Cytoprotective Role of HSP72 in Renal Cell Injury

描述（由申请人提供）：BCL2蛋白介导的线粒体膜损伤导致肾细胞死亡和缺血性急性肾损伤（AKI）。Bax， BCL2家族中典型的“坏演员”是如何导致线粒体外膜损伤和肾细胞死亡的尚不清楚。我们假设构象活性Bax和核磷蛋白（NPM）之间的相互作用是必需的，核磷蛋白（NPM）是最近描述的Bax伴侣，形成细胞质复合物，将Bax转运到线粒体，导致肾细胞死亡并损害肾功能。我们提出可以通过以下几个步骤抑制缺血（AKI）：减少Bax激活，限制NPM-Bax复合物的形成，或防止增加线粒体对“Bax攻击”易感性的线粒体断裂。由于Hsp70 （Hsp72kDa）可能会在每一步阻断缺血细胞死亡途径，

DESCRIPTION (provided by applicant): Renal cell death and ischemic acute kidney injury (AKI) result from BCL2 protein-mediated mitochondrial membrane injury. How Bax, the quintessential "bad actor" of the BCL2 family causes outer mitochondrial membrane injury and renal cell death is uncertain. We hypothesize that interaction between conformationally active Bax and nucleophosmin (NPM), a recently described Bax chaperone, is required to form cytosolic complexes that translocate Bax to mitochondria, cause renal cell deat and impair kidney function. We propose that ischemic (AKI) can be inhibited at several steps by: reducing Bax activation, limiting NPM-Bax complex formation, or preventing mitochondrial fragmentation that increases mitochondrial susceptibility to "Bax Attack". Since Hsp70 (Hsp72kDa) likely interrupts the ischemic cell death pathway at each step, and a Bax blocking peptide prevents NPM-Bax complex formation, we anticipate that both maneuvers will be highly effective in preventing and accelerating recovery from ischemic AKI. In four AIMS, we will determine: (1) To what extent is conformational Bax activation during renal ischemia regulated by Akt or GSK3¿, stress kinases known to mediate renal cell survival. The protective role of Hsp70 on both Akt and GSK3¿ will be explored~ (2) To what extent is the nucleophosmin-Bax complex required for renal cell injury? We propose that renal ischemia causes regulated NPM translocation from the nucleus into the cytosol, where it complexes with active Bax, enhances mitochondrial Bax accumulation and cell death~ (3) How does Hsp70 decrease stress-induced mitochondrial fragmentation and increase resistance to Bax Attack? We will characterize the mechanism(s) by which Hsp70 prevents mitochondrial fragmentation and Bax Attack and identify additional therapeutic targets in ischemic AKI and (4): To what extent can ischemic AKI be prevented and renal recovery be accelerated? We propose that Hsp70 and a Bax blocking peptide, agents that limit NPM and Bax toxicity, will effectively prevent and treat renal ischemia in vivo. These studies identify new targets of renal ell death that are amenable to intervention and determine the efficacy of Hsp70 induction and disruption of NPM-Bax complex as therapeutic strategies for preventing or accelerating recovery from ischemic AKI, a major challenge to public health for which there is no current therapy.