Low Molecular Weight Protein Nephrotoxicity

描述（由申请人提供）： 低分子量蛋白肾毒性在过去的25年中，在表征由免疫球蛋白游离轻链（在本申请中缩写为FLC）引起的肾小管间质肾损伤以及阐明FLC介导的肾小管损伤中涉及的结构-功能关系方面取得了显著进展。分子发病机制已被详细描述，增加了创造新的治疗方法的潜力，旨在中断病理过程，并防止与单克隆FLC沉积相关的肾功能进行性丧失。氧化应激是细胞功能和命运的关键决定因素，特别是在疾病状态下。该实验室已发表和初步研究表明，FLC的内吞作用产生过氧化氢，并诱导细胞内氧化应激，促进肾上皮细胞活化和损伤。第一个目标将进一步表征FLC对导致细胞凋亡或细胞存活的近端肾小管上皮细胞信号传导事件的影响。该实验室已发表了证明管腔内管型形成的机制和功能意义的开创性观察结果，最近未发表的研究提供了概念实验的关键证据，即管型形成导致急性肾损伤，并且可以通过使用与Tamm-Horsfall蛋白（THP）上的FLC结合结构域（LCBD）结合的竞争肽来预防。这些研究允许将第二个目标的单一焦点集中在FLC与LCBD对THP的相互作用上，作为管型肾病的近因。本申请的总体理论是FLC引起的肾小管间质性肾损伤是一个复杂的过程，涉及近端肾小管细胞的活化和损伤以及管腔内管型形成。这些事件可以单独发生或协同作用，产生急性肾损伤和慢性肾脏疾病的临床综合征。 将追求两个目标：目标1。定义近端肾小管细胞暴露于FLC后改变并影响细胞存活的细胞内信号传导事件。待测试的具体假设是FLC内吞进入近端小管激活c-Src（c-src的60-kDa产物，也称为pp 60 c-src）和凋亡信号调节激酶1（ASK 1）信号传导激酶，其激活协同工作以平衡细胞存活和凋亡的下游分子。目标2.定义FLC和THP上FLC结合结构域（LCBD）之间的分子相互作用以及这种相互作用的功能意义。待检验的假设是小分子量非肽和肽化合物有效地与FLC竞争结合THP上的LCBD并预防管型肾病。 该项目的长期目标-了解这些过程中涉及的分子机制-提供了开发旨在改善单克隆FLC（如多发性骨髓瘤）过度产生的肾衰竭的新治疗方法的潜力。!

DESCRIPTION (provided by applicant): Low Molecular Weight Protein Nephrotoxicity Significant advances have been made over the past twenty-five years in the characterization of tubulointerstitial renal injury caused by immunoglobulin free light chains (abbreviated FLC in this application) and in elucidation of the structure-function relationships involved in FLC-mediated tubular damage. The molecular pathogenesis has been described in some detail, increasing the potential to create novel treatments designed to interrupt pathological proceses and prevent progresive los of renal function related to deposition of monoclonal FLCs. Oxidative stres is a critical determinant of cell function and fate, especially in disease states. Published and preliminary studies from this laboratory demonstrated that endocytosis of FLCs generates hydrogen peroxide and induces intracellular oxidative stress that promotes renal epithelial cell activation and injury. The first aim will characterize further the effects of FLC on proximal tubular epithelial cell signaling events that lead to apoptosis or cell survival. The seminal observations that demonstrated the mechanism and functional significance of intraluminal cast formation have been published by this laboratory, and recent unpublished studies have provided critical proof of concept experiments that cast formation causes acute kidney injury and can be prevented with the use of a competitor peptide that binds to the FLC binding domain (LCBD) on Tamm-Horsfall protein (THP). These studies permit the singular focus of the second aim on the interactions of FLC with the LCBD on THP as the proximate cause of cast nephropathy. The overarching theory of this application is that tubulointerstitial renal damage from FLC is a complex process that involves both activation and injury of proximal tubular cells and intraluminal cast formation. These events can occur independently or synergize to produce the clinical syndromes of acute kidney injury and chronic kidney disease. Two aims will be pursued: Aim 1. Define the intracellular signaling events that are altered and effect cell survival following exposure of proximal tubular cells to FLC. The specific hypothesis to be tested is that endocytosis of FLCs into the proximal tubule activates c-Src (60-kDa product of c- src, also known as pp60c-src) and apoptosis signal-regulating kinase 1 (ASK1) signaling kinases, which activate downstream molecules that work in concert to balance cell survival and apoptosis. Aim 2. Define the molecular interaction between FLCs and the FLC binding domain (LCBD) on THP and the functional significance of this interaction. The hypothesis to be tested is that small molecular weight nonpeptide and peptide compounds effectively compete with FLC binding to the LCBD on THP and prevent cast nephropathy. The long-term goal of this project - understanding the molecular mechanisms involved in these processes - offers the potential to develop new treatments designed to ameliorate renal failure in the setting of overproduction of monoclonal FLC, such as multiple myeloma. !