Osmotic shock induces G1 arrest through p53 phosphorylation at Ser33 by activated p38MAPK without phosphorylation at Ser15 and Ser20.
Osmotic shock induced transient stabilization of p53, possibly due to increased degradation of Mdm2. Stabilized p53 was activated by p38(MAPK), resulting in G(1) arrest through induction of p21(WAF1). Among the postulated phosphorylation sites involved in p53 stabilization or activation (Ser(15), Ser(20), Ser(33), and Ser(46)), only Ser(33) was phosphorylated. Furthermore, interaction of p53 with the transcriptional coactivator p300 was induced, and Lys(382) of p53 was acetylated. Although inhibition of p38(MAPK) did not prevent nuclear accumulation of p53, phosphorylation of Ser(33) was markedly suppressed by SB203580, a specific inhibitor of p38(MAPK). Under these conditions, acetylation of Lys(382) and induction of p21(WAF1) were also inhibited, and cells with elevated levels of p53 showed normal cell cycle progression. Activated p38(MAPK) phosphorylated endogenous p53 at Ser(33) in living cells. In stable transformants expressing dominant negative MKK6, an upstream protein kinase of p38(MAPK), p53 stabilization was induced normally following osmotic shock, but phosphorylation of Ser(33), acetylation of Lys(382), and induction of p21(WAF1) were almost completely inhibited. These results suggest that phosphorylation at Ser(33) by p38(MAPK) is critical for activation of p53 following osmotic shock. Phosphorylation of neither Ser(15) nor Ser(20) was needed in this activation.
Kishi
H
H
Institute of Molecular Embryology and Genetics, Kumamoto University, Kuhonji 4-24-1, Kumamoto 862-0976, Japan.
Nakagawa
K
K
Matsumoto
M
M
Suga
M
M
Ando
M
M
Taya
Y
Y
Yamaizumi
M
M
D000107:Acetylation; D000818:Animals; D015153:Blotting, Western; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002453:Cell Cycle; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D015536:Down-Regulation; D050881:E1A-Associated p300 Protein; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D016193:G1 Phase; D005799:Genes, Dominant; D016158:Genes, p53; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D008156:Luciferases / Q000378:metabolism; D008239:Lysine / Q000737:chemistry; D048669:MAP Kinase Kinase 6; D051379:Mice; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009687:Nuclear Proteins; D009997:Osmotic Pressure; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D011725:Pyridines / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012694:Serine / Q000737:chemistry*; D013997:Time Factors; D015534:Trans-Activators; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases
C493956:CDKN1A protein, human; C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D007093:Imidazoles; D009687:Nuclear Proteins; D011725:Pyridines; D015534:Trans-Activators; D016159:Tumor Suppressor Protein p53; D012694:Serine; D008156:Luciferases; D050881:E1A-Associated p300 Protein; C494361:Ep300 protein, mouse; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048669:MAP Kinase Kinase 6; C482566:MAP2K6 protein, human; C482567:Map2k6 protein, mouse; D008239:Lysine; C093642:SB 203580