成骨细胞源Reticulocalbin-2对肝脏胰岛素敏感性的影响及机制研究

Insulin resistance is the major pathological characteristic of type 2 diabetes. Our previous study found that osteoblast-secreted Reticulocalbin-2(RCN2) was obviously reduced in high-fat-fed(HFD) mice, and RCN2 recombinant protein could significantly alleviate the insulin resistance of hepatocyte. Therefore, we propose that "the RCN2 secreted by osteoblasts can act on hepatocytes to participate in the regulation of hepatic insulin sensitivity ". To validate this hypothesis, we will construct osteoblast-specific RCN2 knockout mice and observe the effect of RCN2 knockdown on insulin sensitivity in mice liver. And then we identify the specific receptor of RCN2 and its downstream regulatory proteins to construct a signal regulatory network that regulates hepatic insulin sensitivity by immunoprecipitation, mass spectrometry and other techniques. Furthermore, we intend to use RCN2 recombinant protein to intervene HFD mice to observe its effect on liver and body insulin resistance. Together, this project will reveal novel insights to the pathogenesis and treatment of T2DM.

胰岛素抵抗是2型糖尿病的核心病理特征。我们前期研究发现，在高脂喂养的小鼠中，成骨细胞分泌的Reticulocalbin-2(RCN2)显著减少，用RCN2重组蛋白干预棕榈酸处理过的小鼠肝原代细胞和HepG2细胞，可显著改善肝细胞的胰岛素抵抗。因此，我们提出“成骨细胞分泌的RCN2可以作用于肝细胞从而参与调控肝脏的胰岛素敏感性”这一假设。为验证该假设，我们拟构建成骨细胞特异性RCN2基因敲除小鼠，观察RCN2敲除对小鼠肝脏胰岛素敏感性的影响；进而采用免疫共沉淀、质谱分析等技术识别出RCN2在肝脏中的特异性受体及其下游调控蛋白，构建出RCN2调控肝脏胰岛素敏感性的信号调控网络；并采用RCN2重组蛋白干预高脂喂养的小鼠，观察其对小鼠肝脏及机体胰岛素抵抗的疗效。本项目将为探索2型糖尿病的发病机理与防治策略提供新思路和新的潜在药物靶点。

胰岛素抵抗是2型糖尿病的核心病理特征。运动可以有效改善糖尿病和肥胖患者善胰岛素抵抗，但是具体机制未明。申请人研究发现在高脂喂养的小鼠骨髓上清和血清中，RCN2 的蛋白水平均显著降低；RCN2主要由巨噬细胞细胞分泌。用RCN2重组蛋白干预棕榈酸处理过的小鼠肝原代细胞和HepG2细胞，可显著改善肝细胞的胰岛素抵抗。在巨噬细胞特异性RCN2敲除小鼠（高脂喂养12周）中，运动对胰岛素敏感性的改善作用会减弱。RCN2重组蛋白治疗可以显著改善高脂喂养小鼠胰岛素抵抗。以上研究表明RCN2对于肥胖和糖尿病患者胰岛素抵抗的治疗具有重要意义，为以上疾病的治疗提供新的治疗靶点。