骨钙素在妊娠期糖尿病发病过程中的生物学机制研究

Growing evidence supports the role of osteocalcin (OCN) in enhancing the production and secretion of insulin. Meanwhile, OCN can bind to Gprc6a receptor and increase the production of adiponectin in adipocyte, thus enhance the insulin sensitivity. Clinical evidence show that OCN was significantly increased in the women with gestational diabetes mellitus (GDM), while adiponectin was decreased. There is a inverse correlation between placenta adiponectin concentration and fetal weight. Although OCN was potentially associated with GDM, however the biological mechanism of OCN in the Development of GDM has not been clarified yet. We hypothesized that the disorder of bone-adipocyte axis may be involved in insulin resistance in GDM, and OCN may regulate fetal glucose metabolism though its effect on adiponectin synthesis in placenta. In order to assess the biological mechanism of osteocalcin in GDM, special pregnant mouse was constructed for GDM model: WT or Ocn-/- pregnant mouse carrying fetal WT, Ocn-/- or Gprc6a-/-, respectively. The effects of deficient, rescue and supra physiologic concentration of OCN on GDM mouse were studied. Serum concentrations of OCN, insulin, glucose, placenta adiponectin secretion and fetal weight were measured at different points during pregnancy. Clarifying the biological mechanism of OCN and its link to adiponectin regulation in GDM will allow a deeper understanding of the biological mechanisms underlying GDM development.

骨钙素（osteocalcin ，OCN）近年来被证明具有糖代谢调节功能，其一方面促进胰岛细胞增殖与分泌，另一方面与GPRC6a受体结合，促进脂肪细胞脂联素分泌，提高胰岛素敏感性。妊娠早、中期，妊娠期糖尿病孕妇血清骨钙素水平高于正常孕妇，但脂联素降低。胎盘脂联素水平与胎儿体重呈负相关关系。我们假设认为：骨（骨钙素）-脂肪（脂联素）调节轴功能紊乱参与了妊娠期糖尿病胰岛素抵抗的发生，骨钙素对胎盘的脂联素分泌具有调节作用，间接影响胎儿糖、脂代谢。课题组前期Cas9打靶已获得Ocn-/-小鼠，拟利用胚胎移植技术，构建WT、Ocn-/-母鼠分别妊娠WT、Ocn-/-、Gprc6a-/-胎鼠的妊娠期糖尿病模型，进行骨钙素缺失、补偿或超生理浓度干预，分别对母鼠、胎鼠、胎盘的骨钙素、脂联素、胰岛素等指标进行检测，探索骨钙素在妊娠期糖尿病发病过程中的生物学机制，为骨钙素在该疾病防治的应用提供理论基础。

妊娠期糖尿病(gestational diabetes mellitus, GDM)发病率高，病因复杂。骨钙素近年来被证明具有调节糖、脂代谢的内分泌功能。本课题分别对分娩期产妇外周血、胎盘脐静脉血的骨钙素、脂联素等生化指标进行检查，分析骨钙素与胎盘内分泌功能，及孕妇和胎儿糖、脂代谢的相关性。以JAR人滋养层细胞为体外模型，进一步探索骨钙素对胎盘滋养层细胞内分泌功能的影响及其信号通路。结果提示，妊娠晚期母亲外周血骨钙素水平在GDM组与对照组无显著差异，然而脐静脉血血清骨钙素水平GDM组显著低于对照组。脐静脉血清骨钙素水平与胎盘脂联素、瘦素表达水平呈正相关关系，与新生儿头围、身长呈正相关关系。骨钙素能促进JAR细胞生长及人绒毛膜促性腺激素（Human Chorionic Gonadotropin， HCG）的分泌。胎盘RNA表达测序结果提示，GDM组比正常对照组炎症反应增强、IL-6和TNF-α表达量增加。基因表达量与临床指标的相关性模块分析提示，GDM组与正常对照组在脂联素和瘦素的相关基因表达上存在显著差异。其枢纽基因分析查找结果待完善。结论：母体骨（骨钙素） -胎盘（脂联素）参与了胎儿糖、脂代谢的调节。