Insulin-like growth factor-I inhibits the stress-activated protein kinase/c-Jun N-terminal kinase.
The pathways involved in the cellular responses to the insulin-like growth factors (IGFs) are numerous and vary according to cell type. Following activation of the IGF-I receptor, the mitogen-activated protein kinase and phosphatidylinositide 3'-kinase (PI3'K) pathways are activated and result in cellular proliferation and inhibition of apoptosis. In this study, we analyzed the IGF-I effect on the stress-activated protein kinase/c-Jun N-terminal kinase (JNK) activity using human embryonic kidney 293 cells, 293 cells transiently expressing hemagglutinin-JNK, and 293 cells stably expressing a hemagglutinin-JNK transgene. In all cell types, endogenous or transfected JNK activity was strongly stimulated by anisomycin or tumor necrosis factor-alpha, and 10 nM IGF-I pretreatment suppressed the induced JNK activity. To determine whether the effect of IGF-I on JNK activity involves the mitogen-activated protein kinase or PI3'K pathway, we used the specific MEK1 inhibitor PD098059 and the PI3'K inhibitor LY 294002. PD098059 did not alter the IGF-I suppressive effect on stressor-induced JNK activity, but LY 294002 suppressed the IGF-I effect. Moreover, in transiently transfected parental 293 cells expressing dominant-negative Akt, anisomycin-increased JNK activity was not suppressed by pretreatment with IGF-I. Our results demonstrate that the action of IGF-I on JNK in these cells is via PI3'K and Akt.
Okubo
Y
Y
Diabetes Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA.
Blakesley
V A
VA
Stannard
B
B
Gutkind
S
S
Le Roith
D
D
D000841:Anisomycin / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors*; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D048031:JNK Mitogen-Activated Protein Kinases; D007668:Kidney / Q000196:embryology; D020928:Mitogen-Activated Protein Kinases; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D013312:Stress, Physiological / Q000503:physiopathology*; D014162:Transfection / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000841:Anisomycin; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002867:Chromones; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007334:Insulin-Like Growth Factor I; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D014409:Tumor Necrosis Factor-alpha; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one