Role of Meprins in Ischemia Reperfusion induced renal injury

描述（由申请人提供）：缺血再灌注（IR）引起的肾损伤导致急性肾功能衰竭，发病率和死亡率高。IR肾损伤的细胞机制尚不清楚。Meprins是一种在近端肾小管刷状边界膜（BBM）中大量表达的金属蛋白酶，与IR的病理有关。meprins水平较低的小鼠品系在接受IR时肾损伤较少。Meprin抑制剂和Meprin基因的靶向破坏都可以保护小鼠免受IR诱导的肾损伤。我们最近证明，meprins可切割肌动蛋白和绒毛蛋白，这是近端小管细胞骨架的关键成分，这表明观察到的肾损伤部分是由于细胞骨架蛋白的降解。Meprin B也切割蛋白激酶A （PKA）的催化亚基，PKA是一种调节许多细胞信号通路的蛋白质。OS-9是一种参与缺氧反应的蛋白质，已被证明与meprin的羧基末端尾部相互作用。然而，目前尚不清楚OS-9是否是meprin的底物，以及OS-9与meprin的相互作用是否在IR诱导的肾损伤病理中起作用。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IR相关肾衰竭治疗的发展。中心假设是meprins在肾IR中观察到的损伤中起关键作用。这部分是由于细胞骨架蛋白（如绒毛蛋白和肌动蛋白）、紧密连接复合物中存在的蛋白质和细胞外基质（ECM）蛋白的切割。Meprins也可能通过切割调节特定信号通路（如PKA和OS-9）的蛋白质而发挥间接作用，从而影响由这些通路驱动的基因的表达。拟议的研究将使用meprin敲除小鼠和蛋白质组学方法来鉴定在IR中起作用的meprin相关蛋白并阐明潜在的细胞机制。中心假设将通过以下三个具体目标来验证：(i)确定在IR诱导的肾损伤中起作用的meprins相关蛋白，（ii）确定meprins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meprins与细胞信号分子之间的相互作用是否起作用

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.