Role of phospholipase C-gamma1 in insulin-like growth factor I-induced muscle differentiation of H9c2 cardiac myoblasts.
Insulin-like growth factor-I (IGF-I) regulates muscle differentiation through phosphatidylinositol 3-kinase (PI 3-kinase). Also it was recently reported that PI 3-kinase is involved in the activation of phospholipase C-gamma1 (PLC-gamma1). We investigated whether PLC-gamma1 therefore plays a role in IGF-I-induced muscle differentiation using H9c2 rat cardiac myoblasts as a model. IGF-I was able to activate PLC-gamma1 via both PI 3-kinase-dependent and tyrosine phosphorylation-dependent mechanisms in this model. However, PI 3-kinase appeared to play a more important role than tyrosine phosphorylation in IGF-I activation of PLC-gamma1. In addition, PLC-gamma1 activation was independent of Akt/protein kinase B (Akt/PKB). Importantly, PLC-gamma1 was involved in IGF-I-induced muscle differentiation in parallel with Akt/PKB. Taken together, these results suggest that IGF-I regulation of muscle differentiation is dependent on the activation of PLC-gamma1 and Akt/PKB, both of which are downstream mediators of PI 3-kinase.
Hong
F
F
Department of Molecular Biology, Kyung Hee University, Seoul, 130-701, Korea.
Moon Ka
Kim
S S
SS
Kim
Y S
YS
Choi
Y K
YK
Bae
Y S
YS
Suh
P G
PG
Ryu
S H
SH
Choi
E J
EJ
Ha
J
J
Kim
S S
SS
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007527:Isoenzymes / Q000378:metabolism*; D007700:Kinetics; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051966:Phospholipase C gamma; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000378:metabolism*
D007334:Insulin-Like Growth Factor I; D007527:Isoenzymes; D019869:Phosphatidylinositol 3-Kinases; D051966:Phospholipase C gamma; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D010738:Type C Phospholipases; C494920:Akt1 protein, rat