ERK促进DNA甲基转移酶3B诱导SFRP1启动子甲基化在DN小鼠肾纤维化中的作用和机制研究

糖尿病肾病(DN)已成慢性肾衰竭的主要原因，肾小管间质纤维化(TIF)是DN的重要病理改变，其发病机制未完全阐明。我们前期发现：DN大鼠肾组织DNA甲基转移酶3B(DNMT3B)表达增高，而Wnt/β-catenin通路负调控因子分泌型卷曲相关蛋白1(SFRP1)表达降低，去甲基化药物干预可上调SFRP1表达，减轻TIF病变。另有研究表明ERK通路与DNMT3B表达密切相关。因此，我们推测高糖可能诱导ERK通路活化促进DNMT3B表达，使SFRP1启动子甲基化，从而对Wnt通路的负调控作用减弱，促进TIF发生。本项目拟以DN小鼠和肾小管上皮细胞为对象，采用基因敲除、过表达、高糖及抑制剂干预等方法，探讨ERK通过DNMT3B调控SFRP1启动子甲基化，以及对Wnt/β-catenin通路的影响，明确DNMT3B在DN肾纤维化的作用和机制。为阐明DN发病机制、探寻新的肾纤维化防治靶点提供依据。

Diabetic nephropathy (DN) has become a major cause of chronic renal failure. Tubulointerstitial fibrosis(TIF) is an important pathological change for DN, but its mechanism is still unclear.Our previous study showed that the expression of DNA methyltransferase 3B (DNMT3B) was increased while that of SFRP1, a negative regulator of Wnt/β-catenin pathway, was decreased in DN rats and in renal tubular epithelial cells cultured with high glucose. Interestingly, When renal tubular epithelial cells were treated with demethylated drugs, SFRP1 expression was up-regulated and TIF was alleviated. At the same time, studies have shown that ERK pathway is closely related to the expression of DNMT3B. Therefore, we hypothesized that high glucose might induce the activation of ERK pathway to promote SFRP1 promoter methylation via increasing DNMT3B, thus weakening the negative regulation of Wnt pathway and leading to the occurrence of TIF. This research aims to study DN rats and renal tubular epithelial cells.we will investigate the effect of ERK on DNMT3B expression to induce SFRP1 promoter methylation, and the effect of DNMT3B on Wnt/β-catenin pathway, and illustrate the role and mechanism of DNMT3B in DN renal fibrosis by using gene knockout, overexpression, high glucose and inhibitor intervention experiment. It provides experimental basis for elucidating the pathogenesis of DN and explores new therapeutic targets of renal fibrosis.