Function of semaphorin3a in diabetic nephropathy

描述（由申请人提供）：糖尿病肾病（DN）在大约30%的糖尿病患者中发展，是全球终末期肾脏疾病的主要原因。在一些但不是所有糖尿病患者中诱发DN的因素尚不清楚。需要鉴定新的致病因素作为DN的生物标志物。信号蛋白3a （sema3a）是足细胞分泌的一种引导蛋白，对肾小球滤过屏障的正常发育至关重要。在成年小鼠中，Sema3a的功能获得可阻止裂口膈发育并导致蛋白尿肾小球疾病。我们确定了将sema3a信号与肾素和足细胞肌动蛋白细胞骨架联系起来的信号通路。我们观察到足细胞sema3a在人类晚期DN中增加。糖尿病小鼠的循环sema3a和尿排泄始终升高，晚期DN加剧了这种异常的sema3a排泄。此外，Sema3a功能增益诱导严重DN。总的来说，这些发现提高了sema3a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sema3a成为合适的DN生物标志物和潜在的治疗靶点。本研究的目的是研究sema3a是糖尿病肾病的致病决定因素还是生物标志物（或两者兼而有之），并确定其分子机制，最终目的是开发一种治疗或预防糖尿病肾病的新方法。我们假设糖尿病诱导的过量sema3a通过涉及sema3a受体丛a1的下游信号通路负调控肾素信号和f -肌动蛋白，从而破坏裂口膈，导致足突消失和蛋白尿。Aim 1将在诱导sema3a功能获得或功能丧失的小鼠中使用T1D模型研究sema3a在DN中是否具有致病性，评估DN表型的可逆性以及sema3a抑制是否改善DN；为了评估sema3a是否为DN生物标志物，将通过定量酶联免疫分析法测量T1D和T2D人群尿液和血浆sema3a水平。目的2将研究sema3a- plexina1通路如何通过评估sema3a诱导的肾素转换、plexina1 - micical相互作用、micical需求以及sema3a对RhoA、CRMP和¿3整合素的调节来调节足细胞信号传导和F-actin动力学。这些实验的结果有可能建立sema3a作为DN的一种新的生物标志物，并确定DN治疗干预的靶点。

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.