title: The CUL7 E3 ubiquitin ligase targets insulin receptor substrate 1 for ubiquitin-dependent degradation.
abstract: Recent genetic studies have documented a pivotal growth-regulatory role played by the Cullin 7 (CUL7) E3 ubiquitin ligase complex containing the Fbw8-substrate-targeting subunit, Skp1, and the ROC1 RING finger protein. In this report, we identified insulin receptor substrate 1 (IRS-1), a critical mediator of the insulin/insulin-like growth factor 1 signaling, as a proteolytic target of the CUL7 E3 ligase in a manner that depends on mammalian target of rapamycin and the p70 S6 kinase activities. Interestingly, while embryonic fibroblasts of Cul7-/- mice were found to accumulate IRS-1 and exhibit increased activation of IRS-1's downstream Akt and MEK/ERK pathways, these null cells grew poorly and displayed phenotypes reminiscent of those associated with oncogene-induced senescence. Taken together, our findings demonstrate a key role for the CUL7 E3 in targeting IRS-1 for degradation, a process that may contribute to the regulation of cellular senescence.
authors.affiliation: Department of Oncological Sciences, The Mount Sinai School of Medicine, New York, NY 10029-6574, USA.
authors.forename: Xinsong
authors.initials: X
authors.lastname: Xu
authors.forename: Antonio
authors.initials: A
authors.lastname: Sarikas
authors.forename: Dora C
authors.initials: DC
authors.lastname: Dias-Santagata
authors.forename: Georgia
authors.initials: G
authors.lastname: Dolios
authors.forename: Pascal J
authors.initials: PJ
authors.lastname: Lafontant
authors.forename: Shih-Chong
authors.initials: SC
authors.lastname: Tsai
authors.forename: Wuqiang
authors.initials: W
authors.lastname: Zhu
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Nakajima
authors.forename: Hisako O
authors.initials: HO
authors.lastname: Nakajima
authors.forename: Loren J
authors.initials: LJ
authors.lastname: Field
authors.forename: Rong
authors.initials: R
authors.lastname: Wang
authors.forename: Zhen-Qiang
authors.initials: ZQ
authors.lastname: Pan
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D016922:Cellular Senescence; D044842:Cullin Proteins / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism; D044783:F-Box Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D055504:Insulin Receptor Substrate Proteins; D051379:Mice; D018345:Mice, Knockout; D010641:Phenotype; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D058570:TOR Serine-Threonine Kinases; D025801:Ubiquitin / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C494817:Cul7 protein, mouse; D044842:Cullin Proteins; D044783:F-Box Proteins; C526292:IRS1 protein, human; D055504:Insulin Receptor Substrate Proteins; C526295:Irs1 protein, mouse; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D025801:Ubiquitin; D011494:Protein Kinases; C546842:MTOR protein, human; C546843:mTOR protein, mouse; D058570:TOR Serine-Threonine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases