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Kim J, Ji S, Lee JY, Lorquin J, Orlikova-Boyer B, Cerella C, Mazumder A, Muller F, Dicato M, Detournay O, Diederich M. Marine Polyether Phycotoxin Palytoxin Induces Apoptotic Cell Death via Mcl-1 and Bcl-2 Downregulation. Mar Drugs 2023; 21:md21040233. [PMID: 37103372 PMCID: PMC10143546 DOI: 10.3390/md21040233] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 03/28/2023] [Accepted: 03/28/2023] [Indexed: 04/28/2023] Open
Abstract
Palytoxin is considered one of the most potent biotoxins. As palytoxin-induced cancer cell death mechanisms remain to be elucidated, we investigated this effect on various leukemia and solid tumor cell lines at low picomolar concentrations. As palytoxin did not affect the viability of peripheral blood mononuclear cells (PBMC) from healthy donors and did not create systemic toxicity in zebrafish, we confirmed excellent differential toxicity. Cell death was characterized by a multi-parametric approach involving the detection of nuclear condensation and caspase activation assays. zVAD-sensitive apoptotic cell death was concomitant with a dose-dependent downregulation of antiapoptotic Bcl-2 family proteins Mcl-1 and Bcl-xL. Proteasome inhibitor MG-132 prevented the proteolysis of Mcl-1, whereas the three major proteasomal enzymatic activities were upregulated by palytoxin. Palytoxin-induced dephosphorylation of Bcl-2 further exacerbated the proapoptotic effect of Mcl-1 and Bcl-xL degradation in a range of leukemia cell lines. As okadaic acid rescued cell death triggered by palytoxin, protein phosphatase (PP)2A was involved in Bcl-2 dephosphorylation and induction of apoptosis by palytoxin. At a translational level, palytoxin abrogated the colony formation capacity of leukemia cell types. Moreover, palytoxin abrogated tumor formation in a zebrafish xenograft assay at concentrations between 10 and 30 pM. Altogether, we provide evidence of the role of palytoxin as a very potent and promising anti-leukemic agent, acting at low picomolar concentrations in cellulo and in vivo.
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Affiliation(s)
- Jaemyun Kim
- Department of Pharmacy, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08626, Republic of Korea
| | - Seungwon Ji
- Department of Pharmacy, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08626, Republic of Korea
| | - Jin-Young Lee
- Department of Pharmacy, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08626, Republic of Korea
| | - Jean Lorquin
- Institut Méditerranéen d'Océanologie, 163 Avenue de Luminy, CEDEX 09, 13288 Marseille, France
| | - Barbora Orlikova-Boyer
- Department of Pharmacy, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08626, Republic of Korea
- Laboratoire de Biologie Moléculaire et Cellulaire du Cancer (LBMCC), BAM3 Pavillon 2, 6A Rue Nicolas-Ernest Barblé, L-1210 Luxembourg, Luxembourg
| | - Claudia Cerella
- Department of Pharmacy, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08626, Republic of Korea
- Laboratoire de Biologie Moléculaire et Cellulaire du Cancer (LBMCC), BAM3 Pavillon 2, 6A Rue Nicolas-Ernest Barblé, L-1210 Luxembourg, Luxembourg
| | - Aloran Mazumder
- Department of Pharmacy, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08626, Republic of Korea
| | - Florian Muller
- Laboratoire de Biologie Moléculaire et Cellulaire du Cancer (LBMCC), BAM3 Pavillon 2, 6A Rue Nicolas-Ernest Barblé, L-1210 Luxembourg, Luxembourg
| | - Mario Dicato
- Laboratoire de Biologie Moléculaire et Cellulaire du Cancer (LBMCC), BAM3 Pavillon 2, 6A Rue Nicolas-Ernest Barblé, L-1210 Luxembourg, Luxembourg
| | - Olivier Detournay
- Planktovie SAS, 45 Rue Frédéric Joliot Curie, CEDEX 13, 13013 Marseille, France
| | - Marc Diederich
- Department of Pharmacy, College of Pharmacy, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08626, Republic of Korea
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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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Regulation of Cardiac PKA Signaling by cAMP and Oxidants. Antioxidants (Basel) 2021; 10:antiox10050663. [PMID: 33923287 PMCID: PMC8146537 DOI: 10.3390/antiox10050663] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/16/2021] [Accepted: 04/20/2021] [Indexed: 12/31/2022] Open
Abstract
Pathologies, such as cancer, inflammatory and cardiac diseases are commonly associated with long-term increased production and release of reactive oxygen species referred to as oxidative stress. Thereby, protein oxidation conveys protein dysfunction and contributes to disease progression. Importantly, trials to scavenge oxidants by systemic antioxidant therapy failed. This observation supports the notion that oxidants are indispensable physiological signaling molecules that induce oxidative post-translational modifications in target proteins. In cardiac myocytes, the main driver of cardiac contractility is the activation of the β-adrenoceptor-signaling cascade leading to increased cellular cAMP production and activation of its main effector, the cAMP-dependent protein kinase (PKA). PKA-mediated phosphorylation of substrate proteins that are involved in excitation-contraction coupling are responsible for the observed positive inotropic and lusitropic effects. PKA-actions are counteracted by cellular protein phosphatases (PP) that dephosphorylate substrate proteins and thus allow the termination of PKA-signaling. Both, kinase and phosphatase are redox-sensitive and susceptible to oxidation on critical cysteine residues. Thereby, oxidation of the regulatory PKA and PP subunits is considered to regulate subcellular kinase and phosphatase localization, while intradisulfide formation of the catalytic subunits negatively impacts on catalytic activity with direct consequences on substrate (de)phosphorylation and cardiac contractile function. This review article attempts to incorporate the current perception of the functionally relevant regulation of cardiac contractility by classical cAMP-dependent signaling with the contribution of oxidant modification.
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El-Sayyad SM, Ali MA, Kandil LS, Ragab GM, Abdelhamid Ibrahim SS. Metformin and omega-3 fish oil elicit anti-inflammatory effects via modulation of some dysregulated micro RNAs expression and signaling pathways in experimental induced arthritis. Int Immunopharmacol 2021; 92:107362. [PMID: 33453674 DOI: 10.1016/j.intimp.2020.107362] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 11/27/2020] [Accepted: 12/29/2020] [Indexed: 01/13/2023]
Abstract
OBJECTIVE Rheumatoid arthritis is a progressive inflammatory disease with multiple dysfunctional intracellular signaling pathways that necessitate new approaches for its management. Hence, the study aimed to inspect the ability of the combination therapy of metformin and omega-3 to modulate different signaling pathways and micro RNAs such as (miR-155, miR-146a and miR-34) as new targets in order to mitigate adjuvant-induced arthritis and compare their effect to that of methotrexate. METHODS Fourteen days post adjuvant injection, Sprague-Dawley rats were treated orally with metformin (200 mg/kg/day) and/or omega-3 (300 mg/kg/day) or intraperitoneally with methotrexate (2 mg/kg/week) for 4 weeks. RESULTS AND CONCLUSION All drug treatments amended the arthrogram score and hind paw swelling as well as decreased serum tumor necrosis factor (TNF)-α and interleukin (IL)-1β levels. On the molecular level, all therapies activated phospho-5'adenosine monophosphate-activated protein kinase (p-AMPK) and protein phosphatase 2A (PP2A), while they inhibited phospho-mammalian target of rapamycin (p-mTOR), phospho-signal transducers and activators of transcription (p-STAT3), nuclear factor (NF)-κB p65 subunit, phosho38 mitogen-activated protein kinase (p38 MAPK) and phospho- c-Jun N-terminal kinase (p-JNK). In addition, they decreased the elevated expression level of miRNA-155, 146a and increased the expression level of miRNA-34 and they decreased the expression level of retinoic acid receptor related orphan receptor γT (RORγT) and increased that of fork head box P3 (FOXP3), correcting Th17/Treg cells balance. On most of the aforementioned parameters, the effect of the combination therapy was comparable to that of methotrexate, emphasizing that this combination possesses better additive anti-inflammatory effect than either drug when used alone. In addition, the combination was capable of normalizing the serum transaminases levels as compared to untreated group offering hepatoprotective effect and suggesting the possibility of its use as a replacement therapeutic strategy for MTX in rheumatoid arthritis.
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Affiliation(s)
- Shorouk M El-Sayyad
- Department of Pharmacology & Toxicology, October 6 University, 12585 Giza, Egypt
| | - Mennatallah A Ali
- Department of Pharmacology &Therapeutics, Pharos University in Alexandria, Alexandria, Egypt
| | - Lamia S Kandil
- Department of Pharmacology &Therapeutics, Pharos University in Alexandria, Alexandria, Egypt
| | - Ghada M Ragab
- Department of Pharmacology and Toxicology, Misr University for Science and Technology, 6 th of October City, Egypt
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Karkache IY, Damodaran JR, Molstad DHH, Bradley EW. Serine/threonine phosphatases in osteoclastogenesis and bone resorption. Gene 2020; 771:145362. [PMID: 33338510 DOI: 10.1016/j.gene.2020.145362] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 11/24/2020] [Accepted: 12/08/2020] [Indexed: 12/27/2022]
Abstract
Maintenance of optimal bone mass is controlled through the concerted functions of several cell types, including bone resorbing osteoclasts. Osteoclasts function to remove calcified tissue during developmental bone modeling, and degrade bone at sites of damage during bone remodeling. Changes to bone homeostasis can arise with alterations in osteoclastogenesis and/or catabolic activity that are not offset by anabolic activity; thus, factors that regulate osteoclastogenesis and bone resorption are of interest to further our understanding of basic bone biology, and as potential targets for therapeutic intervention. Several key cytokines, including RANKL and M-CSF, as well as co-stimulatory factors elicit kinase signaling cascades that promote osteoclastogenesis. These kinase cascades are offset by the action of protein phosphatases, including members of the serine/threonine phosphatase family. Here we review the functions of serine/threonine phosphatases and their control of osteoclast differentiation and function, while highlighting deficiencies in our understanding of this understudied class of proteins within the field.
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Affiliation(s)
- Ismael Y Karkache
- Department of Orthopedic Surgery, University of Minnesota, Minneapolis, MN 55455, United States
| | - Jeyaram R Damodaran
- Department of Orthopedic Surgery, University of Minnesota, Minneapolis, MN 55455, United States
| | - David H H Molstad
- Department of Orthopedic Surgery, University of Minnesota, Minneapolis, MN 55455, United States
| | - Elizabeth W Bradley
- Department of Orthopedic Surgery, University of Minnesota, Minneapolis, MN 55455, United States; Stem Cell Institute, University of Minnesota, Minneapolis, MN 55455, United States.
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Xu K, Liu X, Yin D, Ren G, Zhao Y. PP2A alleviates oxidized LDL-induced endothelial dysfunction by regulating LOX-1/ROS/MAPK axis. Life Sci 2020; 243:117270. [PMID: 31923421 DOI: 10.1016/j.lfs.2020.117270] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 01/03/2020] [Accepted: 01/03/2020] [Indexed: 11/25/2022]
Abstract
AIMS The purpose of this study is to investigate the effect of PP2A on the progression of AS and the special molecular mechanism. MAIN METHODS The expression of PP2A in Human umbilical vein endothelial cells (HUVECs) induced by different concentrations of Ox-LDL was measured by RT-PCR and Western blot. The binding activity of PP2A and LOX-1 was determined by CoIP assay. Western blot was used to measure the protein expression of VCAM-1, ICAM-1 and MCP-1. KEY FINDING The results revealed that the expression of PP2A was decreased with the increase of Ox-LDL concentration in HUVECs. Overexpression of PP2A alleviated Ox-LDL-induced dysfunction and inflammatory response in HUVECs. The results of Co-immunoprecipitation (CoIP) showed that PP2A had direct effect on LOX-1, and PP2A inhibited the expression of LOX-1. In addition, overexpression of LOX-1 reversed the inhibitory effect of PP2A on Ox-LDL-induced dysfunction and inflammatory response in HUVECs. What is more, PP2A inhibited LOX-1/ROS/MAPK axis. SIGNIFICANCE it suggests that PP2A alleviates Ox-LDL-induced dysfunction and inflammatory response of HUVECs potentially by regulating the LOX-1/ROS/MAPK axis,which suggests that PP2A has anti-inflammatory effect during the formation of as, and the molecular therapy of PP2A provides a theoretical basis.
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Affiliation(s)
- Kaicheng Xu
- Department of Anesthesiology, China-Japan Union hospital JiLin University, Chang chun, JiLin 130033, China
| | - Xiwen Liu
- Department of vascular surgery, China-Japan Union hospital JiLin University, Chang chun, JiLin 130033, China
| | - Dexin Yin
- Department of vascular surgery, China-Japan Union hospital JiLin University, Chang chun, JiLin 130033, China
| | - Guanghao Ren
- Department of vascular surgery, China-Japan Union hospital JiLin University, Chang chun, JiLin 130033, China
| | - Yue Zhao
- Department of vascular surgery, China-Japan Union hospital JiLin University, Chang chun, JiLin 130033, China.
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Koutsioumpa M, Chen HW, O'Brien N, Koinis F, Mahurkar-Joshi S, Vorvis C, Soroosh A, Luo T, Issakhanian S, Pantuck AJ, Georgoulias V, Iliopoulos D, Slamon DJ, Drakaki A. MKAD-21 Suppresses the Oncogenic Activity of the miR-21/PPP2R2A/ERK Molecular Network in Bladder Cancer. Mol Cancer Ther 2018; 17:1430-1440. [PMID: 29703843 DOI: 10.1158/1535-7163.mct-17-1049] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Revised: 02/20/2018] [Accepted: 04/16/2018] [Indexed: 11/16/2022]
Abstract
Bladder cancer represents a disease associated with significant morbidity and mortality. MiR-21 has been found to have oncogenic activity in multiple cancers, including bladder cancer, whereas inhibition of its expression suppresses tumor growth. Here, we examine the molecular network regulated by miR-21 in bladder cancer and evaluate the effects of i.v. and i.p. administration of a novel miR-21 chemical inhibitor in vivo LNA miR-21 reduced the oncogenic potential of bladder cancer cells, whereas the MKAD-21 chemically modified antisense oligo against miR-21 dose-dependently blocked xenograft growth. I.v. administration of LNA miR-21 was more effective in suppressing tumor growth than was i.p. administration. Integration of computational and transcriptomic analyses in a panel of 28 bladder cancer lines revealed a 15-gene signature that correlates with miR-21 levels. Protein Phosphatase 2 Regulatory Subunit Balpha (PPP2R2A) was one of these 15 genes and was experimentally validated as a novel miR-21 direct target gene. Gene network and molecular analyses showed that PPP2R2A is a potent negative regulator of the ERK pathway activation and bladder cancer cell proliferation. Importantly, we show that PPP2R2A acts as a mediator of miR-21-induced oncogenic effects in bladder cancer. Integrative analysis of human bladder cancer tumors and a large panel of human bladder cancer cell lines revealed a novel 15-gene signature that correlates with miR-21 levels. Importantly, we provide evidence that PPP2R2A represents a new miR-21 direct target and regulator of the ERK pathway and bladder cancer cell growth. Furthermore, i.v. administration of the MKAD-21 inhibitor effectively suppressed tumor growth through regulation of the PPP2R2A-ERK network in mice. Mol Cancer Ther; 17(7); 1430-40. ©2018 AACR.
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Affiliation(s)
- Marina Koutsioumpa
- Center for Systems Biomedicine, Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Hsiao-Wang Chen
- Division of Hematology-Oncology, Department of Medicine, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Neil O'Brien
- Division of Hematology-Oncology, Department of Medicine, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Filippos Koinis
- Laboratory of Tumor Cell Biology and Department of Medical Oncology, School of Medicine, University of Crete, Heraklion, Greece
| | - Swapna Mahurkar-Joshi
- Center for Systems Biomedicine, Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Christina Vorvis
- Center for Systems Biomedicine, Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Artin Soroosh
- Center for Systems Biomedicine, Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Tong Luo
- Division of Hematology-Oncology, Department of Medicine, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Shawnt Issakhanian
- Division of Hematology-Oncology, Department of Medicine, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Allan J Pantuck
- Department of Urology, Institute of Urologic Oncology, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Vassilis Georgoulias
- Laboratory of Tumor Cell Biology and Department of Medical Oncology, School of Medicine, University of Crete, Heraklion, Greece
| | - Dimitrios Iliopoulos
- Center for Systems Biomedicine, Vatche and Tamar Manoukian Division of Digestive Diseases, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Dennis J Slamon
- Division of Hematology-Oncology, Department of Medicine, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Alexandra Drakaki
- Division of Hematology-Oncology, Department of Medicine, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, UCLA, Los Angeles, California.
- Department of Urology, Institute of Urologic Oncology, David Geffen School of Medicine, UCLA, Los Angeles, California
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Zheng HY, Shen FJ, Tong YQ, Li Y. PP2A Inhibits Cervical Cancer Cell Migration by Dephosphorylation of p-JNK, p-p38 and the p-ERK/MAPK Signaling Pathway. Curr Med Sci 2018; 38:115-123. [DOI: 10.1007/s11596-018-1854-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 01/03/2018] [Indexed: 02/06/2023]
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Corre I, Paris F, Huot J. The p38 pathway, a major pleiotropic cascade that transduces stress and metastatic signals in endothelial cells. Oncotarget 2017; 8:55684-55714. [PMID: 28903453 PMCID: PMC5589692 DOI: 10.18632/oncotarget.18264] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 05/03/2017] [Indexed: 12/29/2022] Open
Abstract
By gating the traffic of molecules and cells across the vessel wall, endothelial cells play a central role in regulating cardiovascular functions and systemic homeostasis and in modulating pathophysiological processes such as inflammation and immunity. Accordingly, the loss of endothelial cell integrity is associated with pathological disorders that include atherosclerosis and cancer. The p38 mitogen-activated protein kinase (MAPK) cascades are major signaling pathways that regulate several functions of endothelial cells in response to exogenous and endogenous stimuli including growth factors, stress and cytokines. The p38 MAPK family contains four isoforms p38α, p38β, p38γ and p38δ that are encoded by four different genes. They are all widely expressed although to different levels in almost all human tissues. p38α/MAPK14, that is ubiquitously expressed is the prototype member of the family and is referred here as p38. It regulates the production of inflammatory mediators, and controls cell proliferation, differentiation, migration and survival. Its activation in endothelial cells leads to actin remodeling, angiogenesis, DNA damage response and thereby has major impact on cardiovascular homeostasis, and on cancer progression. In this manuscript, we review the biology of p38 in regulating endothelial functions especially in response to oxidative stress and during the metastatic process.
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Affiliation(s)
- Isabelle Corre
- CRCINA, INSERM, CNRS, Université de Nantes, Nantes, France
| | - François Paris
- CRCINA, INSERM, CNRS, Université de Nantes, Nantes, France
| | - Jacques Huot
- Le Centre de Recherche du CHU de Québec-Université Laval et le Centre de Recherche sur le Cancer de l'Université Laval, Québec, Canada
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Shah M, Smolko CM, Kinicki S, Chapman ZD, Brautigan DL, Janes KA. Profiling Subcellular Protein Phosphatase Responses to Coxsackievirus B3 Infection of Cardiomyocytes. Mol Cell Proteomics 2017; 16:S244-S262. [PMID: 28174228 DOI: 10.1074/mcp.o116.063487] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 01/31/2017] [Indexed: 01/23/2023] Open
Abstract
Cellular responses to stimuli involve dynamic and localized changes in protein kinases and phosphatases. Here, we report a generalized functional assay for high-throughput profiling of multiple protein phosphatases with subcellular resolution and apply it to analyze coxsackievirus B3 (CVB3) infection counteracted by interferon signaling. Using on-plate cell fractionation optimized for adherent cells, we isolate protein extracts containing active endogenous phosphatases from cell membranes, the cytoplasm, and the nucleus. The extracts contain all major classes of protein phosphatases and catalyze dephosphorylation of plate-bound phosphosubstrates in a microtiter format, with cellular activity quantified at the end point by phosphospecific ELISA. The platform is optimized for six phosphosubstrates (ERK2, JNK1, p38α, MK2, CREB, and STAT1) and measures specific activities from extracts of fewer than 50,000 cells. The assay was exploited to examine viral and antiviral signaling in AC16 cardiomyocytes, which we show can be engineered to serve as susceptible and permissive hosts for CVB3. Phosphatase responses were profiled in these cells by completing a full-factorial experiment for CVB3 infection and type I/II interferon signaling. Over 850 functional measurements revealed several independent, subcellular changes in specific phosphatase activities. During CVB3 infection, we found that type I interferon signaling increases subcellular JNK1 phosphatase activity, inhibiting nuclear JNK1 activity that otherwise promotes viral protein synthesis in the infected host cell. Our assay provides a high-throughput way to capture perturbations in important negative regulators of intracellular signal-transduction networks.
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Affiliation(s)
- Millie Shah
- From the ‡Department of Biomedical Engineering
| | | | | | | | - David L Brautigan
- the ‖Center for Cell Signaling and Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908
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11
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Marschall R, Tudzynski P. Reactive oxygen species in development and infection processes. Semin Cell Dev Biol 2016; 57:138-146. [PMID: 27039026 DOI: 10.1016/j.semcdb.2016.03.020] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 03/29/2016] [Accepted: 03/29/2016] [Indexed: 12/31/2022]
Abstract
Reactive oxygen species (ROS) are important signaling molecules that affect vegetative and pathogenic processes in pathogenic fungi. There is growing evidence that ROS are not only secreted during the interaction of host and pathogen but also involved in tightly controlled intracellular processes. The major ROS producing enzymes are NADPH oxidases (Nox). Recent investigations in fungi revealed that Nox-activity is responsible for the formation of infection structures, cytoskeleton architecture as well as interhyphal communication. However, information about the localization and site of action of the Nox complexes in fungi is limited and signaling pathways and intracellular processes affected by ROS have not been fully elucidated. This review focuses on the role of ROS as signaling molecules in fungal "model" organisms: it examines the role of ROS in vegetative and pathogenic processes and gives special attention to Nox complexes and their function as important signaling hubs.
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Affiliation(s)
- Robert Marschall
- Institut für Biologie und Biotechnologie der Pflanzen, Westfälische Wilhelms Universität, Schlossplatz 8, D-48143 Münster, Germany
| | - Paul Tudzynski
- Institut für Biologie und Biotechnologie der Pflanzen, Westfälische Wilhelms Universität, Schlossplatz 8, D-48143 Münster, Germany.
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12
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Abstract
Articular cartilage is a unique load-bearing connective tissue with a low intrinsic capacity for repair and regeneration. Its avascularity makes it relatively hypoxic and its unique extracellular matrix is enriched with cations, which increases the interstitial fluid osmolarity. Several physicochemical and biomechanical stimuli are reported to influence chondrocyte metabolism and may be utilized for regenerative medical approaches. In this review article, we summarize the most relevant stimuli and describe how ion channels may contribute to cartilage homeostasis, with special emphasis on intracellular signaling pathways. We specifically focus on the role of calcium signaling as an essential mechanotransduction component and highlight the role of phosphatase signaling in this context.
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Affiliation(s)
- Holger Jahr
- Department of Orthopaedic Surgery, University Hospital RWTH Aachen University, Pauwelsstraße 30, 52074 Aachen, Germany
- The D-BOARD European Consortium for Biomarker Discovery, Surrey, UK
| | - Csaba Matta
- The D-BOARD European Consortium for Biomarker Discovery, Surrey, UK
- Department of Veterinary Preclinical Sciences, School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Duke of Kent Building, Guildford, Surrey GU2 7XH UK
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, Nagyerdei krt. 98, Debrecen, 4032 Hungary
| | - Ali Mobasheri
- The D-BOARD European Consortium for Biomarker Discovery, Surrey, UK
- Department of Veterinary Preclinical Sciences, School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Duke of Kent Building, Guildford, Surrey GU2 7XH UK
- Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis, Arthritis Research UK Pain Centre, Medical Research Council and Arthritis Research UK Centre for Musculoskeletal Ageing Research, University of Nottingham, Queen’s Medical Centre, Nottingham, NG7 2UH UK
- Center of Excellence in Genomic Medicine Research (CEGMR), King Fahd Medical Research Center (KFMRC), King AbdulAziz University, Jeddah, 21589 Kingdom of Saudi Arabia
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Sun Y, Liu JH, Huang P, Guo ZL, Xu LH. Alterations of tau and VASP during microcystin-LR-induced cytoskeletal reorganization in a human liver cell line. ENVIRONMENTAL TOXICOLOGY 2015; 30:92-100. [PMID: 23929704 DOI: 10.1002/tox.21898] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 07/04/2013] [Accepted: 07/11/2013] [Indexed: 06/02/2023]
Abstract
Previously, we have reported alterations to HSP27 during Microcystin-LR (MC-LR)-induced cytoskeletal reorganization in the human liver cell line HL7702. To further elucidate the detailed mechanism of MC-LR-induced cytoskeletal assembly, we focused on two cytoskeletal-related proteins, Tau and VASP. These two proteins phosphorylated status influences their ability to bind and stabilize cytoskeleton. We found that MC-LR markedly increased the level of Tau phosphorylation with the dissociation of phosphorylated Tau from the cytoskeleton. Furthermore, the phosphorylation of Tau induced by MC-LR was suppressed by an activator of PP2A and by an inhibitor of p38 MAPK. VASP was also hyperphosphorylated upon MC-LR exposure; however, its phosphorylation appeared to regulate its cellular localization rather than cytoskeletal dynamics, and its phosphorylation was unaffected by the PP2A activator. These data suggest that phosphorylated Tau is regulated by p38 MAPK, possibly as a consequence of PP2A inhibition. Tau hyperphosphorylation is likely an important factor leading to the cytoskeletal destabilization triggered by MC-LR and the role of VASP alteration upon MC-LR exposure needs to be studied further. To our knowledge, the finding that Tau is implicated in cytoskeletal destabilization in MC-LR-treated hepatocytes and MC-LR-induced VASP's alteration has not been reported previously.
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Affiliation(s)
- Yu Sun
- Department of Biochemistry, School of Medicine, Zhejiang University, Hangzhou, 310058, People's Republic of China
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Chao CY, Lii CK, Ye SY, Li CC, Lu CY, Lin AH, Liu KL, Chen HW. Docosahexaenoic acid inhibits vascular endothelial growth factor (VEGF)-induced cell migration via the GPR120/PP2A/ERK1/2/eNOS signaling pathway in human umbilical vein endothelial cells. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:4152-8. [PMID: 24734983 DOI: 10.1021/jf5007165] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Cell migration plays an important role in angiogenesis and wound repair. Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen that is essential for endothelial cell survival, proliferation, and migration. Docosahexaenoic acid (DHA), an n-3 polyunsaturated fatty acid, shows both anti-inflammatory and antioxidant activities in vitro and in vivo. This study investigated the molecular mechanism by which DHA down-regulates VEGF-induced cell migration. HUVECs were used as the study model, and the MTT assay, Western blot, wound-healing assay, and phosphatase activity assay were used to explore the effects of DHA on cell migration. GPR120 is the putative receptor for DHA action. The results showed that DHA, PD98059 (an ERK1/2 inhibitor), and GW9508 (a GPR120 agonist) inhibited VEGF-induced cell migration. In contrast, pretreatment with okadaic acid (OA, a PP2A inhibitor) and S-nitroso-N-acetyl-DL-penicillamine (an NO donor) reversed the inhibition of cell migration by DHA. VEGF-induced cell migration was accompanied by phosphorylation of ERK1/2 and eNOS. Treatment of HUVECs with DHA increased PP2A enzyme activity and decreased VEGF-induced phosphorylation of ERK1/2 and eNOS. However, pretreatment with OA significantly decreased DHA-induced PP2A enzyme activity and reversed the DHA inhibition of VEGF-induced ERK1/2 and eNOS phosphorylation. These results suggest that stimulation of PP2A activity and inhibition of the VEGF-induced ERK1/2/eNOS signaling pathway may be involved in the DHA suppression of VEGF-induced cell migration. Thus, the effect of DHA on angiogenesis and wound repair is at least partly by virtue of its attenuation of cell migration.
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Affiliation(s)
- Che-Yi Chao
- Department of Health and Nutrition Biotechnology, Asia University , Taichung, Taiwan
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15
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Zhang Y, Chen Y, Sun L, Liang J, Guo Z, Xu L. Protein phosphatases 2A as well as reactive oxygen species involved in tributyltin-induced apoptosis in mouse livers. ENVIRONMENTAL TOXICOLOGY 2014; 29:234-242. [PMID: 22223438 DOI: 10.1002/tox.21751] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 11/25/2011] [Indexed: 05/31/2023]
Abstract
Tributyltin (TBT), a highly toxic environmental contaminant, has been shown to induce caspase-3-dependent apoptosis in human amniotic cells through protein phosphatase 2A (PP2A) inhibition and consequent JNK activation. This in vivo study was undertaken to further verify the results derived from our previous in vitro study. Mice were orally dosed with 0, 10, 20, and 60 mg/kg of body weight TBT, and levels of PP2A, reactive oxygen species (ROS), mitogen-activated protein kinase (MAPK), Bax/Bcl-2, and caspase-3 were detected in the mouse livers. Apoptosis was also evaluated using the TUNEL assay. The results showed that PP2A activity was inhibited, ROS levels were elevated, and MAPKs including ERK, JNK, and p38 were activated in mouse livers treated with the highest dose of TBT. Additionally, the ratio of Bax/Bcl-2 was increased, caspase-3 was activated, and apoptosis in mouse livers could be detected in the highest dose group. Therefore, a possible signaling pathway in TBT-induced apoptosis in mouse livers involves PP2A inhibition and ROS elevation serving a pivotal function as upstream activators of MAPKs; activation of MAPKs in turn leads to an increase in the Bax/Bcl-2 ratio, ultimately leading to the activation of caspase-3. The results give a comprehensive and novel description of the mechanism of TBT-induced toxicity.
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Affiliation(s)
- Yali Zhang
- Department of Biochemistry and Genetics, School of medicine, Zhejiang University, 866th Yu Hang Tang Road, 310058, Hangzhou, China
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16
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Zhang Y, Liang J, Sun L, Guo Z, Xu L. Inhibition of PP2A and the consequent activation of JNK/c-Jun are involved in tributyltin-induced apoptosis in human amnionic cells. ENVIRONMENTAL TOXICOLOGY 2013; 28:390-400. [PMID: 21626652 DOI: 10.1002/tox.20730] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Revised: 04/03/2011] [Accepted: 04/04/2011] [Indexed: 05/30/2023]
Abstract
Tributyltin (TBT), a highly toxic environmental contaminant, has been shown to induce mitochondrial-dependent apoptosis in several mammalian cells. However, the upstream signal transduction pathways involved in TBT-induced apoptosis are still not fully elucidated. In this study, the protein phosphatase (PP) 2A, microtubule organization, and mitogen-activated protein kinases (MAPKs), including JNK, p38 and their downstream transcription factors, c-Jun and ATF-2, respectively, were investigated in human amnionic cells treated by TBT. Furthermore, the activation of procaspase-3 after blocking either one of these MAPK pathways was also observed. The results showed that TBT effectively induced apoptosis characterized by caspase-3 activation. In apoptotic cells, the inhibition of PP2A activity and microtubule depolymerization was detected. Additionally, JNK and p38, as well as their downstream targets, c-Jun and ATF-2, were activated. Moreover, a JNK inhibitor, but not p38 inhibitor, significantly reduced caspase-3 activation. It can be concluded that the inhibition of PP2A may (1) play as a role in the activation of JNK and c-Jun and the concomitant promotion of microtubule depolymerization and (2) lead to the activation of caspase-3 in TBT-induced apoptotic cells. The results of this study suggest a critical role of PP2A in the TBT toxicity mechanism.
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Affiliation(s)
- Yali Zhang
- Department of Biochemistry and Genetics, School of medicine, Zhejiang University, 388 Yu Hang Tang Road, 310058, Hangzhou, China
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17
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Liu XP, Zheng HY, Qu M, Zhang Y, Cao FY, Wang Q, Ke D, Liu GP, Wang JZ. Upregulation of astrocytes protein phosphatase-2A stimulates astrocytes migration via inhibiting p38 MAPK in tg2576 mice. Glia 2012; 60:1279-88. [PMID: 22729898 DOI: 10.1002/glia.22347] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 04/13/2012] [Indexed: 12/30/2022]
Abstract
One of the earliest neuropathological changes in Alzheimer disease (AD) is the accumulation of astrocytes at sites of β-amyloid (Aβ) deposits, but the cause of this cellular response is unclear. As the activity of protein phosphatase 2A (PP2A) is significantly decreased in the AD brains, we studied the role of PP2A in astrocytes migration. We observed unexpectedly that PP2A activity associated with glial fibrillary acidic protein, an astrocyte marker, was significantly upregulated in tg2576 mice, demonstrated by an increased enzyme activity, a decreased demethylation at leucine-309 (DM-PP2Ac), and a decreased phosphorylation at tyrosine-307 of PP2A (pY307-PP2Ac). Further studies by using in vitro wound-healing model and transwell assay demonstrated that upregulation of PP2A pharmacologically and genetically could stimulate astrocytes migration. Activation of PP2A promotes actin organization and inhibits p38 mitogen-activated protein kinases (p38 MAPK), while simultaneous activation of p38 MAPK partially abolishes the PP2A-induced astrocytes migration. Our data suggest that activation of astrocytes PP2A in tg2567 mice may stimulate the migration of astrocytes to the amyloid plaques by p38 MAPK inhibition, implying that PP2A deficits observed in AD may cause Aβ accumulation via hindering the astrocytes migration.
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Affiliation(s)
- Xiu-Ping Liu
- Pathophysiology Department, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, HuBei, People's Republic of China
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Abstract
During normal pregnancy, dramatically increased placental blood flow is critical for fetal growth and survival as well as neonatal birth weights and survivability. This increased blood flow results from angiogenesis, vasodilatation, and vascular remodeling. Locally produced growth factors including fibroblast growth factor 2 (FGF2) and vascular endothelial growth factor A (VEGFA) are key regulators of placental endothelial functions including cell proliferation, migration, and vasodilatation. However, the precise signaling mechanisms underlying such regulation in fetoplacental endothelium are less well defined, specifically with regard to the interactions amongst protein kinases (PKs), protein phosphatase, and nitric oxide (NO). Recently, we and other researchers have obtained solid evidence showing that different signaling mechanisms participate in FGF2- and VEGFA-regulated fetoplacental endothelial cell proliferation and migration as well as NO production. This review will briefly summarize currently available data on signaling mediating fetoplacental angiogenesis with a specific emphasis on PKs, ERK1/2, AKT1, and p38 MAPK and protein phosphatases, PPP2 and PPP3.
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Affiliation(s)
- Kai Wang
- Clinical and Translational Research Center, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai 200040, China
| | - Jing Zheng
- Department of Obstetrics and Gynecology, University of Wisconsin, Madison, WI 53715
- Address correspondence and reprint requests to: Jing Zheng, Ph.D., Departments of Obstetrics and Gynecology, Perinatal Research Laboratories, University of Wisconsin, PAB1 Meriter Hospital, 202 S Park St., Madison, WI 53715. Phone: (608) 417-6314 Fax: (608) 257-1304.
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Chen JY, Lin YY, Jou TS. Phosphorylation of EBP50 negatively regulates β-PIX-dependent Rac1 activity in anoikis. Cell Death Differ 2012; 19:1027-37. [PMID: 22301917 DOI: 10.1038/cdd.2012.4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We demonstrated a protein kinase C (PKC)-dependent phosphorylation of canine ezrin/radixin/moesin (ERM)-binding phosphoprotein 50 (EBP50) at serine 347/348 by site-directed mutagenesis and a phospho-specific antibody. Cell fractionation and confocal imaging revealed the relocation of EBP50 from the plasma membrane to cytosol that accompanied this phosphorylation event. Increased phosphorylation at these serine residues led to the dissociation of EBP50 from ezrin and β-PIX, which are two upstream regulators of Rac1 activation. Cells overexpressing an EBP50 mutant, mimicking serine 347/348 phosphorylation, became refractory to hepatocyte growth factor-induced cell spreading and scattering, which is normally mediated by Rac1 activation. Detachment of cells from the substratum also elicited an increase in EBP50 phosphorylation, apparently due to counteracting activities of PKC and protein phosphastase 2A, which resulted in decreased Rac1 activation and induction of anoikis. Cells overexpressing an EBP50 mutant defective in serine 347/348 phosphorylation did not undergo apoptosis in suspension culture. These studies reveal a signaling cascade in which different phosphorylation states and subcellular localization of EBP50 regulate Rac1 function.
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Affiliation(s)
- J-Y Chen
- Graduate Institute of Molecular Medicine, National Taiwan University, No.7, Chung-Shan S. Road, Taipei 100, Taiwan. [corrected]
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20
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Janzen C, Sen S, Cuevas J, Reddy ST, Chaudhuri G. Protein phosphatase 2A promotes endothelial survival via stabilization of translational inhibitor 4E-BP1 following exposure to tumor necrosis factor-α. Arterioscler Thromb Vasc Biol 2012; 31:2586-94. [PMID: 21903942 DOI: 10.1161/atvbaha.111.230946] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Tumor necrosis factor-α (TNFα) may change from a stimulator of reversible activation of endothelial cells (ECs) to a killer when combined with cycloheximide (CHX). The means by which endothelial cells are destined to either the survival pathway or the apoptotic pathway are not fully understood. We investigated the role of p38 mitogen-activated protein kinase (MAPK) and protein phosphatase 2A (PP2A) activation and their regulation of 4E-BP1 stability in ECs to determine whether this pathway contributes to apoptosis induced by TNFα and CHX. METHODS AND RESULTS Apoptosis was induced in human umbilical vein ECs (HUVECs) by treating them with a combination of TNFα and CHX (TNFα/CHX). Activation of p38 MAPK was increased in HUVECs undergoing apoptosis, which was associated with degradation of eukaryotic initiation factor 4A regulator 4E-BP1 in a p38 MAPK-dependent manner. CHX attenuated a TNFα-stimulated increase in the expression and activity of PP2A. Silencing PP2A expression with small interfering RNA transfection mimicked CHX sensitization, increasing HUVEC apoptosis with TNFα stimulation and suggesting a protective role for PP2A in the apoptotic process. CONCLUSION Our data suggest that (1) TNFα stimulates PP2A and HUVECs elude apoptosis by PP2A-dependent dephosphorylation of p38 MAPK, and (2) CHX-induced inhibition of PP2A leads to maintenance of p38 activity and degradation of 4E-BP1, resulting in enhanced TNFα-induced apoptosis.
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Affiliation(s)
- Carla Janzen
- Department of Obstetrics and Gynecology, David Geffen School of Medicine at University of California, Los Angeles, CA 90095, USA
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21
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Ukil A, Kar S, Srivastav S, Ghosh K, Das PK. Curative effect of 18β-glycyrrhetinic acid in experimental visceral leishmaniasis depends on phosphatase-dependent modulation of cellular MAP kinases. PLoS One 2011; 6:e29062. [PMID: 22194991 PMCID: PMC3237588 DOI: 10.1371/journal.pone.0029062] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 11/20/2011] [Indexed: 11/18/2022] Open
Abstract
We earlier showed that 18β-glycyrrhetinic acid (GRA), a pentacyclic triterpenoid from licorice root, could completely cure visceral leishmaniasis in BALB/c mouse model. This was associated with induction of nitric oxide and proinflammatory cytokine production through the up regulation of NF-κB. In the present study we tried to decipher the underlying cellular mechanisms of the curative effect of GRA. Analysis of MAP kinase pathways revealed that GRA caused strong activation of p38 and to a lesser extent, ERK in bone marrow-derived macrophages (BMDM). Almost complete abrogation of GRA-induced cytokine production in presence of specific inhibitors of p38 and ERK1/2 confirmed the involvement of these MAP kinases in GRA-mediated responses. GRA induced mitogen- and stress-activated protein kinase (MSK1) activity in a time-dependent manner suggested that GRA-mediated NF-κB transactivation is mediated by p38, ERK and MSK1 pathway. As kinase/phosphatase balance plays an important role in modulating infection, the effect of GRA on MAPK directed phosphatases (MKP) was studied. GRA markedly reduced the expression and activities of three phosphatases, MKP1, MKP3 and protein phosphatase 2A (PP2A) along with a substantial reduction of p38 and ERK dephosphorylation in infected BMDM. Similarly in the in vivo situation, GRA treatment of L. donovani-infected BALB/c mice caused marked reduction of spleen parasite burden associated with concomitant decrease of individual phosphatase levels. However, activation of kinases also played an important role as the protective effect of GRA was significantly abrogated by pharmacological inhibition of p38 and ERK pathway. Curative effect of GRA may, therefore, be associated with restoration of proper cellular kinase/phosphatase balance, rather than modulation of either kinases or phosphatases.
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Affiliation(s)
- Anindita Ukil
- Department of Biochemistry, Calcutta University, Kolkata, India
| | - Susanta Kar
- Molecular Cell Biology Laboratory, Infectious Diseases and Immunology Division, Indian Institute of Chemical Biology, Kolkata, India
| | - Supriya Srivastav
- Molecular Cell Biology Laboratory, Infectious Diseases and Immunology Division, Indian Institute of Chemical Biology, Kolkata, India
| | - Kuntal Ghosh
- Department of Biochemistry, Calcutta University, Kolkata, India
| | - Pijush K. Das
- Molecular Cell Biology Laboratory, Infectious Diseases and Immunology Division, Indian Institute of Chemical Biology, Kolkata, India
- * E-mail:
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Meng G, Sun Y, Fu W, Guo Z, Xu L. Microcystin-LR induces cytoskeleton system reorganization through hyperphosphorylation of tau and HSP27 via PP2A inhibition and subsequent activation of the p38 MAPK signaling pathway in neuroendocrine (PC12) cells. Toxicology 2011; 290:218-29. [DOI: 10.1016/j.tox.2011.09.085] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2011] [Revised: 09/23/2011] [Accepted: 09/28/2011] [Indexed: 11/16/2022]
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Regulation of heat shock protein 27 phosphorylation during microcystin-LR-induced cytoskeletal reorganization in a human liver cell line. Toxicol Lett 2011; 207:270-7. [DOI: 10.1016/j.toxlet.2011.09.025] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2011] [Revised: 09/22/2011] [Accepted: 09/23/2011] [Indexed: 11/24/2022]
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Bourdonnay E, Morzadec C, Fardel O, Vernhet L. Arsenic increases lipopolysaccharide-dependent expression of interleukin-8 gene by stimulating a redox-sensitive pathway that strengthens p38-kinase activation. Mol Immunol 2011; 48:2069-78. [DOI: 10.1016/j.molimm.2011.06.443] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 06/27/2011] [Accepted: 06/28/2011] [Indexed: 01/23/2023]
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Christensen DJ, Ohkubo N, Oddo J, Van Kanegan MJ, Neil J, Li F, Colton CA, Vitek MP. Apolipoprotein E and peptide mimetics modulate inflammation by binding the SET protein and activating protein phosphatase 2A. THE JOURNAL OF IMMUNOLOGY 2011; 186:2535-42. [PMID: 21289314 DOI: 10.4049/jimmunol.1002847] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The molecular mechanism by which apolipoprotein E (apoE) suppresses inflammatory cytokine and NO production is unknown. Using an affinity purification approach, we found that peptide mimetics of apoE, derived from its receptor binding domain residues 130-150, bound to the SET protein, which is a potent physiological inhibitor of protein phosphatase 2A (PP2A). Both holo-apoE protein and apoE-mimetic peptides bound to the C-terminal region of SET, which is then associated with an increase in PP2A-mediated phosphatase activity. As physiological substrates for PP2A, the LPS-induced phosphorylation status of signaling MAPK and Akt kinase is reduced following treatment with apoE-mimetic peptides. On the basis of our previous report, in which apoE-mimetic peptides reduced I-κB kinase and NF-κB activation, we also demonstrate a mechanism for reduced production of inducible NO synthase protein and its NO product. These data provide evidence for a novel molecular mechanism by which apoE and apoE-mimetic peptides antagonize SET, thereby enhancing endogenous PP2A phosphatase activity, which reduces levels of phosphorylated kinases, signaling, and inflammatory response.
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Sun W, Wang H, Zhao X, Yu Y, Fan Y, Wang H, Wang X, Lu X, Zhang G, Fu S, Yang J. Protein phosphatase 2A acts as a mitogen-activated protein kinase kinase kinase 3 (MEKK3) phosphatase to inhibit lysophosphatidic acid-induced IkappaB kinase beta/nuclear factor-kappaB activation. J Biol Chem 2010; 285:21341-8. [PMID: 20448038 DOI: 10.1074/jbc.m110.104224] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
MEKK3 is a central intermediate signaling component in lysophosphatidic acid (LPA)-induced activation of the nuclear factor-kappaB (NF-kappaB). However, the precise mechanism for the termination of MEKK3 kinase activity is not fully understood. Using a functional genomic approach, we have identified a protein serine/threonine phosphatase, protein phosphatase 2A (PP2A), as a MEKK3 phosphatase. Overexpression of PP2A catalytic subunit (PP2Ac) beta-isoform results in dephosphorylation of MEKK3 at Thr-516 and Ser-520 and termination of MEKK3-mediated NF-kappaB activation. PP2Ac associates with the phosphorylated form of MEKK3 and the interaction between PP2Ac and MEKK3 is induced by LPA in a transient fashion in the cells. Furthermore, knockdown of PP2Ac expression enhances LPA-induced MEKK3-mediated IkappaB kinase beta (IKKbeta) phosphorylation and NF-kappaB activation. These data suggest that PP2A plays an important role in the termination of LPA-mediated NF-kappaB activation through dephosphorylating and inactivating MEKK3.
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Affiliation(s)
- Wenjing Sun
- Texas Children's Cancer Center Department of Pediatrics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas 77030, USA
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27
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Song Y, Wang K, Chen DB, Magness RR, Zheng J. Suppression of protein phosphatase 2 differentially modulates VEGF- and FGF2-induced signaling in ovine fetoplacental artery endothelial cells. Placenta 2009; 30:907-13. [PMID: 19692121 DOI: 10.1016/j.placenta.2009.07.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 07/08/2009] [Accepted: 07/09/2009] [Indexed: 10/20/2022]
Abstract
Vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2) elicit cellular responses via activation of protein kinases and phosphatases. We have reported that the MEK1/2/ERK1/2 and PI3K/AKT1 pathways are critical for VEGF- and FGF2-stimulated ovine fetoplacental artery endothelial (OFPAE) cell proliferation. We have also shown that protein phosphatase 3 (PPP3) differentially modulates VEGF- and FGF2-stimulated cell proliferation and activation of ERK1/2 and AKT1 in OFPAE cells. Herein, we investigated if protein phosphatase 2 (PPP2) modulated VEGF- and FGF2-induced ERK1/2, AKT1, and p38 MAPK activation and VEGF- and FGF2-stimulated cell proliferation in OFPAE cells. Small interfering RNA (siRNA) specifically targeting human PPP2CA catalytic subunit alpha (PPP2CA) was used to suppress PPP2CA expression in OFPAE cells. When compared with scrambled siRNA, PPP2CA siRNA decreased (p<0.05) PPP2CA protein levels (approximately 70%) and activity (approximately 50%) without altering protein levels of PPP3 catalytic subunit alpha (PPP3CA), nitric oxide synthase 3 (NOS3), ERK1/2, AKT1, and p38 MAPK. FGF2, but not VEGF rapidly (< or =5 min) induced p38 MAPK phosphorylation. Suppression of PPP2CA enhanced (p<0.05) VEGF-induced AKT1, but not ERK1/2 phosphorylation, whereas inhibited (p<0.05) FGF2-induced ERK1/2 and p38 MAPK and slightly attenuated FGF2-induced AKT1 phosphorylation. Suppression of PPP2CA did not significantly affect VEGF- and FGF2-stimulated OFPAE cell proliferation. Thus, suppression of PPP2CA alone differentially modulated VEGF- and FGF2-induced ERK1/2, AKT1, and p38 MAPK activation, without altering VEGF- and FGF2-stimulated cell proliferation in OFPAE cells. These data also suggest that signaling molecules other than ERK1/2, AKT1, and p38 MAPK are important mediators for VEGF- and FGF2-stimulated OFPAE cell proliferation after PPP2CA suppression.
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Affiliation(s)
- Y Song
- Department of Obstetrics and Gynecology, Perinatal Research Laboratories, University of Wisconsin, Madison, WI 53715, USA
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Cyclic stretch-induced TGFbeta1/Smad signaling inhibits adipogenesis in umbilical cord progenitor cells. Biochem Biophys Res Commun 2008; 377:1147-51. [PMID: 18983975 DOI: 10.1016/j.bbrc.2008.10.131] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Accepted: 10/22/2008] [Indexed: 12/12/2022]
Abstract
Human umbilical cord perivascular cells (HUCPVCs) can differentiate along numerous lineages making them a favourable cell source for tissue regeneration. However, how these cells respond to biomechanical forces is unclear. This study aimed to determine whether cyclic stretch could regulate adipogenic differentiation of HUCPVCs, and to elucidate the mechanism of this regulation. In adipogenic culture, HUCPVCs expressed the adipocyte-specific transcription factors PPARgamma and C/EBPalpha and accumulated cytoplasmic lipid droplets. Exposure of these cells to equibiaxial cyclic stretch (10%, 0.5 Hz) in the presence of adipogenic medium, increased Smad2 phosphorylation compared to static samples and inhibited the expression of adipocyte markers; ERK1/2 phosphorylation was not changed. Inhibiting TGFbeta1 signaling decreased Smad2 phosphorylation and prevented the inhibition of adipogenic differentiation by cyclic stretch. These results demonstrate that cyclic equibiaxial stretch regulates HUCPVC differentiation even in the presence of an adipogenic milieu and should be an important consideration in developing future progenitor cell therapies.
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Kuo YC, Huang KY, Yang CH, Yang YS, Lee WY, Chiang CW. Regulation of phosphorylation of Thr-308 of Akt, cell proliferation, and survival by the B55alpha regulatory subunit targeting of the protein phosphatase 2A holoenzyme to Akt. J Biol Chem 2007; 283:1882-92. [PMID: 18042541 DOI: 10.1074/jbc.m709585200] [Citation(s) in RCA: 291] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Akt is a protein serine/threonine kinase that is involved in the regulation of diverse cellular processes. Phosphorylation of Akt at regulatory residues Thr-308 and Ser-473 leads to its full activation. The protein phosphatase 2A (PP2A) has long been known to negatively regulate Akt activity. The PP2A holoenzyme consists of the structural subunit (A), catalytic subunit (C), and a variable regulatory subunit (B). Here we report the identification of the specific B regulatory subunit that targets the PP2A holoenzyme to Akt. We found endogenous association of PP2A AB55C holoenzymes with Akt by co-immunoprecipitation analyses in pro-lymphoid FL5.12 cells. Akt was shown to associate with ectopically expressed B55alpha subunit in NIH3T3 cells. The direct interaction between B55alpha subunit and Akt was confirmed using in vitro pulldown analyses. Intriguingly, we found that overexpression of B55alpha subunit significantly impaired phosphorylation at Thr-308, but to a lesser extent at Ser-473 of Akt in both FL5.12 and NIH3T3 cells. Concomitantly, phosphorylation of a subset of Akt substrates, including FoxO3a, was substantially decreased by B55alpha overexpression in these cells. Silencing of B55alpha expression markedly increased phosphorylation at Thr-308 but not at Ser-473 in both FL5.12 cells and NIH3T3 cells. Consistently, PP2A AB55alphaC holoenzymes preferentially dephosphorylated phospho-Thr-308 rather than phospho-Ser-473 in in vitro dephosphorylation assays. Furthermore, B55alpha overexpression retarded proliferation of NIH3T3 cells, and knockdown of B55alpha expression increased survival of FL5.12 cells upon interleukin-3 deprivation. Together, our data demonstrate that B55alpha-dependent targeting of the PP2A holoenzyme to Akt selectively regulates Akt phosphorylation at Thr-308 to regulate cell proliferation and survival.
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Affiliation(s)
- Yi-Chun Kuo
- Institute of Molecular Medicine, Center for Gene Regulation and Signal Transduction Research, National Cheng Kung University Medical College, 701 Tainan, Taiwan
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Hoshino Y, Nishimura K, Sumpio BE. Phosphatase PTEN is inactivated in bovine aortic endothelial cells exposed to cyclic strain. J Cell Biochem 2007; 100:515-26. [PMID: 16927376 DOI: 10.1002/jcb.21085] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Hemodynamic forces, including cyclic strain (CS) and shear stress (SS), have been recognized as important modulators of vascular cell morphology and function. PTEN (also known as MMAC1/TEP1) is a lipid phosphatase that leads to a decrease in intracellular phosphatidylinositol 3,4,5 trisphosphate (PIP3) and therefore can modulate the stimulating effect of phosphatidylinositol 3-kinase (PI3K). In this study, we focused on the upstream regulators of the PI3K-Akt pathway by assessing Akt, PTEN, casein kinase 2 (CK2) (a kinase that catalyzes phosphorylation of PTEN), and PI3K activity in endothelial cells (EC) exposed to CS. The activity of phospho-PTEN (n = 4) and phospho-CK2 (n = 4) increased in a time-dependent fashion, reaching maximal activity by 10 min of CS stimulation. The peak of phospho-Akt activity (n = 4) occurred later, at 60 min. Akt activity was altered by transfection of EC with dominant negative PTEN plasmids. Furthermore, CS increased PIP3 immunoreactivity in a time-dependent manner, reaching maximal activity after 60 min of CS stimulation, and these effects were affected by transfection of EC with dominant negative PTEN plasmids. Inhibition of PTEN activity had no effect on CS-mediated cell proliferation but inhibited CS-mediated suppression of apoptosis.
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Affiliation(s)
- Yuji Hoshino
- Department of Surgery, Section of Vascular Surgery, Yale University School of Medicine and Veterans Administration Health Care System, New Haven, Connecticut 06520, USA
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31
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Boudreau RTM, Conrad DM, Hoskin DW. Apoptosis induced by protein phosphatase 2A (PP2A) inhibition in T leukemia cells is negatively regulated by PP2A-associated p38 mitogen-activated protein kinase. Cell Signal 2007; 19:139-51. [PMID: 16844342 DOI: 10.1016/j.cellsig.2006.05.030] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2006] [Revised: 05/29/2006] [Accepted: 05/31/2006] [Indexed: 01/21/2023]
Abstract
Serine/threonine phosphatase regulation of phosphorylation-mediated intracellular signaling controls a number of important processes in mammalian cells. In this study, we show that constitutively active protein phosphatase 2A (PP2A), which is a serine/threonine phosphatase, is essential for T leukemia cell survival. Jurkat and CCRF-CEM T leukemia cells treated with the PP2A-selective inhibitor okadaic acid (OA) showed a dose- and time-dependent induction of apoptosis, as indicated by loss of mitochondrial transmembrane potential (delta psi(m)), cleavage-induced activation of caspase-3, -8, and -9, and DNA fragmentation. In addition, caspase-8 or caspase-9 inhibition with z-IETD-fmk or z-LEHD-fmk, respectively, largely prevented OA-induced apoptosis. Although OA treatment did not affect constitutive Bcl-2 expression, overexpression of Bcl-2 prevented both OA-induced DNA fragmentation and dissipation of delta psi(m). Furthermore, inhibition of caspase-3, -8, or -9 partially protected against OA-induced loss of delta psi(m). In addition, caspase-9 and caspase-3 inhibition largely prevented procaspase-3 and procaspase-8 cleavage, respectively, while caspase-8 inhibition partially interfered with procaspase-9 cleavage in OA-treated T leukemia cells. Thus, PP2A inhibition triggered the intrinsic pathway of apoptosis, which was enhanced by a mitochondrial feedback amplification loop. PP2A has also been implicated in the regulation of p38 mitogen-activated protein kinase (MAPK). Co-immunoprecipitation analysis revealed a physical association between the catalytic subunit of PP2A and p38 MAPK in T leukemia cells. Moreover, OA treatment caused p38 MAPK to be phosphorylated in a dose- and time-dependent fashion, indicating that PP2A prevented p38 MAPK activation. Although p38 MAPK activation usually promotes apoptosis, pharmacologic inhibition of p38 MAPK exacerbated OA-induced DNA fragmentation and loss of delta psi(m) in T leukemia cells, suggesting that, in this instance, the p38 MAPK signaling pathway promoted cell survival. Collectively, these findings indicate that PP2A and p38 MAPK have coordinate effects on signaling pathways that regulate the survival of T leukemia cells.
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Affiliation(s)
- Robert T M Boudreau
- Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University, Sir Charles Tupper Medical Building, 5850 University Ave., Halifax, Nova Scotia, Canada B3H 1X5
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Sun HW, Li CJ, Chen HQ, Lin HL, Lv HX, Zhang Y, Zhang M. Involvement of integrins, MAPK, and NF-kappaB in regulation of the shear stress-induced MMP-9 expression in endothelial cells. Biochem Biophys Res Commun 2006; 353:152-8. [PMID: 17174275 DOI: 10.1016/j.bbrc.2006.12.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Accepted: 12/01/2006] [Indexed: 10/23/2022]
Abstract
Variations in the matrix metalloproteinase (MMP)-9 gene are related to the presence and severity of atherosclerosis. The aim of this study was to determine the signaling pathways of MMP-9 in endothelial cells subjected to low fluid shear stress. We found that low fluid shear stress significantly increased MMP-9 expression, IkappaBalpha degradation, NF-kappaB DNA-binding activity and phosphorylation of MAPK in cultured human umbilical vein endothelial cells (HUVECs). Inhibition of NF-kappaB resulted in remarkable downregulation of stress-induced MMP-9 expression. Pretreatment of HUVECs with inhibitors of p38 mitogen-activating protein kinase (MAPK) and extracellular signal-regulated kinase1/2 (ERK1/2) also led to significant suppression of stress-induced MMP-9 expression and NF-kappaB DNA-binding activity. Similarly, addition of integrins inhibitor to HUVECs suppressed the stress-induced MMP-9 expression, IkappaBalpha degradation, NF-kappaB DNA-binding activity and the phosphorylation of p38 MAPK, ERK1/2. Our findings demonstrated that the shear stress-induced MMP-9 expression involved integrins-p38 MAPK or ERK1/2-NF-kappaB signaling pathways.
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Affiliation(s)
- Hui-Wen Sun
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Shandong University Qilu Hospital, Jinan, Shandong 250012, PR China
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Sharma SV, Gajowniczek P, Way I, Lee D, Jiang J, Yuza Y, Classon M, Haber DA, Settleman J. A common signaling cascade may underlie "addiction" to the Src, BCR-ABL, and EGF receptor oncogenes. Cancer Cell 2006; 10:425-35. [PMID: 17097564 PMCID: PMC2673136 DOI: 10.1016/j.ccr.2006.09.014] [Citation(s) in RCA: 185] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2006] [Revised: 07/10/2006] [Accepted: 09/08/2006] [Indexed: 10/23/2022]
Abstract
"Oncogene addiction" describes an unexplained dependency of cancer cells on a particular cellular pathway for survival or proliferation. We report that differential attenuation rates of prosurvival and proapoptotic signals in oncogene-dependent cells contribute to cell death following oncogene inactivation. Src-, BCR-ABL-, and EGF receptor-dependent cells exhibit a similar profile of signal attenuation following oncogene inactivation characterized by rapid diminution of phospho-ERK, -Akt, and -STAT3/5, and a delayed accumulation of the proapoptotic effector phospho-p38 MAPK. These findings implicate a transient imbalance in survival and apoptotic oncogenic outputs in the apoptotic response to oncogene inactivation. Moreover, these observations implicate a common profile of signal attenuation for multiple oncogenes and suggest that "addiction" associated with apoptosis reflects an active rather than a passive process.
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Affiliation(s)
- Sreenath V. Sharma
- Massachusetts General Hospital Cancer Center and Harvard Medical School, 149 13 St., Charlestown, MA 02129
| | - Patrycja Gajowniczek
- Massachusetts General Hospital Cancer Center and Harvard Medical School, 149 13 St., Charlestown, MA 02129
| | - Inna Way
- Massachusetts General Hospital Cancer Center and Harvard Medical School, 149 13 St., Charlestown, MA 02129
| | - Diana Lee
- Massachusetts General Hospital Cancer Center and Harvard Medical School, 149 13 St., Charlestown, MA 02129
| | - Jane Jiang
- Dana Farber Cancer Research Institute, 44 Binney Street, Boston, MA 02115
| | - Yuki Yuza
- Dana Farber Cancer Research Institute, 44 Binney Street, Boston, MA 02115
| | - Marie Classon
- Massachusetts General Hospital Cancer Center and Harvard Medical School, 149 13 St., Charlestown, MA 02129
| | - Daniel A. Haber
- Massachusetts General Hospital Cancer Center and Harvard Medical School, 149 13 St., Charlestown, MA 02129
| | - Jeffrey Settleman
- Massachusetts General Hospital Cancer Center and Harvard Medical School, 149 13 St., Charlestown, MA 02129
- Correspondence: Telephone: 617-724-9556, Fax: 617-726-7808,
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Zhang J, Owen CR, Sanders MA, Turner JR, Basson MD. The motogenic effects of cyclic mechanical strain on intestinal epithelial monolayer wound closure are matrix dependent. Gastroenterology 2006; 131:1179-89. [PMID: 17030187 DOI: 10.1053/j.gastro.2006.08.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Accepted: 06/28/2006] [Indexed: 01/14/2023]
Abstract
BACKGROUND & AIMS Complex deformation during normal digestion due to peristalsis or villous motility may be trophic for the intestinal mucosa. Because tissue fibronectin is increased in inflammatory states that may accompany mucosal injury, we evaluated the effects of cyclic mechanical strain and fibronectin on intestinal epithelial monolayer wound closure in Caco-2 and IEC-6 intestinal epithelial cells. METHODS Wounds created in intestinal epithelial monolayers were subjected to cyclic deformation. Wound closure was assessed by morphometry using microscopic imaging. Cell signals were assessed by Western blot and confocal microscopy. RESULTS Mechanical strain stimulated wound closure on fibronectin but inhibited closure on collagen in Caco-2 and IEC-6 cells. The effect was independent of proliferation or cell spreading. Myosin light chain (MLC) and extracellular signal-regulated kinase (ERK) were phosphorylated in response to strain in confluent monolayers on both collagen and fibronectin. Blocking MLC or ERK phosphorylation inhibited the motogenic effect of strain on fibronectin. Although phosphorylated MLC was redistributed to the leading edge of migrating cells following 6 hours of strain on collagen and fibronectin, phosphorylated ERK was redistributed to the lamellipodial edge only on fibronectin. CONCLUSIONS Strain promotes intestinal epithelial wound closure by a pathway requiring ERK and MLC kinase. Fibronectin-dependent ERK redistribution in response to strain in confluent migrating cells may explain the matrix dependence of the motogenic effect. Repetitive deformation stimulates intestinal epithelial proliferation on a collagen substrate, but not fibronectin. Deformation may exert matrix-dependent effects on intestinal epithelial cells, promoting epithelial restitution in fibronectin-rich tissue and proliferation in fibronectin-poor mucosa.
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Affiliation(s)
- Jianhu Zhang
- Department of Surgery, John D. Dingell VA Medical Center, 4646 John R. Street, Detroit, MI 48301, USA
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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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Tao GZ, Toivola DM, Zhou Q, Strnad P, Xu B, Michie SA, Omary MB. Protein phosphatase-2A associates with and dephosphorylates keratin 8 after hyposmotic stress in a site- and cell-specific manner. J Cell Sci 2006; 119:1425-32. [PMID: 16554440 DOI: 10.1242/jcs.02861] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Keratins 8 and 18 (K8 and K18) are regulated by site-specific phosphorylation in response to multiple stresses. We examined the effect and regulation of hyposmotic stress on keratin phosphorylation. K8 phospho-Ser431 (Ser431-P) becomes dephosphorylated in HT29 cells, but hyperphosphorylated on other K8 but not K18 sites in HRT18 and Caco2 cells and in normal human colonic ex vivo cultures. Hyposmosis-induced dephosphorylation involves K8 but not K18, K19 or K20, occurs preferentially in mitotically active cells, and peaks by 6-8 hours then returns to baseline by 12-16 hours. By contrast, hyperosmosis causes K8 Ser431 hyperphosphorylation in all tested cell lines. Hyposmosis-induced dephosphorylation of K8 Ser431-P is inhibited by okadaic acid but not by tautomycin or cyclosporine. The PP2A catalytic subunit co-immunoprecipitated with K8 and K18 after hyposmotic stress in HT29 cells, but not in HRT18 or Caco2 cells where K8 Ser431 becomes hyperphosphorylated. K8 Ser431-P dephosphorylation after hyposmosis was independent of PP2A levels but correlated with increased PP2A activity towards K8 Ser431-P. Therefore, hyposmotic stress alters K8 phosphorylation in a cell-dependent manner, and renders K8 Ser431-P a physiologic substrate for PP2A in HT29 cells as a result of PP2A activation and the physical association with K8 and K18. The divergent hyposmosis versus hyperosmosis K8 Ser431 phosphorylation changes in HT29 cells suggest that there are unique signaling responses to osmotic stress.
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Affiliation(s)
- Guo-Zhong Tao
- Department of Medicine, Palo Alto VA Medical Center, 3801 Miranda Avenue, Mail Code 154J, Palo Alto, CA 94304, USA.
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Keen JC, Zhou Q, Park BH, Pettit C, Mack KM, Blair B, Brenner K, Davidson NE. Protein phosphatase 2A regulates estrogen receptor alpha (ER) expression through modulation of ER mRNA stability. J Biol Chem 2005; 280:29519-24. [PMID: 15965230 DOI: 10.1074/jbc.m505317200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein phosphatase 2A (PP2A) is a ubiquitously expressed member of the serine-threonine phosphatase family that is involved in regulation of many cellular processes including transcription, translation, cellular metabolism, and apoptosis. Because of a correlation between PP2A and estrogen receptor alpha (ER) expression in several human breast cancer cell lines, the effect of PP2A on regulation of ER expression in the human breast cancer cell line MCF-7 was studied. Inhibition of PP2A using the pharmacologic inhibitor okadaic acid at 250 nm for 16 h resulted in a 60% reduction in PP2A activity in MCF-7 cells concurrent with a 75% reduction in ER mRNA and protein expression. Similar results were obtained with a small interfering RNA probe that specifically inhibited PP2A expression. ER promoter studies showed that regulation of ER through the PP2A pathway did not occur through transcriptional activation. Rather, PP2A mediated ER expression through modulation of ER mRNA stability through degradation of ER mRNA, reversible with concomitant treatment with the proteasomal inhibitor MG 132. These data suggest a novel pathway controlling ER expression resulting from the activation of PP2A, potentially providing a novel therapeutic target.
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Affiliation(s)
- Judith C Keen
- Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, Maryland 21231, USA
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Abstract
Recent studies show that activation of p38 mitogen-activated protein kinase (MAPK) results in cancer cell apoptosis initiated by retinoids, cisplatin and other chemotherapeutic agents. The observation that divergent therapies act through a common signal transduction pathway raises the possibility of developing new anti-cancer agents that lack the side-effects caused by events upstream of p38 MAPK. Here, we review p38-MAPK-mediated tumor cell apoptosis and implications for cancer therapeutics.
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Affiliation(s)
- James M Olson
- Fred Hutchinson Cancer Research Center, and Department of Pediatrics, University of Washington, Seattle, WA, USA.
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Boudreau RTM, Hoskin DW, Lin TJ. Phosphatase inhibition potentiates IL-6 production by mast cells in response to FcepsilonRI-mediated activation: involvement of p38 MAPK. J Leukoc Biol 2004; 76:1075-81. [PMID: 15316034 DOI: 10.1189/jlb.1003498] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Mast cells are crucial effector cells in the immune response through mediator secretion and release of cytokines. A coordinated balance between protein kinases and phosphatases plays an essential role in the regulation of mast cell mediator secretion. We have previously shown that treatment of mast cells with okadaic acid (OA), a protein phosphatase 2A (PP2A) inhibitor, results in a dose-dependent increase in interleukin (IL)-6 production. We show here for the first time a synergism between OA and immunoglobulin E (IgE)-mediated IL-6 secretion by murine bone marrow-derived mast cells (BMMC). Selective p38 mitogen-activated protein kinase (p38 MAPK) inhibition reduces OA and IgE-mediated IL-6 production. Regulation of p38 MAPK by PP2A was demonstrated, as OA treatment caused a dose-dependent increase in p38 MAPK phosphorylation. Antigen-mediated activation of murine mast cells also resulted in an increase in p38 MAPK phosphorylation, which was potentiated by cotreatment of the cells with OA. Lastly, in two mast cell lines (human mast cell-1 5C6 and murine MC/9) and primary-cultured murine BMMC, we show by coimmunoprecipitation an interaction between p38 MAPK and PP2A. These data support a role for PP2A through interaction with p38 MAPK in the regulation of IgE-dependent mast cell activation.
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Affiliation(s)
- Robert T M Boudreau
- Department of Microbiology, Dalhousie University, Halifax, Nova Scotia, Canada
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Liu XM, Ensenat D, Wang H, Schafer AI, Durante W. Physiologic cyclic stretch inhibits apoptosis in vascular endothelium. FEBS Lett 2003; 541:52-6. [PMID: 12706818 DOI: 10.1016/s0014-5793(03)00285-0] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Since apoptosis of endothelial cells (ECs) plays an important role in the pathogenesis of atherosclerosis, we investigated the effect of cyclic stretch on EC apoptosis. Application of moderate, physiologic levels of cyclic stretch (6-10% at 1 Hz) inhibited EC apoptosis. This anti-apoptotic effect was dependent on the activation of phosphatidylinositol 3-kinase and associated with the activation of Akt and the phosphorylation of Bad. Interestingly, a higher potentially pathologic level of cyclic stretch (20% at 1 Hz) stimulated EC apoptosis. The ability of physiologic cyclic stretch to inhibit EC apoptosis may provide a previously unrecognized mechanism by which hemodynamic forces exert an anti-atherogenic effect.
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Affiliation(s)
- Xiao-ming Liu
- VA Medical Center and the Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA
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