PKC alpha regulates thrombin-induced PDGF-B chain gene expression in mesangial cells.
Thrombin is a potent mitogen for mesangial cells and stimulates PDGF B-chain gene expression in these cells. It also activates phospholipase C (PLC) resulting in an increase in cytosolic Ca2+ and diacylglycerol (DAG) that are the physiological activators of protein kinase C (PKC). Immunoprecipitation of specific PKC isotypes from thrombin-stimulated mesangial cells with subsequent measurement of their enzymatic activity shows activation of Ca(2+)-dependent PKC alpha and Ca(2+)-independent PKC zeta in a time dependent manner. Optimum activation of both of these isozymes was obtained at 60 minutes. PKC alpha activity increased 83% over basal while activity of PKC zeta increased 104%. Prolonged exposure of mesangial cells to phorbol myristate acetic acid (PMA) inhibited the enzymatic activity of PKC alpha but not PKC zeta. This inhibition of PKC alpha had no effect on thrombin-induced DNA synthesis but abolished PDGF B-chain gene expression induced by thrombin. These data provide the first evidence that PKC alpha activation is necessary for thrombin-induced PDGF B-chain gene expression but not for thrombin-induced DNA synthesis.
Biswas
P
P
Department of Medicine, University of Texas Health Science Center at San Antonio 78284, USA.
Abboud
H E
HE
Kiyomoto
H
H
Wenzel
U O
UO
Grandaliano
G
G
Choudhury
G G
GG
D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D004789:Enzyme Activation; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D005920:Glomerular Mesangium / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D007527:Isoenzymes / Q000378:metabolism*; D007672:Kidney Cortex / Q000378:metabolism; D046911:Macromolecular Substances; D010982:Platelet-Derived Growth Factor / Q000096:biosynthesis*; D011493:Protein Kinase C / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D013755:Tetradecanoylphorbol Acetate; D013917:Thrombin / Q000494:pharmacology*; D013936:Thymidine / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
D007527:Isoenzymes; D046911:Macromolecular Substances; D010982:Platelet-Derived Growth Factor; D012333:RNA, Messenger; D004247:DNA; D011493:Protein Kinase C; D013917:Thrombin; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; D013936:Thymidine