, we also observed that severe T cell motility defect caused by high degrees of cofilin hyperactivation was not repairable by the anti-integrin antibody, demonstrating a mechanistic hindrance to restore immune functions in vivo. Our study suggests that cofilin is a key molecule that may need to be therapeutically targeted early for T cell tissue repopulation, immune reconstitution, and immune control of viremia.
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Affiliation(s)
- Sijia He
- Key Laboratory of AIDS Immunology of National Health Commission, Department of Laboratory Medicine, The First Affiliated Hospital, China Medical University, Shenyang, Liaoning 110001, P. R. China
- Key Laboratory of AIDS Immunology, Chinese Academy of Medical Sciences, Shenyang, Liaoning 110001, P. R. China
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, VA 20110, USA
| | - Yajing Fu
- Key Laboratory of AIDS Immunology of National Health Commission, Department of Laboratory Medicine, The First Affiliated Hospital, China Medical University, Shenyang, Liaoning 110001, P. R. China
- Key Laboratory of AIDS Immunology, Chinese Academy of Medical Sciences, Shenyang, Liaoning 110001, P. R. China
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, VA 20110, USA
| | - Jia Guo
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, VA 20110, USA
| | - Mark Spear
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, VA 20110, USA
| | - Jiuling Yang
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, VA 20110, USA
| | - Benjamin Trinité
- Department of Basic Science, New York University College of Dentistry, New York, NY 10010, USA
| | - Chaolong Qin
- Key Laboratory of AIDS Immunology of National Health Commission, Department of Laboratory Medicine, The First Affiliated Hospital, China Medical University, Shenyang, Liaoning 110001, P. R. China
- Key Laboratory of AIDS Immunology, Chinese Academy of Medical Sciences, Shenyang, Liaoning 110001, P. R. China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou 310003, P. R. China
| | - Shuai Fu
- Key Laboratory of AIDS Immunology of National Health Commission, Department of Laboratory Medicine, The First Affiliated Hospital, China Medical University, Shenyang, Liaoning 110001, P. R. China
- Key Laboratory of AIDS Immunology, Chinese Academy of Medical Sciences, Shenyang, Liaoning 110001, P. R. China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou 310003, P. R. China
| | - Yongjun Jiang
- Key Laboratory of AIDS Immunology of National Health Commission, Department of Laboratory Medicine, The First Affiliated Hospital, China Medical University, Shenyang, Liaoning 110001, P. R. China
- Key Laboratory of AIDS Immunology, Chinese Academy of Medical Sciences, Shenyang, Liaoning 110001, P. R. China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou 310003, P. R. China
| | - Zining Zhang
- Key Laboratory of AIDS Immunology of National Health Commission, Department of Laboratory Medicine, The First Affiliated Hospital, China Medical University, Shenyang, Liaoning 110001, P. R. China
- Key Laboratory of AIDS Immunology, Chinese Academy of Medical Sciences, Shenyang, Liaoning 110001, P. R. China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou 310003, P. R. China
| | - Junjie Xu
- Key Laboratory of AIDS Immunology of National Health Commission, Department of Laboratory Medicine, The First Affiliated Hospital, China Medical University, Shenyang, Liaoning 110001, P. R. China
- Key Laboratory of AIDS Immunology, Chinese Academy of Medical Sciences, Shenyang, Liaoning 110001, P. R. China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou 310003, P. R. China
| | - Haibo Ding
- Key Laboratory of AIDS Immunology of National Health Commission, Department of Laboratory Medicine, The First Affiliated Hospital, China Medical University, Shenyang, Liaoning 110001, P. R. China
- Key Laboratory of AIDS Immunology, Chinese Academy of Medical Sciences, Shenyang, Liaoning 110001, P. R. China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou 310003, P. R. China
| | - David N. Levy
- Department of Basic Science, New York University College of Dentistry, New York, NY 10010, USA
| | - Wanjun Chen
- Mucosal Immunology Section, NIDCR, NIH, Bethesda, MD 20892, USA
| | - Emanuel Petricoin
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA 20110, USA
| | - Lance A. Liotta
- Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA 20110, USA
| | - Hong Shang
- Key Laboratory of AIDS Immunology of National Health Commission, Department of Laboratory Medicine, The First Affiliated Hospital, China Medical University, Shenyang, Liaoning 110001, P. R. China
- Key Laboratory of AIDS Immunology, Chinese Academy of Medical Sciences, Shenyang, Liaoning 110001, P. R. China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou 310003, P. R. China
| | - Yuntao Wu
- National Center for Biodefense and Infectious Diseases, School of Systems Biology, George Mason University, Manassas, VA 20110, USA
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18
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Battaglia-Hsu SF, Ghemrawi R, Coelho D, Dreumont N, Mosca P, Hergalant S, Gauchotte G, Sequeira JM, Ndiongue M, Houlgatte R, Alberto JM, Umoret R, Robert A, Paoli J, Jung M, Quadros EV, Guéant JL. Inherited disorders of cobalamin metabolism disrupt nucleocytoplasmic transport of mRNA through impaired methylation/phosphorylation of ELAVL1/HuR. Nucleic Acids Res 2018; 46:7844-7857. [PMID: 30016500 PMCID: PMC6125644 DOI: 10.1093/nar/gky634] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 06/26/2018] [Accepted: 07/12/2018] [Indexed: 12/12/2022] Open
Abstract
The molecular mechanisms that underlie the neurological manifestations of patients with inherited diseases of vitamin B12 (cobalamin) metabolism remain to date obscure. We observed transcriptomic changes of genes involved in RNA metabolism and endoplasmic reticulum stress in a neuronal cell model with impaired cobalamin metabolism. These changes were related to the subcellular mislocalization of several RNA binding proteins, including the ELAVL1/HuR protein implicated in neuronal stress, in this cell model and in patient fibroblasts with inborn errors of cobalamin metabolism and Cd320 knockout mice. The decreased interaction of ELAVL1/HuR with the CRM1/exportin protein of the nuclear pore complex and its subsequent mislocalization resulted from hypomethylation at R-217 produced by decreased S-adenosylmethionine and protein methyl transferase CARM1 and dephosphorylation at S221 by increased protein phosphatase PP2A. The mislocalization of ELAVL1/HuR triggered the decreased expression of SIRT1 deacetylase and genes involved in brain development, neuroplasticity, myelin formation, and brain aging. The mislocalization was reversible upon treatment with siPpp2ca, cobalamin, S-adenosylmethionine, or PP2A inhibitor okadaic acid. In conclusion, our data highlight the key role of the disruption of ELAVL1/HuR nuclear export, with genomic changes consistent with the effects of inborn errors of Cbl metabolisms on brain development, neuroplasticity and myelin formation.
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Affiliation(s)
- Shyue-Fang Battaglia-Hsu
- INSERM UMRS 954 NGERE – Nutrition, Genetics, and Environmental Risk Exposure and National Center of Inborn Errors of Metabolism, Faculty of Medicine of Nancy, University of Lorraine and University Regional Hospital Center of Nancy, Vandoeuvre-lès-Nancy, F-54000, France
| | - Rose Ghemrawi
- INSERM UMRS 954 NGERE – Nutrition, Genetics, and Environmental Risk Exposure and National Center of Inborn Errors of Metabolism, Faculty of Medicine of Nancy, University of Lorraine and University Regional Hospital Center of Nancy, Vandoeuvre-lès-Nancy, F-54000, France
| | - David Coelho
- INSERM UMRS 954 NGERE – Nutrition, Genetics, and Environmental Risk Exposure and National Center of Inborn Errors of Metabolism, Faculty of Medicine of Nancy, University of Lorraine and University Regional Hospital Center of Nancy, Vandoeuvre-lès-Nancy, F-54000, France
| | - Natacha Dreumont
- INSERM UMRS 954 NGERE – Nutrition, Genetics, and Environmental Risk Exposure and National Center of Inborn Errors of Metabolism, Faculty of Medicine of Nancy, University of Lorraine and University Regional Hospital Center of Nancy, Vandoeuvre-lès-Nancy, F-54000, France
| | - Pauline Mosca
- INSERM UMRS 954 NGERE – Nutrition, Genetics, and Environmental Risk Exposure and National Center of Inborn Errors of Metabolism, Faculty of Medicine of Nancy, University of Lorraine and University Regional Hospital Center of Nancy, Vandoeuvre-lès-Nancy, F-54000, France
| | - Sébastien Hergalant
- INSERM UMRS 954 NGERE – Nutrition, Genetics, and Environmental Risk Exposure and National Center of Inborn Errors of Metabolism, Faculty of Medicine of Nancy, University of Lorraine and University Regional Hospital Center of Nancy, Vandoeuvre-lès-Nancy, F-54000, France
| | - Guillaume Gauchotte
- INSERM UMRS 954 NGERE – Nutrition, Genetics, and Environmental Risk Exposure and National Center of Inborn Errors of Metabolism, Faculty of Medicine of Nancy, University of Lorraine and University Regional Hospital Center of Nancy, Vandoeuvre-lès-Nancy, F-54000, France
| | - Jeffrey M Sequeira
- Division of Hematology/Oncology, Department of Medicine, SUNY-Downstate Medical Center, Brooklyn, New York, NY, USA
| | - Mariam Ndiongue
- INSERM UMRS 954 NGERE – Nutrition, Genetics, and Environmental Risk Exposure and National Center of Inborn Errors of Metabolism, Faculty of Medicine of Nancy, University of Lorraine and University Regional Hospital Center of Nancy, Vandoeuvre-lès-Nancy, F-54000, France
| | - Rémi Houlgatte
- INSERM UMRS 954 NGERE – Nutrition, Genetics, and Environmental Risk Exposure and National Center of Inborn Errors of Metabolism, Faculty of Medicine of Nancy, University of Lorraine and University Regional Hospital Center of Nancy, Vandoeuvre-lès-Nancy, F-54000, France
| | - Jean-Marc Alberto
- INSERM UMRS 954 NGERE – Nutrition, Genetics, and Environmental Risk Exposure and National Center of Inborn Errors of Metabolism, Faculty of Medicine of Nancy, University of Lorraine and University Regional Hospital Center of Nancy, Vandoeuvre-lès-Nancy, F-54000, France
| | - Remy Umoret
- INSERM UMRS 954 NGERE – Nutrition, Genetics, and Environmental Risk Exposure and National Center of Inborn Errors of Metabolism, Faculty of Medicine of Nancy, University of Lorraine and University Regional Hospital Center of Nancy, Vandoeuvre-lès-Nancy, F-54000, France
| | - Aurélie Robert
- INSERM UMRS 954 NGERE – Nutrition, Genetics, and Environmental Risk Exposure and National Center of Inborn Errors of Metabolism, Faculty of Medicine of Nancy, University of Lorraine and University Regional Hospital Center of Nancy, Vandoeuvre-lès-Nancy, F-54000, France
| | - Justine Paoli
- INSERM UMRS 954 NGERE – Nutrition, Genetics, and Environmental Risk Exposure and National Center of Inborn Errors of Metabolism, Faculty of Medicine of Nancy, University of Lorraine and University Regional Hospital Center of Nancy, Vandoeuvre-lès-Nancy, F-54000, France
| | - Martin Jung
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Building 44, Homburg 66421, Germany
| | - Edward V Quadros
- Division of Hematology/Oncology, Department of Medicine, SUNY-Downstate Medical Center, Brooklyn, New York, NY, USA
| | - Jean-Louis Guéant
- INSERM UMRS 954 NGERE – Nutrition, Genetics, and Environmental Risk Exposure and National Center of Inborn Errors of Metabolism, Faculty of Medicine of Nancy, University of Lorraine and University Regional Hospital Center of Nancy, Vandoeuvre-lès-Nancy, F-54000, France
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19
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Camoni L, Barbero F, Aducci P, Maffei ME. Spodoptera littoralis oral secretions inhibit the activity of Phaseolus lunatus plasma membrane H+-ATPase. PLoS One 2018; 13:e0202142. [PMID: 30096181 PMCID: PMC6086434 DOI: 10.1371/journal.pone.0202142] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 07/27/2018] [Indexed: 12/03/2022] Open
Abstract
Biotic stresses induced by herbivores result in diverse physiological changes in plants. In the interaction between the Lima bean (Phaseolus lunatus) and the herbivore Spodoptera littoralis, the earliest event induced by feeding on leaves is the depolarization of the plasma membrane potential (Vm), which is the results of both mechanical damage and insect oral secretions (OS). Although this herbivore-induced Vm depolarization depends on a calcium-dependent opening of potassium channels, the attacked leaf remains depolarized for an extended period, which cannot be explained by the sole action of potassium channels. Here we show that the plasma membrane H+-ATPase of P. lunatus leaves is strongly inhibited by S. littoralis OS. Inhibition of the H+-ATPase was also found in plasma membranes purified from leaf sections located distally from the application zone of OS, thus suggesting a long-distance transport of a signaling molecule(s). S. littoralis’ OS did not influence the amount of the plasma membrane H+-ATPase, whereas the levels of membrane-bound 14-3-3 proteins were significantly decreased in membranes purified from treated leaves. Furthermore, OS strongly reduced the in vitro interaction between P. lunatus H+-ATPase and 14-3-3 proteins. The results of this work demonstrate that inhibition of the plasma membrane H+-ATPase is a key component of the S. littoralis OS mechanism leading to an enduring Vm depolarization in P. lunatus wounded leaves.
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Affiliation(s)
- Lorenzo Camoni
- Dept. Biology, Universtity of Rome Tor Vergata, Via della Ricerca Scientifica, Rome, Italy
| | - Francesca Barbero
- Dept. Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - Patrizia Aducci
- Dept. Biology, Universtity of Rome Tor Vergata, Via della Ricerca Scientifica, Rome, Italy
| | - Massimo E. Maffei
- Dept. Life Sciences and Systems Biology, University of Turin, Turin, Italy
- * E-mail:
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20
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Tang K, Boudreau CG, Brown CM, Khadra A. Paxillin phosphorylation at serine 273 and its effects on Rac, Rho and adhesion dynamics. PLoS Comput Biol 2018; 14:e1006303. [PMID: 29975690 PMCID: PMC6053249 DOI: 10.1371/journal.pcbi.1006303] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 07/19/2018] [Accepted: 06/13/2018] [Indexed: 12/16/2022] Open
Abstract
Focal adhesions are protein complexes that anchor cells to the extracellular matrix. During migration, the growth and disassembly of these structures are spatiotemporally regulated, with new adhesions forming at the leading edge of the cell and mature adhesions disassembling at the rear. Signalling proteins and structural cytoskeletal components tightly regulate adhesion dynamics. Paxillin, an adaptor protein within adhesions, is one of these proteins. Its phosphorylation at serine 273 (S273) is crucial for maintaining fast adhesion assembly and disassembly. Paxillin is known to bind to a GIT1-βPIX-PAK1 complex, which increases the local activation of the small GTPase Rac. To understand quantitatively the behaviour of this system and how it relates to adhesion assembly/disassembly, we developed a mathematical model describing the dynamics of the small GTPases Rac and Rho as determined by paxillin S273 phosphorylation. Our model revealed that the system possesses bistability, where switching between uninduced (active Rho) and induced (active Rac) states can occur through a change in rate of paxillin phosphorylation or PAK1 activation. The bistable switch is characterized by the presence of memory, minimal change in the levels of active Rac and Rho within the induced and uninduced states, respectively, and the limited regime of monostability associated with the uninduced state. These results were validated experimentally by showing the presence of bimodality in adhesion assembly and disassembly rates, and demonstrating that Rac activity increases after treating Chinese Hamster Ovary cells with okadaic acid (a paxillin phosphatase inhibitor), followed by a modest recovery after 20 min washout. Spatial gradients of phosphorylated paxillin in a reaction-diffusion model gave rise to distinct regions of Rac and Rho activities, resembling polarization of a cell into front and rear. Perturbing several parameters of the model also revealed important insights into how signalling components upstream and downstream of paxillin phosphorylation affect dynamics. Cellular migration is crucial in both physiological and pathological functions. Maintenance of proper migration and development of aberrant migration are effectuated by cellular machinery involving protein complexes, called adhesions, that anchor the cell to its environment. Over time, these adhesions assemble at the leading edge, as the cell extends forward, anchoring the front of the cells to its substrate, while those at the cell rear disassemble, allowing detachment and forward movement. Their dynamics are controlled by a number of regulatory factors, occurring on both cell-wide and adhesion-level scales. The coordination of these regulatory factors is complex, but insights about their dynamics can be gained from the use of mathematical modeling techniques which integrate many of these components together. Here, we developed several molecularly explicit models to explore how local regulation of paxillin, an adhesion protein, interacts with the activities of Rac and Rho to produce cell-wide polarization associated with motility and directionality. By altering paxillin phosphorylation/dephosphorylation within such models, we have advanced our understanding of how a shift from a non-motile state to a highly motile state occurs. Deciphering these key processes quantitatively thus helped us gain insight into the subcellular factors underlying polarity and movement.
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Affiliation(s)
- Kaixi Tang
- Department of Physiology, McGill University, Montreal, Québec, Canada
| | | | - Claire M. Brown
- Department of Physiology, McGill University, Montreal, Québec, Canada
- Advanced BioImaging Facility (ABIF), McGill University, Montreal, Québec, Canada
- Cell Information Systems, McGill University, Montreal, Québec, Canada
- Department of Anatomy and Cell Biology, McGill University, Montreal, Québec, Canada
| | - Anmar Khadra
- Department of Physiology, McGill University, Montreal, Québec, Canada
- * E-mail:
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21
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Koehler D, Shah ZA, Hensley K, Williams FE. Lanthionine ketimine-5-ethyl ester provides neuroprotection in a zebrafish model of okadaic acid-induced Alzheimer's disease. Neurochem Int 2018; 115:61-68. [PMID: 29475037 PMCID: PMC5865644 DOI: 10.1016/j.neuint.2018.02.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 01/18/2018] [Accepted: 02/01/2018] [Indexed: 11/16/2022]
Abstract
Okadaic acid (OKA) is a protein phosphatase 2A inhibitor that is used to induce neurodegeneration and study disease states such as Alzheimer's disease (AD). Lanthionine ketimine-5-ethyl ester (LKE) is a bioavailable derivative of the naturally occurring brain sulfur metabolite, lanthionine ketimine (LK). In previously conducted studies, LKE exhibited neuroprotective and neurotrophic properties in murine models but its mechanism of action remains to be clarified. In this study, a recently established zebrafish OKA-induced AD model was utilized to further elucidate the neuroprotective and neurotrophic properties of LKE in the context of an AD-like condition. The fish were divided into 3 groups containing 8 fish per group. Group #1 = negative control, Group #2 = 100 nM OKA, Group #3 = 100 nM OKA +500 μM LKE. OKA caused severe cognitive impairments in the zebrafish, but concomitant treatment with LKE protected against cognitive impairments. Further, LKE significantly and substantially reduced the number of apoptotic brain cells, increased brain-derived neurotrophic factor (BDNF), and increased phospho-activation of the pro-survival factors pAkt (Ser 473) and pCREB (Ser133). These findings clarify the neuroprotective and neurotrophic effects of LKE by highlighting particular survival pathways that are bolstered by the experimental therapeutic LKE.
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Affiliation(s)
- Daniel Koehler
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, USA
| | - Zahoor A Shah
- Department of Medicinal and Biological Chemistry, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, USA
| | - Kenneth Hensley
- Department of Biochemistry, Molecular and Cell Science, Arkansas College of Osteopathic Medicine, Fort Smith, Arkansas, USA
| | - Frederick E Williams
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, OH, USA.
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22
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Su KC, Barry Z, Schweizer N, Maiato H, Bathe M, Cheeseman IM. A Regulatory Switch Alters Chromosome Motions at the Metaphase-to-Anaphase Transition. Cell Rep 2017; 17:1728-1738. [PMID: 27829144 PMCID: PMC5130098 DOI: 10.1016/j.celrep.2016.10.046] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 09/09/2016] [Accepted: 10/13/2016] [Indexed: 12/19/2022] Open
Abstract
To achieve chromosome segregation during mitosis, sister chromatids must undergo a dramatic change in their behavior to switch from balanced oscillations at the metaphase plate to directed poleward motion during anaphase. However, the factors that alter chromosome behavior at the metaphase-to-anaphase transition remain incompletely understood. Here, we perform time-lapse imaging to analyze anaphase chromosome dynamics in human cells. Using multiple directed biochemical, genetic, and physical perturbations, our results demonstrate that differences in the global phosphorylation states between metaphase and anaphase are the major determinant of chromosome motion dynamics. Indeed, causing a mitotic phosphorylation state to persist into anaphase produces dramatic metaphase-like oscillations. These induced oscillations depend on both kinetochore-derived and polar ejection forces that oppose poleward motion. Thus, our analysis of anaphase chromosome motion reveals that dephosphorylation of multiple mitotic substrates is required to suppress metaphase chromosome oscillatory motions and achieve directed poleward motion for successful chromosome segregation.
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Affiliation(s)
- Kuan-Chung Su
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA
| | - Zachary Barry
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Nina Schweizer
- Chromosome Instability and Dynamics Laboratory, Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal; i3S - Instituto de Investigação e Inovação em Saúdem, Universidade do Porto, 4200-135 Porto, Portugal
| | - Helder Maiato
- Chromosome Instability and Dynamics Laboratory, Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal; i3S - Instituto de Investigação e Inovação em Saúdem, Universidade do Porto, 4200-135 Porto, Portugal; Cell Division Unit, Department of Experimental Biology, Faculdade de Medicina, Universidade do Porto, 4200-135 Porto, Portugal
| | - Mark Bathe
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Iain McPherson Cheeseman
- Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
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23
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Ramírez-Valadez KA, Vázquez-Victorio G, Macías-Silva M, González-Espinosa C. Fyn kinase mediates cortical actin ring depolymerization required for mast cell migration in response to TGF-β in mice. Eur J Immunol 2017; 47:1305-1316. [PMID: 28586109 DOI: 10.1002/eji.201646876] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 04/13/2017] [Accepted: 06/03/2017] [Indexed: 12/31/2022]
Abstract
Transforming growth factor-β (TGF-β) is a potent mast cell (MC) chemoattractant able to modulate local inflammatory reactions. The molecular mechanism leading to TGF-β-directed MC migration is not fully described. Here we analyzed the role of the Src family protein kinase Fyn on the main TGF-β-induced cytoskeletal changes leading to MC migration. Utilizing bone marrow-derived mast cells (BMMCs) from WT and Fyn-deficient mice we found that BMMC migration to TGF-β was impaired in the absence of the kinase. TGF-β caused depolymerization of the cortical actin ring and changes on the phosphorylation of cofilin, LIMK and CAMKII only in WT cells. Defective cofilin activation and phosphorylation of regulatory proteins was detected in Fyn-deficient BMMCs and this finding correlated with a lower activity of the catalytic subunit of the phosphatase PP2A. Diminished TGF-β-induced chemotaxis of Fyn-deficient cells was also observed in an in vivo model of MC migration (bleomycin-induced scleroderma). Our results show that Fyn kinase is an important positive effector of TGF-β-induced chemotaxis through the control of PP2A activity and this is relevant to pathological processes that are related to TGF-β-dependent mast cell migration.
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Affiliation(s)
- Karla A Ramírez-Valadez
- Departamento de Farmacobiología, Centro de Investigación y de Estudios Avanzados del IPN, México
| | - Genaro Vázquez-Victorio
- Departamento de Biología Celular y Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México
| | - Marina Macías-Silva
- Departamento de Biología Celular y Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México
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Chi C, Giri SS, Jun JW, Kim HJ, Kim SW, Yun S, Park SC. Effects of algal toxin okadaic acid on the non-specific immune and antioxidant response of bay scallop (Argopecten irradians). Fish Shellfish Immunol 2017; 65:111-117. [PMID: 28323217 DOI: 10.1016/j.fsi.2017.03.031] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 03/10/2017] [Accepted: 03/16/2017] [Indexed: 06/06/2023]
Abstract
Okadaic acid (OA) is produced by dinoflagellates during harmful algal blooms and is a diarrhetic shellfish-poisoning (DSP) toxin. This toxin is particularly problematic for bivalves that are cultured for human consumption. This study aimed to reveal the effects of exposure to OA on the non-specific immune responses of bay scallop, Argopecten irradians. Various immunological parameters (superoxide dismutase (SOD), acid phosphatase (ACP), alkaline phosphatase (ALP), lysozyme activities, and total protein level) were assessed in the hemolymph of bay scallops at 3, 6, 12, 24, and 48 h post-exposure (hpe) to different concentrations (50, 100, and 500 nM) of OA. Moreover, the expression of immune system-related genes (MnSOD, PrxV, PGRP, and BD) was also measured. Results showed that SOD and ACP activities were decreased between 12 and 48 hpe. The ALP, lysozyme activities, and total protein levels were also modulated after exposure to different concentrations of OA. The expression of immune-system-related genes was also assessed at different time points during the exposure period. Overall, our results suggest that the exposure to OA had negative effects on the antioxidant and non-specific immune responses, and even disrupted the metabolism of bay scallops, making them more vulnerable to environmental stress-inducing agents; they provide a better understanding of the response status of bivalves against DSP toxins.
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Affiliation(s)
- Cheng Chi
- Laboratory of Aquatic Biomedicine, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 151742, South Korea.
| | - Sib Sankar Giri
- Laboratory of Aquatic Biomedicine, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 151742, South Korea.
| | - Jin Woo Jun
- Laboratory of Aquatic Biomedicine, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 151742, South Korea.
| | - Hyoun Joong Kim
- Laboratory of Aquatic Biomedicine, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 151742, South Korea
| | - Sang Wha Kim
- Laboratory of Aquatic Biomedicine, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 151742, South Korea
| | - Saekil Yun
- Laboratory of Aquatic Biomedicine, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 151742, South Korea
| | - Se Chang Park
- Laboratory of Aquatic Biomedicine, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul 151742, South Korea.
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Abstract
Limaol (1), along with a dinophysistoxin 1 derivative and an okadaic acid (OA) derivative, was isolated from the large-scale cultivation of the benthic marine dinoflagellate Prorocentrum lima. The structure of 1 was determined by a combination of NMR spectroscopy and mass spectrometry and contained tetrahydropyran, 1,3,5,7-tetra(methylene)heptane, and octahydrospiro[pyran-2,2'-pyrano[3,2-b]pyran] moieties. The absolute configuration of 1 was completely elucidated on the basis of ROESY correlations, J-based configuration analysis, and modified Mosher's ester analysis. Limaol showed moderate cytotoxicity when compared to OA against three cancer cell lines.
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Affiliation(s)
- A Reum Yang
- Department of Marine Biotechnology, Kunsan National University , 558 Daehak-ro, Gunsan 54150, South Korea
| | - Sangbum Lee
- Department of Marine Biotechnology, Kunsan National University , 558 Daehak-ro, Gunsan 54150, South Korea
| | - Young Du Yoo
- Department of Marine Biotechnology, Kunsan National University , 558 Daehak-ro, Gunsan 54150, South Korea
| | - Hyung Seop Kim
- Department of Marine Biotechnology, Kunsan National University , 558 Daehak-ro, Gunsan 54150, South Korea
| | - Eun Ju Jeong
- Department of Agronomy & Medicinal Plant Resources, Gyeongnam National University of Science and Technology , JinJu 660-758, South Korea
| | - Jung-Rae Rho
- Department of Marine Biotechnology, Kunsan National University , 558 Daehak-ro, Gunsan 54150, South Korea
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Wu X, Kosaraju J, Tam KY. SLM, a novel carbazole-based fluorophore attenuates okadaic acid-induced tau hyperphosphorylation via down-regulating GSK-3β activity in SH-SY5Y cells. Eur J Pharm Sci 2017; 110:101-108. [PMID: 28359686 DOI: 10.1016/j.ejps.2017.03.037] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 03/25/2017] [Accepted: 03/25/2017] [Indexed: 12/23/2022]
Abstract
Phosphorylated tau dissociates from microtubules and aggregates to form neurofibrillary tangles resulting in neuronal toxicity and cognitive deficits. Attenuating tau hyperphosphorylation is considered as an effective therapeutic approach for Alzheimer's disease (AD). From our previous study, SLM, a carbazole-based fluorophore prevents Aβ aggregation, reduced glycogen synthase kinase-3β (GSK-3β) activity and tau hyperphosphorylation in triple transgenic mouse model of AD. However, the mechanism by which SLM attenuates tau hyperphosphorylation warrants further investigation. In the current study, we intend to evaluate the effects of SLM against okadaic acid (OA)-induced tau hyperphosphorylation and microtubules instability in human neuroblastoma (SH-SY5Y) cells. The results showed that, SLM reduced the OA-induced cell neurotoxicity and tau hyperphosphorylation in SH-SY5Y cells. SLM treatment down-regulated GSK-3β activity. However, in the presence of GSK-3β inhibitor (SB216763, 10μM), SLM treatment could not reduce GSK-3β activity and tau hyperphosphorylation as compared with SB216763 treatment alone. Furthermore, SLM treatment also ameliorated OA-induced microtubules instability and cytoskeleton damage. Collectively, SLM attenuated OA-induced tau hyperphosphorylation via down-regulating GSK-3β activity in SH-SY5Y cells. Therefore, this study supports SLM as a potential compound for AD and other tau pathology-related neurodegenerative disorders.
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Affiliation(s)
- Xiaoli Wu
- Faculty of Health Sciences, University of Macau, Taipa, Macau, China
| | | | - Kin Yip Tam
- Faculty of Health Sciences, University of Macau, Taipa, Macau, China.
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Penberthy KK, Buckley MW, Arandjelovic S, Ravichandran K. Ex vivo modulation of the Foxo1 phosphorylation state does not lead to dysfunction of T regulatory cells. PLoS One 2017; 12:e0173386. [PMID: 28267764 PMCID: PMC5340387 DOI: 10.1371/journal.pone.0173386] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 02/20/2017] [Indexed: 12/17/2022] Open
Abstract
Peripheral regulatory CD4+ T cells (Treg cells) prevent maladaptive inflammatory responses to innocuous foreign antigens. Treg cell dysfunction has been linked to many inflammatory diseases, including allergic airway inflammation. Glucocorticoids that are used to treat allergic airway inflammation and asthma are thought to work in part by promoting Treg cell differentiation; patients who are refractory to these drugs have defective induction of anti-inflammatory Treg cells. Previous observations suggest that Treg cells deficient in the transcription factor FoxO1 are pro-inflammatory, and that FoxO1 activity is regulated by its phosphorylation status and nuclear localization. Here, we asked whether altering the phosphorylation state of FoxO1 through modulation of a regulatory phosphatase might affect Treg cell function. In a mouse model of house dust mite-induced allergic airway inflammation, we observed robust recruitment of Treg cells to the lungs and lymph nodes of diseased mice, without an apparent increase in the Treg cytokine interleukin-10 in the airways. Intriguingly, expression of PP2A, a serine/threonine phosphatase linked to the regulation of FoxO1 phosphorylation, was decreased in the mediastinal lymph nodes of HDM-treated mice, mirroring the decreased PP2A expression seen in peripheral blood monocytes of glucocorticoid-resistant asthmatic patients. When we asked whether modulation of PP2A activity alters Treg cell function via treatment with the PP2A inhibitor okadaic acid, we observed increased phosphorylation of FoxO1 and decreased nuclear localization. However, dysregulation of FoxO1 did not impair Treg cell differentiation ex vivo or cause Treg cells to adopt a pro-inflammatory phenotype. Moreover, inhibition of PP2A activity did not affect the suppressive function of Treg cells ex vivo. Collectively, these data suggest that modulation of the phosphorylation state of FoxO1 via PP2A inhibition does not modify Treg cell function ex vivo. Our data also highlight the caveat in using ex vivo assays of Treg cell differentiation and function, in that while these assays are useful, they may not fully recapitulate Treg cell phenotypes that are observed in vivo.
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Affiliation(s)
- Kristen Kelley Penberthy
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America
- Center for Cell Clearance, University of Virginia, Charlottesville, Virginia, United States of America
- Carter Immunology Center, University of Virginia, Charlottesville, Virginia, United States of America
| | - Monica Weaver Buckley
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America
- Center for Cell Clearance, University of Virginia, Charlottesville, Virginia, United States of America
- Carter Immunology Center, University of Virginia, Charlottesville, Virginia, United States of America
| | - Sanja Arandjelovic
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America
- Center for Cell Clearance, University of Virginia, Charlottesville, Virginia, United States of America
- Carter Immunology Center, University of Virginia, Charlottesville, Virginia, United States of America
| | - Kodi Ravichandran
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, Virginia, United States of America
- Center for Cell Clearance, University of Virginia, Charlottesville, Virginia, United States of America
- Carter Immunology Center, University of Virginia, Charlottesville, Virginia, United States of America
- * E-mail:
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Abstract
Akt substrate of 160 kDa (AS160) phosphorylation on Thr(642) and Ser(588) by Akt is essential for insulin's full effect on glucose transport. However, protein phosphorylation is determined by the balance of actions by kinases and phosphatases, and the specific phosphatase(s) controlling AS160 dephosphorylation is (are) unknown. Accordingly, we assessed roles of highly expressed skeletal muscle serine/threonine phosphatases (PP1, PP2A, PP2B, and PP2C) on AS160 dephosphorylation. Preliminary screening of candidate phosphatases used an AS160 dephosphorylation assay. Lysates from insulin-stimulated skeletal muscle were treated with pharmacological phosphatase inhibitors and assessed for AS160 Ser(588) and Thr(642) dephosphorylation. AS160 dephosphorylation on both phosphorylation sites was unaltered by PP2B or PP2C inhibitors. Okadaic acid (low dose inhibits PP2A; high dose inhibits PP1) delayed AS160 Ser(588) (both doses) and Thr(642) (high dose only) dephosphorylation concomitant with greater Akt phosphorylation (both doses). AS160 was coimmunoprecipitated with PP1-α but not with PP1-β, PP1-γ1, or PP2A. Recombinant inhibitor-2 protein (a selective PP1 inhibitor) delayed AS160 dephosphorylation on both phosphorylation sites without altering Akt phosphorylation. Furthermore, knockdown of PP1-α but not PP1-β or PP1-γ1 by small interfering RNA caused greater AS160 Ser(588) and Thr(642) phosphorylation concomitant with unaltered Akt phosphorylation. Together, these results identified PP1-α as a regulator of AS160 Thr(642) and Ser(588) dephosphorylation in skeletal muscle.
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Affiliation(s)
- Pragya Sharma
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI
| | - Edward B Arias
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI
| | - Gregory D Cartee
- Muscle Biology Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, MI Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI Institute of Gerontology, University of Michigan, Ann Arbor, MI
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Somrit M, Watthammawut A, Chotwiwatthanakun C, Weerachatyanukul W. The key molecular events during Macrobrachium rosenbergii nodavirus (MrNV) infection and replication in Sf9 insect cells. Virus Res 2016; 223:1-9. [PMID: 27327530 PMCID: PMC7126520 DOI: 10.1016/j.virusres.2016.06.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 06/16/2016] [Accepted: 06/17/2016] [Indexed: 01/01/2023]
Abstract
The successful infection and replication of MrNV in Sf9 cells should facilitate long-term and in-depth investigation of MrNV infection pathway. MrNV internalization favors caveolin (CAV)-mediated pathway which can be halted and reactivated by genistein and okadaic acid. Replication of MrNV (at 72 h p.i.) resulted in cytopathic effects (CPE) and multiplication of virion number in the infected cells.
In this study we demonstrated that Macrobrachium rosenbergii nodavirus (MrNV) was able to internalize and replicate in Sf9 insect cells, with levels of infection altered by substances affecting the caveolin-(CAV) mediated endocytosis pathway. The use of Sf9 cells for efficient MrNV replication and propagation was demonstrated by confocal microscopy and PCR amplification, through which early viral binding and internalization were initially detectable at 30 min post-infection; whereas at 72 h, the distinguishable sign of late-MrNV infection was observable as the gradual accumulation of a cytopathic effect (CPE) in the cells, ultimately resulting in cellular disruption. Moreover, during the early period of infection, the MrNV signals were highly co-localized with CAV1 signals of the CAV-mediated endocytosis pathway. The use of genistein as an inhibitor of the CAV-mediated endocytosis pathway significantly reduced MrNV and CAV1 co-localization, and also reduced the levels of MrNV infection in Sf9 cells as shown by PCR and ELISA. Moreover, the addition of the pathway agonist okadaic acid not only recovered but also augmented both the levels of MrNV co-localization with CAV1 and of Sf9 infection in the presence of genistein inhibition; therefore demonstrating that MrNV infection in Sf9 cells was associated with the CAV-mediated endocytosis pathway machinery.
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Affiliation(s)
- Monsicha Somrit
- Department of Anatomy, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand
| | - Atthaboon Watthammawut
- Department of Anatomy, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand
| | | | - Wattana Weerachatyanukul
- Department of Anatomy, Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand.
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Zhang H, Wang P, Hou H, Wen H, Zhou H, Gao F, Wu J, Qiu Z, Li L. Histone Modification Is Involved in Okadaic Acid (OA) Induced DNA Damage Response and G2-M Transition Arrest in Maize. PLoS One 2016; 11:e0155852. [PMID: 27196101 PMCID: PMC4873197 DOI: 10.1371/journal.pone.0155852] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 05/05/2016] [Indexed: 12/28/2022] Open
Abstract
Histone modifications are involved in regulation of chromatin structure. To investigate the relationship between chromatin modification and cell cycle regulation during plant cell proliferation, Okadaic acid (OA), a specific inhibitor of serine/threonine protein phosphatase, was applied in this study. The results showed that OA caused the cell cycle arrest at preprophase, leading to seedling growth inhibition. Western blotting assay revealed that the spatial distribution of phosphorylation of Ser10 histone H3 tails (H3S10ph) signals was altered under OA treatment. Reactive oxygen species (ROS) was found to be at higher levels and TdT-mediated dUTP nick end labeling (TUNEL) assay displayed DNA breaks happened at the chromatin after treatment with OA, companied with an increase in the acetylation of histone H4 at lysine 5 (H4K5ac) level. From these observations, we speculated that the alteration of the spatial distribution of H3S10ph and the level of H4K5ac was involved in the procedure that OA induced DNA breaks and G2-M arrested by the accumulation of ROS, and that the histone H3S10ph and H4K5ac might facilitate DNA repair by their association with the chromatin decondensation.
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Affiliation(s)
- Hao Zhang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Pu Wang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Haoli Hou
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Huan Wen
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Hong Zhou
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Fei Gao
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Jinping Wu
- Industrial Crops Institute of Hubei Academy of Agricultural Sciences, Hongshan District, Wuhan City, Hubei Province, China
| | - Zhengming Qiu
- Industrial Crops Institute of Hubei Academy of Agricultural Sciences, Hongshan District, Wuhan City, Hubei Province, China
| | - Lijia Li
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
- * E-mail:
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31
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Zhao L, Xiao Y, Wang XL, Pei J, Guan ZZ. Original Research: Influence of okadaic acid on hyperphosphorylation of tau and nicotinic acetylcholine receptors in primary neurons. Exp Biol Med (Maywood) 2016; 241:1825-33. [PMID: 27190248 DOI: 10.1177/1535370216650759] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Accepted: 04/25/2016] [Indexed: 11/15/2022] Open
Abstract
The aim of the study was to investigate the influence of hyperphosphorylation of tau induced by okadaic acid on the expression of nicotinic acetylcholine receptors and the neurotoxicity of β-amyloid peptide. Primary cultures of neurons isolated from the hippocampus of the brains of neonatal rats were exposed to okadaic acid or/and Aβ1-42 Tau phosphorylated at Ser404 and Ser202, and the protein expressions of α7, α4 and α3 nAChR subunits were quantified by Western blotting, and their corresponding mRNAs by real-time PCR. Superoxide dismutase activity was assayed biochemically and malondialdehyde by thiobarbituric acid-reactive substance. As compared to controls, phosphorylations of tau at Ser404 and Ser202 in the neurons were elevated by exposure to 20 nM okadaic acid for 48 h but not by 1 or 2 µM Aβ1-42 Treatment with 20 nM okadaic acid or 1 µM Aβ1-42 for 48 h resulted in the reduced α7, α4 and α3 proteins, and α4 and α3 mRNAs, as well as the decreased activity of superoxide dismutase and the increased malondialdehyde. Okadaic acid and Aβ1-42 together caused more pronounced changes in the expressions of α7 and α4, superoxide dismutase activity and lipid peroxidation than either alone. When pre-treatment with vitamin E or lovastatin, the neurotoxicity induced by okadaic acid was significantly attenuated. These findings indicate that hyperphosphorylation of tau induced by okadaic acid inhibits the expression of nicotinic acetylcholine receptors at both the protein and mRNA levels, as well as enhances the neurotoxicity of β-amyloid peptide.
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Affiliation(s)
- Liang Zhao
- Department of Pathology at the Affiliated Hospital, Guizhou Medical University, Guiyang 550004, Guizhou, PR China
| | - Yan Xiao
- The Key Laboratory of Medical Molecular Biology, Guizhou Medical University, Guiyang 550004, Guizhou, PR China
| | - Xiao-Liang Wang
- The Key Laboratory of Medical Molecular Biology, Guizhou Medical University, Guiyang 550004, Guizhou, PR China
| | - Jinjing Pei
- KI-Alzheimer Disease Research Center, Karolinska Institutet, Novum, SE14186 Huddinge, Sweden
| | - Zhi-Zhong Guan
- Department of Pathology at the Affiliated Hospital, Guizhou Medical University, Guiyang 550004, Guizhou, PR China The Key Laboratory of Medical Molecular Biology, Guizhou Medical University, Guiyang 550004, Guizhou, PR China
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Kii I, Sumida Y, Goto T, Sonamoto R, Okuno Y, Yoshida S, Kato-Sumida T, Koike Y, Abe M, Nonaka Y, Ikura T, Ito N, Shibuya H, Hosoya T, Hagiwara M. Selective inhibition of the kinase DYRK1A by targeting its folding process. Nat Commun 2016; 7:11391. [PMID: 27102360 PMCID: PMC4844702 DOI: 10.1038/ncomms11391] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 03/22/2016] [Indexed: 12/12/2022] Open
Abstract
Autophosphorylation of amino-acid residues is part of the folding process of various protein kinases. Conventional chemical screening of mature kinases has missed inhibitors that selectively interfere with the folding process. Here we report a cell-based assay that evaluates inhibition of a kinase at a transitional state during the folding process and identify a folding intermediate-selective inhibitor of dual-specificity tyrosine-phosphorylation-regulated kinase 1A (DYRK1A), which we refer to as FINDY. FINDY suppresses intramolecular autophosphorylation of Ser97 in DYRK1A in cultured cells, leading to its degradation, but does not inhibit substrate phosphorylation catalysed by the mature kinase. FINDY also suppresses Ser97 autophosphorylation of recombinant DYRK1A, suggesting direct inhibition, and shows high selectivity for DYRK1A over other DYRK family members. In addition, FINDY rescues DYRK1A-induced developmental malformations in Xenopus laevis embryos. Our study demonstrates that transitional folding intermediates of protein kinases can be targeted by small molecules, and paves the way for developing novel types of kinase inhibitors.
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Affiliation(s)
- Isao Kii
- Department of Anatomy and Developmental Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Kyoto 606-8501, Japan
- Pathophysiological and Health Science Team, Imaging Application Group, Division of Bio-Function Dynamics Imaging, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Yuto Sumida
- Laboratory of Chemical Bioscience, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Tokyo 101-0062, Japan
| | - Toshiyasu Goto
- Department of Molecular Cell Biology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Tokyo 113-8510, Japan
| | - Rie Sonamoto
- Department of Anatomy and Developmental Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Kyoto 606-8501, Japan
| | - Yukiko Okuno
- Department of Anatomy and Developmental Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Kyoto 606-8501, Japan
| | - Suguru Yoshida
- Laboratory of Chemical Bioscience, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Tokyo 101-0062, Japan
| | - Tomoe Kato-Sumida
- Laboratory of Chemical Bioscience, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Tokyo 101-0062, Japan
| | - Yuka Koike
- Department of Anatomy and Developmental Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Kyoto 606-8501, Japan
- Pathophysiological and Health Science Team, Imaging Application Group, Division of Bio-Function Dynamics Imaging, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Minako Abe
- Department of Structural Biology, Graduate School of Medical and Dental Sciences, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Tokyo 113-8510, Japan
| | - Yosuke Nonaka
- Department of Structural Biology, Graduate School of Medical and Dental Sciences, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Tokyo 113-8510, Japan
| | - Teikichi Ikura
- Department of Structural Biology, Graduate School of Medical and Dental Sciences, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Tokyo 113-8510, Japan
| | - Nobutoshi Ito
- Department of Structural Biology, Graduate School of Medical and Dental Sciences, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Tokyo 113-8510, Japan
| | - Hiroshi Shibuya
- Department of Molecular Cell Biology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45, Yushima, Tokyo 113-8510, Japan
| | - Takamitsu Hosoya
- Laboratory of Chemical Bioscience, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Tokyo 101-0062, Japan
| | - Masatoshi Hagiwara
- Department of Anatomy and Developmental Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Kyoto 606-8501, Japan
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Zhang Y, Jiang X, Qin C, Cuevas S, Jose PA, Armando I. Dopamine D2 receptors' effects on renal inflammation are mediated by regulation of PP2A function. Am J Physiol Renal Physiol 2016; 310:F128-34. [PMID: 26290374 PMCID: PMC4719046 DOI: 10.1152/ajprenal.00453.2014] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 06/15/2015] [Indexed: 01/11/2023] Open
Abstract
Lack or downregulation of the dopamine D2 receptor (D2R) results in increased renal expression of injury markers and proinflammatory factors that is independent of a blood pressure increase. This study aimed to determine the mechanisms involved in the regulation of renal inflammation by D2Rs. Silencing D2Rs in mouse renal proximal tubule cells increased the expression of the proinflammatory TNF-α, monocyte chemoattractant protein-1 (MCP-1), and IL-6. D2R downregulation also increased Akt phosphorylation and activity, and glycogen synthase kinase-3β (GSK3β) phosphorylation and cyclin D1 expression, downstream targets of Akt; however. phosphatidylinositol 3-kinase (PI3K) activity was not affected. Conversely, D2R stimulation decreased Akt and GSK3β phosphorylation and cyclin D1 expression. Increased phospho-Akt, in the absence of increased PI3K activity, may result from decreased Akt dephosphorylation. Inhibition of protein phosphatase 2A (PP2A) with okadaic acid reproduced the effects of D2R downregulation on Akt, GSK3β, and cyclin D1. The PP2A catalytic subunit and regulatory subunit PPP2R2C coimmunoprecipitated with the D2R. Basal phosphatase activity and the expression of PPP2R2C were decreased by D2R silencing that also blunted the increase in phosphatase activity induced by D2R stimulation. Similarly, silencing PPP2R2C also increased the phosphorylation of Akt and GSK3β. Moreover, downregulation of PPP2R2C resulted in increased expression of TNF-α, MCP-1, and IL-6, indicating that decreased phosphatase activity may be responsible for the D2R effect on inflammatory factors. Indeed, the increase in NF-κB reporter activity induced by D2R silencing was blunted by increasing PP2A activity with protamine. Our results show that D2R controls renal inflammation, at least in part, by modulation of the Akt pathway through effects on PP2A activity/expression.
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Affiliation(s)
- Yanrong Zhang
- Division of Nephrology, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland; Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences (CAMS) and Comparative Medicine Centre, Peking Union Medical Collage (PUMC), Beijing, P. R. China; and
| | - Xiaoliang Jiang
- Division of Nephrology, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland; Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences (CAMS) and Comparative Medicine Centre, Peking Union Medical Collage (PUMC), Beijing, P. R. China; and
| | - Chuan Qin
- Division of Nephrology, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland; Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences (CAMS) and Comparative Medicine Centre, Peking Union Medical Collage (PUMC), Beijing, P. R. China; and
| | - Santiago Cuevas
- Division of Nephrology, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Pedro A Jose
- Division of Nephrology, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland; Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Ines Armando
- Division of Nephrology, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
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Cristóbal I, González-Alonso P, Daoud L, Solano E, Torrejón B, Manso R, Madoz-Gúrpide J, Rojo F, García-Foncillas J. Activation of the Tumor Suppressor PP2A Emerges as a Potential Therapeutic Strategy for Treating Prostate Cancer. Mar Drugs 2015; 13:3276-86. [PMID: 26023836 PMCID: PMC4483628 DOI: 10.3390/md13063276] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 05/13/2015] [Indexed: 12/29/2022] Open
Abstract
Protein phosphatase 2A (PP2A) is a tumor suppressor complex that has recently been reported as a novel and highly relevant molecular target in prostate cancer (PCa). However, its potential therapeutic value remains to be fully clarified. We treated PC-3 and LNCaP cell lines with the PP2A activators forskolin and FTY720 alone or combined with the PP2A inhibitor okadaic acid. We examined PP2A activity, cell growth, prostasphere formation, levels of PP2A phosphorylation, CIP2A and SET expression, and AKT and ERK activation. Interestingly, both forskolin and FTY720 dephosphorylated and activated PP2A, impairing proliferation and prostasphere formation and inducing changes in AKT and ERK phosphorylation. Moreover, FTY720 led to reduced CIP2A levels. Treatment with okadaic acid impaired PP2A activation thus demonstrating the antitumoral PP2A-dependent mechanism of action of both forskolin and FTY720. Levels of PP2A phosphorylation together with SET and CIP2A protein expression were studied in 24 PCa patients and both were associated with high Gleason scores and presence of metastatic disease. Altogether, our results suggest that PP2A inhibition could be involved in PCa progression, and the use of PP2A-activating drugs might represent a novel alternative therapeutic strategy for treating PCa patients.
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Affiliation(s)
- Ion Cristóbal
- Translational Oncology Division, Oncohealth Institute, IIS-Fundacion Jimenez Diaz, UAM, University Hospital “Fundacion Jimenez Diaz”, E-28040 Madrid, Spain; E-Mail:
- Authors to whom correspondence should be addressed; E-Mails: (I.C.); (F.R.); (J.G.-F.); Tel.: +34-915504800 (ext. 2824)
| | - Paula González-Alonso
- Group of Cancer Biomarkers, Pathology Department, IIS-Fundacion Jimenez Diaz, UAM, E-28040 Madrid, Spain; E-Mails: (P.G.-A.); (L.D.); (E.S.); (R.M.); (J.M.-G.)
| | - Lina Daoud
- Group of Cancer Biomarkers, Pathology Department, IIS-Fundacion Jimenez Diaz, UAM, E-28040 Madrid, Spain; E-Mails: (P.G.-A.); (L.D.); (E.S.); (R.M.); (J.M.-G.)
| | - Esther Solano
- Group of Cancer Biomarkers, Pathology Department, IIS-Fundacion Jimenez Diaz, UAM, E-28040 Madrid, Spain; E-Mails: (P.G.-A.); (L.D.); (E.S.); (R.M.); (J.M.-G.)
| | - Blanca Torrejón
- Translational Oncology Division, Oncohealth Institute, IIS-Fundacion Jimenez Diaz, UAM, University Hospital “Fundacion Jimenez Diaz”, E-28040 Madrid, Spain; E-Mail:
| | - Rebeca Manso
- Group of Cancer Biomarkers, Pathology Department, IIS-Fundacion Jimenez Diaz, UAM, E-28040 Madrid, Spain; E-Mails: (P.G.-A.); (L.D.); (E.S.); (R.M.); (J.M.-G.)
| | - Juan Madoz-Gúrpide
- Group of Cancer Biomarkers, Pathology Department, IIS-Fundacion Jimenez Diaz, UAM, E-28040 Madrid, Spain; E-Mails: (P.G.-A.); (L.D.); (E.S.); (R.M.); (J.M.-G.)
| | - Federico Rojo
- Group of Cancer Biomarkers, Pathology Department, IIS-Fundacion Jimenez Diaz, UAM, E-28040 Madrid, Spain; E-Mails: (P.G.-A.); (L.D.); (E.S.); (R.M.); (J.M.-G.)
- Authors to whom correspondence should be addressed; E-Mails: (I.C.); (F.R.); (J.G.-F.); Tel.: +34-915504800 (ext. 2824)
| | - Jesús García-Foncillas
- Translational Oncology Division, Oncohealth Institute, IIS-Fundacion Jimenez Diaz, UAM, University Hospital “Fundacion Jimenez Diaz”, E-28040 Madrid, Spain; E-Mail:
- Authors to whom correspondence should be addressed; E-Mails: (I.C.); (F.R.); (J.G.-F.); Tel.: +34-915504800 (ext. 2824)
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Li W, Jiang M, Xiao Y, Zhang X, Cui S, Huang G. Folic acid inhibits tau phosphorylation through regulation of PP2A methylation in SH-SY5Y cells. J Nutr Health Aging 2015; 19:123-9. [PMID: 25651436 DOI: 10.1007/s12603-014-0514-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Neurofibrillary tangles (NFTs), which are composed of intracellular filamentous aggregates of hyperphosphorylated tau protein, are one of the pathological hallmarks of Alzheimer's disease (AD). Because tau phosphorylation is regulated by phosphatases, abnormal metabolism of protein phosphatase 2A (PP2A) has been proposed to be a contributing factor to the disease process. RESULTS To determine the function of folic acid on tau phosphorylation, an in vitro model of human neuroblastoma cells (SH-SY5Y) were exposed to folic acid (0-40 μmol/L) for 96 h, in the presence or absence of the phosphoesterase inhibitor okadaic acid (OA) (10 nmol/L) for 9 h. The data of western blot showed tau phosphorylation at the Ser396 site in OA-incubated SH-SY5Y cells was inhibited by folic acid in a concentration-dependent manner, with the folic acid concentration of 40 μmol/L providing maximal inhibition. Folic acid can downregulate tau protein phosphorylation by inhibiting the demethylation reactions of PP2A. High folic acid concentrations (20 and 40 μmol/L) increased SAM:SAH ratios and cell viability. CONCLUSION Therefore, we can speculate that folate deficiency may be a cause of PP2A deregulation, which can in turn lead to expression of the abnormal hyperphosphorylated form of tau.
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Affiliation(s)
- W Li
- Guowei Huang, Department of Nutrition and Food Science, School of Public Health, Tianjin Medical University, 22 Qixiangtai Road, Heping District, Tianjin 300070, P. R. China. Tel: +86-22-83336606. Fax: +86-22-83336603. E-mail:
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Du J, Cao Y, Wang Q, Zhang N, Liu X, Chen D, Liu X, Xu Q, Ma W. Unique subcellular distribution of phosphorylated Plk1 (Ser137 and Thr210) in mouse oocytes during meiotic division and pPlk1(Ser137) involvement in spindle formation and REC8 cleavage. Cell Cycle 2015; 14:3566-79. [PMID: 26654596 PMCID: PMC4825778 DOI: 10.1080/15384101.2015.1100770] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 09/17/2015] [Accepted: 09/22/2015] [Indexed: 12/20/2022] Open
Abstract
Polo-like kinase 1 (Plk1) is pivotal for proper mitotic progression, its targeting activity is regulated by precise subcellular positioning and phosphorylation. Here we assessed the protein expression, subcellular localization and possible functions of phosphorylated Plk1 (pPlk1(Ser137) and pPlk1(Thr210)) in mouse oocytes during meiotic division. Western blot analysis revealed a peptide of pPlk1(Ser137) with high and stable expression from germinal vesicle (GV) until metaphase II (MII), while pPlk1(Thr210) was detected as one large single band at GV stage and 2 small bands after germinal vesicle breakdown (GVBD), which maintained stable up to MII. Immunofluorescence analysis showed pPlk1(Ser137) was colocalized with microtubule organizing center (MTOC) proteins, γ-tubulin and pericentrin, on spindle poles, concomitantly with persistent concentration at centromeres and dynamic aggregation between chromosome arms. Differently, pPlk1(Thr210) was persistently distributed across the whole body of chromosomes after meiotic resumption. The specific Plk1 inhibitor, BI2536, repressed pPlk1(Ser137) accumulation at MTOCs and between chromosome arms, consequently disturbed γ-tubulin and pericentrin recruiting to MTOCs, destroyed meiotic spindle formation, and delayed REC8 cleavage, therefore arresting oocytes at metaphase I (MI) with chromosome misalignment. BI2536 completely reversed the premature degradation of REC8 and precocious segregation of chromosomes induced with okadaic acid (OA), an inhibitor to protein phosphatase 2A. Additionally, the protein levels of pPlk1(Ser137) and pPlk1(Thr210), as well as the subcellular distribution of pPlk1(Thr210), were not affected by BI2536. Taken together, our results demonstrate that Plk1 activity is required for meiotic spindle assembly and REC8 cleavage, with pPlk1(Ser137) is the action executor, in mouse oocytes during meiotic division.
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Affiliation(s)
- Juan Du
- Department of Histology and Embryology; School of Basic Medical Sciences; Capital Medical University; Beijing, China
| | - Yan Cao
- Department of Histology and Embryology; School of Basic Medical Sciences; Capital Medical University; Beijing, China
| | - Qian Wang
- Department of Histology and Embryology; School of Basic Medical Sciences; Capital Medical University; Beijing, China
| | - Nana Zhang
- Department of Histology and Embryology; School of Basic Medical Sciences; Capital Medical University; Beijing, China
| | - Xiaoyu Liu
- Department of Histology and Embryology; School of Basic Medical Sciences; Capital Medical University; Beijing, China
| | - Dandan Chen
- Department of Histology and Embryology; School of Basic Medical Sciences; Capital Medical University; Beijing, China
| | - Xiaoyun Liu
- Department of Histology and Embryology; School of Basic Medical Sciences; Capital Medical University; Beijing, China
| | - Qunyuan Xu
- Department of Neurobiology; School of Basic Medical Sciences; Capital Medical University; Beijing, China
| | - Wei Ma
- Department of Histology and Embryology; School of Basic Medical Sciences; Capital Medical University; Beijing, China
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Park DM, Li J, Okamoto H, Akeju O, Kim SH, Lubensky I, Vortmeyer A, Dambrosia J, Weil RJ, Oldfield EH, Park JK, Zhuang Z. N-CoR Pathway Targeting Induces Glioblastoma Derived Cancer Stem Cell Differentiation. Cell Cycle 2014; 6:467-70. [PMID: 17312396 DOI: 10.4161/cc.6.4.3856] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Nuclear receptor corepressor (N-CoR) is a critical regulator of neural stem cell differentiation. Nuclear localization of N-CoR is a feature of undifferentiated neural stem cells and cytoplasmic translocation of N-CoR leads to astrocytic differentiation. Comparative proteomic analysis of microdissected glioblastoma multiforme (GBM) specimens and matched normal glial tissue reveals increased expression of N-CoR in GBM. In GBM primary cell cultures, tumor cells with nuclear localization of N-CoR demonstrate an undifferentiated phenotype, but are subject to astroglial differentiation upon exposure to agents promoting phosphorylation of N-CoR and its subsequent translocation to the cytoplasm. Treatment of glioma cell lines with a combination of retinoic acid and low-dose okadaic acid decreases the corepressor effect of N-CoR and has a striking synergistic effect on growth inhibition. The identification of N-CoR in GBM provides insights into the tumorigenesis process and supports the development of differentiation-based therapeutic strategies.
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Affiliation(s)
- Deric M Park
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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Yuan DZ, Ding XL, Yu HL, Cheng Z, Tang XR, He YP, Zhang JH, Blok LJ, Hanifi-Moghaddam P, Burger CW, Yue LM. Progesterone-induced cyclin G1 inhibits the proliferation of endometrial epithelial cell and its possible molecular mechanism. Horm Metab Res 2014; 46:761-7. [PMID: 25007270 DOI: 10.1055/s-0034-1383647] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Under normal conditions, progesterone inhi-bits the estrogen-induced proliferation of endometrial epithelium. Our previous studies have shown that cyclin G1 was progesterone-dependent in mouse endometrial epithelium at peri-implantation, and exogenous cyclin G1 suppressed the proliferation of endometrial cancer cells. The objectives of this study are to determine whether cyclin G1, as a negative regulator of the cell cycle, is involved in the antiproliferative action of progesterone on endometrial epithelial cells, and to explore the possible molecular mechanism of cyclin G1 inhibition. The siRNA-mediated elimination of cyclin G1 attenuated the antiproliferative action of progesterone on endometrial epithelial cells. Immunoprecipitation showed that progesterone-induced cyclin G1 could interact with PP2A to mediate its phosphatase activity. The block of PP2A activity also attenuated the antiproliferative action of progesterone on endometrial epithelial cells and increased the phosphorylated Rb. In conclusion, progesterone-induced cyclin G1 mediates the inhibitory effect of progesterone on endometrial epithelial cell proliferation possibly through the recruitment of PP2A to dephosphorylate Rb.
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Affiliation(s)
- D-z Yuan
- Department of Physiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, P. R. China
| | - X-l Ding
- Department of Physiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, P. R. China
| | - H-l Yu
- Department of Physiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, P. R. China
| | - Z Cheng
- Department of Physiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, P. R. China
| | - X-r Tang
- Department of Physiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, P. R. China
| | - Y-p He
- Department of Physiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, P. R. China
| | - J-h Zhang
- Department of Physiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, P. R. China
| | - L J Blok
- Department of Obstetrics and Gynecology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - P Hanifi-Moghaddam
- Department of Obstetrics and Gynecology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - C W Burger
- Department of Obstetrics and Gynecology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - L-M Yue
- Department of Physiology, West China School of Preclinical and Forensic Medicine, Sichuan University, Chengdu, P. R. China
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Kew VG, Yuan J, Meier J, Reeves MB. Mitogen and stress activated kinases act co-operatively with CREB during the induction of human cytomegalovirus immediate-early gene expression from latency. PLoS Pathog 2014; 10:e1004195. [PMID: 24945302 PMCID: PMC4055774 DOI: 10.1371/journal.ppat.1004195] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 05/06/2014] [Indexed: 11/19/2022] Open
Abstract
The devastating clinical consequences associated with human cytomegalovirus (HCMV) infection and reactivation underscores the importance of understanding triggers of HCMV reactivation in dendritic cells (DC). Here we show that ERK-mediated reactivation is dependent on the mitogen and stress activated kinase (MSK) family. Furthermore, this MSK mediated response is dependent on CREB binding to the viral major immediate early promoter (MIEP). Specifically, CREB binding to the MIEP provides the target for MSK recruitment. Importantly, MSK mediated phosphorylation of histone H3 is required to promote histone de-methylation and the subsequent exit of HCMV from latency. Taken together, these data suggest that CREB binding to the MIEP is necessary for the recruitment of the kinase activity of MSKs to initiate the chromatin remodelling at the MIEP required for reactivation. Thus the importance of CREB during HCMV reactivation is to promote chromatin modifications conducive for viral gene expression as well as acting as a classical transcription factor. Clearly, specific inhibition of this interaction between CREB and MSKs could provide a strategy for therapeutic intervention.
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Affiliation(s)
- Verity G. Kew
- Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Jinxiang Yuan
- Department of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Jeffery Meier
- Department of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Matthew B. Reeves
- Department of Medicine, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
- Institute of Immunity & Transplantation, Division of Infection & Immunity, Royal Free Hospital, University College London, London, United Kingdom
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Fujimori K, Yano M, Miyake H, Kimura H. Termination mechanism of CREB-dependent activation of COX-2 expression in early phase of adipogenesis. Mol Cell Endocrinol 2014; 384:12-22. [PMID: 24378735 DOI: 10.1016/j.mce.2013.12.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 12/07/2013] [Accepted: 12/20/2013] [Indexed: 12/12/2022]
Abstract
We elucidated the molecular mechanism of prostaglandin (PG) E2- and PGF2α-mediated suppression of the early phase of adipogenesis through enhanced COX-2 expression in 3T3-L1 cells. 3-Isobutyl-1-methylxanthine, an inhibitor of phosphodiesterase which catalyzes the conversion of cAMP to AMP, enhanced the activity of protein kinase A (PKA). Dibutyryl cAMP activated PKA and enhanced the phosphorylation of cAMP response element (CRE)-binding protein (CREB). The ability of CREB binding to the CRE of the COX-2 promoter was elevated for enhancement of the expression of the COX-2 gene. CREB siRNA suppressed the expression of the COX-2 gene. Furthermore, okadaic acid, a protein phosphatase (PP) 1/2A inhibitor, suppressed the progression of adipogenesis by preventing PP1/2A-mediated suppression of CREB-dependent COX-2 expression, thus resulting in increased production of anti-adipogenic PGE2 and PGF2α. These results indicate that CREB-dependent expression of COX-2 for the production of anti-adipogenic PGs is critical for the regulation of the early phase of adipogenesis.
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Affiliation(s)
- Ko Fujimori
- Laboratory of Biodefense and Regulation, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan.
| | - Mutsumi Yano
- Laboratory of Biodefense and Regulation, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Haruka Miyake
- Laboratory of Biodefense and Regulation, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Hiroko Kimura
- Laboratory of Biodefense and Regulation, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
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Fakira AK, Portugal GS, Carusillo B, Melyan Z, Morón JA. Increased small conductance calcium-activated potassium type 2 channel-mediated negative feedback on N-methyl-D-aspartate receptors impairs synaptic plasticity following context-dependent sensitization to morphine. Biol Psychiatry 2014; 75:105-14. [PMID: 23735878 PMCID: PMC3992971 DOI: 10.1016/j.biopsych.2013.04.026] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 04/17/2013] [Accepted: 04/29/2013] [Indexed: 12/21/2022]
Abstract
BACKGROUND Hippocampal long-term potentiation (LTP) is impaired following repeated morphine administration paired with a novel context. This procedure produces locomotor sensitization that can be abolished by blocking calcium (Ca(2+))-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs) in the hippocampus. However, the mechanisms underlying LTP impairment remain unclear. Here, we investigate the role of N-methyl-D-aspartate receptors (NMDARs), AMPARs, and small conductance Ca(2+)-activated potassium type 2 (SK2) channels in LTP induction after context-dependent sensitization to morphine. METHODS Mice were treated with saline or escalating doses of morphine (5, 8, 10, and 15 mg/kg) every 12 hours in a locomotor activity chamber and a challenge dose of 5 mg/kg morphine was given 1 week later. After the challenge, the hippocampi were removed to assay phosphatase 2A (PP2A) activity, NMDAR, and SK2 channel synaptic expression or to perform electrophysiological recordings. RESULTS Impaired hippocampal LTP, which accompanied morphine-induced context-dependent sensitization, could not be restored by blocking Ca(2+)-permeable AMPARs. Context-dependent sensitization to morphine altered hippocampal NMDAR subunit composition and enhanced the SK2 channel-mediated negative feedback on NMDAR. Increased PP2A activity observed following context-dependent sensitization suggests that the potentiated SK2 channel effect on NMDAR was mediated by increased SK2 sensitivity to Ca(2+). Finally, inhibition of SK2 channel or PP2A activity restored LTP. CONCLUSIONS Our studies demonstrate that the SK2 channel-NMDAR feedback loop plays a role in opiate-induced impairment of hippocampal plasticity and that the positive modulation of SK2 channels occurs via increases in PP2A activity. This provides further evidence that small conductance Ca(2+)-activated potassium channels play a role in drug-induced plasticity.
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Affiliation(s)
- Amanda K Fakira
- Department of Anesthesiology, College of Physicians and Surgeons, Columbia University Medical Center, New York, New York
| | - George S Portugal
- Department of Anesthesiology, College of Physicians and Surgeons, Columbia University Medical Center, New York, New York
| | - Brianna Carusillo
- Department of Anesthesiology, College of Physicians and Surgeons, Columbia University Medical Center, New York, New York
| | - Zare Melyan
- Department of Anesthesiology, College of Physicians and Surgeons, Columbia University Medical Center, New York, New York
| | - Jose A Morón
- Department of Anesthesiology, College of Physicians and Surgeons, Columbia University Medical Center, New York, New York.
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del Campo M, Toledo H, Lagos N. Okadaic acid toxin at sublethal dose produced cell proliferation in gastric and colon epithelial cell lines. Mar Drugs 2013; 11:4751-60. [PMID: 24317467 PMCID: PMC3877884 DOI: 10.3390/md11124751] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Revised: 10/29/2013] [Accepted: 11/12/2013] [Indexed: 12/29/2022] Open
Abstract
The aim of this study was to analyze the effect of Okadaic Acid (OA) on the proliferation of gastric and colon epithelial cells, the main target tissues of the toxin. We hypothesized that OA, at sublethal doses, activates multiple signaling pathways, such as Erk and Akt, through the inhibition of PP2A. To demonstrate this, we carried out curves of doses and time response against OA in AGS, MKN-45 and Caco 2 cell lines, and found an increase in the cell proliferation at sublethal doses, at 24 h or 48 h exposure. Indeed, cells can withstand high concentrations of the toxin at 4 h exposure, the time chosen considering the maximum time before total gastric emptying. We have proved that this increased proliferation is due to an overexpression of Cyclin B, a cyclin that promotes the passage from G2 to mitosis. In addition, we have demonstrated that OA induces activation of Akt and Erk in the three cells lines, showing that OA can activate pathways involved in oncogenesis. In conclusion, this study contributes to the knowledge about the possible effects of chronic OA consumption.
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Affiliation(s)
- Miguel del Campo
- Laboratory of Membrane Biochemistry, Program of Physiology and Biophysics, Faculty of Medicine, University of Chile, Independencia 1027, Correo 7, Santiago 8380000, Chile; E-Mail:
| | - Héctor Toledo
- Laboratory of Molecular Microbiology, Program of Cellular and Molecular Biology, Faculty of Medicine, University of Chile, Independencia 1027, Correo 7, Santiago 8380000, Chile; E-Mail:
| | - Néstor Lagos
- Laboratory of Membrane Biochemistry, Program of Physiology and Biophysics, Faculty of Medicine, University of Chile, Independencia 1027, Correo 7, Santiago 8380000, Chile; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel./Fax: +56-02-2978-6309
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Pivovarov AS, Murzina GB, Tret'iakova MS, Makhnovskiĭ DA. [Role of serine/threonine and tyrosine protein phosphatases in command Helix lucorum neurons at the cellular correlate of habituation]. Zh Vyssh Nerv Deiat Im I P Pavlova 2013; 63:256-68. [PMID: 23866612 DOI: 10.7868/s0044467713020081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Effects of some inhibitors of serine/threonine and tyrosine protein phosphatases on the depression and spontaneous recovery of the acetylcholine-induced inward current (ACh-current) in command Helix neurons of defensive behavior at the cellular correlate of habituation were investigated. The following drugs were used: okadaic acid (reduces activity ofphosphatases PP1 and PP2A), endothall (PP2A), cyclosporine A and cypermethrin (PP2B), CCT007093 (PPM1D), dephostatin (blocks tyrosine phosphatases). All used inhibitors modify the depression flow, and endothall reduces spontaneous recovery of ACh-current also. Obtained results indicate that changes in cholinosensitivity of command neurons depend on activity of all investigated protein phosphatases. Mathematical model considers the possibility of different localizations of receptors in a neuron and regularity of transitions between them. This model makes it possible to conclude participation indicated phosphatases in mobility of membrane cholinoreceptors ensuring the ACh-current modification at the cellular correlate of habituations. Comparison of experimental and calculated curves of ACh-current change allows to conclude that the main target of protein phosphatases is the transport system of a neuron--cytoskeleton and motor proteins.
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Gao LL, Liu XQ, Xu BQ, Jiang SW, Cui YG, Liu JY. SET/PP2A system regulates androgen production in ovarian follicles in vitro. Mol Cell Endocrinol 2013; 374:108-16. [PMID: 23628604 DOI: 10.1016/j.mce.2013.04.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2012] [Revised: 03/15/2013] [Accepted: 04/19/2013] [Indexed: 01/31/2023]
Abstract
SET has multiple cell functions including nucleosome assembly, histone binding, transcription control, and cell apoptosis. In ovaries SET is predominantly expressed in theca cells and oocytes. In our study, SET overexpression in theca cells stimulated testosterone production whereas SET knockdown decreased testosterone production. Moreover, SET negatively regulated PP2A activity. Treatment with PP2A inhibitor okadaic acid (OA) led to increased testosterone synthesis, while treatment with PP2A activators resulted in the decreased testosterone synthesis. Furthermore, PP2A knockdown confirmed the key role of PP2A in the testosterone synthesis, and OA was able to block the AdH1-SiRNA/SET-mediated inhibition of testosterone production. The central role of PP2A in SET-mediated regulation of testosterone production was confirmed by the finding that SET promoted the lyase activity of P450c17 and that PP2A inhibited its lyase activity. Taken together, these results reveal a specific, SET-initiated, PP2A-mediated, pathway that leads to the increased lyase activity of P450c17 and testosterone biosynthesis.
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Affiliation(s)
- Ling-Ling Gao
- The State Key Laboratory of Reproductive Medicine, Clinical Center of Reproductive Medicine, First Affiliated Hospital, Nanjing Medical University, Nanjing 210029, China.
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Cruz PG, Norte M, Hernández Creus A, Fernández JJ, Hernández Daranas A. Self-association of okadaic acid: structural and pharmacological significance. Mar Drugs 2013; 11:1866-77. [PMID: 23760016 PMCID: PMC3721210 DOI: 10.3390/md11061866] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 05/06/2013] [Accepted: 05/07/2013] [Indexed: 02/08/2023] Open
Abstract
Okadaic acid (OA) has been an invaluable pharmacological tool in the study of cellular signaling. The great affinity of this polyether for its targets together with its high specificity to inhibit certain protein phosphatases enables the differential study of these proteins. Crystallographic structures of protein phosphatases in complex with OA show a 1:1 protein to toxin ratio. Nevertheless, it has been found that OA is able to self-associate under certain conditions although very little is known about the importance of this phenomenon. Here we review the available knowledge on the latter topic and we report on the existence of an unusual self-associated tetrameric form. The structure of these oligomers is proposed based on spectroscopic data and molecular modeling calculations.
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Affiliation(s)
- Patricia G. Cruz
- University Institute for Bio-Organic Chemistry “Antonio González” (IUBO), University of La Laguna (ULL), Astrofísico Francisco Sánchez 2, 38206 La Laguna, Tenerife, Spain; E-Mails: (P.G.C.); (M.N.)
- Pharma Mar, Avda. de los Reyes, 1 P.I. La Mina-Norte, Colmenar Viejo, Madrid 28770, Spain
| | - Manuel Norte
- University Institute for Bio-Organic Chemistry “Antonio González” (IUBO), University of La Laguna (ULL), Astrofísico Francisco Sánchez 2, 38206 La Laguna, Tenerife, Spain; E-Mails: (P.G.C.); (M.N.)
- Department of Organic Chemistry, University of La Laguna (ULL), Astrofísico Francisco Sánchez 1, 38206 La Laguna, Tenerife, Spain
| | - Alberto Hernández Creus
- Department of Physical Chemistry, University Institute of Materials and Nanotechnology, University of La Laguna (ULL), Astrofísico Francisco Sánchez 1, 38206 La Laguna, Tenerife, Spain; E-Mail:
| | - José J. Fernández
- University Institute for Bio-Organic Chemistry “Antonio González” (IUBO), University of La Laguna (ULL), Astrofísico Francisco Sánchez 2, 38206 La Laguna, Tenerife, Spain; E-Mails: (P.G.C.); (M.N.)
- Department of Organic Chemistry, University of La Laguna (ULL), Astrofísico Francisco Sánchez 1, 38206 La Laguna, Tenerife, Spain
- Authors to whom correspondence should be addressed; E-Mails: (J.J.F.); (A.H.D.); Tel.: +34-922-318587; Fax: +34-922-318571
| | - Antonio Hernández Daranas
- University Institute for Bio-Organic Chemistry “Antonio González” (IUBO), University of La Laguna (ULL), Astrofísico Francisco Sánchez 2, 38206 La Laguna, Tenerife, Spain; E-Mails: (P.G.C.); (M.N.)
- Department of Chemical Engineering and Pharmaceutical Technology, University of La Laguna (ULL), Astrofísico Francisco Sánchez 1, 38206 La Laguna, Tenerife, Spain
- Authors to whom correspondence should be addressed; E-Mails: (J.J.F.); (A.H.D.); Tel.: +34-922-318587; Fax: +34-922-318571
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Medina M, Avila J, Villanueva N. Use of okadaic acid to identify relevant phosphoepitopes in pathology: a focus on neurodegeneration. Mar Drugs 2013; 11:1656-68. [PMID: 23697949 PMCID: PMC3707166 DOI: 10.3390/md11051656] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 04/02/2013] [Accepted: 04/16/2013] [Indexed: 12/24/2022] Open
Abstract
Protein phosphorylation is involved in the regulation of a wide variety of physiological processes and is the result of a balance between protein kinase and phosphatase activities. Biologically active marine derived compounds have been shown to represent an interesting source of novel compounds that could modify that balance. Among them, the marine toxin and tumor promoter, okadaic acid (OA), has been shown as an inhibitor of two of the main cytosolic, broad-specificity protein phosphatases, PP1 and PP2A, thus providing an excellent cell-permeable probe for examining the role of protein phosphorylation, and PP1 and PP2A in particular, in any physiological or pathological process. In the present work, we review the use of okadaic acid to identify specific phosphoepitopes mainly in proteins relevant for neurodegeneration. We will specifically highlight those cases of highly dynamic phosphorylation-dephosphorylation events and the ability of OA to block the high turnover phosphorylation, thus allowing the detection of modified residues that could be otherwise difficult to identify. Finally, its effect on tau hyperhosphorylation and its relevance in neurodegenerative pathologies such as Alzheimer’s disease and related dementia will be discussed.
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Affiliation(s)
- Miguel Medina
- CIBERNED (Center for Networked Biomedical Research in Neurodegenerative Diseases), Valderrebollo 5, Madrid 28041, Spain; E-Mail:
| | - Jesús Avila
- CIBERNED (Center for Networked Biomedical Research in Neurodegenerative Diseases), Valderrebollo 5, Madrid 28041, Spain; E-Mail:
- Center of Molecular Biology “Severo Ochoa” CSIC-UAM, Nicolás Cabrera 1, Madrid 28049, Spain
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +34-91-196-4803; Fax: +34-91-196-4715
| | - Nieves Villanueva
- National Center of Microbiology (CNM), Carlos III Institute of Health (ISCIII), Crta. Majadahonda-Pozuelo km 2, Majadahonda, Madrid 28220, Spain; E-Mail:
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Ruzsnavszky O, Dienes B, Oláh T, Vincze J, Gáll T, Balogh E, Nagy G, Bátori R, Lontay B, Erdődi F, Csernoch L. Differential effects of phosphatase inhibitors on the calcium homeostasis and migration of HaCaT keratinocytes. PLoS One 2013; 8:e61507. [PMID: 23646108 PMCID: PMC3640006 DOI: 10.1371/journal.pone.0061507] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 03/10/2013] [Indexed: 11/18/2022] Open
Abstract
Changes in intracellular calcium concentration ([Ca2+]i) as well as in the phosphorylation state of proteins have been implicated in keratinocyte wound healing revealed in scratch assays. Scratching confluent HaCaT monolayers decreased the number of cells displaying repetitive Ca2+ oscillations as well as the frequency of their Ca2+-transients in cells close to the wounded area and initiated migration of the cells into the wound bed. In contrast, calyculin-A (CLA) and okadaic acid (OA), known cell permeable inhibitors of protein phosphatase-1 and 2A, increased the level of resting [Ca2+]i and suppressed cell migration and wound healing of HaCaT cells. Furthermore, neither CLA nor OA influenced how scratching affected Ca2+ oscillations. It is assumed that changes in and alterations of the phosphorylation level of Ca2+-transport and contractile proteins upon phosphatase inhibition mediates cell migration and wound healing.
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Affiliation(s)
- Olga Ruzsnavszky
- Department of Physiology, University of Debrecen, Debrecen, Hungary
| | - Beatrix Dienes
- Department of Physiology, University of Debrecen, Debrecen, Hungary
| | - Tamás Oláh
- Department of Physiology, University of Debrecen, Debrecen, Hungary
| | - János Vincze
- Department of Physiology, University of Debrecen, Debrecen, Hungary
| | - Tamás Gáll
- Department of Physiology, University of Debrecen, Debrecen, Hungary
| | - Enikő Balogh
- 1st Department of Internal Medicine, University of Debrecen, Debrecen, Hungary
| | - Gábor Nagy
- Department of Microbial Biotechnology and Cell Biology, University of Debrecen, Debrecen, Hungary
| | - Róbert Bátori
- Department of Medical Chemistry, University of Debrecen, Debrecen, Hungary
| | - Beáta Lontay
- Department of Medical Chemistry, University of Debrecen, Debrecen, Hungary
| | - Ferenc Erdődi
- Department of Medical Chemistry, University of Debrecen, Debrecen, Hungary
| | - Laszlo Csernoch
- Department of Physiology, University of Debrecen, Debrecen, Hungary
- * E-mail:
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Barajas-López JDD, Kremnev D, Shaikhali J, Piñas-Fernández A, Strand Å. PAPP5 is involved in the tetrapyrrole mediated plastid signalling during chloroplast development. PLoS One 2013; 8:e60305. [PMID: 23555952 PMCID: PMC3612061 DOI: 10.1371/journal.pone.0060305] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 02/25/2013] [Indexed: 12/17/2022] Open
Abstract
The initiation of chloroplast development in the light is dependent on nuclear encoded components. The nuclear genes encoding key components in the photosynthetic machinery are regulated by signals originating in the plastids. These plastid signals play an essential role in the regulation of photosynthesis associated nuclear genes (PhANGs) when proplastids develop into chloroplasts. One of the plastid signals is linked to the tetrapyrrole biosynthesis and accumulation of the intermediates the Mg-ProtoIX and its methyl ester Mg-ProtoIX-ME. Phytochrome-Associated Protein Phosphatase 5 (PAPP5) was isolated in a previous study as a putative Mg-ProtoIX interacting protein. In order to elucidate if there is a biological link between PAPP5 and the tetrapyrrole mediated signal we generated double mutants between the Arabidopsis papp5 and the crd mutants. The crd mutant over-accumulates Mg-ProtoIX and Mg-ProtoIX-ME and the tetrapyrrole accumulation triggers retrograde signalling. The crd mutant exhibits repression of PhANG expression, altered chloroplast morphology and a pale phenotype. However, in the papp5crd double mutant, the crd phenotype is restored and papp5crd accumulated wild type levels of chlorophyll, developed proper chloroplasts and showed normal induction of PhANG expression in response to light. Tetrapyrrole feeding experiments showed that PAPP5 is required to respond correctly to accumulation of tetrapyrroles in the cell and that PAPP5 is most likely a component in the plastid signalling pathway down stream of the tetrapyrrole Mg-ProtoIX/Mg-ProtoIX-ME. Inhibition of phosphatase activity phenocopied the papp5crd phenotype in the crd single mutant demonstrating that PAPP5 phosphatase activity is essential to mediate the retrograde signal and to suppress PhANG expression in the crd mutant. Thus, our results suggest that PAPP5 receives an inbalance in the tetrapyrrole biosynthesis through the accumulation of Mg-ProtoIX and acts as a negative regulator of PhANG expression during chloroplast biogenesis and development.
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Affiliation(s)
| | - Dmitry Kremnev
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
| | - Jehad Shaikhali
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
| | - Aurora Piñas-Fernández
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
| | - Åsa Strand
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, Sweden
- * E-mail:
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Arteaga MF, Mikesch JH, Qiu J, Christensen J, Helin K, Kogan SC, Dong S, So CWE. The histone demethylase PHF8 governs retinoic acid response in acute promyelocytic leukemia. Cancer Cell 2013; 23:376-89. [PMID: 23518351 PMCID: PMC6812572 DOI: 10.1016/j.ccr.2013.02.014] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 11/26/2012] [Accepted: 02/15/2013] [Indexed: 10/27/2022]
Abstract
While all-trans retinoic acid (ATRA) treatment in acute promyelocytic leukemia (APL) has been the paradigm of targeted therapy for oncogenic transcription factors, the underlying mechanisms remain largely unknown, and a significant number of patients still relapse and become ATRA resistant. We identified the histone demethylase PHF8 as a coactivator that is specifically recruited by RARα fusions to activate expression of their downstream targets upon ATRA treatment. Forced expression of PHF8 resensitizes ATRA-resistant APL cells, whereas its downregulation confers resistance. ATRA sensitivity depends on the enzymatic activity and phosphorylation status of PHF8, which can be pharmacologically manipulated to resurrect ATRA sensitivity to resistant cells. These findings provide important molecular insights into ATRA response and a promising avenue for overcoming ATRA resistance.
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MESH Headings
- Animals
- Drug Resistance, Neoplasm
- Histone Demethylases/genetics
- Histone Demethylases/metabolism
- Histones
- Humans
- Leukemia, Promyelocytic, Acute/drug therapy
- Leukemia, Promyelocytic, Acute/metabolism
- Mice
- Mice, Inbred NOD
- Mice, SCID
- Neoplasm Proteins/metabolism
- Okadaic Acid/pharmacology
- Oncogene Proteins, Fusion/metabolism
- Phosphorylation
- RNA Interference
- RNA, Small Interfering
- Receptors, Retinoic Acid/genetics
- Receptors, Retinoic Acid/metabolism
- Retinoic Acid Receptor alpha
- Signal Transduction
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transcription, Genetic
- Tretinoin/pharmacology
- Tumor Cells, Cultured
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Affiliation(s)
- Maria Francisca Arteaga
- Leukaemia and Stem Cell Biology Group, Department of Haematological Medicine, King’s College London, Denmark Hill, London SE5 9NU, UK
| | - Jan-Henrik Mikesch
- Leukaemia and Stem Cell Biology Group, Department of Haematological Medicine, King’s College London, Denmark Hill, London SE5 9NU, UK
| | - Jihui Qiu
- Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Kristian Helin
- Biotech Research and Innovation Centre (BRIC)
- Centre for Epigenetics
- The Danish Stem Cell Center (Danstem), University of Copenhagen, 2200 Copenhagen, Denmark
| | - Scott C. Kogan
- Helen Diller Family Comprehensive Cancer Center and Department of Laboratory Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Shuo Dong
- Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Chi Wai Eric So
- Leukaemia and Stem Cell Biology Group, Department of Haematological Medicine, King’s College London, Denmark Hill, London SE5 9NU, UK
- Correspondence:
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Abstract
Thioredoxin-interacting protein (Txnip) is a metabolic regulator, which modulates insulin sensitivity and likely plays a role in type 2 diabetes. We studied the regulation of Txnip in 3T3-L1 adipocytes. Cells were incubated under different conditions and Txnip was measured by immunoblotting. We confirmed that high glucose markedly increases Txnip expression by promoting transcription. Insulin decreases Txnip protein levels. Rapamycin under most conditions decreased Txnip, suggesting that mTOR complex-1 is involved. The acute effects of insulin are mainly posttranscriptional; insulin (100 nM) accelerates Txnip degradation more than tenfold. This effect is cell type specific. It works in adipocytes, preadipocytes and in L6 myotubes but not in HepG2 or in HEK 293 cells or in a pancreatic β-cell line. The ubiquitin/proteasome pathway is involved. Degradation of Txnip occurred within 15 min in the presence of 3 nM insulin and overnight with 0.6 nM insulin. Proteasomal Txnip degradation is not mediated by a cysteine protease or an anti-calpain enzyme. Okadaic acid (OKA), an inhibitor of phosphoprotein phosphatases (pp), markedly reduced Txnip protein and stimulated its further decrease by insulin. The latter occurred after incubation with 1 or 1000 nM OKA, suggesting that insulin enhances the phosphorylation of a pp2A substrate. Incubation with 0.1 μM Wortmannin, a PI3 kinase inhibitor, increased Txnip protein twofold and significantly inhibited its insulin-induced decrease. Thus, while OKA mimics the effect of insulin, Wortmannin opposes it. In summary, insulin stimulates Txnip degradation by a PI3 kinase-dependent mechanism, which activates the ubiquitin/proteasome pathway and likely serves to mitigate insulin resistance.
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Affiliation(s)
- Katherine A Robinson
- Division of Endocrinology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
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