1
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Enomoto A, Fukasawa T, Terunuma H, Nakagawa K, Yoshizaki A, Sato S, Hosoya N, Miyagawa K. Deregulated JNK signaling enhances apoptosis during hyperthermia. Int J Hyperthermia 2024; 41:2335199. [PMID: 38565204 DOI: 10.1080/02656736.2024.2335199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 03/22/2024] [Indexed: 04/04/2024] Open
Abstract
PURPOSE c-Jun N-terminal kinases (JNKs) comprise a subfamily of mitogen-activated protein kinases (MAPKs). The JNK group is known to be activated by a variety of stimuli. However, the molecular mechanism underlying heat-induced JNK activation is largely unknown. The aim of this study was to clarify how JNK activity is stimulated by heat. METHODS AND MATERIALS The expression levels of various MAPK members in HeLa cells, with or without hyperthermia treatment, were evaluated via western blotting. The kinase activity of MAPK members was assessed through in vitro kinase assays. Cell death was assessed in the absence or presence of siRNAs targeting MAPK-related members. RESULTS Hyperthermia decreased the levels of MAP3Ks, such as ASK1 and MLK3 which are JNK kinase kinase members, but not those of the downstream MAP2K/SEK1 and MAPK/JNK. Despite the reduced or transient phosphorylation of ASK1, MLK3, or SEK1, downstream JNK was phosphorylated in a temperature-dependent manner. In vitro kinase assays demonstrated that heat did not directly stimulate SEK1 or JNK. However, the expression levels of DUSP16, a JNK phosphatase, were decreased upon hyperthermia treatment. DUSP16 knockdown enhanced the heat-induced activation of ASK1-SEK1-JNK pathway and apoptosis. CONCLUSION JNK was activated in a temperature-dependent manner despite reduced or transient phosphorylation of the upstream MAP3K and MAP2K. Hyperthermia-induced degradation of DUSP16 may induce activation of the ASK1-SEK1-JNK pathway and subsequent apoptosis.
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Affiliation(s)
- Atsushi Enomoto
- Laboratory of Molecular Radiology, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Takemichi Fukasawa
- Department of Dermatology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Clinical Cannabinoid Research, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | | | - Keiichi Nakagawa
- Comprehensive Radiation Oncology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Ayumi Yoshizaki
- Department of Dermatology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Clinical Cannabinoid Research, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Shinichi Sato
- Department of Dermatology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Noriko Hosoya
- Laboratory of Molecular Radiology, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Kiyoshi Miyagawa
- Laboratory of Molecular Radiology, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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2
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Niu J, Holland SM, Ketschek A, Collura KM, Hesketh NL, Hayashi T, Gallo G, Thomas GM. Palmitoylation couples the kinases DLK and JNK3 to facilitate prodegenerative axon-to-soma signaling. Sci Signal 2022; 15:eabh2674. [PMID: 35349303 DOI: 10.1126/scisignal.abh2674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Dual leucine-zipper kinase (DLK; a MAP3K) mediates neuronal responses to diverse injuries and insults through the c-Jun N-terminal kinase (JNK) family of mitogen-activated protein kinases (MAPKs). Here, we identified two ways through which DLK is coupled to the neural-specific isoform JNK3 to control prodegenerative signaling. JNK3 catalyzed positive feedback phosphorylation of DLK that further activated DLK and locked the DLK-JNK3 module in a highly active state. Neither homologous MAP3Ks nor a homologous MAPK could support this positive feedback loop. Unlike the related JNK1 isoform JNK2 and JNK3 promote prodegenerative axon-to-soma signaling and were endogenously palmitoylated. Moreover, palmitoylation targeted both DLK and JNK3 to the same axonal vesicles, and JNK3 palmitoylation was essential for axonal retrograde signaling in response to optic nerve crush injury in vivo. These findings provide previously unappreciated insights into DLK-JNK signaling relevant to neuropathological conditions and answer long-standing questions regarding the selective prodegenerative roles of JNK2 and JNK3.
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Affiliation(s)
- Jingwen Niu
- Shriners Hospitals Pediatric Research Center (Center for Neurorehabilitation and Neural Repair), Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, Philadelphia, PA 19140, USA
| | - Sabrina M Holland
- Shriners Hospitals Pediatric Research Center (Center for Neurorehabilitation and Neural Repair), Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, Philadelphia, PA 19140, USA
| | - Andrea Ketschek
- Shriners Hospitals Pediatric Research Center (Center for Neurorehabilitation and Neural Repair), Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, Philadelphia, PA 19140, USA
| | - Kaitlin M Collura
- Shriners Hospitals Pediatric Research Center (Center for Neurorehabilitation and Neural Repair), Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, Philadelphia, PA 19140, USA
| | - Natasha L Hesketh
- Shriners Hospitals Pediatric Research Center (Center for Neurorehabilitation and Neural Repair), Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, Philadelphia, PA 19140, USA
| | - Takashi Hayashi
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central6 (6-10), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Gianluca Gallo
- Shriners Hospitals Pediatric Research Center (Center for Neurorehabilitation and Neural Repair), Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, Philadelphia, PA 19140, USA.,Department of Neural Sciences, Lewis Katz School of Medicine at Temple University, 3500 N. Broad St., Philadelphia, PA 19140, USA
| | - Gareth M Thomas
- Shriners Hospitals Pediatric Research Center (Center for Neurorehabilitation and Neural Repair), Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, Philadelphia, PA 19140, USA.,Department of Neural Sciences, Lewis Katz School of Medicine at Temple University, 3500 N. Broad St., Philadelphia, PA 19140, USA
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Sarwar Z, Nabi N, Bhat SA, Gillani SQ, Reshi I, Un Nisa M, Adelmant G, Marto J, Andrabi S. Interaction of DBC1 with polyoma small T antigen promotes its degradation and negatively regulates tumorigenesis. J Biol Chem 2021; 298:101496. [PMID: 34921839 PMCID: PMC8784333 DOI: 10.1016/j.jbc.2021.101496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 11/09/2021] [Accepted: 12/10/2021] [Indexed: 12/05/2022] Open
Abstract
Deleted in Breast Cancer 1 (DBC1) is an important metabolic sensor. Previous studies have implicated DBC1 in various cellular functions, notably cell proliferation, apoptosis, histone modification, and adipogenesis. However, current reports about the role of DBC1 in tumorigenesis are controversial and designate DBC1 alternatively as a tumor suppressor or a tumor promoter. In the present study, we report that polyoma small T antigen (PyST) associates with DBC1 in mammalian cells, and this interaction leads to the posttranslational downregulation of DBC1 protein levels. When coexpressed, DBC1 overcomes PyST-induced mitotic arrest and promotes the exit of cells from mitosis. Using both transient and stable modes of PyST expression, we also show that cellular DBC1 is subjected to degradation by LKB1, a tumor suppressor and cellular energy sensor kinase, in an AMP kinase-independent manner. Moreover, LKB1 negatively regulates the phosphorylation as well as activity of the prosurvival kinase AKT1 through DBC1 and its downstream pseudokinase substrate, Tribbles 3 (TRB3). Using both transient transfection and stable cell line approaches as well as soft agar assay, we demonstrate that DBC1 has oncogenic potential. In conclusion, our study provides insight into a novel signaling axis that connects LKB1, DBC1, TRB3, and AKT1. We propose that the LKB1–DBC1–AKT1 signaling paradigm may have an important role in the regulation of cell cycle and apoptosis and consequently tumorigenesis.
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Affiliation(s)
- Zarka Sarwar
- Department of Biochemistry, University of Kashmir, Srinagar, India, 190006
| | - Nusrat Nabi
- Department of Biochemistry, University of Kashmir, Srinagar, India, 190006
| | - Sameer Ahmed Bhat
- Department of Biochemistry, University of Kashmir, Srinagar, India, 190006
| | | | - Irfana Reshi
- Department of Biochemistry, University of Kashmir, Srinagar, India, 190006
| | - Misbah Un Nisa
- Department of Biochemistry, University of Kashmir, Srinagar, India, 190006
| | - Guillaume Adelmant
- Blais Proteomics Centre, Dana Farber Cancer Institute, Harvard University, Boston, USA
| | - Jarrod Marto
- Blais Proteomics Centre, Dana Farber Cancer Institute, Harvard University, Boston, USA
| | - Shaida Andrabi
- Department of Biochemistry, University of Kashmir, Srinagar, India, 190006.
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4
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Altunoglu U, Börklü E, Shukla A, Escande-Beillard N, Ledig S, Azaklı H, Nayak SS, Eraslan S, Girisha KM, Kennerknecht I, Kayserili H. Expanding the spectrum of syndromic PPP2R3C-related XY gonadal dysgenesis to XX gonadal dysgenesis. Clin Genet 2021; 101:221-232. [PMID: 34750818 DOI: 10.1111/cge.14086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/20/2021] [Accepted: 11/04/2021] [Indexed: 01/09/2023]
Abstract
Homozygous variants in PPP2R3C have been reported to cause a syndromic 46,XY complete gonadal dysgenesis phenotype with extragonadal manifestations (GDRM, MIM# 618419) in patients from four unrelated families, whereas heterozygous variants have been linked to reduced fertility with teratozoospermia (SPGF36, MIM# 618420) in male carriers. We present eight patients from four unrelated families of Turkish and Indian descent with three different germline homozygous PPP2R3C variants including a novel in-frame duplication (c.639_647dupTTTCTACTC, p.Ser216_Tyr218dup). All patients exhibit recognizable facial dysmorphisms allowing gestalt diagnosis. In two 46,XX patients with hypergonadotropic hypogonadism and nonvisualized gonads, primary amenorrhea along with absence of secondary sexual characteristics and/or unique facial gestalt led to the diagnosis. 46,XY affected individuals displayed a spectrum of external genital phenotypes from ambiguous genitalia to complete female. We expand the spectrum of syndromic PPP2R3C-related XY gonadal dysgenesis to both XY and XX gonadal dysgenesis. Our findings supported neither ocular nor muscular involvement as major criteria of the syndrome. We also did not encounter infertility problems in the carriers. Since both XX and XY individuals were affected, we hypothesize that PPP2R3C is essential in the early signaling cascades controlling sex determination in humans.
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Affiliation(s)
- Umut Altunoglu
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey.,Medical Genetics Department, Istanbul University Istanbul Medical School, Istanbul, Turkey
| | - Esra Börklü
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey
| | - Anju Shukla
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Nathalie Escande-Beillard
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey.,Institute of Medical Biology, A*STAR, Singapore, Singapore
| | - Susanne Ledig
- Institut für Humangenetik, Westfaelische Wilhelms-Universitaet Muenster, Muenster, Germany
| | - Hülya Azaklı
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey
| | - Shalini S Nayak
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Serpil Eraslan
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey
| | - Katta Mohan Girisha
- Department of Medical Genetics, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India
| | - Ingo Kennerknecht
- Institut für Humangenetik, Westfaelische Wilhelms-Universitaet Muenster, Muenster, Germany
| | - Hülya Kayserili
- Medical Genetics Department, Koç University School of Medicine (KUSoM) and Hospital, Istanbul, Turkey.,Medical Genetics Department, Istanbul University Istanbul Medical School, Istanbul, Turkey
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5
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Tadjalli A, Seven YB, Perim RR, Mitchell GS. Systemic inflammation suppresses spinal respiratory motor plasticity via mechanisms that require serine/threonine protein phosphatase activity. J Neuroinflammation 2021; 18:28. [PMID: 33468163 PMCID: PMC7816383 DOI: 10.1186/s12974-021-02074-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 01/05/2021] [Indexed: 01/05/2023] Open
Abstract
Background Inflammation undermines multiple forms of neuroplasticity. Although inflammation and its influence on plasticity in multiple neural systems has been extensively studied, its effects on plasticity of neural networks controlling vital life functions, such as breathing, are less understood. In this study, we investigated the signaling mechanisms whereby lipopolysaccharide (LPS)-induced systemic inflammation impairs plasticity within the phrenic motor system—a major spinal respiratory motor pool that drives contractions of the diaphragm muscle. Here, we tested the hypotheses that lipopolysaccharide-induced systemic inflammation (1) blocks phrenic motor plasticity by a mechanism that requires cervical spinal okadaic acid-sensitive serine/threonine protein phosphatase (PP) 1/2A activity and (2) prevents phosphorylation/activation of extracellular signal-regulated kinase 1/2 mitogen activated protein kinase (ERK1/2 MAPK)—a key enzyme necessary for the expression of phrenic motor plasticity. Methods To study phrenic motor plasticity, we utilized a well-characterized model for spinal respiratory plasticity called phrenic long-term facilitation (pLTF). pLTF is characterized by a long-lasting, progressive enhancement of inspiratory phrenic nerve motor drive following exposures to moderate acute intermittent hypoxia (mAIH). In anesthetized, vagotomized and mechanically ventilated adult Sprague Dawley rats, we examined the effect of inhibiting cervical spinal serine/threonine PP 1/2A activity on pLTF expression in sham-vehicle and LPS-treated rats. Using immunofluorescence optical density analysis, we compared mAIH-induced phosphorylation/activation of ERK 1/2 MAPK with and without LPS-induced inflammation in identified phrenic motor neurons. Results We confirmed that mAIH-induced pLTF is abolished 24 h following low-dose systemic LPS (100 μg/kg, i.p.). Cervical spinal delivery of the PP 1/2A inhibitor, okadaic acid, restored pLTF in LPS-treated rats. LPS also prevented mAIH-induced enhancement in phrenic motor neuron ERK1/2 MAPK phosphorylation. Thus, a likely target for the relevant okadaic acid-sensitive protein phosphatases is ERK1/2 MAPK or its upstream activators. Conclusions This study increases our understanding of fundamental mechanisms whereby inflammation disrupts neuroplasticity in a critical population of motor neurons necessary for breathing, and highlights key roles for serine/threonine protein phosphatases and ERK1/2 MAPK kinase in the plasticity of mammalian spinal respiratory motor circuits.
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Affiliation(s)
- Arash Tadjalli
- Breathing Research and Therapeutics Center, Department of Physical Therapy and The McKnight Brain Institute, College of Public Health & Health Professions, University of Florida, 1225 Center Drive, PO Box 100154, Gainesville, FL, 32610, USA
| | - Yasin B Seven
- Breathing Research and Therapeutics Center, Department of Physical Therapy and The McKnight Brain Institute, College of Public Health & Health Professions, University of Florida, 1225 Center Drive, PO Box 100154, Gainesville, FL, 32610, USA
| | - Raphael R Perim
- Breathing Research and Therapeutics Center, Department of Physical Therapy and The McKnight Brain Institute, College of Public Health & Health Professions, University of Florida, 1225 Center Drive, PO Box 100154, Gainesville, FL, 32610, USA
| | - Gordon S Mitchell
- Breathing Research and Therapeutics Center, Department of Physical Therapy and The McKnight Brain Institute, College of Public Health & Health Professions, University of Florida, 1225 Center Drive, PO Box 100154, Gainesville, FL, 32610, USA.
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6
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Hsiao PC, Chang JH, Lee WJ, Ku CC, Tsai MY, Yang SF, Chien MH. The Curcumin Analogue, EF-24, Triggers p38 MAPK-Mediated Apoptotic Cell Death via Inducing PP2A-Modulated ERK Deactivation in Human Acute Myeloid Leukemia Cells. Cancers (Basel) 2020; 12:cancers12082163. [PMID: 32759757 PMCID: PMC7464750 DOI: 10.3390/cancers12082163] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 07/30/2020] [Accepted: 07/31/2020] [Indexed: 12/14/2022] Open
Abstract
Curcumin (CUR) has a range of therapeutic benefits against cancers, but its poor solubility and low bioavailability limit its clinical use. Demethoxycurcumin (DMC) and diphenyl difluoroketone (EF-24) are natural and synthetic curcumin analogues, respectively, with better solubilities and higher anti-carcinogenic activities in various solid tumors than CUR. However, the efficacy of these analogues against non-solid tumors, particularly in acute myeloid leukemia (AML), has not been fully investigated. Herein, we observed that both DMC and EF-24 significantly decrease the proportion of viable AML cells including HL-60, U937, and MV4-11, harboring different NRAS and Fms-like tyrosine kinase 3 (FLT3) statuses, and that EF-24 has a lower half maximal inhibitory concentration (IC50) than DMC. We found that EF-24 treatment induces several features of apoptosis, including an increase in the sub-G1 population, phosphatidylserine (PS) externalization, and significant activation of extrinsic proapoptotic signaling such as caspase-8 and -3 activation. Mechanistically, p38 mitogen-activated protein kinase (MAPK) activation is critical for EF-24-triggered apoptosis via activating protein phosphatase 2A (PP2A) to attenuate extracellular-regulated protein kinase (ERK) activities in HL-60 AML cells. In the clinic, patients with AML expressing high level of PP2A have the most favorable prognoses compared to various solid tumors. Taken together, our results indicate that EF-24 is a potential therapeutic agent for treating AML, especially for cancer types that lose the function of the PP2A tumor suppressor.
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Affiliation(s)
- Pei-Ching Hsiao
- School of Medicine, Chung Shan Medical University, Taichung 402, Taiwan;
- Department of Internal Medicine, Chung Shan Medical University Hospital, Taichung 402, Taiwan
| | - Jer-Hwa Chang
- School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei 110, Taiwan;
- Division of Pulmonary Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei 116, Taiwan
- Pulmonary Research Center, Wan Fang Hospital, Taipei Medical University, Taipei 116, Taiwan
| | - Wei-Jiunn Lee
- Department of Urology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 110, Taiwan;
- Department of Medical Education and Research, Wan Fang Hospital, Taipei Medical University, Taipei 116, Taiwan
| | - Chia-Chi Ku
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 110, Taiwan;
| | - Meng-Ying Tsai
- Institute of Medicine, Chung Shan Medical University, Taichung 402, Taiwan;
- Department of Medical Research, Chung Shan Medical University Hospital, Taichung 402, Taiwan
| | - Shun-Fa Yang
- Institute of Medicine, Chung Shan Medical University, Taichung 402, Taiwan;
- Department of Medical Research, Chung Shan Medical University Hospital, Taichung 402, Taiwan
- Correspondence: (S.-F.Y.); (M.-H.C.); Tel.: +886-2-2736-1661 (ext. 3237) (M.-H.C.); +886-4-2473-9595 (ext. 34253) (S.-F.Y.); Fax: +886-2-2739-0500 (M.-H.C.); +886-4-2472-3229 (S.-F.Y.)
| | - Ming-Hsien Chien
- Pulmonary Research Center, Wan Fang Hospital, Taipei Medical University, Taipei 116, Taiwan
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 110, Taiwan;
- TMU Research Center of Cancer Translational Medicine, Taipei Medical University, Taipei 110, Taiwan
- Traditional Herbal Medicine Research Center, Taipei Medical University Hospital, Taipei 110, Taiwan
- Correspondence: (S.-F.Y.); (M.-H.C.); Tel.: +886-2-2736-1661 (ext. 3237) (M.-H.C.); +886-4-2473-9595 (ext. 34253) (S.-F.Y.); Fax: +886-2-2739-0500 (M.-H.C.); +886-4-2472-3229 (S.-F.Y.)
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7
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Clark AR, Ohlmeyer M. Protein phosphatase 2A as a therapeutic target in inflammation and neurodegeneration. Pharmacol Ther 2019; 201:181-201. [PMID: 31158394 PMCID: PMC6700395 DOI: 10.1016/j.pharmthera.2019.05.016] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 05/29/2019] [Indexed: 12/11/2022]
Abstract
Protein phosphatase 2A (PP2A) is a highly complex heterotrimeric enzyme that catalyzes the selective removal of phosphate groups from protein serine and threonine residues. Emerging evidence suggests that it functions as a tumor suppressor by constraining phosphorylation-dependent signalling pathways that regulate cellular transformation and metastasis. Therefore, PP2A-activating drugs (PADs) are being actively sought and investigated as potential novel anti-cancer treatments. Here we explore the concept that PP2A also constrains inflammatory responses through its inhibitory effects on various signalling pathways, suggesting that PADs may be effective in the treatment of inflammation-mediated pathologies.
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Affiliation(s)
- Andrew R Clark
- Institute of Inflammation and Ageing, College of Medical and Dental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom.
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8
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da Costa Fernandes CJ, Ferreira MR, Bezerra FJB, Zambuzzi WF. Zirconia stimulates ECM-remodeling as a prerequisite to pre-osteoblast adhesion/proliferation by possible interference with cellular anchorage. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2018; 29:41. [PMID: 29582191 DOI: 10.1007/s10856-018-6041-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 03/05/2018] [Indexed: 06/08/2023]
Abstract
The biological response to zirconia (ZrO2) is not completely understood, which prompted us to address its effect on pre-osteoblastic cells in both direct and indirect manner. Our results showed that zirconia triggers important intracellular signaling mainly by governing survival signals which leads to cell adhesion and proliferation by modulating signaling cascade responsible for dynamic cytoskeleton rearrangement, as observed by fluorescence microscopy. The phosphorylations of Focal Adhesion Kinase (FAK) and Rac1 decreased in response to ZrO2 enriched medium. This corroborates the result of the crystal violet assay, which indicated a significant decrease of pre-osteoblast adhesion in responding to ZrO2 enriched medium. However, we credit this decrease on pre-osteoblast adhesion to the need to govern intracellular repertory of intracellular pathways involved with cell cycle progression, because we found a significant up-phosphorylation of Mitogen-Activated Protein Kinase (MAPK)-p38 and Cyclin-dependent kinase 2 (CDK2), while p15 (a cell cycle suppressor) decreased. Importantly, Protein phosphatase 2 A (PP2A) activity decreased, guaranteeing the significant up-phosphorylation of MAPK -p38 in response to ZrO2 enriched medium. Complementarily, there was a regulation of Matrix Metalloproteinases (MMPs) in response to Zirconia and this remodeling could affect cell phenotype by interfering on cell anchorage. Altogether, our results show a repertory of signaling molecules, which suggests that ECM remodel as a pre-requisite to pre-osteoblast phenotype by affecting their anchoring in responding to zirconia.
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Affiliation(s)
- Celio J da Costa Fernandes
- Bioassays and Cell Dynamics Lab, Dept. of Chemistry and Biochemistry, Bioscience Institute, Universidade Estadual Paulista - UNESP, Botucatu, Sao Paulo, Brazil
| | - Marcel Rodrigues Ferreira
- Bioassays and Cell Dynamics Lab, Dept. of Chemistry and Biochemistry, Bioscience Institute, Universidade Estadual Paulista - UNESP, Botucatu, Sao Paulo, Brazil
| | - Fábio J B Bezerra
- Bioassays and Cell Dynamics Lab, Dept. of Chemistry and Biochemistry, Bioscience Institute, Universidade Estadual Paulista - UNESP, Botucatu, Sao Paulo, Brazil
| | - Willian F Zambuzzi
- Bioassays and Cell Dynamics Lab, Dept. of Chemistry and Biochemistry, Bioscience Institute, Universidade Estadual Paulista - UNESP, Botucatu, Sao Paulo, Brazil.
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9
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Jones DS, Jenney AP, Joughin BA, Sorger PK, Lauffenburger DA. Inflammatory but not mitogenic contexts prime synovial fibroblasts for compensatory signaling responses to p38 inhibition. Sci Signal 2018; 11:11/520/eaal1601. [PMID: 29511118 DOI: 10.1126/scisignal.aal1601] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Rheumatoid arthritis (RA) is a chronic inflammatory disorder that causes joint pain, swelling, and loss of function. Development of effective new drugs has proven challenging in part because of the complexities and interconnected nature of intracellular signaling networks that complicate the effects of pharmacological interventions. We characterized the kinase signaling pathways that are activated in RA and evaluated the multivariate effects of targeted inhibitors. Synovial fluids from RA patients activated the kinase signaling pathways JAK, JNK, p38, and MEK in synovial fibroblasts (SFs), a stromal cell type that promotes RA progression. Kinase inhibitors enhanced signaling of "off-target" pathways in a manner dependent on stimulatory context. Inhibitors of p38, which have been widely explored in clinical trials for RA, resulted in undesirable increases in nuclear factor κB (NF-κB), JNK, and MEK signaling in SFs in inflammatory, but not mitogenic, contexts. This was mediated by the transcription factor CREB, which functions in part within a negative feedback loop in MAPK signaling. CREB activation was induced predominately by p38 in response to inflammatory stimuli, but by MEK in response to mitogenic stimuli; hence, the effects of drugs targeting p38 or MEK were markedly different in SFs cultured under mitogenic or inflammatory conditions. Together, these findings illustrate how stimulatory context can alter dominance in pathway cross-talk even for a fixed network topology, thereby providing a rationale for why p38 inhibitors deliver limited benefits in RA and demonstrating the need for careful consideration of p38-targeted drugs in inflammation-related disorders.
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Affiliation(s)
- Douglas S Jones
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Laboratory of Systems Pharmacology, Library of Integrated Network-based Cellular Signatures Center, Harvard Medical School, Boston, MA 02115, USA
| | - Anne P Jenney
- Laboratory of Systems Pharmacology, Library of Integrated Network-based Cellular Signatures Center, Harvard Medical School, Boston, MA 02115, USA
| | - Brian A Joughin
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Koch Institute for Integrative Cancer Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Peter K Sorger
- Laboratory of Systems Pharmacology, Library of Integrated Network-based Cellular Signatures Center, Harvard Medical School, Boston, MA 02115, USA
| | - Douglas A Lauffenburger
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. .,Koch Institute for Integrative Cancer Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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10
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MiR-181b modulates EGFR-dependent VCAM-1 expression and monocyte adhesion in glioblastoma. Oncogene 2017; 36:5006-5022. [PMID: 28459461 DOI: 10.1038/onc.2017.129] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 03/06/2017] [Accepted: 03/27/2017] [Indexed: 12/25/2022]
Abstract
Tumor-associated macrophages (TAMs) originate as circulating monocytes, and are recruited to gliomas, where they facilitate tumor growth and migration. Understanding the interaction between TAM and cancer cells may identify therapeutic targets for glioblastoma multiforme (GBM). Vascular cell adhesion molecule-1 (VCAM-1) is a cytokine-induced adhesion molecule expressed on the surface of cancer cells, which is involved in interactions with immune cells. Analysis of the glioma patient database and tissue immunohistochemistry showed that VCAM-1 expression correlated with the clinico-pathological grade of gliomas. Here, we found that VCAM-1 expression correlated positively with monocyte adhesion to GBM, and knockdown of VCAM-1 abolished the enhancement of monocyte adhesion. Importantly, upregulation of VCAM-1 is dependent on epidermal-growth-factor-receptor (EGFR) expression, and inhibition of EGFR effectively reduced VCAM-1 expression and monocyte adhesion activity. Moreover, GBM possessing higher EGFR levels (U251 cells) had higher VCAM-1 levels compared to GBMs with lower levels of EGFR (GL261 cells). Using two- and three-dimensional cultures, we found that monocyte adhesion to GBM occurs via integrin α4β1, which promotes tumor growth and invasion activity. Increased proliferation and tumor necrosis factor-α and IFN-γ levels were also observed in the adherent monocytes. Using a genetic modification approach, we demonstrated that VCAM-1 expression and monocyte adhesion were regulated by the miR-181 family, and lower levels of miR-181b correlated with high-grade glioma patients. Our results also demonstrated that miR-181b/protein phosphatase 2A-modulated SP-1 de-phosphorylation, which mediated the EGFR-dependent VCAM-1 expression and monocyte adhesion to GBM. We also found that the EGFR-dependent VCAM-1 expression is mediated by the p38/STAT3 signaling pathway. Our study suggested that VCAM-1 is a critical modulator of EGFR-dependent interaction of monocytes with GBM, which raises the possibility of developing effective and improved therapies for GBM.
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Abstract
Protein phosphatase 2A (PP2A) plays a critical multi-faceted role in the regulation of the cell cycle. It is known to dephosphorylate over 300 substrates involved in the cell cycle, regulating almost all major pathways and cell cycle checkpoints. PP2A is involved in such diverse processes by the formation of structurally distinct families of holoenzymes, which are regulated spatially and temporally by specific regulators. Here, we review the involvement of PP2A in the regulation of three cell signaling pathways: wnt, mTOR and MAP kinase, as well as the G1→S transition, DNA synthesis and mitotic initiation. These processes are all crucial for proper cell survival and proliferation and are often deregulated in cancer and other diseases.
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Affiliation(s)
- Nathan Wlodarchak
- a McArdle Laboratory for Cancer Research, University of Wisconsin-Madison , Madison , WI , USA
| | - Yongna Xing
- a McArdle Laboratory for Cancer Research, University of Wisconsin-Madison , Madison , WI , USA
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Crotty Alexander LE, Shin S, Hwang JH. Inflammatory Diseases of the Lung Induced by Conventional Cigarette Smoke: A Review. Chest 2016; 148:1307-1322. [PMID: 26135024 DOI: 10.1378/chest.15-0409] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Smoking-induced lung diseases were extremely rare prior to the 20th century. With commercialization and introduction of machine-made cigarettes, worldwide use skyrocketed and several new pulmonary diseases have been recognized. The majority of pulmonary diseases caused by cigarette smoke (CS) are inflammatory in origin. Airway epithelial cells and alveolar macrophages have altered inflammatory signaling in response to CS, which leads to recruitment of lymphocytes, eosinophils, neutrophils, and mast cells to the lungs-depending on the signaling pathway (nuclear factor-κB, adenosine monophosphate-activated protein kinase, c-Jun N-terminal kinase, p38, and signal transducer and activator of transcription 3) activated. Multiple proteins are upregulated and secreted in response to CS exposure, and many of these have immunomodulatory activities that contribute to disease pathogenesis. In particular, metalloproteases 9 and 12, surfactant protein D, antimicrobial peptides (LL-37 and human β defensin 2), and IL-1, IL-6, IL-8, and IL-17 have been found in higher quantities in the lungs of smokers with ongoing inflammation. However, many underlying mechanisms of smoking-induced inflammatory diseases are not yet known. We review here the known cellular and molecular mechanisms of CS-induced diseases, including COPD, respiratory bronchiolitis-interstitial lung disease, desquamative interstitial pneumonia, acute eosinophilic pneumonia, chronic rhinosinusitis, pulmonary Langerhans cell histiocytosis, and chronic bacterial infections. We also discuss inflammation induced by secondhand and thirdhand smoke exposure and the pulmonary diseases that result. New targeted antiinflammatory therapeutic options are currently under investigation and hopefully will yield promising results for the treatment of these highly prevalent smoking-induced diseases.
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Affiliation(s)
- Laura E Crotty Alexander
- Veterans Affairs San Diego Healthcare System; and University of California, San Diego, La Jolla, CA..
| | - Stephanie Shin
- Veterans Affairs San Diego Healthcare System; and University of California, San Diego, La Jolla, CA
| | - John H Hwang
- Veterans Affairs San Diego Healthcare System; and University of California, San Diego, La Jolla, CA
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Feng H, Gerilechaogetu F, Golden HB, Nizamutdinov D, Foster DM, Glaser SS, Dostal DE. p38α MAPK inhibits stretch-induced JNK activation in cardiac myocytes through MKP-1. Int J Cardiol 2016; 203:145-55. [DOI: 10.1016/j.ijcard.2015.10.109] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 09/20/2015] [Accepted: 10/12/2015] [Indexed: 01/18/2023]
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Geraghty P, Eden E, Pillai M, Campos M, McElvaney NG, Foronjy RF. α1-Antitrypsin activates protein phosphatase 2A to counter lung inflammatory responses. Am J Respir Crit Care Med 2014; 190:1229-42. [PMID: 25341065 PMCID: PMC4315812 DOI: 10.1164/rccm.201405-0872oc] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 09/25/2014] [Indexed: 12/26/2022] Open
Abstract
RATIONALE α1-Antitrypsin (A1AT) was identified as a plasma protease inhibitor; however, it is now recognized as a multifunctional protein that modulates immunity, inflammation, proteostasis, apoptosis, and cellular senescence. Like A1AT, protein phosphatase 2A (PP2A), a major serine-threonine phosphatase, regulates similar biologic processes and plays a key role in chronic obstructive pulmonary disease. OBJECTIVES Given their common effects, this study investigated whether A1AT acts via PP2A to alter tumor necrosis factor (TNF) signaling, inflammation, and proteolytic responses in this disease. METHODS PP2A activity was measured in peripheral blood neutrophils from A1AT-deficient (PiZZ) and healthy (PiMM) individuals and in alveolar macrophages from normal (60 mg/kg) and high-dose (120 mg/kg) A1AT-treated PiZZ subjects. PP2A activation was assessed in human neutrophils, airway epithelial cells, and peripheral blood monocytes treated with plasma purified A1AT protein. Similarly, lung PP2A activity was measured in mice administered intranasal A1AT. PP2A was silenced in lung epithelial cells treated with A1AT and matrix metalloproteinase and cytokine production was then measured following TNF-α stimulation. MEASUREMENTS AND MAIN RESULTS PP2A was significantly lower in neutrophils isolated from PiZZ compared with PiMM subjects. A1AT protein activated PP2A in human alveolar macrophages, monocytes, neutrophils, airway epithelial cells, and in mouse lungs. This activation required functionally active A1AT protein and protein tyrosine phosphatase 1B expression. A1AT treatment acted via PP2A to prevent p38 and IκBα phosphorylation and matrix metalloproteinase and cytokine induction in TNF-α-stimulated epithelial cells. CONCLUSIONS Together, these data indicate that A1AT modulates PP2A to counter inflammatory and proteolytic responses induced by TNF signaling in the lung.
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Affiliation(s)
- Patrick Geraghty
- 1 Division of Pulmonary and Critical Care Medicine, Mount Sinai Roosevelt Hospital, New York, New York
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15
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Ahmad A, Hayat I, Arif S, Masud T, Khalid N, Ahmed A. Mechanisms Involved in the Therapeutic Effects of Soybean (Glycine Max). INTERNATIONAL JOURNAL OF FOOD PROPERTIES 2014. [DOI: 10.1080/10942912.2012.714828] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Fortin CF, Mayer TZ, Cloutier A, McDonald PP. Translational control of human neutrophil responses by MNK1. J Leukoc Biol 2013; 94:693-703. [PMID: 23401599 DOI: 10.1189/jlb.0113012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A growing number of inflammatory and immune processes in vivo have been shown to be influenced by neutrophil-derived cytokines. Whereas the underlying transcriptional mechanisms are increasingly well understood, the translational regulation of this neutrophil response remains largely unexplored. Here, we show that the MNK1, which participates in translational control in several cell types, is activated in response to physiological neutrophil agonists (LPS, TNF-α) in the cytoplasmic and nuclear compartments. With the use of various pharmacological inhibitors, we found that MNK1 activation takes place downstream of the TAK1-p38 MAPK axis in neutrophils, whereas the MEK/ERK, JNK, PI3K, and PKC pathways are not involved. Pharmacological blockade of MNK1, as well as overexpression experiments, established that cytokine protein synthesis (but not gene expression) is under the control of MNK1 in neutrophils. Likewise, MNK1 inhibition reversed the antiapoptotic effect of LPS and TNF-α in neutrophils, and this was accompanied by a decreased expression of the antiapoptotic protein Mcl-1. Thus, MNK1 appears to be an important regulator of neutrophil responses. Although MNK1 inhibition did not affect protein recruitment to mRNA caps, it decreased the phosphorylation of molecules implicated in translation initiation control, such as S6K, S6, and hyperphosphorylated 4E-BP1. These molecular targets of MNK1 are shared with those of PI3K in neutrophils, and accordingly, MNK1 inhibition partially impaired the belated PI3K/Akt activation elicited by LPS or TNF in these cells. Given the importance of neutrophils and their products in numerous chronic inflammatory disorders, MNK1 could represent an attractive therapeutic target.
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Affiliation(s)
- Carl F Fortin
- 1.Pulmonary Division/Research, Université de Sherbrooke, 3001, 12e avenue Nord, pièce 4849 Sherbrooke, Québec, Canada J1H 5N4. Twitter: http://pages.usherbrooke.ca./mcdonaldlab
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Wong J, Smith LB, Magun EA, Engstrom T, Kelley-Howard K, Jandhyala DM, Thorpe CM, Magun BE, Wood LJ. Small molecule kinase inhibitors block the ZAK-dependent inflammatory effects of doxorubicin. Cancer Biol Ther 2012; 14:56-63. [PMID: 23114643 PMCID: PMC3566053 DOI: 10.4161/cbt.22628] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The adverse side effects of doxorubicin, including cardiotoxicity and cancer treatment-related fatigue, have been associated with inflammatory cytokines, many of which are regulated by mitogen-activated protein kinases (MAPKs). ZAK is an upstream kinase of the MAPK cascade. Using mouse primary macrophages cultured from ZAK-deficient mice, we demonstrated that ZAK is required for the activation of JNK and p38 MAPK by doxorubicin. Nilotinib, ponatinib and sorafenib strongly suppressed doxorubicin-mediated phosphorylation of JNK and p38 MAPK. In addition, these small molecule kinase inhibitors blocked the expression of IL-1β, IL-6 and CXCL1 RNA and the production of these proteins. Co-administration of nilotinib and doxorubicin to mice decreased the expression of IL-1β RNA in the liver and suppressed the level of IL-6 protein in the serum compared with mice that were injected with doxorubicin alone. Therefore, by reducing the production of inflammatory mediators, the inhibitors identified in the current study may be useful in minimizing the side effects of doxorubicin and potentially other chemotherapeutic drugs.
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Affiliation(s)
- John Wong
- School of Nursing, Oregon Health & Science University, Portland, OR, USA
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18
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Park CH, Chung JH. Epidermal growth factor-induced matrix metalloproteinase-1 expression is negatively regulated by p38 MAPK in human skin fibroblasts. J Dermatol Sci 2011; 64:134-41. [DOI: 10.1016/j.jdermsci.2011.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Revised: 07/15/2011] [Accepted: 07/25/2011] [Indexed: 10/17/2022]
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19
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RATAJCZAK-WRONA WIOLETTA, JABLONSKA EWA, GARLEY MARZENA, JABLONSKI JAKUB, RADZIWON PIOTR. Effect of N-nitrosodimethylamine on inducible nitric oxide synthase expression and production of nitric oxide by neutrophils and mononuclear cells: the role of JNK signalling pathway. APMIS 2011; 119:431-41. [DOI: 10.1111/j.1600-0463.2011.02750.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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20
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Abstract
DNA fragmentation is a hallmark of apoptosis that is induced by apoptotic stimuli in various cell types. Apoptotic signal pathways, which eventually cause DNA fragmentation, are largely mediated by the family of cysteinyl aspartate-specific protease caspases. Caspases mediate apoptotic signal transduction by cleavage of apoptosis-implicated proteins and the caspases themselves. In the process of caspase activation, reversible protein phosphorylation plays an important role. The activation of various proteins is regulated by phosphorylation and dephosphorylation, both upstream and downstream of caspase activation. Many kinases/phosphatases are involved in the control of cell survival and death, including the mitogen-activated protein kinase signal transduction pathways. Reversible protein phosphorylation is involved in the widespread regulation of cellular signal transduction and apoptotic processes. Therefore, phosphatase/kinase inhibitors are commonly used as apoptosis inducers/inhibitors. Whether protein phosphorylation induces apoptosis depends on many factors, such as the type of phosphorylated protein, the degree of activation and the influence of other proteins. Phosphorylation signaling pathways are intricately interrelated; it was previously shown that either induction or inhibition of phosphorylation causes cell death. Determination of the relationship between protein and phosphorylation helps to reveal how apoptosis is regulated. Here we discuss DNA fragmentation and protein phosphorylation, focusing on caspase and serine/threonine protein phosphatase activation.
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Affiliation(s)
- Ikuko Kitazumi
- Bio Process Research and Development Laboratories, Kyowa Hakko Kirin Co. Ltd, Takasaki, Gunma, Japan
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Strippoli R, Benedicto I, Foronda M, Perez-Lozano ML, Sánchez-Perales S, López-Cabrera M, Del Pozo MÁ. p38 maintains E-cadherin expression by modulating TAK1-NF-kappa B during epithelial-to-mesenchymal transition. J Cell Sci 2010; 123:4321-31. [PMID: 21098640 DOI: 10.1242/jcs.071647] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Epithelial-to-mesenchymal transition (EMT) of peritoneal mesothelial cells is a pathological process that occurs during peritoneal dialysis. EMT leads to peritoneal fibrosis, ultrafiltration failure and eventually to the discontinuation of therapy. Signaling pathways involved in mesothelial EMT are thus of great interest, but are mostly unknown. We used primary mesothelial cells from human omentum to analyze the role of the p38 MAPK signaling pathway in the induction of EMT. The use of specific inhibitors, a dominant-negative p38 mutant and lentiviral silencing of p38α demonstrated that p38 promotes E-cadherin expression both in untreated cells and in cells co-stimulated with the EMT-inducing stimuli transforming growth factor (TGF)-β1 and interleukin (IL)-1β. p38 inhibition also led to disorganization and downregulation of cytokeratin filaments and zonula occludens (ZO)-1, whereas expression of vimentin was increased. Analysis of transcription factors that repress E-cadherin expression showed that p38 blockade inhibited expression of Snail1 while increasing expression of Twist. Nuclear translocation and transcriptional activity of p65 NF-κB, an important inducer of EMT, was increased by p38 inhibition. Moreover, p38 inhibition increased the phosphorylation of TGF-β-activated kinase 1 (TAK1), NF-κB and IκBα. The effect of p38 inhibition on E-cadherin expression was rescued by modulating the TAK1-NF-κB pathway. Our results demonstrate that p38 maintains E-cadherin expression by suppressing TAK1-NF-κB signaling, thus impeding the induction of EMT in human primary mesothelial cells. This represents a novel role of p38 as a brake or 'gatekeeper' of EMT induction by maintaining E-cadherin levels.
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Affiliation(s)
- Raffaele Strippoli
- Integrin Signaling Laboratory, Department of Vascular Biology and Inflammation, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain
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Lee MH, Padmashali R, Koria P, Andreadis ST. JNK regulates binding of alpha-catenin to adherens junctions and cell-cell adhesion. FASEB J 2010; 25:613-23. [PMID: 21030692 DOI: 10.1096/fj.10-161380] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
We recently reported that c-Jun N-terminal kinase (JNK) is associated with adherens junctions and phosphorylates β-catenin at serine 33/37 and threonine 41. Here, we report that inhibition of JNK led to formation of adherens junctions, which was accompanied by dissociation of α-catenin from the β-catenin/E-cadherin complex and increased association of α-catenin with the cytoskeleton. Conversely, activation of JNK increased binding of α-catenin to β-catenin, which was blocked by the JNK inhibitor SP600125 or JNK siRNA. In addition, inhibition of JNK failed to lead to adherens junction formation in cells where α-catenin was absent or knocked down. Conversely, introduction of α-catenin restored the responsiveness of cells to JNK inhibition and led to cell-cell adhesion. Experiments with domain deletion mutants showed that binding of α-catenin to β-catenin was required for transport of adherens junction complexes to the cell surface, while binding to actin was required for translocation to the cell-cell contact sites. Collectively, our results suggest that JNK affects the association of α-catenin with the adherens junction complex and regulates adherens junctions.
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Affiliation(s)
- Meng-Horng Lee
- Bioengineering Laboratory, Department of Chemical and Biological Engineering, University at Buffalo, State University of New York, Amherst, NY 14260-4200, USA
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Habrukowich C, Han DK, Le A, Rezaul K, Pan W, Ghosh M, Li Z, Dodge-Kafka K, Jiang X, Bittman R, Hla T. Sphingosine interaction with acidic leucine-rich nuclear phosphoprotein-32A (ANP32A) regulates PP2A activity and cyclooxygenase (COX)-2 expression in human endothelial cells. J Biol Chem 2010; 285:26825-26831. [PMID: 20558741 DOI: 10.1074/jbc.m110.147058] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Sphingolipid metabolites regulate cell fate by acting on specific cellular targets. Although the influence of sphingolipids in cellular signaling has been well recognized, the exact molecular targets and how these targets influence cellular signaling mechanisms remain poorly understood. Toward this goal, we used affinity chromatography coupled with proteomics technology and identified acidic leucine-rich nuclear phosphoprotein-32A (ANP32A), an inhibitor of protein phosphatase 2A (PP2A) as a direct target of sphingosine, N,N'-dimethyl sphingosine (DMS) and phytosphingosine but not dihydrosphingosine or sphingosine 1-phosphate. Treatment of human umbilical vein endothelial cells (HUVEC) with DMS, which is not phosphorylated by sphingosine kinases, led to the activation of PP2A activity. Suppression of ANP32A with siRNA enhanced basal and DMS-activated PP2A activity suggesting that the sphingoid base binds to and relieves the inhibitory action of ANP32A on the PP2A complex. Indeed, DMS relieved the ANP32A-mediated inhibition of PP2A enzyme complex in vitro. Interestingly, DMS treatment induced the p38 stress-activated protein kinase (SAPK) and expression of cyclooxygenase (COX)-2 transcript and protein. Knockdown of ANP32A expression further induced p38 SAPK and COX-2. These data identify ANP32A as a novel molecular target of sphingoid bases that regulates cellular signaling events and inflammatory gene expression.
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Affiliation(s)
- Cheryl Habrukowich
- Center for Vascular Biology, University of Connecticut Health Center, Farmington, Connecticut 06030-3501
| | - David K Han
- Center for Vascular Biology, University of Connecticut Health Center, Farmington, Connecticut 06030-3501
| | - Andrew Le
- Calhoun Cardiology Center, Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut 06030-3501
| | - Karim Rezaul
- Center for Vascular Biology, University of Connecticut Health Center, Farmington, Connecticut 06030-3501
| | - Wei Pan
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021
| | - Mallika Ghosh
- Center for Vascular Biology, University of Connecticut Health Center, Farmington, Connecticut 06030-3501
| | - Zaiguo Li
- Department of Chemistry and Biochemistry, Queens College, City University of New York, New York, New York 11367
| | - Kimberly Dodge-Kafka
- Calhoun Cardiology Center, Department of Cell Biology, University of Connecticut Health Center, Farmington, Connecticut 06030-3501
| | - Xuejun Jiang
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021
| | - Robert Bittman
- Department of Chemistry and Biochemistry, Queens College, City University of New York, New York, New York 11367
| | - Timothy Hla
- Center for Vascular Biology, University of Connecticut Health Center, Farmington, Connecticut 06030-3501; Center for Vascular Biology, Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, Cornell University, New York, New York 10065.
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Ear T, Fortin CF, Simard FA, McDonald PP. Constitutive Association of TGF-β–Activated Kinase 1 with the IκB Kinase Complex in the Nucleus and Cytoplasm of Human Neutrophils and Its Impact on Downstream Processes. THE JOURNAL OF IMMUNOLOGY 2010; 184:3897-906. [DOI: 10.4049/jimmunol.0902958] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Fan WJ, van Vuuren D, Genade S, Lochner A. Kinases and phosphatases in ischaemic preconditioning: a re-evaluation. Basic Res Cardiol 2010; 105:495-511. [PMID: 20127248 DOI: 10.1007/s00395-010-0086-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 01/12/2010] [Accepted: 01/14/2010] [Indexed: 11/30/2022]
Abstract
Activation of several protein kinases occurs during myocardial ischaemia and during subsequent reperfusion. In contrast to the intensive investigation into the significance of kinase activation in cardioprotection, relatively little is known about the role of the phosphatases in this regard. The aim of this study was to re-evaluate the putative roles of PP1 and PP2A in ischaemia/reperfusion and in triggering ischaemic preconditioning. Isolated perfused working rat hearts were subjected to sustained global (15 or 20 min) or regional ischaemia (35 min), followed by reperfusion. Hearts were preconditioned using global ischaemia (1 x 5 or 3 x 5 min, alternated with 5 min reperfusion). To inhibit both PP1 and PP2A cantharidin (5 muM) was used. To inhibit PP2A only, okadaic acid (7.5 nM) was used. The drugs were administered during the preconditioning protocol, before onset of sustained ischaemia (pretreatment) or during reperfusion. Endpoints were mechanical recovery during reperfusion, infarct size and activation of PKB/Akt, p38 MAPK and ERK p42/p44, as determined by Western blot. Pretreatment of hearts with okadaic acid or cantharidin caused a significant reduction in mechanical recovery after 15 or 20 min global ischaemia. Administration of the drugs during an ischaemic preconditioning protocol abolished functional recovery during reperfusion and significantly increased infarct size. Administration of the drugs during reperfusion had no deleterious effects and increased functional recovery in 3 x PC hearts. To find an explanation for the differential effects of the inhibitors depending on the time of administration, hearts were freeze-clamped at different time points during the perfusion protocol. Administration of cantharidin before 5 min ischaemia activated all kinases. Subsequent reperfusion for 5 min without the drug maintained activation of the kinases until the onset of sustained ischaemia. Cantharidin given during preconditioning was associated with activation of p38MAPK and PKB/Akt during reperfusion after sustained ischaemia. However, administration of the drug during reperfusion only after sustained ischaemia caused activation of both PKB/Akt and ERK p42/p44. Phosphatase inhibition immediately prior to the onset of sustained ischaemia or during preconditioning abolishes protection during reperfusion, while inhibition of these enzymes during reperfusion either had no effect or enhanced the cardioprotective effects of preconditioning. It is proposed that inhibition of phosphatases during reperfusion may prolong the period of RISK activation and hence protect the heart.
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Affiliation(s)
- W J Fan
- Division of Medical Physiology, Department of Biomedical Sciences, Faculty of Health Sciences, University of Stellenbosch, Tygerberg, Republic of South Africa
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Calvo N, de Boland AR, Gentili C. PTH inactivates the AKT survival pathway in the colonic cell line Caco-2. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1803:343-51. [PMID: 20005908 DOI: 10.1016/j.bbamcr.2009.11.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Revised: 11/25/2009] [Accepted: 11/30/2009] [Indexed: 12/28/2022]
Abstract
In previous works, we found that PTH promotes the apoptosis of human Caco-2 intestinal cells, through the mitochondrial pathway. This study was conducted to investigate the modulation of different players implicated in the AKT survival pathway in PTH-induced intestinal cell apoptosis. We demonstrate, for the first time, that PTH modulates AKT phosphorylation in response to apoptosis via the serine/threonine phosphatase PP2A. PTH treatment induces an association of AKT with the catalytic subunit of PP2A and increases its phosphatase activity. PTH also promotes the translocation of PP2Ac from the cytosol to the mitochondria. Furthermore, our results suggest that PP2A plays a role in hormone-dependent Caco-2 cells viability and in the cleavage of caspase-3 and its substrate PARP. The cAMP pathway also contributes to PTH-mediated AKT dephosphorylation while PKC and p38 MAPK do not participate in this event. Finally, we show that PTH induces the dissociation between 14-3-3 and AKT, but the significance of this response remains unknown. In correlation with PTH-induced Bad dephosphorylation, the hormone also decreases the basal association of 14-3-3 and Bad. Overall, our data suggest that in Caco-2 cells, PP2A and the cAMP pathway act in concert to inactivate the AKT survival pathway in PTH-induced intestinal cell apoptosis.
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Affiliation(s)
- Natalia Calvo
- Department Biología, Bioquímica y Farmacia, Universidad Nacional del Sur, San Juan 670, (8000) Bahía Blanca, Argentina
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O'Shaughnessy RFL, Welti JC, Sully K, Byrne C. Akt-dependent Pp2a activity is required for epidermal barrier formation during late embryonic development. Development 2009; 136:3423-31. [PMID: 19762425 DOI: 10.1242/dev.037010] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Acquisition of epidermal barrier function occurs late in mouse gestation. Several days before birth a wave of barrier acquisition sweeps across murine fetal skin, converging on dorsal and ventral midlines. We investigated the molecular pathways active during epidermal barrier formation. Akt signaling increased as the barrier wave crossed epidermis and Jun was transiently dephosphorylated. Inhibitor experiments on embryonic explants showed that the dephosphorylation of Jun was dependent on both Akt and protein phosphatase 2A (Pp2a). Inhibition of Pp2a and Akt signaling also caused defects in epidermal barrier formation. These data are compatible with a model for developmental barrier acquisition mediated by Pp2a regulation of Jun dephosphorylation, downstream of Akt signaling. Support for this model was provided by siRNA-mediated knockdown of Ppp2r2a (Pr55alpha or B55alpha), a regulatory subunit of Pp2a expressed in an Akt-dependent manner in epidermis during barrier formation. Ppp2r2a reduction caused significant increase in Jun phosphorylation and interfered with the acquisition of barrier function, with barrier acquisition being restored by inhibition of Jun phosphorylation. Our data provide strong evidence that Ppp2r2a is a regulatory subunit of Pp2a that targets this phosphatase to Jun, and that Pp2a action is necessary for barrier formation. We therefore describe a novel Akt-dependent Pp2a activity that acts at least partly through Jun to affect initial barrier formation during late embryonic epidermal development.
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Affiliation(s)
- Ryan F L O'Shaughnessy
- Centre for Cutaneous Research, Institute of Cell and Molecular Science, Barts and the London School of Medicine and Dentistry, London, UK.
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Kurdi M, Booz GW. JAK redux: a second look at the regulation and role of JAKs in the heart. Am J Physiol Heart Circ Physiol 2009; 297:H1545-56. [PMID: 19717737 DOI: 10.1152/ajpheart.00032.2009] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A number of type 1 receptor cytokine family members protect the heart from acute and chronic oxidative stress. This protection involves activation of two intracellular signaling cascades: the reperfusion injury salvage kinase (RISK) pathway, which entails activation of phosphatidylinositol 3-kinase (PI3-kinase) and ERK1/2, and JAK-STAT signaling, which involves activation of transcription factor signal transducer and activator of transcription 3 (STAT3). Obligatory for activation of both RISK and STAT3 by nearly all of these cytokines are the kinases JAK1 and JAK2. Yet surprisingly little is known about how JAK1 and JAK2 are regulated in the heart or how they couple to PI3-kinase activation. Although the JAKs are linked to antioxidative stress programs in the heart, we recently reported that these kinases are inhibited by oxidative stress in cardiac myocytes. In contrast, others have reported that cardiac JAK2 is activated by acute oxidative stress by an undefined process. Here we summarize recent insights into the regulation of JAK1 and JAK2. Besides oxidative stress, inhibitory regulation involves phosphorylation, nitration, and intramolecular restraints. Stimulatory regulation involves phosphorylation and adaptor proteins. The net effect of stress on JAK activity in the heart likely represents the sum of both inhibitory and stimulatory processes, along with their dynamic interaction. Thus the regulation of JAKs in the heart, once touted as the paragon of simplicity, is proving rather complicated indeed, requiring a second look. It is our contention that a better understanding of the regulation of this kinase family that is implicated in cardiac protection could translate into effective therapeutic strategies for preventing myocardial damage or repairing the injured heart.
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Affiliation(s)
- Mazen Kurdi
- Department of Chemistry and Biochemistry, Faculty of Sciences, Lebanese University, Rafic Hariri Educational Campus, Hadath, Lebanon
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Lee MH, Koria P, Qu J, Andreadis ST. JNK phosphorylates beta-catenin and regulates adherens junctions. FASEB J 2009; 23:3874-83. [PMID: 19667122 DOI: 10.1096/fj.08-117804] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The c-Jun amino-terminal kinase (JNK) is an important player in inflammation, proliferation, and apoptosis. More recently, JNK was found to regulate cell migration by phosphorylating paxillin. Here, we report a novel role of JNK in cell adhesion. Specifically, we provide evidence that JNK binds to E-cadherin/beta-catenin complex and phosphorylates beta-catenin at serine 37 and threonine 41, the sites also phosphorylated by GSK-3beta. Inhibition of JNK kinase activity using dominant-negative constructs reduces phosphorylation of beta-catenin and promotes localization of E-cadherin/beta-catenin complex to cell-cell contact sites. Conversely, activation of JNK induces beta-catenin phosphorylation and disruption of cell contacts, which are prevented by JNK siRNA. We propose that JNK binds to beta-catenin and regulates formation of adherens junctions, ultimately controlling cell-to-cell adhesion.
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Affiliation(s)
- Meng-Horng Lee
- Bioengineering Laboratory, 908 Furnas Hall, Department of Chemical and Biological Engineering, University at Buffalo, State University of New York, Amherst, NY 14260, USA
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Cornell TT, Hinkovska-Galcheva V, Sun L, Cai Q, Hershenson MB, Vanway S, Shanley TP. Ceramide-dependent PP2A regulation of TNFalpha-induced IL-8 production in respiratory epithelial cells. Am J Physiol Lung Cell Mol Physiol 2009; 296:L849-56. [PMID: 19286927 DOI: 10.1152/ajplung.90516.2008] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
IL-8 is a key mediator in the pathophysiology of acute lung injury. TNFalpha stimulates IL-8 production in respiratory epithelial cells by activating both the NF-kappaB and MAP kinase pathways. The precise mechanism by which these pathways are downregulated to terminate IL-8 production remains unclear. We studied the regulatory role of the serine/threonine phosphatase, PP2A, on the signaling pathways involved in IL-8 production from respiratory epithelial cells. Inhibition of PP2A using okadaic acid or gene knockdown using siRNA resulted in an augmentation of TNFalpha-induced IL-8 production. We also found that PP2A inhibition resulted in prolonged activation of JNK, p38, and ERK resulting in both increased transcriptional activation of the IL-8 promoter and posttranscriptional stabilization of IL-8 mRNA. Because TNFalpha had been shown to activate ceramide accumulation, and separate studies had linked ceramide with activation of PP2A, we hypothesized the pathway of TNFalpha-inducing ceramide to activate PP2A comprised an endogenous regulatory pathway. Inhibition of the immediate sphingomyelinase-dependent pathway as well as the de novo synthesis pathway of ceramide production reduced serine/threonine phosphatase activity and augmented IL-8 production. These data suggest that ceramide plays a role in activating PP2A to terminate ongoing IL-8 production. In summary, our data suggest that in respiratory epithelium, TNFalpha induces ceramide accumulation, resulting in subsequent activation of PP2A, which targets those kinases responsible for transcriptional activation of IL-8.
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Affiliation(s)
- Timothy T Cornell
- Division of Pediatric Critical Care Medicine, C. S. Mott Children's Hospital, Ann Arbor, MI 48109-0243, USA.
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Yoon CH, Kim MJ, Park MT, Byun JY, Choi YH, Yoo HS, Lee YM, Hyun JW, Lee SJ. Activation of p38 Mitogen-Activated Protein Kinase Is Required for Death Receptor–Independent Caspase-8 Activation and Cell Death in Response to Sphingosine. Mol Cancer Res 2009; 7:361-70. [DOI: 10.1158/1541-7786.mcr-08-0069] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Schwartz L, Abolhassani M, Pooya M, Steyaert JM, Wertz X, Israël M, Guais A, Chaumet-Riffaud P. Hyperosmotic stress contributes to mouse colonic inflammation through the methylation of protein phosphatase 2A. Am J Physiol Gastrointest Liver Physiol 2008; 295:G934-41. [PMID: 18755808 DOI: 10.1152/ajpgi.90296.2008] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
There are several reports suggesting hyperosmotic contents in the feces of patients suffering from inflammatory bowel disease (IBD). Previous works have documented that hyperosmolarity can cause inflammation attributable to methylation of the catalytic subunit of protein phosphatase 2A (PP2A) and subsequent NF-kappaB activation resulting in cytokine secretion. In this study, we demonstrate that dextran sulfate sodium (DSS) induces colitis due to hyperosmolarity and subsequent PP2A activation. Mice were randomized and fed with increased concentrations of DSS (0 mOsm, 175 mOsm, 300 mOsm, and 627 mOsm) for a duration of 3 wk or with hyperosmotic concentrations of DSS (627 mOsm) or mannitol (450 mOsm) for a duration of 12 wk. Long-term oral administration of hyposmotic DSS or mannitol had no demonstrable effect. Hyperosmotic DSS or mannitol produced a significant increase in colonic inflammation, as well as an increase in the weight of sacral lymph nodes and in serum amyloid A protein levels. Similar results were obtained through the ingestion of comparable osmolarities of mannitol. Hyperosmolarity induces the methylation of PP2A, nuclear p65 NF-kappaB activation. and cytokine secretion. The rectal instillation of okadaic acid, a well-known PP2A inhibitor, reverses the IBD. Short inhibiting RNAs (siRNAs) targeted toward PP2Ac reverse the effect of hyperosmotic DSS. The present study strongly suggests that DSS-induced chronic colitis is a consequence of the methylation of PP2Ac induced by hyperosmolarity.
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Affiliation(s)
- Laurent Schwartz
- Service de Radiothérapie Hôpital Pitié-Salpétrière, bd. de l'Hôpital, 75013 Paris, France.
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Zhang YY, Mei ZQ, Wu JW, Wang ZX. Enzymatic activity and substrate specificity of mitogen-activated protein kinase p38alpha in different phosphorylation states. J Biol Chem 2008; 283:26591-601. [PMID: 18669639 PMCID: PMC3258911 DOI: 10.1074/jbc.m801703200] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Revised: 07/10/2008] [Indexed: 11/06/2022] Open
Abstract
The mitogen-activated protein (MAP) kinases are essential signaling molecules that mediate many cellular effects of growth factors, cytokines, and stress stimuli. Full activation of the MAP kinases requires dual phosphorylation of the Thr and Tyr residues in the TXY motif of the activation loop by MAP kinase kinases. Down-regulation of MAP kinase activity can be initiated by multiple serine/threonine phosphatases, tyrosine-specific phosphatases, and dual specificity phosphatases (MAP kinase phosphatases). This would inevitably lead to the formation of monophosphorylated MAP kinases. However, the biological functions of these monophosphorylated MAP kinases are currently not clear. In this study, we have prepared MAP kinase p38alpha, a member of the MAP kinase family, in all phosphorylated forms and characterized their biochemical properties. Our results indicated the following: (i) p38alpha phosphorylated at both Thr-180 and Tyr-182 was 10-20-fold more active than p38alpha phosphorylated at Thr-180 only, whereas p38alpha phosphorylated at Tyr-182 alone was inactive; (ii) the dual-specific MKP5, the tyrosine-specific hematopoietic protein-tyrosine phosphatase, and the serine/threonine-specific PP2Calpha are all highly specific for the dephosphorylation of p38alpha, and the dephosphorylation rates were significantly affected by different phosphorylated states of p38alpha; (iii) the N-terminal domain of MPK5 has no effect on enzyme catalysis, whereas deletion of the MAP kinase-binding domain in MKP5 leads to a 370-fold decrease in k(cat)/K(m) for the dephosphorylation of p38alpha. This study has thus revealed the quantitative contributions of phosphorylation of Thr, Tyr, or both to the activation of p38alpha and to the substrate specificity for various phosphatases.
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Affiliation(s)
- Yuan-Yuan Zhang
- Key Laboratory of Ministry of Education
for Bioinformatics, Department of Biological Sciences and Biotechnology,
Tsinghua University, Beijing 100084 and National
Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica,
Beijing 100101, China
| | - Zi-Qing Mei
- Key Laboratory of Ministry of Education
for Bioinformatics, Department of Biological Sciences and Biotechnology,
Tsinghua University, Beijing 100084 and National
Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica,
Beijing 100101, China
| | - Jia-Wei Wu
- Key Laboratory of Ministry of Education
for Bioinformatics, Department of Biological Sciences and Biotechnology,
Tsinghua University, Beijing 100084 and National
Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica,
Beijing 100101, China
| | - Zhi-Xin Wang
- Key Laboratory of Ministry of Education
for Bioinformatics, Department of Biological Sciences and Biotechnology,
Tsinghua University, Beijing 100084 and National
Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica,
Beijing 100101, China
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McLaughlin NJD, Banerjee A, Khan SY, Lieber JL, Kelher MR, Gamboni-Robertson F, Sheppard FR, Moore EE, Mierau GW, Elzi DJ, Silliman CC. Platelet-activating factor-mediated endosome formation causes membrane translocation of p67phox and p40phox that requires recruitment and activation of p38 MAPK, Rab5a, and phosphatidylinositol 3-kinase in human neutrophils. THE JOURNAL OF IMMUNOLOGY 2008; 180:8192-203. [PMID: 18523285 DOI: 10.4049/jimmunol.180.12.8192] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Neutrophils (polymorphonuclear leukocytes, PMNs) are vital to innate immunity and receive proinflammatory signals that activate G protein-coupled receptors (GPCRs). Because GPCRs transduce signals through clathrin-mediated endocytosis (CME), we hypothesized that platelet-activating factor (PAF), an effective chemoattractant that primes the PMN oxidase, would signal through CME, specifically via dynamin-2 activation and endosomal formation resulting in membrane translocation of cytosolic phagocyte oxidase (phox) proteins. PMNs were incubated with buffer or 2 muM PAF for 1-3 min, and in some cases activated with PMA, and O(2)(-) was measured, whole-cell lysates and subcellular fractions were prepared, or the PMNs were fixed onto slides for digital or electron microscopy. PAF caused activation of dynamin-2, resulting in endosomal formation that required PI3K and contained early endosomal Ag-1 (EEA-1) and Rab5a. The apoptosis signal-regulating kinase-1/MAPK kinase-3/p38 MAPK signalosome assembled on Rab5a and phosphorylated EEA-1 and Rab GDP dissociation inhibitor, with the latter causing Rab5a activation. Electron microscopy demonstrated that PAF caused two distinct sites for activation of p38 MAPK. EEA-1 provided a scaffold for recruitment of the p40(phox)-p67(phox) complex and PI3K-dependent Akt1 phosphorylation of these two phox proteins. PAF induced membrane translocation of p40(phox)-p67(phox) localizing to gp91(phox), which was PI3K-, but not p47(phox)-, dependent. In conclusion, PAF transduces signals through CME, and such GPCR signaling may allow for pharmacological manipulation of these cells to decrease PMN-mediated acute organ injury.
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Affiliation(s)
- Nathan J D McLaughlin
- Bonfils Blood Center, University of Colorado Denver School of Medicine, Children's Hospital, Denver, CO 80230, USA
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Eichhorn PJA, Creyghton MP, Bernards R. Protein phosphatase 2A regulatory subunits and cancer. Biochim Biophys Acta Rev Cancer 2008; 1795:1-15. [PMID: 18588945 DOI: 10.1016/j.bbcan.2008.05.005] [Citation(s) in RCA: 273] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Revised: 05/20/2008] [Accepted: 05/21/2008] [Indexed: 01/06/2023]
Abstract
The serine/threonine protein phosphatase (PP2A) is a trimeric holoenzyme that plays an integral role in the regulation of a number of major signaling pathways whose deregulation can contribute to cancer. The specificity and activity of PP2A are highly regulated through the interaction of a family of regulatory B subunits with the substrates. Accumulating evidence indicates that PP2A acts as a tumor suppressor. In this review we summarize the known effects of specific PP2A holoenzymes and their roles in cancer relevant pathways. In particular we highlight PP2A function in the regulation of MAPK and Wnt signaling.
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Affiliation(s)
- Pieter J A Eichhorn
- Division of Molecular Carcinogenesis, Center for Cancer Genomics and Center for Biomedical Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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36
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Eichhorn PJA, Creyghton MP, Wilhelmsen K, van Dam H, Bernards R. A RNA interference screen identifies the protein phosphatase 2A subunit PR55gamma as a stress-sensitive inhibitor of c-SRC. PLoS Genet 2008; 3:e218. [PMID: 18069897 PMCID: PMC2134945 DOI: 10.1371/journal.pgen.0030218] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2007] [Accepted: 10/15/2007] [Indexed: 11/18/2022] Open
Abstract
Protein Phosphatase type 2A (PP2A) represents a family of holoenzyme complexes with diverse biological activities. Specific holoenzyme complexes are thought to be deregulated during oncogenic transformation and oncogene-induced signaling. Since most studies on the role of this phosphatase family have relied on the use of generic PP2A inhibitors, the contribution of individual PP2A holoenzyme complexes in PP2A-controlled signaling pathways is largely unclear. To gain insight into this, we have constructed a set of shRNA vectors targeting the individual PP2A regulatory subunits for suppression by RNA interference. Here, we identify PR55γ and PR55δ as inhibitors of c-Jun NH2-terminal kinase (JNK) activation by UV irradiation. We show that PR55γ binds c-SRC and modulates the phosphorylation of serine 12 of c-SRC, a residue we demonstrate to be required for JNK activation by c-SRC. We also find that the physical interaction between PR55γ and c-SRC is sensitive to UV irradiation. Our data reveal a novel mechanism of c-SRC regulation whereby in response to stress c-SRC activity is regulated, at least in part, through loss of the interaction with its inhibitor, PR55γ. Protein Phosphatase type 2A (PP2A) represent a family of holoenzyme complexes involved in wide range of activities such as growth, differentiation, and cell death. The PP2A holoenzyme complex is made up of a catalytic, a structural, and one of various “B” subunits. These “B” subunits are thought to provide the substrate specificity required for PP2A activity. Previous work on PP2A has mostly been derived by inhibiting the catalytic subunit through chemical inhibition, as such inhibiting all of the pathways associated with PP2A. To identify individual “B” subunits involved in specific cellular processes we have generated a “B” subunit gene knockdown library, which allows us to inhibit each of the known “B” subunits individually. One of the many pathways regulated by PP2A is the c-Jun NH2-terminal kinase (JNK) kinase pathway, which, depending on stimulus, can affect either cell survival or cell proliferation. Here we report that the “B” subunit PR55γ acts as a negative regulator of JNK activity and cell death. We show that PR55γ influences JNK activity by inhibiting one of its upstream regulators, the proto-oncogene c-SRC, through dephosphorylation at one of the key residues on c-SRC, a site we show to be critical for c-SRC activation following cell stress. Overall our work describes the novel function of a specific PP2A subunit involved in cell survival and identifies a novel mechanism of c-SRC regulation.
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Affiliation(s)
- Pieter J. A Eichhorn
- Division of Molecular Carcinogenesis, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Menno P Creyghton
- Division of Molecular Carcinogenesis, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Kevin Wilhelmsen
- Division of Cell Biology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
- Center for Biomedical Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Hans van Dam
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - René Bernards
- Division of Molecular Carcinogenesis, The Netherlands Cancer Institute, Amsterdam, The Netherlands
- * To whom correspondence should be addressed. E-mail:
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Carneiro AMD, Cook EH, Murphy DL, Blakely RD. Interactions between integrin alphaIIbbeta3 and the serotonin transporter regulate serotonin transport and platelet aggregation in mice and humans. J Clin Invest 2008; 118:1544-52. [PMID: 18317590 DOI: 10.1172/jci33374] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2007] [Accepted: 01/09/2008] [Indexed: 01/08/2023] Open
Abstract
The essential contribution of the antidepressant-sensitive serotonin (5-HT) transporter SERT (which is encoded by the SLC6A4 gene) to platelet 5-HT stores suggests an important role of this transporter in platelet function. Here, using SERT-deficient mice, we have established a role for constitutive SERT expression in efficient ADP- and thrombin-triggered platelet aggregation. Additionally, using pharmacological blockers of SERT and the vesicular monoamine transporter (VMAT), we have identified a role for ongoing 5-HT release and SERT activity in efficient human platelet aggregation. We have also demonstrated that fibrinogen, an activator of integrin alphaIIbbeta3, enhances SERT activity in human platelets and that integrin alphaIIbbeta3 interacts directly with the C terminus of SERT. Consistent with these findings, knockout mice lacking integrin beta3 displayed diminished platelet SERT activity. Conversely, HEK293 cells engineered to express human SERT and an activated form of integrin beta3 exhibited enhanced SERT function that coincided with elevated SERT surface expression. Our results support an unsuspected role of alphaIIbbeta3/SERT associations as well as alphaIIbbeta3 activation in control of SERT activity in vivo that may have broad implications for hyperserotonemia, cardiovascular disorders, and autism.
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Affiliation(s)
- Ana Marin D Carneiro
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-8548, USA
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Hanke NT, Finch JS, Bowden GT. Loss of catalase increases malignant mouse keratinocyte cell growth through activation of the stress activated JNK pathway. Mol Carcinog 2008; 47:349-60. [PMID: 17935202 DOI: 10.1002/mc.20391] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A cell line that produces mouse squamous cell carcinoma (6M90) was modified to develop a cell line with an introduced Tet-responsive catalase transgene (MTOC2). We have previously reported that the overexpressed catalase in the MTOC2 cells reverses the malignant phenotype in part by decreasing epidermal growth factor receptor (EGFR) signaling. With this work we expanded the investigation into the differences between these two cell lines. We found that the decreased EGFR pathway activity of the MTOC2 cells is not because of reduced autocrine secretion of an epidermal growth factor (EGF) ligand but rather because of lower basal receptor activity. Phosphorylated levels of the mitogen-activated protein kinase (MAPK) members JNK and p38 were both higher in the 6M90 cells with low catalase when compared with the MTOC2 cell line. Although treatment with an EGFR inhibitor, AG1478, blocked the increased activity of JNK in the 6M90 cells, a similar effect was not observed for p38. Basal levels of downstream c-jun transcription were also found to be higher in the 6M90 cells versus MTOC2 cells. Activated p38 was found to down-regulate the JNK MAPK pathway in the 6M90 cells. However, the 6M90 cells contain constitutively high levels of phosphorylated JNK, generating higher levels of phosphorylated c-jun and total c-jun than those in the MTOC2 cells. Inhibition of JNK activity in the 6M90 cells reduced AP-1 transcription and cell proliferation. The data confirm the inhibitory effects of catalase on tumor cell growth, specifically through a ligand-independent decrease in the stress activated JNK pathway.
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Affiliation(s)
- Neale T Hanke
- Arizona Cancer Center, University of Arizona, Tucson, AZ 85724-5024, USA
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GONG Y, ZHANG Z. Alternative Pathway Approach for Automating Analysis and Validation of Cell Perturbation Networks and Design of Perturbation Experiments. Ann N Y Acad Sci 2007; 1115:267-85. [DOI: 10.1196/annals.1407.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Sukhumavasi W, Egan CE, Denkers EY. Mouse Neutrophils Require JNK2 MAPK for Toxoplasma gondii-Induced IL-12p40 and CCL2/MCP-1 Release. THE JOURNAL OF IMMUNOLOGY 2007; 179:3570-7. [PMID: 17785791 DOI: 10.4049/jimmunol.179.6.3570] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The MAPK family member JNK/stress-activated MAPK (SAPK) is involved in extracellular stress and proinflammatory cytokine responses, including production of cytokines such as IL-12. The JNK1 and 2 isoforms are widely expressed, but JNK3 is largely restricted to tissues of the brain, testis, and heart. In this study, we focus on mouse neutrophils, a cell type in which JNK/SAPK expression and activity has been given little study. We used Western blot analysis to examine expression patterns of JNK/SAPK in wild-type and JNK2-/- polymorphonuclear leukocytes (PMN). Surprisingly, neutrophils displayed a major deficiency in JNK1 expression, in contrast to macrophages that expressed high levels of both JNK1 and JNK2 MAPK. JNK1 expression was steadily reduced during the neutrophil maturation in bone marrow. We used PMN infection with the protozoan parasite Toxoplasma gondii to determine whether neutrophil JNK2 was functional. The parasite induced rapid JNK2 phosphorylation and intracellular FACS staining demonstrated preferential activation in infected neutrophils. Use of JNK2-/- neutrophils revealed that this MAPK family member was required for PMN IL-12p40 and CCL2/MCP-1 production. The chemotactic response displayed a minor JNK2 dependence but phagocytosis and oxidative burst activity did not require this MAPK. These findings are important because they demonstrate 1) a previously unrecognized unusual JNK expression pattern in mouse neutrophils, 2) JNK2 in PMN is activated by Toxoplasma invasion, and 3) a requirement for JNK2 in PMN IL-12p40 and CCL2/MCP-1 production in response to a microbial pathogen.
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Affiliation(s)
- Woraporn Sukhumavasi
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
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41
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Park HY, Song MG, Lee JS, Kim JW, Jin JO, Park JI, Chang YC, Kwak JY. Apoptosis of human neutrophils induced by protein phosphatase 1/2A inhibition is caspase-independent and serine protease-dependent. J Cell Physiol 2007; 212:450-62. [PMID: 17311286 DOI: 10.1002/jcp.21039] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Protein phosphatase (PP) activity is associated with the regulation of apoptosis in neutrophils. However, the underlying regulatory mechanism(s) in apoptosis remain unclear. The type of cell death induced by okadaic acid (OA), the inhibitor of PP1 and PP2A, is characterized by apoptotic morphological changes of the cells and annexin V-positive staining without DNA fragmentation. The apoptotic effects of OA and calyculin A on neutrophils were observed at concentrations ranging from 50 to 200 nM, or 10 to 50 nM, respectively. Cyclosporine A (a PP2B specific inhibitor), however, did not exhibit any pro-apoptotic effects. OA and calyculin A, but not cyclosporine A, exhibited significant effects on protein levels and on the electrophoretic mobility of Mcl-1. zVAD-fmk, a pancaspase inhibitor, failed to inhibit the effect of OA on the caspase-3 activity, procaspase-3 processing, and the apoptotic rate of neutrophils. However, 4-(2-aminoethyl) benzenesulfonylfluoride (AEBSF), a general serine protease inhibitor, significantly abrogated the OA-induced mobility shift in procaspase-3, caspase-3 activation, and the apoptotic morphological changes in neutrophils. Moreover, OA enhanced the serine protease activity of the neutrophils. The addition of the proteinase-3 protein increased the rate of neutrophil apoptosis, which was also blocked by AEBSF but not by zVAD-fmk. These results suggest that OA induces procaspase-3 processing but that OA-induced apoptosis is caspase-independent and serine protease-dependent.
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Affiliation(s)
- Hae-Young Park
- Department of Biochemistry, School of Medicine and Medical Research Center for Cancer Molecular Therapy, Dong-A University, Busan, Korea
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42
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Prickett TD, Brautigan DL. Cytokine activation of p38 mitogen-activated protein kinase and apoptosis is opposed by alpha-4 targeting of protein phosphatase 2A for site-specific dephosphorylation of MEK3. Mol Cell Biol 2007; 27:4217-27. [PMID: 17438131 PMCID: PMC1900036 DOI: 10.1128/mcb.00067-07] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Revised: 02/09/2007] [Accepted: 03/26/2007] [Indexed: 12/20/2022] Open
Abstract
alpha-4 is an essential gene and is a dominant antiapoptotic factor in various tissues that is a regulatory subunit for type 2A protein phosphatases. A multiplexed phosphorylation site screen revealed that knockdown of alpha-4 by small interfering RNA (siRNA) increased p38 mitogen-activated protein kinase (MAPK) and c-Jun phosphorylation without changes in JNK or ERK. FLAG-alpha-4 coprecipitated hemagglutinin-MEK3 plus endogenous protein phosphatase 2A (PP2A) and selectively enhanced dephosphorylation of Thr193, but not Ser189, in the activation loop of MEK3. Overexpression of alpha-4 suppressed p38 MAPK activation in response to tumor necrosis factor alpha (TNF-alpha). The alpha-4 dominant-negative domain (DND) (residues 220 to 340) associated with MEK3, but not PP2A, and its overexpression sensitized cells to activation of p38 MAPK by TNF-alpha and interleukin-1beta, but not by ansiomycin or sorbitol. The response was diminished by nocodazole or by siRNA knockdown of the Opitz syndrome protein Mid1 that binds alpha-4 to microtubules. Interference by alpha-4 DND or alpha-4 siRNA increased caspase 3/7 activation in response to TNF-alpha. Growth of transformed cells in soft agar was enhanced by alpha-4 and suppressed by alpha-4 DND. The results show that alpha-4 targets PP2A activity to MEK3 to suppress p38 MAPK activation by cytokines, thereby inhibiting apoptosis and anoikis.
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Affiliation(s)
- Todd D Prickett
- Center for Cell Signaling and Department of Microbiology, University of Virginia School of Medicine, Jefferson Park Avenue, Hospital West Complex, Room 7225, Charlottesville, VA 22908-1400, USA
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Stantchev TS, Markovic I, Telford WG, Clouse KA, Broder CC. The tyrosine kinase inhibitor genistein blocks HIV-1 infection in primary human macrophages. Virus Res 2006; 123:178-89. [PMID: 17030448 PMCID: PMC1847631 DOI: 10.1016/j.virusres.2006.09.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2006] [Revised: 09/06/2006] [Accepted: 09/07/2006] [Indexed: 11/27/2022]
Abstract
Binding of HIV-1 envelope glycoprotein (Env) to its cellular receptors elicits a variety of signaling events, including the activation of select tyrosine kinases. To evaluate the potential role of such signaling, we examined the effects of the tyrosine kinase inhibitor, genistein, on HIV-1 entry and infection of human macrophages using a variety of assays. Without altering cell viability, cell surface expression of CD4 and CCR5 or their abilities to interact with Env, genistein inhibited infection of macrophages by reporter gene-encoding, beta-lactamase containing, or wild type virions, as well as Env-mediated cell-fusion. The observation that genistein blocked virus infection if applied before, during or immediately after the infection period, but not 24h later; coupled with a more pronounced inhibition of infection in the reporter gene assays as compared to both beta-lactamase and p24 particle entry assays, imply that genistein exerts its inhibitory effects on both entry and early post-entry steps. These findings suggest that other exploitable targets, or steps, of the HIV-1 infection process may exist and could serve as additional opportunities for the development of new therapeutics.
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Affiliation(s)
- Tzanko S Stantchev
- Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University Bethesda, 4301 Jones Bridge Road, MD 20814, USA
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44
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Imajo M, Tsuchiya Y, Nishida E. Regulatory mechanisms and functions of MAP kinase signaling pathways. IUBMB Life 2006; 58:312-7. [PMID: 16754324 DOI: 10.1080/15216540600746393] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Mitogen-activated protein kinase (MAPK) pathways play central roles in controlling diverse cellular functions. They are finely regulated by several mechanisms, including scaffolding of their components, and phosphorylation/dephosphorylation and compartmentalization of MAPKs. A number of molecules have been identified as regulators involved in these mechanisms. They modulate the magnitude and the specificity of MAPK signaling, and thereby regulate the wide variety of signaling outputs. Recent studies have identified novel functions of the MAPK signaling pathways. It is becoming clear that strict regulation of the MAPK pathways underlies their manifold functions in numerous biological processes.
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Affiliation(s)
- Masamichi Imajo
- Department of Cell and Developmental Biology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
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45
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Glaser ND, Lukyanenko YO, Wang Y, Wilson GM, Rogers TB. JNK activation decreases PP2A regulatory subunit B56alpha expression and mRNA stability and increases AUF1 expression in cardiomyocytes. Am J Physiol Heart Circ Physiol 2006; 291:H1183-92. [PMID: 16603688 PMCID: PMC1564198 DOI: 10.1152/ajpheart.01162.2005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A central feature of heart disease is a molecular remodeling of signaling pathways in cardiac myocytes. This study focused on novel molecular elements of MAPK-mediated alterations in the pattern of gene expression of the protein phosphatase 2A (PP2A). In an established model of sustained JNK activation, a 70% decrease in expression of the targeting subunit of PP2A, B56alpha, was observed in either neonatal or adult cardiomyocytes. This loss in protein abundance was accompanied by a decrease of 69% in B56alpha mRNA steady-state levels. Given that the 3'-untranslated region of this transcript contains adenylate-uridylate-rich elements known to regulate mRNA degradation, experiments explored the notion that instability of B56alpha mRNA accounts for the response. mRNA time-course analyses with real-time PCR methods showed that B56alpha transcript was transformed from a stable (no significant decay over 1 h) to a labile form that rapidly degraded within minutes. These results were supported by complementary experiments that revealed that the RNA-binding protein AUF1, known to destabilize target mRNA, was increased fourfold in JNK-activated cells. A variety of other stress-related stimuli, such as p38 MAPK activation and phorbol ester, upregulated AUF1 expression in cultured cardiac cells as well. In addition, gel mobility shift assays demonstrated that p37AUF1 binds with nanomolar affinity to segments of the B56alpha 3'-untranslated region. Thus these studies provide new evidence that signaling-induced mRNA instability is an important mechanism that underlies the changes in the pattern of gene expression evoked by stress-activated pathways in cardiac cells.
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Affiliation(s)
- Nicole D. Glaser
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland and
| | - Yevgeniya O. Lukyanenko
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland and
| | - Yibin Wang
- Departments of Anesthesiology and Medicine, University of California at Los Angeles, Los Angeles, California
| | - Gerald M. Wilson
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland and
| | - Terry B. Rogers
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland and
- Institute of Molecular Cardiology, Medical Biotechnology Center, University of Maryland Biotechnology Institute, Baltimore, Maryland
- To whom correspondence should be addressed: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene Street, Baltimore, MD 21201. Tel: 410-706-3169; Fax: 410-706-6676;
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46
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Thirone ACP, JeBailey L, Bilan PJ, Klip A. Opposite effect of JAK2 on insulin-dependent activation of mitogen-activated protein kinases and Akt in muscle cells: possible target to ameliorate insulin resistance. Diabetes 2006; 55:942-51. [PMID: 16567515 DOI: 10.2337/diabetes.55.04.06.db05-1265] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Many cytokines increase their receptor affinity for Janus kinases (JAKs). Activated JAK binds to signal transducers and activators of transcription, insulin receptor substrates (IRSs), and Shc. Intriguingly, insulin acting through its own receptor kinase also activates JAK2. However, the impact of such activation on insulin action remains unknown. To determine the contribution of JAK2 to insulin signaling, we transfected L6 myotubes with siRNA against JAK2 (siJAK2), reducing JAK2 protein expression by 75%. Insulin-dependent phosphorylation of IRS1/2 and Shc was not affected by siJAK2, but insulin-induced phosphorylation of the mitogen-activated protein kinases (MAPKs) extracellular signal-related kinase, p38, and Jun NH2-terminal kinase and their respective upstream kinases MKK1/2, MKK3/6, and MKK4/7 was significantly lowered when JAK2 was depleted, correlating with a significant drop in insulin-mediated cell proliferation. These effects were reproduced by the JAK2 inhibitor AG490. Conversely, insulin-stimulated Akt phosphorylation, glucose uptake, and GLUT4 translocation were not affected by siJAK2. Interestingly, in two insulin-resistant states, siJAK2 led to partial restoration of Akt phosphorylation and glucose uptake stimulation but not of the MAPK pathway. These results suggest that JAK2 may depress the Akt to glucose uptake signaling axis selectively in insulin-resistant states. Inhibition of JAK2 may be a useful strategy to relieve insulin resistance of metabolic outcomes.
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Affiliation(s)
- Ana C P Thirone
- The Hospital for Sick Children, 555 University Ave., Toronto, Ontario, Canada M5G 1X8
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47
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Lahti A, Sareila O, Kankaanranta H, Moilanen E. Inhibition of p38 mitogen-activated protein kinase enhances c-Jun N-terminal kinase activity: implication in inducible nitric oxide synthase expression. BMC Pharmacol 2006; 6:5. [PMID: 16504051 PMCID: PMC1402273 DOI: 10.1186/1471-2210-6-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2006] [Accepted: 02/21/2006] [Indexed: 11/10/2022] Open
Abstract
Background Nitric oxide (NO) is an inflammatory mediator, which acts as a cytotoxic agent and modulates immune responses and inflammation. p38 mitogen-activated protein kinase (MAPK) signal transduction pathway is activated by chemical and physical stress and regulates immune responses. Previous studies have shown that p38 MAPK pathway regulates NO production induced by inflammatory stimuli. The aim of the present study was to investigate the mechanisms involved in the regulation of inducible NO synthesis by p38 MAPK pathway. Results p38 MAPK inhibitors SB203580 and SB220025 stimulated lipopolysaccharide (LPS)-induced inducible nitric oxide synthase (iNOS) expression and NO production in J774.2 murine macrophages. Increased iNOS mRNA expression was associated with reduced degradation of iNOS mRNA. Treatment with SB220025 increased also LPS-induced c-Jun N-terminal kinase (JNK) activity. Interestingly, JNK inhibitor SP600125 reversed the effect of SB220025 on LPS-induced iNOS mRNA expression and NO production. Conclusion The results suggest that inhibition of p38 MAPK by SB220025 results in increased JNK activity, which leads to stabilisation of iNOS mRNA, to enhanced iNOS expression and to increased NO production.
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Affiliation(s)
- Aleksi Lahti
- The Immunopharmacology Research Group, Medical School, University of Tampere and Tampere University Hospital, Tampere, Finland
| | - Outi Sareila
- The Immunopharmacology Research Group, Medical School, University of Tampere and Tampere University Hospital, Tampere, Finland
| | - Hannu Kankaanranta
- The Immunopharmacology Research Group, Medical School, University of Tampere and Tampere University Hospital, Tampere, Finland
| | - Eeva Moilanen
- The Immunopharmacology Research Group, Medical School, University of Tampere and Tampere University Hospital, Tampere, Finland
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48
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Choi KS, Park JT, Dumler JS. Anaplasma phagocytophilum delay of neutrophil apoptosis through the p38 mitogen-activated protein kinase signal pathway. Infect Immun 2006; 73:8209-18. [PMID: 16299317 PMCID: PMC1307085 DOI: 10.1128/iai.73.12.8209-8218.2005] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Human granulocytic anaplasmosis is caused by the obligate intracellular bacterium Anaplasma phagocytophilum. The bacterium avoids host innate defenses in part by infecting, surviving in, and propagating in neutrophils, as well as by inhibiting neutrophil apoptosis. However, the mechanisms of A. phagocytophilum survival in neutrophils and the inhibition of spontaneous apoptosis are not well understood. In this study, we demonstrated that antiapoptotic Mcl-1 protein (Bcl-2 family) expression is maintained and that inhibition of procaspase-3 processing occurs in A. phagocytophilum-infected human neutrophils. An evaluation of p38 mitogen-activated protein kinase (MAPK) showed evidence of increased phosphorylation with infection. Moreover, antagonism of p38 MAPK by the inhibitor SB203580 reversed apoptosis inhibition in live or heat-killed A. phagocytophilum-infected neutrophils. A role for the autocrine or paracrine production of antiapoptotic interleukin 8 (IL-8) expressed with A. phagocytophilum infection was excluded by the use of IL-8-, IL-8R1 (CXCR1)-, and IL-8R2 (CXCR2)-blocking antibodies. As previously demonstrated, the antiapoptotic effect was initially mediated by exposure to A. phagocytophilum components in heat-killed bacteria. However, an important role for active infection is demonstrated by the additional delay in apoptosis with intracellular growth and the refractory abrogation of this response by the p38 MAPK inhibitor 3 to 6 h after neutrophil infection. These results suggest that the initial activation of the p38 MAPK pathway leading to A. phagocytophilum-delayed neutrophil apoptosis is bypassed with active intracellular infection. Moreover, active intracellular infection contributes more to the overall delay in apoptosis than do components of heat-killed A. phagocytophilum alone.
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Affiliation(s)
- Kyoung-Seong Choi
- Division of Medical Microbiology, Department of Pathology, The Johns Hopkins University School of Medicine, 720 Rutland Avenue, Ross 624, Baltimore, MD 21205, USA.
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49
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Derouet M, Thomas L, Moulding DA, Akgul C, Cross A, Moots RJ, Edwards SW. Sodium Salicylate Promotes Neutrophil Apoptosis by Stimulating Caspase-Dependent Turnover of Mcl-1. THE JOURNAL OF IMMUNOLOGY 2006; 176:957-65. [PMID: 16393981 DOI: 10.4049/jimmunol.176.2.957] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Mcl-1 is an antiapoptotic member of the Bcl-2 family of proteins that plays a central role in cell survival of neutrophils and other cells. The protein is unusual among family members in that it has a very short half-life of 2-3 h. In this report, we show that sodium salicylate (at 10 mM) greatly enhances the rate at which neutrophils undergo apoptosis and, in parallel, greatly accelerates the turnover rate of Mcl-1, decreasing its half-life to only 90 min. Whereas constitutive and GM-CSF-modified Mcl-1 turnover is regulated by the proteasome, the accelerated sodium salicylate-induced Mcl-1 turnover is mediated largely via caspases. Sodium salicylate resulted in rapid activation of caspase-3, -8, -9, and -10, and salicylate-accelerated Mcl-1 turnover was partly blocked by caspase inhibitors. Sodium salicylate also induced dramatic changes in the activities of members of the MAPK family implicated in Mcl-1 turnover and apoptosis. For example, sodium salicylate blocked GM-CSF-stimulated Erk and Akt activation, but resulted in rapid and sustained activation of p38-MAPK, an event mimicked by okadaic acid that also accelerates Mcl-1 turnover and neutrophil apoptosis. These data thus shed important new insights into the dynamic and highly regulated control of neutrophil apoptosis that is effected by modification in the rate of Mcl-1 turnover.
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Affiliation(s)
- Mathieu Derouet
- School of Biological Sciences, University of Liverpool, United Kingdom
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50
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Adams DG, Coffee RL, Zhang H, Pelech S, Strack S, Wadzinski BE. Positive regulation of Raf1-MEK1/2-ERK1/2 signaling by protein serine/threonine phosphatase 2A holoenzymes. J Biol Chem 2005; 280:42644-54. [PMID: 16239230 DOI: 10.1074/jbc.m502464200] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein serine/threonine phosphatase 2A (PP2A) regulates a wide variety of cellular signal transduction pathways. The predominant form of PP2A in cells is a heterotrimeric holoenzyme consisting of a scaffolding (A) subunit, a regulatory (B) subunit, and a catalytic (C) subunit. Although PP2A is known to regulate Raf1-MEK1/2-ERK1/2 signaling at multiple steps in this pathway, the specific PP2A holoenzymes involved remain unclear. To address this question, we established tetracycline-inducible human embryonic kidney 293 cell lines for overexpression of FLAG-tagged Balpha/delta regulatory subunits by approximately 3-fold or knock-down of Balpha by greater than 70% compared with endogenous levels. The expression of functional epitope-tagged B subunits was confirmed by the detection of A and C subunits as well as phosphatase activity in FLAG immune complexes from extracts of cells overexpressing the FLAG-Balpha/delta subunit. Western analysis of the cell extracts using phosphospecific antibodies for MEK1/2 and ERK1/2 demonstrated that activation of these kinases in response to epidermal growth factor was markedly diminished in Balpha knock-down cells but elevated in Balpha- and Bdelta-overexpressing cells as compared with control cells. In parallel with the activation of MEK1/2 and ERK1/2, the inhibitory phosphorylation site of Raf1 (Ser-259) was dephosphorylated in cells overexpressing Balpha or Bdelta. Pharmacological inhibitor studies as well as reporter assays for ERK-dependent activation of the transcription factor Elk1 revealed that the PP2A holoenzymes ABalphaC and ABdeltaC act downstream of Ras and upstream of MEK1 to promote activation of this MAPK signaling cascade. Furthermore both PP2A holoenzymes were found to associate with Raf1 and catalyze dephosphorylation of inhibitory phospho-Ser-259. Together these findings indicate that PP2A ABalphaC and ABdeltaC holoenzymes function as positive regulators of Raf1-MEK1/2-ERK1/2 signaling by targeting Raf1.
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Affiliation(s)
- Deanna G Adams
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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