干扰视黄醇结合蛋白4对猪脂肪细胞PI3K/Akt信号通路的影响

Effects of retinol binding protein 4 knockdown on the PI3K/Akt pathways in porcine adipocytes

摘要:

视黄醇结合蛋白4 (Retinol binding protein 4，RBP4) 是一种脂肪细胞分泌因子，其表达水平的升高与胰岛素抵抗及Ⅱ型糖尿病等疾病密切相关，但具体作用机制尚不清楚。为明确此机制，通过包装RBP4干扰慢病毒并侵染猪前体脂肪细胞。运用胰岛素激活及诱导胰岛素抵抗模型，利用QRT-PCR及Western blotting方法检测RBP4的干扰效率及处理组PI3K/Akt信号通路相关基因的表达。结果显示RBP4的基因及蛋白的干扰效率达到60％ (P＜0.01) 以上。进一步研究发现在胰岛素诱导及胰岛素抵抗的情况下，LH1-shRBP4干扰后可显著提高胰岛素信号通路AKT2、PI3K、GLUT4和IRS1基因mRNA的表达；明显促进AKT2、PI3K和IRS1蛋白的磷酸化；提高AKT2、PI3K和GLUT4基因的总蛋白水平。总之，RBP4干扰通过上调PI3K/Akt胰岛素信号通路相关因子的表达及其磷酸化水平，提高了胰岛素敏感性。此研究将为胰岛素抵抗相关疾病的治疗提供新思路。

Abstract:

Retinol-binding protein 4 (RBP4) is adipocyte-derived secreted adipokines and elevated RBP4 expression level was closely related to insulin resistance and type II diabetes mellitus. However, the exact mechanisms are unknown. To clarify the mechanism, RBP4 lentivirus particles were packaged to infect porcine preadipocytes. Then procine preadipocytes were activated by insulin or induced model of insulin resistance. RBP4 interference efficiency and the gene expression of each treatment groups in PI3K/Akt pathways were examined by QRT-PCR and Western blotting. The result shows that RBP4 mRNA and protein expressions were suppressed more than 60% (P<0.01). Furthermore, no matter under insulin stimulation or insulin resistance, RBP4 knockdown significantly increased the mRNA expressions of AKT2, PI3K, GLUT4 and IRS1 compared with the control. The protein phosphorylate levels of AKT2, PI3K, IRS1 arised, meanwhile enhanced the AKT2, PI3K, GLUT4 total protein expressions. Collectively, knockdown of RBP4 increased the insulin sensitivity through upregulated PI3K/Akt pathways related factors’ expression and phosphorylation in porcine adipocytes. This research will provide a new idea to treat insulin resistance related diseases.