脂肪酸结合蛋白4（FABP4）在缺血再灌注致急性肾损伤中的作用及机制研究

Acute kidney injury (AKI) is a common clinical syndrome associated with adverse outcomes. Ischemic renal injury is one of the leading causes for AKI. Our previous research showed that the expression of FABP4 and proteins associated with endoplasmic reticulum stress (PERK and CHOP) in renal tubular epithelial cells were significantly upregulated in acute renal ischemia-reperfusion injury; while treatment with FABP4 inhibitor alleviated tubular injury in both in vivo and in vitro studies, accompanied by reduced endoplasmic reticulum stress. Besides, under ischemic reperfusion condition, RNA sequencing analysis revealed no difference of the transcription of the genes encoding proteins associated with endoplasmic reticulum stress (PERK, ATF4, CHOP) in Fabp4 knockout mice when compared with the wildtype littlemates. Thus, we hypothesized that, ischemia-reperfusion upregulates FABP4 and endoplasmic reticulum stress, and promotes renal tubular epithelial cells apoptosis and inflammation via the PERK/eIF2α-ATF4-CHOP pathway. In the current study, in vivo study on Fabp4 conditional knockout (tubular epithelial cells) mice and in vitro study on HK-2 cells will be conducted to further explore the underlying mechanism of the induction of AKI by FABP4 via endoplasmic reticulum stress, and to identify novel intervention targets for the prevention and treatment of AKI.

急性肾损伤（AKI）患病率高，预后不良，治疗手段有限。缺血性肾损伤是AKI最常见病因之一。课题组前期研究发现：缺血再灌注致AKI的肾小管上皮细胞中FABP4蛋白水平显著升高，伴PERK、CHOP等内质网应激相关蛋白表达上调；而靶向抑制剂干预FABP4和基因敲除均可显著改善缺血再灌注致肾小管损伤，并缓解肾脏内质网应激。Fabp4基因敲除小鼠假手术和造模组肾脏RNA测序显示，内质网应激蛋白PERK、ATF4、CHOP的编码基因转录无差异。由此我们提说假设：缺血再灌注损伤诱导肾小管上皮细胞FABP4高表达和内质网应激，并通过PERK/eIF2α-ATF4-CHOP通路介导细胞凋亡和炎症反应，参与AKI发生和发展。本项目拟通过肾小管上皮细胞Fabp4条件基因敲除动物和细胞基因敲低研究，阐明FABP4介导内质网应激参与肾小管损伤的作用机制，为AKI防治提供全新理论依据。

急性肾损伤（AKI）患病率高，预后不良，治疗手段有限。课题组前期研究发现，脂肪酸结合蛋白4（FABP4）参与AKI的发生发展，但其具体机制仍待阐明。本研究中，FABP4基因敲除和抑制剂BMS309403能够有效保护缺血再灌注致AKI，结合生信分析发现FABP4与自噬、线粒体自噬和凋亡，以及PERK/eIF2α-ATF4-CHOP通路、细胞外泌体等相关联。我们进一步构建Fabp4肾小管上皮细胞和巨噬细胞条件敲除小鼠，发现Fabp4野生型AKI小鼠中内质网应激相关的通路分子表达升高、伴随细胞凋亡和炎症因子活化，而这些改变在Fabp4敲除小鼠中受抑制，同时肾损伤程度减轻。此外，在本课题的支持下，我们通过体内和体外实验发现，FABP4还通过促进炎症、纤维化、线粒体功能障碍等机制在毒素诱发AKI和高尿酸肾病等条件下产生肾损伤致病效应。这些结果为AKI提出新机制和干预新靶点，并为后续进一步深入研究奠定基础。