Role of Collagen Binding Receptors in Glomerulosclerosis

描述(由申请人提供)： 我们的长期目标是了解糖尿病肾小球胶原周转调节的机制，以设计更有效的治疗方法来预防糖尿病肾小球硬化。糖尿病患者，肾小球内基质成分(主要是胶原蛋白)沉积增加，从而导致功能性肾小球丧失和终末期肾病。肾小球细胞与周围基质之间的相互作用已成为控制基质动态平衡以及纤维化发生和发展的关键因素。细胞与细胞外基质的相互作用是由多种细胞受体实现的，包括Discoidin结构域受体(DDR)-1，一种由胶原激活的受体酪氨酸激酶，也是基质稳态的关键调节因子。在健康的肾小球中，DDR1通常是检测不到的；然而，在肾小球损伤中，它的表达与胶原蛋白一起上调。DDR1的上调是有益于抗纤维化，还是有害并促进纤维化，这一问题仍未解决。来自我们实验室和其他实验室的结果 提示DDR1的缺失在肾脏损伤过程中是有益的，因为DDR1缺失的小鼠可以保护肾小球免受部分肾切除、高血压或遗传性IV型胶原疾病引起的肾小球损伤。这种保护伴随着肾小球胶原沉积的减少和蛋白尿的总体减少。此外，我们提供了缺乏DDR1的系膜细胞比野生型细胞分泌更少的胶原的证据。基于这些发现，此次VA Merit更新的总体目标是了解DDR1在肾小球疾病中的作用，并确定阻断其功能是否有利于肾小球硬化的治疗。我们推测，DDR1及其天然配体胶原蛋白的上调可能通过促进过量的依赖于DDR1的基质合成而导致糖尿病所致的肾小球损伤。这项资助的目的是：目的1。确定DDR1在糖尿病肾小球损伤进展中的作用。由于DDR1的缺失导致损伤后肾小球损伤和基质沉积的减少，我们假设DDR1是肾小球损伤的关键调节因子，其缺失/抑制在糖尿病介导的肾小球损伤过程中具有保护作用。将使用遗传学方法(使用DDR1缺失的小鼠)和药理学方法(使用商业上可获得的DDR1抑制剂)在体内确定该受体在糖尿病肾小球病变中的作用。目的2.探讨糖尿病肾小球损伤中肾上腺皮质激素受体1调节胶原合成的分子机制(S)。我们假设在损伤后，胶原对DDR1的激活增加会导致无法控制的胶原沉积，从而导致肾小球硬化。为此，我们将1)分析DDR1/胶原相互作用如何控制胶原的合成；2)确定抑制DDR1是否阻止胶原的合成；3)设计新的高选择性和有效的小分子量非肽DDR1激酶抑制剂。我们相信，这项研究将对DDR1调节糖尿病肾病胶原合成的分子基础产生新的见解。此外，高选择性和高效的DDR1抑制剂的产生可能为糖尿病肾病的治疗和理想的预防提供一种全新的治疗方法。

DESCRIPTION (provided by applicant): Our long term goal is to understand the mechanisms that underlie the modulation of collagen turnover in the diabetic glomerulus in order to devise more effective therapies to prevent diabetic glomerulosclerosis. In diabetes, the deposition of matrix components (mainly collagens) within the glomeruli increases thus leading to loss of functional glomeruli and end-stage renal disease. Interaction between glomerular cells with the surrounding matrix has emerged as a key factor involved in the control of matrix homeostasis as well as initiation and progression to fibrosis. Cell-extracellular matrix interactions are made possible by various cellular receptors, including Discoidin Domain Receptor (DDR)-1, a receptor tyrosine kinase activated by collagen and a key regulator of matrix homeostasis. In healthy glomeruli DDR1 is usually undetectable; however, its expression, together with that of collagens, is upregulated in glomeruli injury. The question of whether the upregulation of DDR1 is beneficial to counteract fibrosis or is deleterious and contributes to fibrosis is still unresolved. Results from our laboratory and others suggest that loss of DDR1 is beneficial in the course of renal injury, as DDR1-null mice are protected against glomerular injury induced by partial renal ablation, hypertension, or hereditary collagen IV disease. This protection is accompanied by reduced deposition of glomerular collagens and overall reduced proteinuria. In addition, we provide evidence that mesangial cells lacking DDR1 secrete less collagen than wild type cells. Based on these findings, the overall goal of this VA Merit renewal is to understand the role of DDR1 in glomerular disease and define whether blocking its function is beneficial for the treatment of glomerulosclerosis. We hypothesize that upregulation of DDR1 and its natural ligands collagens contributes to diabetes-mediated glomerular injury by promoting excessive DDR1-dependent matrix synthesis. The aims of this grant are: Aim 1. Determine the role of DDR1 in the progression of diabetic glomerular injury. Since loss of DDR1 results in decreased glomerular damage and matrix deposition following injury, we hypothesize that DDR1 is a critical modulator of glomerular injury and its loss/inhibition is protective in the course of diabetes-mediated glomerular damage. A genetic approach (use of DDR1-null mice) and a pharmacological approach (use of a commercially available DDR1 inhibitor) will be used to determine in vivo the role of this receptor in diabetic glomerulopathy. Aim 2. Determine the molecular mechanism(s) whereby DDR1 modulates collagen synthesis in diabetic glomerular injury. We hypothesize that following injury, increased activation of DDR1 by collagen leads to uncontrolled collagen deposition and consequent glomerulosclerosis. In this aim we will 1) analyze how DDR1/collagen interactions control collagen synthesis; 2) determine whether inhibition of DDR1 prevents collagen synthesis; and 3) devise new highly selective and potent small molecular weight non-peptide DDR1 kinase inhibitors. We believe this study will generate novel insights into the molecular basis whereby DDR1 regulates collagen synthesis in diabetic nephropathy. In addition, the generation of highly selective and potent DDR1 inhibitors could provide a completely novel therapeutic approach for the treatment and ideally prevention of diabetic nephropathy.