Mindin/JNK在肾缺血再灌注损伤中的作用和机制

Ischemia-reperfusion (IR) induced acute kidney injury are characterized with tubular epithelium cell (TECs) necrosis, apoptosis and inflammation, and subsequent interstitial fibrosis，leading to the end stage of renal failure，but the mechanisms involved are not fully understood. Mindin is an extracellular matrix protein, which is involved in cell hemostasis and extracellular matrix deposition．Our recently data show that IR induces Mindin overexpression, Mindin Knockout protects renal function, kidney injury and suppresses the JNK cell signaling. The project intends to clarify the roles of Mindin in tubular jury and interstitial fibrosis and its underlying mechanisms after IR injury at cell, animal and molecular levels by the following three aims: 1)We will employ Mindin knockout and tubular specific Mindin transgenic mice to investigate its roles using a renal ischemia-reperfusion injury animal model; 2) We will explore the mechanism of Mindin/JNK in vitro with primary culture of renal tubular epithelial cells with Mindin knockdown/overexpression, treated with hypoxia/re-oxygen or/and JNK inhibitor ; and 3) We will block or activate the key molecules of Mindin and JNK downstream related cell signaling via drugs or genetic engineering approaches to reverse the phenotype caused by Mindin knockout or overexpression and try to clarify the mechanisms involved.

肾缺血再灌注（IR）所致的小管损伤和异常修复伴随的间质纤维化贯穿于急、慢性肾损伤的全过程，但机制尚未完全阐明。Mindin是一种细胞外基质蛋白，介导细胞稳态和基质沉积。我们最近研究发现IR导致肾小管上皮Mindin过表达，敲除Mindin基因保护IR所致肾小管损伤和间质纤维化，抑制JNK信号通路的激活。本项目拟从动物、细胞和分子水平阐明Mindin在肾IR所致的肾小管损伤和间质纤维化中的作用和机制：1）利用Mindin基因敲除和肾小管特异性转基因小鼠建立肾IR模型，明确Mindin在IR损伤和修复中的作用；2）通过缺氧复氧和TGF-β1刺激Mindin 基因缺失和过表达的肾小管原代细胞，从体外明确其机制，明确与JNK信号通路的关系；3）通过药物或基因工程手段调控Mindin下游分子及JNK信号通路,以期逆转Mindin敲除和转基因所致的表型，为急性肾损伤的防治提供策略。

肾缺血再灌注（IR）所致的小管损伤和异常修复伴随的间质纤维化贯穿于急、慢性肾损伤的全过程，但机制尚未完全阐明。Mindin是一种细胞外基质蛋白，介导细胞稳态和基质沉积。本项目拟从动物、细胞和分子水平阐明Mindin在肾IR所致的肾小管损伤和间质纤维化中的作用和机制：1）利用Mindin基因敲除小鼠建立肾IR模型，明确Mindin在IR损伤和修复中的作用；2）通过缺氧复氧和TGF-β1刺激Mindin基因缺失和过表达的肾小管细胞，从体外明确其机制，明确与JNK信号通路的关系；3）通过药物或基因工程手段调控Mindin下游分子及JNK信号通路,以期逆转Mindin敲除和转基因所致的表型，为急性肾损伤的防治提供策略。因此，本项目首先在细胞和动物水平构建IR诱导的急性肾损伤模型，研究发现Mindin基因在急性肾损伤过程中显著增加，敲除Mindin基因后抑制急性肾损伤的发生发展，深入研究发现Mindin通过抑制TLR4/JNK/NF-κB信号通路激活，进而抑制下游炎症因子释放，延缓急性肾损伤发展。急性肾损伤产生炎症反应，肾小管间质细胞负反馈释放大量促纤维化相关细胞因子促进肾小管异常修复，从而产生细胞外基质大量沉积，进而引起肾间质纤维化。本项目利用野生型小鼠构建肾缺血再灌注损伤诱导的肾纤维化模型，细胞水平通过利用TGF-β药物干预肾小管上皮细胞构建肾纤维化模型，研究发现Mindin表达量显著增加，证实Mindin在肾间质纤维化中发挥作用，随后，利用分子生物学技术发现Mindin基因可能通过调控NF-κB信号通路和TGF-β/Smad 信号通路，从而诱导肾小管上皮细胞长期发生炎症反应，进一步促进细胞外基质蛋白沉积，导致肾小管间质细胞发生纤维化。总之，本项目发现Mindin基因极有可能是IR诱导的急、慢性损伤中的重要治疗靶点。接下来，我们将着手利用肾小管特异性Mindin敲除小鼠，进一步深入探索Mindin基因与肾小管在IR所致的小管损伤和异常修复伴随间质纤维化中的潜在机制。