LINC00355调控CTNNBIP1启动子甲基化促进内质网应激致糖尿病肾病足细胞损伤机制研究

Endoplasmic reticulum stress (ER stress) is involved in podocyte injury in diabetic nephropathy. Wnt/β-catenin signaling modulates ER stress, yet the epigenetic regulation of β-catenin in ER stress and podocyte injury is still unclear. Our preliminary data have shown that upregulation of long noncoding RNA LINC00355 in DN triggers ER stress and worsens renal function. LINC00355 is localized in the nucleus and exerts biological functions by directly binding EZH1, which epigenetically targets CTNNBIP1, the inhibitor of Wnt/β-catenin, through repressive trimethylation of H3K4 and activates Wnt/β-catenin signaling and ER stress. Based on the preliminary results, we propose that LINC00355 recruits EZH1 to the promoter region of CTNNBIP1 and trimethylates H3K4 to regulate ER-stress induced podocyte injury in DN. By using renal biopsy samples from DN patients as well as in vitro and in vivo assays and LINC00355 transgenic mice, we will interrogate the regulated epigenetic network of LINC00355/EZH1/CTNNBIP1. The function of LINC00355 will be investigated and biological regulatory mechanisms will be elucidated in DN.

内质网应激参与糖尿病肾病足细胞损伤。Wnt/β-catenin通路调节内质网应激，但其在糖尿病肾病足细胞内质网应激与表观遗传调控中的作用尚不清楚。申请者前期研究表明：LINC00355长链非编码RNA在糖尿病肾病患者肾组织上调促进足细胞内质网应激并恶化肾功能；LINC00355定位于足细胞胞核并特异结合EZH1，增加β-catenin抑制子CTNNBIP1启动子H3K4三甲基化抑制其表达，从而激活β-catenin通路活化内质网应激。为此，我们提出LINC00355招募EZH1增加CTNNBIP1启动子H3K4三甲基化通过表观遗传调控内质网应激和糖尿病足细胞损伤的科学假说。为验证假说，我们拟应用糖尿病肾病患者肾组织并通过体内外实验和转基因动物，深入研究LINC00355/EZH1/CTNNBIP1的表观遗传调控网络，阐明LINC00355在糖尿病肾病中的作用，明确其生物学功能及调控机制。

足细胞损伤是糖尿病肾病发生发展的关键始动因素和重要的治疗靶点。本研究按照研究计划在体内、体外水平研究了LINC00355在糖尿病肾病足细胞损伤中的作用，证实了LINC00355通过表观遗传调控促进内质网应激致糖尿病肾病足细胞损伤，完成了项目研究计划，获得了预期结果。本研究发现，LINC00355在糖尿病肾病患者肾小球足细胞中的表达明显升高，且其表达水平和患者的蛋白尿水平呈正相关。体外细胞和体内动物实验进一步发现LINC00355可促进足细胞损伤；LINC00355通过激活Wnt/β-catenin信号通路，促进内质网应激致足细胞损伤。在此基础上，本研究进一步发现LINC00355通过募集EZH1至CTNNBIP1启动子区，引起CTNNBIP启动子区甲基化，从而激活Wnt/β-catenin信号通路促进内质网应激。本研究深入研究了LINC00355/EZH1/CTNNBIP1的表观遗传网络，阐明了LINC00355在糖尿病肾病足细胞损伤中作用及其机制，为糖尿病肾病的治疗提供了潜在的治疗靶点，具有一定科学价值和应用前景。