Signalling pathways regulating the dephosphorylation of Ser729 in the hydrophobic domain of protein kinase Cepsilon upon cell passage.
We have recently demonstrated that in quiescent fibroblasts protein kinase C (PKC) epsilon(95) is phosphorylated at Ser(729), Ser(703), and Thr(566) and that upon passage of quiescent cells phosphorylation at Ser(729) is lost, giving rise to PKCepsilon(87). Ser(729) may be rephosphorylated later, suggesting cycling between PKCepsilon(87) and PKCepsilon(95). Here we show that the dephosphorylation at Ser(729) is insensitive to okadaic acid, calyculin, ascomycin C, and cyclosporin A, suggesting that dephosphorylation at this site is not mediated through protein phosphatases 1, 2A or 2B. We demonstrate that this dephosphorylation at Ser(729) requires serum and cell readhesion and is sensitive to rapamycin, PD98059, chelerythrine, and Ro-31-8220. These results suggest that the phosphorylation status of Ser(729) in the hydrophobic domain at Ser(729) is regulated independently of the phosphorylation status of other sites in PKCepsilon, by a mTOR-sensitive phosphatase. The mitogen-activated protein kinase pathway and PKC are also implicated in regulating the dephosphorylation at Ser(729).
England
K
K
Department of Biology, University of York, York YO10 5DD, United Kingdom. kengland@ucc.ie
Watson
J
J
Beale
G
G
Warner
M
M
Cross
J
J
Rumsby
M
M
D016475:3T3 Cells; D000470:Alkaloids; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D053119:Benzophenanthridines; D015153:Blotting, Western; D019703:Calcineurin / Q000378:metabolism; D002448:Cell Adhesion; D002460:Cell Line; D003470:Culture Media / Q000378:metabolism; D016572:Cyclosporine / Q000494:pharmacology; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000737:chemistry*; D020935:MAP Kinase Signaling System; D008387:Marine Toxins; D008715:Methionine / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D019319:Okadaic Acid / Q000494:pharmacology; D010080:Oxazoles / Q000494:pharmacology; D010617:Phenanthridines / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D011493:Protein Kinase C / Q000737:chemistry* / Q000378:metabolism; D051744:Protein Kinase C-epsilon; D017434:Protein Structure, Tertiary; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology; D016559:Tacrolimus / Q000031:analogs & derivatives* / Q000494:pharmacology; D014162:Transfection
D000470:Alkaloids; D000900:Anti-Bacterial Agents; D053119:Benzophenanthridines; D003470:Culture Media; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007211:Indoles; D007527:Isoenzymes; D008387:Marine Toxins; D010080:Oxazoles; D010617:Phenanthridines; D019319:Okadaic Acid; D012694:Serine; C059041:calyculin A; D016572:Cyclosporine; D008715:Methionine; C058028:immunomycin; C016299:chelerythrine; C497256:Prkce protein, mouse; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D020123:Sirolimus; C064758:Ro 31-8220; D016559:Tacrolimus