Association of insulin receptor substrate proteins with Bcl-2 and their effects on its phosphorylation and antiapoptotic function.
Insulin receptor substrate (IRS) proteins are docking proteins that couple growth factor receptors to various effector molecules, including phosphoinositide-3 kinase, Grb-2, Syp, and Nck. Here we show that IRS-1 associates with the loop domain of Bcl-2 and synergistically up-regulates antiapoptotic function of Bcl-2. IRS-2 but not IRS-3 binds to Bcl-2, and IRS-1 associates with Bcl-XL but not with Bax or Bik. Overexpression of IRS-1 suppresses phosphorylation of Bcl-2 induced by stimulation with insulin, and the hypophosphorylation may lead to its enhanced antiapoptotic activity. The binding site for Bcl-2 is located on the carboxyl half-domain of IRS-1. IRS-3, which lacks the corresponding region, dominant-negatively abrogates the survival effects of IRS-1 and Bcl-2. For the antiapoptotic activity of IRS-1, binding to Bcl-2 is more critical than activating phosphoinositide-3 kinase. Our results indicate that IRS proteins transmit signals from the insulin receptor to Bcl-2, thus regulating cell survival probably through regulating phosphorylation of Bcl-2.
Ueno
H
H
Department of Hematology and Oncology, Graduate School of Medicine, University of Tokyo, Tokyo 113, Japan.
Kondo
E
E
Yamamoto-Honda
R
R
Tobe
K
K
Nakamoto
T
T
Sasaki
K
K
Mitani
K
K
Furusaka
A
A
Tanaka
T
T
Tsujimoto
Y
Y
Kadowaki
T
T
Hirai
H
H
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins; D001665:Binding Sites; D002460:Cell Line; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D008954:Models, Biological; D008970:Molecular Weight; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
D051017:Apoptosis Regulatory Proteins; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins; D019000:Phosphotyrosine; D011506:Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; C494826:BAX protein, human; C494811:BCL2L1 protein, human; C096820:BIK protein, human; C526292:IRS1 protein, human; C526297:IRS2 protein, human; C491585:IRS3P protein, human