A role for nuclear factor kappaB in the antiapoptotic function of insulin.
We previously reported that insulin activates nuclear factor kappaB (NF-kappaB) in Chinese hamster ovary (CHO)-R cells overexpressing wild-type insulin receptors (IRs) through a pathway requiring IR tyrosine kinase and Raf-1 kinase activities. We now investigated whether the activation of NF-kappaB by insulin could serve an antiapoptotic function. Insulin (10(-9)-10(-7) M) inhibited apoptosis induced by serum withdrawal in CHO-R cells in a concentration-dependent manner. Insulin antiapoptotic signaling: (i) was dependent on IR number and IR tyrosine kinase activity since it was reduced in parental CHO cells and was abolished in CHO-Y2 cells overexpressing IRs mutated at Tyr1162/1163; (ii) was, like insulin activation of NF-kappaB, dependent on Raf-1 but not on mitogen-activated protein kinase activity since both processes were decreased by the dominant-negative Raf-1 mutant Raf-C4 whereas they persisted in mitogen-activated protein kinase-depleted cells; and (iii) required NF-kappaB activation since it was decreased by proteasome inhibitors and the dominant-negative IkappaB-alpha (A32/36) mutant and was mimicked by overexpression of the NF-kappaB c-Rel subunit. We also show that insulin antiapoptotic signaling but not insulin activation of NF-kappaB involved phosphatidylinositol 3-kinase (PI 3-kinase), as supported by the inhibition of the former but not of the latter process by the PI 3-kinase inhibitor LY294002. Inhibition of both NF-kappaB and PI 3-kinase totally abolished insulin antiapoptotic signaling. Thus insulin exerts a specific antiapoptotic function which is dependent on IR tyrosine kinase activity and is mediated by both a Raf-1-dependent pathway that leads to NF-kappaB activation and a PI 3-kinase-dependent pathway.
Bertrand
F
F
INSERM U.402, Institut Fédératif de Recherche 65, Laboratoire de Biologie Cellulaire, Faculté de Médecine Saint-Antoine, 27 rue Chaligny, 75571 Paris, Cedex 12, France.
Atfi
A
A
Cadoret
A
A
L'Allemain
G
G
Robin
H
H
Lascols
O
O
Capeau
J
J
Cherqui
G
G
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D016466:CHO Cells; D002867:Chromones / Q000494:pharmacology; D006224:Cricetinae; D007328:Insulin / Q000494:pharmacology*; D009025:Morpholines / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism*; D009842:Oligopeptides / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D011972:Receptor, Insulin / Q000378:metabolism; D015398:Signal Transduction
D002867:Chromones; D007328:Insulin; D009025:Morpholines; D016328:NF-kappa B; D009842:Oligopeptides; C090535:benzyloxycarbonyl-isoleucyl-glutamyl(O-tert-butyl)-alanyl-leucinal; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D019869:Phosphatidylinositol 3-Kinases; D011972:Receptor, Insulin; D019908:Proto-Oncogene Proteins c-raf