Function of semaphorin3a in diabetic nephropathy

描述（由申请人提供）：糖尿病肾病（DN）发生在约30%的糖尿病患者中，是全球终末期肾病的主要原因。在一些但不是所有糖尿病患者中诱导DN的因素知之甚少。需要鉴定作为DN生物标志物的新致病因子。semaphorin 3a（sema 3a）是一种由足细胞分泌的导向蛋白，对肾小球滤过屏障的正常发育至关重要。Sema 3a功能获得性可防止裂膈发育并导致成年小鼠蛋白尿性肾小球疾病我们确定的信号通路，连接sema 3a信号的nephrin和足细胞肌动蛋白细胞骨架的机制。我们观察到足细胞sema 3a在人类晚期DN中增加。因此，糖尿病小鼠循环中的sema 3a和尿排泄增加，并且晚期DN加重了这种异常的sema 3a排泄。此外，Sema 3a功能获得性诱导严重DN。总的来说，这些发现提高了sema 3a水平升高驱动糖尿病环境中肾小球损伤或加重这种损伤的可能性，使sema 3a成为合适的DN生物标志物和潜在的治疗靶点。该提案的目的是研究sema 3a是否是糖尿病肾病的致病决定因素或生物标志物（或两者），并确定所涉及的分子机制，最终目标是开发一种新的方法来治疗或预防DN。我们假设糖尿病诱导的过量sema 3a通过涉及sema 3a受体plexinA 1下游信号传导的途径负调节nephrin信号传导和F-actin，从而破坏裂膈，引起足突消失和蛋白尿。目的1将在具有诱导型Sema 3a功能获得或功能丧失的小鼠中使用T1 D模型研究sema 3a在DN中是否是致病性的，评估DN表型可逆性以及sema 3a抑制是否改善DN;为了评价sema 3a是否是DN生物标志物，将通过定量酶联免疫测定法在T1 D和T2 D人类队列中测量尿液和血浆sema 3a水平。目的2将通过评估sema 3a诱导的nephrin周转、plexinA 1-MICAL相互作用、MICAL需求以及sema 3a对RhoA、CRMP和<$3整合素的调节来研究sema 3a-plexinA 1通路如何调节足细胞信号传导和F-actin动力学。所提出的实验的结果有可能建立作为一种新的生物标志物的糖尿病肾病，并确定治疗干预DN的目标。

DESCRIPTION (provided by applicant): Diabetic nephropathy (DN) develops in approximately 30% of diabetic patients, and represents the leading cause of end-stage renal disease worldwide. The factors that induce DN in some but not all diabetics are poorly understood. Identification of novel pathogenic factors that serve as biomarkers for DN is needed. Semaphorin3a (sema3a), a guidance protein secreted by podocytes, is essential for normal glomerular filtration barrier development. Sema3a gain-of-function prevents slit-diaphragm development and leads to proteinuric glomerular disease in adult mice. We identified the signaling pathway that links sema3a signals to nephrin and the podocyte actin cytoskeleton mechanistically. We observed that podocyte sema3a is increased in human advanced DN. Consistently, circulating sema3a and urinary excretion are elevated in diabetic mice, and advanced DN exacerbates this abnormal sema3a excretion. Moreover, Sema3a gain-of- function induced severe DN. Collectively, these findings raise the possibility that elevated sema3a levels drive glomerular damage in the diabetic milieu, or accentuate such damage, making sema3a a suitable DN biomarker and a potential therapeutic target. The goals of this proposal are to investigate whether sema3a is a pathogenic determinant or a biomarker of diabetic nephropathy (or both), and to identify the molecular mechanisms involved, with the ultimate objective of developing a novel approach to treat or prevent DN. We hypothesize that diabetes-induced excess sema3a negatively regulates nephrin signaling and F-actin via a pathway that involves sema3a receptor plexinA1, downstream signaling, thereby disrupting slit-diaphragms, causing foot process effacement and proteinuria. Aim 1 will investigate whether sema3a is pathogenic in DN using a T1D model in mice with inducible Sema3a gain-of-function or loss-of-function, assess DN phenotype reversibility and whether sema3a inhibition improves DN; to evaluate whether sema3a is a DN biomarker, urine and plasma sema3a levels will be measured in T1D and T2D human cohorts by quantitative enzyme-linked immunoassay. Aim 2 will examine how the sema3a-plexinA1 pathway regulates podocyte signaling and F-actin dynamics by evaluating sema3a-induced nephrin turnover, plexinA1-MICAL interaction, MICAL requirement, and modulation of RhoA, CRMP and ¿3 integrin by sema3a. Results of the proposed experiments have the potential to establish sema3a as a novel biomarker of DN and to identify targets for therapeutic intervention in DN.