Mitochondrial biogenesis in kidney disease

描述(申请人提供)：急性肾损伤(AKI)是住院患者的主要并发症，而肾脏缺血是主要的危险因素。对缺血后肾功能障碍机制的深入研究尚未转化为新的治疗方法，部分原因是不同形式的缺血可能涉及不重叠的分子通路。原理：PGC-1a是一种线粒体生物发生的调节因子，在近端小管大量表达，在脓毒症和缺血再灌注损伤时早期受到抑制，在这两种情况下，当基因从近端小管上删除时，会加剧肾功能。人近端肾小管上皮细胞通过抑制PGC-1a下游效应因子和减少氧气消耗来对炎症介质作出反应，而PGC-1a的强制表达逆转了这种变化。假设：这项提议将验证这样的假设，即抑制PGC-1a可能是两种形式的缺血性AKI-脓毒症和缺血再灌注损伤(IRI)加重肾功能的共同机制。目的：第一个目标是研究炎症介质抑制原代人近端肾小管上皮细胞PGC-1a表达的机制。第二个目标将使用近端肾小管PGC-1a基因敲除小鼠的脓毒症和IRI模型来阐明PGC-1a的关键下游效应，这些效应可能在这两种形式的AKI中是独特的或相同的。第三个目标将询问近端小管诱导PGC-1a是否可以通过在野生型、全局和小管特异性基因敲除小鼠中应用药物诱导剂来改善这些形式的AKI。研究设计：该设计提供功能损失和功能增益实验，以检查PGC-1a的上游调节因子和下游效应因子。实验设计将整合细胞和活体动物实验、成像模式和生化研究的结果，使用严格的遗传工具来解决核心假设。

DESCRIPTION (provided by applicant): Acute kidney injury (AKI) is a major complication for hospitalized patients, and renal ischemia is a predominant risk factor. Intensive research into mechanisms underlying renal dysfunction following ischemia have not translated to new therapies, in part because different forms of ischemia may involve non- overlapping molecular pathways. RATIONALE: PGC-1a, a regulator of mitochondrial biogenesis, is heavily expressed in the proximal tubule, becomes suppressed early during sepsis and ischemia-reperfusion injury, and in both situations, exacerbates renal function when genetically deleted from the proximal tubule. Human proximal tubular cells respond to inflammatory mediators by suppressing downstream effectors of PGC-1a and diminishing oxygen consumption, changes reversed by forced expression of PGC-1a. HYPOTHESIS: This proposal will test the hypothesis that suppression of PGC-1a may be a shared mechanism that exacerbates renal function in two forms of ischemic AKI, sepsis and ischemia-reperfusion injury (IRI). AIMS: The first aim will investigate mechanisms that enable inflammatory mediators to suppress PGC-1a expression in primary human proximal tubular cells. The second aim will use models of sepsis and IRI in proximal tubular PGC-1a knockout mice to elucidate critical downstream effectors of PGC-1a that may be unique or shared in these two forms of AKI. The third aim will ask whether proximal tubular induction of PGC- 1a can ameliorate these forms of AKI by applying pharmaceutical inducers in wildtype, global and tubule- specific knockout mice. RESEARCH DESIGN: The design offers loss- and gain-of-function experiments to examine upstream regulators and downstream effectors of PGC-1a. The experimental design will integrate findings across cellular and live animal experiments, imaging modalities and biochemical studies, using stringent genetic tools to address the core hypothesis.