Role of Meprins in Ischemia Reperfusion induced renal injury

描述(由申请人提供)：缺血再灌注(IR)引起的肾损伤会导致急性肾功能衰竭，并与高发病率和死亡率有关。IR肾损伤的细胞机制尚不清楚。在近端肾小管刷状缘膜(BBM)中大量表达的金属蛋白水解酶MEPRIPs参与了IR的病理过程。当接受IR时，MEPRIPSS水平较低的小鼠品系发生的肾脏损伤较少。Meprin抑制剂和meprin基因的靶向阻断都能保护小鼠免受IR所致的肾脏损伤。我们最近证实了近曲小管细胞细胞骨架的关键成分--肌动蛋白和绒毛蛋白的裂解，表明所观察到的肾脏损伤部分是由于细胞骨架蛋白的降解所致。Meprin B还切割蛋白激酶A(PKA)的催化亚单位，PKA是一种调节许多细胞信号通路的蛋白质。OS-9是一种参与低氧反应的蛋白质，已被证明与梅普林的羧基末端尾巴相互作用。然而，目前尚不清楚OS-9是否是meprin底物，以及OS-9和meprin之间的相互作用是否在IR所致肾损伤的病理过程中起作用。该项目的长期目标是阐明IR引起肾损伤的细胞机制，并促进预防IR相关性肾功能衰竭的治疗方法的发展。中心假说是MEPRs在肾脏IR所观察到的损伤中起关键作用。这在一定程度上是由于细胞骨架蛋白(如绒毛蛋白和肌动蛋白)、紧密连接复合体中的蛋白质和细胞外基质(ECM)蛋白质的裂解。Meprs还可能通过裂解调节特定信号通路(如PKA和OS-9)的蛋白质，从而影响由这些通路驱动的基因的表达，从而发挥间接作用。拟议的研究将使用meprin基因敲除小鼠和蛋白质组学方法来鉴定在IR中发挥作用的meprin相关蛋白，并阐明潜在的细胞机制。核心假设将通过追求以下三个具体目标来检验：(I)确定在IR诱导的肾损伤中发挥作用的meprin相关蛋白，(Ii)确定meprin在与IR诱导的肾损伤相关的细胞骨架重塑中的作用，(Iii)确定meprin与细胞信号分子之间的相互作用是否起作用 在IR所致的肾损伤中。这些拟议研究的结果有望产生重要的积极影响，因为阐明IR导致肾损伤的潜在机制将有助于开发预防IR所致急性肾功能衰竭的治疗方法。

DESCRIPTION (provided by applicant): Ischemia reperfusion (IR) induced renal injury causes acute renal failure and is associated with high morbidity and mortality rates. The cellular mechanisms underlying IR renal injury are not known. Meprins, metalloproteases that are abundantly expressed in the brush border membranes (BBM) of proximal kidney tubules, have been implicated in the pathology of IR. Mice strains with lower levels of meprins develop less renal injury when subjected to IR. Meprin inhibitors and targeted disruption of the meprin gene both protect mice from IR induced renal injury. We recently demonstrated that meprins cleave actin and villin, the key components of the proximal tubule cell cytoskeleton, suggesting that the observed renal injury is in part due to degradation of cytoskeletal proteins. Meprin B also cleaves the catalytic subunit of protein kinase A (PKA), a protein that modulates many cellular signaling pathways. OS-9, a protein involved in the hypoxia response, has been shown to interact with the carboxyl-terminal tail of meprin. However, it is not known if OS-9 is a meprin substrate, and whether interaction between OS-9 and meprin plays a role in the pathology of IR induced renal injury. The broad long term goal of this project is to elucidate the cellular mechanisms responsible for IR induced kidney injury, and facilitate development of therapies to prevent IR associated renal failure. The central hypothesis is that meprins play a key role in the injuries observed in renal IR. This is in part due to cleavage of cytoskeletal proteins (such as villin and actin), proteins present in tight junction complexes, and extracellular matrix (ECM) proteins. Meprins may also play an indirect role by cleaving proteins that modulate specific signaling pathways (such as PKA and OS-9) and thus impacting expression of genes driven by these pathways. The proposed studies will use meprin knockout mice and proteomic approaches to identify meprin associated proteins that play a role in IR and elucidate underlying cellular mechanisms. The central hypothesis will be tested by pursuing the following three specific aims: (i) to identify meprin-associated proteins that play a role in IR induced renal injuy, (ii) to determine the role of meprins in cytoskeletal remodeling associated with IR induced renal injury, (iii) to determine if interactions between meprins and cell signaling molecules play a role in IR induced kidney injury. Results from the proposed studies are expected to have an important positive impact because elucidating the mechanisms underlying IR induced renal injury will facilitate development of therapies for preventing acute renal failure due to IR.