H-89 potentiates adipogenesis in 3T3-L1 cells by activating insulin signaling independently of protein kinase A.
Among four kinds of protein kinase A (PKA) inhibitors tested, H-89 exhibited a unique action to remarkably enhance adipocyte differentiation of 3T3-L1 cells, whereas the other three PKA inhibitors, PKA inhibitor Fragment 14-22 (PKI), Rp-cAMP, and KT 5720, did not enhance adipocyte differentiation. H-85, which is an inactive form of H-89, exhibited a similar enhancing effect on adipocyte differentiation. H-89 also potentiated the phosphorylation of Akt and extracellular signal-regulated kinase (ERK) 1/2 in 3T3-L1 cells, which function as downstream signaling of insulin. Phosphoinositide 3-kinase (PI3K) inhibitor wortmannin and mitogen-activated protein kinase kinase (MEK) inhibitor PD 98059 suppressed both the H-89-induced promotion of adipocyte differentiation and the H-89-induced potentiation of phosphorylation of Akt and ERK1/2. Rho kinase inhibitor Y-27632 also promoted the phosphorylation of both Akt and ERK1/2 and enhanced adipocyte differentiation, although its effect was somewhat less than that of H-89. Even when cells were treated with a mixture of Y-27632 and H-89, the additive enhancing effects on both the insulin signaling and adipocyte differentiation were not detected. Therefore, it is suggested that the major possible mechanism whereby H-89 potentiates adipocyte differentiation of 3T3-L1 cells is activation of insulin signaling that is elicited mostly by inhibiting Rho/Rho kinase pathway.
Kato
Yoshiro
Y
Department of Endocrinology and Diabetes, Field of Internal Medicine, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan. y-kato@kde.biglobe.ne.jp
Ozaki
Nobuaki
N
Yamada
Tsutomu
T
Miura
Yoshitaka
Y
Oiso
Yutaka
Y
D041721:3T3-L1 Cells; D050156:Adipogenesis / Q000187:drug effects*; D000818:Animals; D015153:Blotting, Western; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D007546:Isoquinolines / Q000494:pharmacology*; D051379:Mice; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects*; D013449:Sulfonamides / Q000494:pharmacology*
D007328:Insulin; D007546:Isoquinolines; D047428:Protein Kinase Inhibitors; D013449:Sulfonamides; D017868:Cyclic AMP-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide