Insulin-induced insulin receptor substrate-1 degradation is mediated by the proteasome degradation pathway

Diabetes ◽  
1999 ◽  
Vol 48 (7) ◽  
pp. 1359-1364 ◽  
Author(s):  
X. J. Sun ◽  
J. L. Goldberg ◽  
L. Y. Qiao ◽  
J. J. Mitchell
2002 ◽  
Vol 22 (4) ◽  
pp. 1016-1026 ◽  
Author(s):  
Rachel Zhande ◽  
John J. Mitchell ◽  
Jiong Wu ◽  
Xiao Jian Sun

ABSTRACT Insulin receptor substrate 1 (IRS-1) plays an important role in the insulin signaling cascade. In vitro and in vivo studies from many investigators have suggested that lowering of IRS-1 cellular levels may be a mechanism of disordered insulin action (so-called insulin resistance). We previously reported that the protein levels of IRS-1 were selectively regulated by a proteasome degradation pathway in CHO/IR/IRS-1 cells and 3T3-L1 adipocytes during prolonged insulin exposure, whereas IRS-2 was unaffected. We have now studied the signaling events that are involved in activation of the IRS-1 proteasome degradation pathway. Additionally, we have addressed structural elements in IRS-1 versus IRS-2 that are required for its specific proteasome degradation. Using ts20 cells, which express a temperature-sensitive mutant of ubiquitin-activating enzyme E1, ubiquitination of IRS-1 was shown to be a prerequisite for insulin-induced IRS-1 proteasome degradation. Using IRS-1/IRS-2 chimeric proteins, the N-terminal region of IRS-1 including the PH and PTB domains was identified as essential for targeting IRS-1 to the ubiquitin-proteasome degradation pathway. Activation of phosphatidylinositol 3-kinase is necessary but not sufficient for activating and sustaining the IRS-1 ubiquitin-proteasome degradation pathway. In contrast, activation of mTOR is not required for IRS-1 degradation in CHO/IR cells. Thus, our data provide insight into the molecular mechanism of insulin-induced activation of the IRS-1 ubiquitin-proteasome degradation pathway.


Author(s):  
Lingling Wu ◽  
Changping Fang ◽  
Jun Zhang ◽  
Yanchou Ye ◽  
Haiyan Zhao

<b><i>Objectives:</i></b> Insulin receptor substrate 1 (IRS1) is a crucial factor in the insulin signaling pathway. IRS1 gene polymorphism rs1801278 in mothers has been reported to be associated with gestational diabetes mellitus (GDM). However, it is not clear whether IRS1 gene polymorphism rs1801278 in fetuses is associated with their mothers’ GDM morbidity. The purpose of this study is to analyze the association between maternal, fetal, or maternal/fetal <i>IRS1</i> gene polymorphism rs1801278 and GDM risk. <b><i>Design:</i></b> The study was a single-center, prospective cohort study. In total, 213 pairs of GDM mothers/fetuses and 191 pairs of control mothers/fetuses were included in this study. They were recruited after they underwent oral glucose tolerance test during 24–28 weeks of gestation and followed up until delivery. All participants received the conventional interventions (diet and exercise), and no special therapy except routine treatment. <b><i>Methods:</i></b> A total of 213 pairs of GDM mothers/fetuses and 191 pairs of normal blood glucose pregnant mothers/fetuses were ge­notyped using PCR and DNA sequencing from January 2015 to September 2016. Maternal/fetal <i>IRS1</i> gene polymorphism rs1801278 was analyzed and compared between 2 groups. <b><i>Results:</i></b> There were no significant differences in the frequency of individual mothers’ or fetuses’ <i>IRS1</i> rs1801278 polymorphisms between 2 groups; if both the mothers and fetuses carried A allele, significantly lower GDM morbidity was observed in the mothers. <b><i>Limitations:</i></b> The sample size was relatively small as a single-center study. <b><i>Conclusions:</i></b> Our study suggested that maternal/fetal rs1801278 polymorphism of <i>IRS1</i> is a modulating factor in GDM; both mothers/fetuses carrying the A allele of rs1801278 may protect the mothers against the development of GDM.


2016 ◽  
Vol 31 (1) ◽  
pp. 68-72 ◽  
Author(s):  
Touraj Mahmoudi ◽  
Keivan Majidzadeh-A ◽  
Khatoon Karimi ◽  
Hamid Farahani ◽  
Reza Dabiri ◽  
...  

Background Given the major role of obesity and insulin resistance (IR) in colorectal cancer (CRC), we investigated whether genetic variants in ghrelin ( GHRL), resistin ( RETN) and insulin receptor substrate 1 ( IRS1) were associated with CRC risk. Methods This study was conducted as a case-control study, and 750 subjects, including 438 controls and 312 patients with CRC, were enrolled and genotyped using the PCR-RFLP method. Results No significant differences were observed for GHRL (rs696217), RETN (rs3745367) and IRS1 (rs1801278, Gly972Arg or G972R) gene variants between the cases and controls. However, the IRS1 G972R R allele compared with the G allele and the G972R RR+GR genotype compared with the GG genotype appeared to be markers of decreased CRC susceptibility in the overweight/obese subjects (p = 0.024; odds ratio [OR] = 0.42, 95% confidence interval [95% CI], 0.20-0.91; and p = 0.048; OR = 0.42, 95% CI, 0.17-0.99, respectively). Furthermore, the R allele and RR+GR genotype were also associated with decreased risks for obesity in the patients with CRC (p = 0.007; OR = 0.35, 95% CI, 0.15-0.77; and p = 0.015; OR = 0.35, 95% CI, 0.15-0.72, respectively). Conclusions In accordance with previous studies, our findings suggest that the IRS1 G972R R allele and RR+GR genotype have protective effects for CRC in overweight/obese patients and for obesity in patients with CRC. Nevertheless, further studies are required to confirm these findings.


2008 ◽  
Vol 8 (1) ◽  
pp. 49-64 ◽  
Author(s):  
Naoto Kubota ◽  
Tetsuya Kubota ◽  
Shinsuke Itoh ◽  
Hiroki Kumagai ◽  
Hideki Kozono ◽  
...  

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