组蛋白甲基化酶G9a调控糖尿病肾病中巨噬细胞极化失衡的机制研究

Distinct subtypes macrophage polarization plays an essential role in diabetic nephropathy (DN). M1/M2 macrophage polarization imbalance is an potential mechanism in the pathogenesis of DN, but the molecular mechanisms are still unclear. Hyperglycemia is the major factor in renal macrophage polarization imbalance, the applicant previously found that histone methyltransferase G9a was decreased in the process of M2 macrophage polarization, and high glucose treatment improved G9a expression.These observations suggest that G9a maybe involved in the regulation of macrophage polarization in diabetic nephropathy. In this study, we will use the streptozotocin-induced diabetic mice to investigate the macrophage polarization imbalance in diabetic nephropathy and the localization and expression of G9a in different macrophage subtypes. Via inducing macrophage polarization in vitro, we will study the macrophage polarization imbalance induced by hyperglycemia, explore the role of G9a in mediating hyperglycemia-regulated M2 macrophage polarization, and demonstrate the mechanisms of G9a in regulating PPARγ which is the key factor to control M2 macrophage polarization. Meanwhile, by means of macrophage specific G9a transgenic mice, we will investigate the role and molecular mechanisms of G9a in mediating macrophage polarization imbalance in diabetic nephropathy, and explore the role of G9a in the development of diabetic nephropathy in vivo. This study will demonstrate a novel regulatory mechanism of macrophage polarization imbalance in diabetic nephropathy.

不同亚型巨噬细胞的极化在糖尿病肾病（DN）中扮演着重要作用。M1/M2型巨噬细胞的极化失衡是DN的潜在致病机制，但其分子机制尚不清楚。高血糖是诱导肾脏巨噬细胞极化失衡的重要因素，申请者前期工作发现组蛋白甲基化酶G9a在M2型巨噬细胞极化过程中表达降低，高糖刺激则促进G9a的表达；提示G9a可能调控DN中巨噬细胞的极化。本课题拟通过链脲佐菌素诱导的糖尿病小鼠模型，研究DN中巨噬细胞的极化失衡和G9a在不同亚型巨噬细胞中的定位和表达情况；采用体外巨噬细胞诱导极化模型，研究高血糖诱导的巨噬细胞极化失衡，探索G9a在高血糖调控M2型巨噬细胞极化中的介导作用，阐明G9a对M2型巨噬细胞极化关键因子PPARγ的调控机制；同时，利用巨噬细胞特异过表达G9a的转基因小鼠，体内研究G9a介导DN中巨噬细胞极化失衡的作用和分子机制，探讨其在DN发展中的作用。本课题将阐明DN中巨噬细胞极化失衡的新的调控机制。

不同亚型巨噬细胞的极化在糖尿病中扮演着重要作用。M1/M2型巨噬细胞的极化失衡是糖尿病并发症的潜在致病机制，但其具体分子机制尚不清楚。. 有研究表明，体外饱和性脂肪酸刺激，例如棕榈酸，能促进巨噬细胞向M1型极化，产生炎症反应。此外，表观遗传学机制也被认为是调控巨噬细胞M1/M2极化的潜在分子机制。因此，在本项目中，我们探索了在糖尿病中脂质通过组蛋白修饰酶诱导M1/M2型巨噬细胞极化失衡的分子机制。我们首先体外构建了棕榈酸诱导M1巨噬细胞极化的模型；发现了组蛋白甲基化酶G9a在棕榈酸诱导M1巨噬细胞极化过程中的介导作用；阐述了G9a通过脂肪酸转运蛋白CD36来实现调控功能的具体分子机制。此外，我们还研究了另一个组蛋白乙酰化酶PCAF在巨噬细胞极化中的调控作用。我们发现了PCAF在巨噬细胞M1极化中异常表达，并负调控巨噬细胞的M1型极化；阐述了PCAF调控转录因子KLF2和KLF4的具体分子机制。. 本项目的研究阐明了糖尿病中巨噬细胞极化失衡的新的表观遗传学调控机制，发现了新的潜在调控靶点，为疾病的治疗提供了一定的理论依据。