The Role Of SOCS3 In Porcine Adipocyte Insulin Signaling

Insulin resistance is a major player in the pathogenesis of type II diabetes, the metabolic syndrome and obesity. Many reasons have been demonstrated to induce insulin resistance, but insulin signaling pathway is blocked or attenuated is one of the major factors leading to insulin resistance. SOCS3 is a member of Suppressor of cytokine signaling (SOCS) family, it mainly participates in the negative regulation of cytokine signal transduction, such as GH,IL-1,IL-2,IL-6,TNF-α,IFN-γand leptin. Recent research demonstrated that SOCS3 is capable of blocking insulin signaling and played an important role in the development of insulin resistance. Porcine is an ideal model of human disease, because porcine is remarkably similar to human biological, metabolic and genetic levels. In this research, to investigate the role of SOCS3 in porcine adipocyte insulin signaling, we firstly tested the effect of 100 nM insulin on adipocyte differentiation and SOCS3 mRNA, protein expression by RT-PCR and Western blotting. Then, we constructed a recombinant adenovirus encoding SOCS3 gene (Ad-SOCS3) which was used to infect differentiated adipocytes for 3 days. The expression and phosphorylation of SOCS3 and main insulin signaling components were determined by RT-PCR and Western blotting. The main results were summarized as following:1.100 nM insulin significantly enhanced the process of porcine preadipocytes differentiation into mature adipocytes and increased SOCS3 mRNA expression of porcine adipocytes in short-time treatment.2. Restriction enzyme and PCR analysis demonstrated that the recombinant adenovirus vector encoding SOCS3 gene (Ad-SOCS3) was constructed correctly, after packaging and purifying, the virus titer reached 1.2×109 PFU/mL.3. Recombinant adenovirus encoding SOCS3 gene (Ad-SOCS3) could effectively infect porcine adipocytes and notably enhance SOCS3 expression of porcine adipocytes.4. Overexpression of SOCS3 in porcine adipocytes significantly decreased IRS1 protein level, insulin-stimulated IRS1 tyrosine phosphorylation, PI3K p85, subsequent Akt serine and threonine phosphorylation, but significantly increased IRS1 serine phosphorylation. So, overexpression of SOCS3 inhibited insulin signaling in porcine adipocytes. In summary, our research indicated that insulin could significantly induce SOCS3 mRNA expression, and overexpression of SOCS3 inhibited insulin signaling in porcine adipocytes. Therefore, SOCS3 is an important negative regulator of insulin signaling in porcine adipocytes, it may be a newly recognized molecular target for the prevention or treatment of insulin resistance.