p38 MAPK regulates phosphorylation of Bad via PP2A-dependent suppression of the MEK1/2-ERK1/2 survival pathway in TNF-alpha induced endothelial apoptosis.
We recently reported that p38 MAPK regulates TNF-induced endothelial apoptosis via phosphorylation and downregulation of Bcl-xL. Here, we describe that such apoptosis includes p38 MAPK-mediated, protein phosphatase 2A (PP2A)-dependent, downregulation of the MEK-ERK pathway. Inhibition of PP2A with fostriecin or calyculin A significantly increased MEK phosphorylation, as did exposure to the p38 MAPK inhibitor SB203580. Inhibition of MEK potentiated TNF-induced caspase-3 activity and cell death, and both those events were suppressed by treatment with fostriecin or calyculin A. Immunoprecipitation experiments revealed an association between p38 MAPK, PP2A and MEK, and the results of a phosphatase assay suggested that PP2A is a downstream target of p38 MAPK. Importantly, phosphorylation of Bad at Ser-112 was found to be regulated by p38 MAPK and PP2A. In summary, the present findings indicate a novel p38 MAPK-mediated apoptosis pathway, involving activation of Bad via PP2A-dependent inhibition of the MEK-ERK pathway.
Lund University, Division of Experimental Pathology, Department of Laboratory Medicine, University Hospital MAS, entrance 78, SE-20502 Malmö, Sweden.
Simone
S
Grethe
M Isabella
MI
Pörn-Ares
D000475:Alkenes / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D015536:Down-Regulation; D042783:Endothelial Cells / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048370:MAP Kinase Kinase 2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008387:Marine Toxins; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000187:drug effects / Q000378:metabolism; D010080:Oxazoles / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010766:Phosphorylation; D011090:Polyenes; D054648:Protein Phosphatase 2; D011725:Pyridines / Q000494:pharmacology; D011753:Pyrones / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D051025:bcl-Associated Death Protein / Q000187:drug effects / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
D000475:Alkenes; C494819:BAD protein, human; D007093:Imidazoles; D008387:Marine Toxins; D010080:Oxazoles; D011090:Polyenes; D011725:Pyridines; D011753:Pyrones; D014409:Tumor Necrosis Factor-alpha; D051025:bcl-Associated Death Protein; C059041:calyculin A; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; C093642:SB 203580; C040313:fostriecin