Cytoprotective Role of HSP72 in Renal Cell Injury

描述(申请人提供)：肾细胞死亡和缺血性急性肾损伤(AKI)是由bcl2蛋白介导的线粒体膜损伤引起的。BCL2家族中典型的“坏演员”Bax是如何导致线粒体膜外膜损伤和肾细胞死亡的尚不确定。我们推测，构象上活性的Bax与新近发现的Bax伴侣核磷蛋白(NPM)之间的相互作用，需要形成胞浆复合体，使Bax移位到线粒体，导致肾细胞病变，损害肾功能。我们认为，可以通过以下几个步骤来抑制缺血(AKI)：减少Bax的激活，限制NPM-Bax复合体的形成，或者防止增加线粒体对Bax攻击的易感性的线粒体碎裂。由于Hsp70(Hsp72 KDa)可能在每一步阻断缺血细胞死亡途径， 而BAX阻断肽可以阻止NPM-BAX复合体的形成，我们预计这两种方法在预防和加速缺血性AKI的恢复方面都将是非常有效的。在四个目标中，我们将确定：(1)肾缺血时构象Bax激活在多大程度上受到Akt或GSK3？的调节，这两种应激蛋白是已知的介导肾细胞存活的应激蛋白。Hsp70对Akt和GSK3的保护作用将被探讨~(2)核磷蛋白-Bax复合体在多大程度上需要肾细胞损伤？我们认为肾脏缺血引起NPM从核到胞浆的调节移位，在那里它与活性的Bax络合，促进线粒体Bax的积聚和细胞死亡。(3)HSP70是如何减少应激诱导的线粒体断裂和增强对Bax攻击的抵抗力的？我们将描述HSP70阻止线粒体碎裂和bax攻击的机制(S)，并确定缺血性AKI的其他治疗靶点和(4)：在多大程度上可以预防缺血性AKI并加速肾脏恢复？我们认为，HSP70和Bax封闭肽是限制NPM和Bax毒性的药物，将在体内有效地预防和治疗肾缺血。这些研究确定了可干预的肾细胞死亡的新靶点，并确定了Hsp70诱导和破坏NPM-Bax复合体作为预防或加速缺血性AKI恢复的治疗策略的有效性，这是公共卫生面临的一个重大挑战，目前尚无治疗方法。

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.