BRG1通过与Wnt/β-catenin信号通路的交互作用诱导肾小管上皮细胞衰老及肾纤维化形成

Renal fibrosis is the underlying cause of poor prognosis in chronic kidney disease (CKD). Based on the irreversibility of cellular senescence and its associated pro-inflammatory and fibrotic secretory phenotype, we hypothesized that the accumulation of aging cells in CKD kidneys may be a potential mechanism for the "spontaneous" progression of renal fibrosis. In previous study, we screened out a differentially expressed protein BRG1, which is closely related to renal fibrosis and mainly expressed by renal tubular epithelial cells. Overexpression of BRG1 could activate the senescence-associated signaling pathway, increase the secretion of pro-inflammatory and fibrotic mediators and up-regulate the expression of β-catenin in renal tubular epithelial cells. Further, blockade of Wnt/beta-catenin pathway could significantly inhibite the expression of senescence-associated gene INK4a/ARF induced by BRG1 overexpression. Based on our previous studies, we hypothesize that BRG1 may induce renal tubular senescence and renal fibrosis through activation of the Wnt/β-catenin signaling pathway. In the current project, lentivirus infection, ultrasound microbubbles mediated gene transduction and co-immunoprecipitation technology will be used to carry out the research from multi-levels, including molecular, cell and organism. The interaction between BRG1 and Wnt/beta-catenin pathway will be taken as a breakthrough point to reveal the role of BRG1 in renal tubular senescence, secretory phenotype transition and renal fibrosis.

肾纤维化是慢性肾脏病（CKD）预后不良的根本原因。基于细胞衰老的不可逆性及与之相伴的促炎促纤维化分泌表型，我们推测CKD肾脏中逐渐增多的衰老细胞是导致肾纤维化“自发性”进展的潜在因素。我们前期筛选出与肾纤维化密切相关的差异表达蛋白BRG1，发现其高表达于肾小管上皮细胞并可激活细胞衰老相关信号通路、诱导促炎促纤维化介质生成并上调β-catenin的表达。阻断Wnt/β-catenin通路可抑制BRG1介导的衰老相关基因INK4a/ARF的表达。据此我们提出假说：BRG1通过激活Wnt/β-catenin通路诱导肾小管上皮细胞衰老与肾纤维化形成。本项目拟利用慢病毒感染、超声微泡介导的基因转导、免疫共沉淀等技术手段，以BRG1与Wnt/β-catenin通路的交互作用为切入点，在分子、细胞和机体水平确立BRG1对肾小管上皮细胞衰老、分泌表型转变以及肾纤维化发生发展的影响。

肾纤维化是慢性肾脏病（CKD）预后不良的根本原因。基于细胞衰老的不可逆性及与之相伴的促炎促纤维化分泌表型，我们推测CKD肾脏中逐渐增多的衰老细胞是导致肾纤维化“自发性”进展的潜在因素。我们前期筛选出与肾纤维化密切相关的差异表达基因BRG1，发现其高表达于肾小管上皮细胞并可激活细胞衰老相关信号通路、诱导促炎促纤维化介质生成并上调β-catenin的表达。阻断Wnt/β-catenin通路可抑制BRG1介导的衰老相关基因INK4a/ARF的表达。据此我们提出假说：BRG1通过激活Wnt/β-catenin通路诱导肾小管上皮细胞衰老进而促进肾纤维化形成。本项目利用肾小管分离及原代细胞培养、脂质体转染及流体力学介导的基因转导、核质蛋白分离、双荧光素梅报告基因、衰老相关β-gal染色、免疫组化及免疫荧光等多种技术手段，揭示了 BRG1 通过诱导肾小管上皮细胞衰老及衰老相关分泌表型（SASP）形成促进肾纤维化进展这一完整机制，同时阐述了 BRG1 与 Wnt/β-catenin 信号通路间的交互作用及其对肾小管上皮细胞衰老的影响，该项目的完成在分子层面上进一步丰富了肾纤维化的形成机制，为肾纤维化的治疗提供了新的靶点，具有一定的理论创新及临床应用价值。