Akt-dependent antiapoptotic action of insulin is sensitive to farnesyltransferase inhibitor.
CHO cells expressing the human insulin receptors (IR) were used to evaluate the effect of the potent farnesyltransferase inhibitor, manumycin, on insulin antiapoptotic function. Cell treatment with manumycin blocked insulin's ability to suppress pro-apoptotic caspase-3 activity which led to time-dependent proteolytic cleavage of two nuclear target proteins. The Raf-1/MEK/ERK cascade and the serine/threonine protein kinase Akt are two survival pathways that may be activated in response to insulin. We tested the hypothesis that inhibition of farnesylated Ras was causally related to manumycin-induced apoptosis and showed that the response to manumycin was found to be independent of K-Ras function because membrane association and activation of endogenous K-Ras proteins in terms of GTP loading and ERK activation were unabated following treatment with manumycin. Moreover, blocking p21Ras/Raf-1/MEK/ERK cascade by the expression of a transdominant inhibitory mSOS1 mutant in CHO-IR cells kept cells sensitive to the antiapoptotic action of insulin. Insulin-dependent activation of Akt was blocked by 4 h treatment with manumycin (P < 0.01), a kinetic too rapid to be explained by Ras inhibition. This study suggests that the depletion of short-lived farnesylated proteins by manumycin suppresses the antiapoptotic action of insulin at least in part by disrupting Akt activation but not that of the K-Ras/Raf-1/ERK-dependent cascade.
Park
D
D
Diabetes Section, Laboratory of Clinical Investigation, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Box 23, Baltimore, Maryland 21224-6825, USA.
Pandey
S K
SK
Maksimova
E
E
Kole
S
S
Bernier
M
M
D019883:Alkyl and Aryl Transferases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D016466:CHO Cells; D002470:Cell Survival / Q000187:drug effects; D006224:Cricetinae; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D051231:Farnesyltranstransferase; D006801:Humans; D007328:Insulin / Q000502:physiology*; D007329:Insulin Antagonists / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011090:Polyenes / Q000494:pharmacology*; D053284:Polyunsaturated Alkamides; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000502:physiology; D020837:SOS1 Protein / Q000235:genetics; D014162:Transfection
D019883:Alkyl and Aryl Transferases; D004791:Enzyme Inhibitors; D051231:Farnesyltranstransferase; D007328:Insulin; D007329:Insulin Antagonists; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011090:Polyenes; D053284:Polyunsaturated Alkamides; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D016283:Proto-Oncogene Proteins p21(ras); D020837:SOS1 Protein; C494918:AKT1 protein, human; C501009:HRAS protein, human; C054474:manumycin