C1qTNF-related protein 1 improve insulin resistance by reducing phosphorylation of serine 1101 in insulin receptor substrate 1

• Published in: ENDOCRINE JOURNAL 2017, Vol.64(8), pp.787-796
• Main Authors: Xin, Yaping, Zhang, Dongming, Fu, Yanqin, Wang, Chongxian, Li, Qingju, Tian, Chenguang, Zhang, Suhe, Lyu, Xiaodong
• Format: Article
• Language: English
• Subjects: Adipocytes; Adipocytes - drug effects; Adipocytes - metabolism; Adipose tissue; Adult; Aged; CTRP1; Diabetes; Diabetes mellitus; Diabetes mellitus (non-insulin dependent); Diabetes Mellitus, Type 2 - metabolism; Female; Humans; Insulin; Insulin - pharmacology; Insulin receptor substrate 1; Insulin Receptor Substrate Proteins - metabolism; Insulin resistance; Insulin Resistance - physiology; IRS-1 Ser1101; Male; Middle Aged; Phosphorylation; Phosphorylation - drug effects; Proteins; Proteins - metabolism; Proteins - pharmacology; Serine; Signal Transduction - drug effects
• ISSN: 0918-8959; 1348-4540
• DOI: 10.1507/endocrj.EJ17-0128

C1qTNF-related protein 1 (CTRP1) is independently associated with type 2 diabetes. However, the relationship between CTRP1 and insulin resistance is still not established. This study aimed to explore the role of CTRP1 under the situation of insulin resistance in adipose tissue. Plasma CTRP1 level was investigated in type 2 diabetic subjects (n = 35) and non-diabetic subjects (n = 35). The relationship between CTRP1 and phosphorylation of multi insulin receptor substrate 1 (IRS-1) serine (Ser) sites was further explored. Our data showed that Plasma CTRP1 was higher and negative correlation with insulin resistance in diabetic subjects (r = -0.283, p = 0.018). Glucose utilisation test revealed that the glucose utilisation rate of mature adipocytes was improved by CTRP1 in the presence of insulin. CTRP1 was not only related to IRS-1 protein, but also negatively correlated with IRS-1 Ser1101 phosphorylation (r = -0.398, p = 0.031). Furthermore, Phosphorylation levels of IRS-1 Ser1101 were significantly lower after incubation with 40 ng/mL CTRP1 in mature adipocytes than those with no intervention (p < 0.05). There was no significant correlation between CTRP1 and other IRS-1 serine sites (Ser302, Ser307, Ser612, Ser636/639, and Ser789). Collectively, our results suggested that CTRP1 might improve insulin resistance by reducing the phosphorylation of IRS-1 Ser1101, induced in the situation of insulin resistance as a feedback adipokine.