Participation of cold shock DNA-binding protein-A in inflammatory kidney diseases

DNA结合蛋白-A（DbpA）属于人类冷休克蛋白超家族，具有与纤维形成、癌发生和转录/翻译调控相关的已知功能。有证据表明DbpA与活化的增殖性肾小管细胞表型有关。除了参与紧密连接相关复合物的形成，我们的数据表明线粒体和外泌体的功能。此外，DbpA蛋白被主动分泌，例如在系膜增生性肾炎中。两种冷休克蛋白，Y-box结合蛋白-1（YB-1）和DbpA的联合作用导致侵袭性、促迁移细胞表型。目前的提案重点关注炎症性肾脏疾病（如单侧输尿管肾病、肾毒性肾炎和糖尿病肾病），旨在研究DbpA的功能作用和参与。我们将确定（i）细胞内和细胞外DbpA实现的功能。对于细胞内DbpA，其参与线粒体能量稳态将被阐明。此外，将建立对可能影响细胞内信号传导/细胞命运决定的细胞表面受体的搜索。(ii)在确定了DbpA和YB-1的相互作用组中的重叠后，我们将表征这两种蛋白质的细胞外和细胞内相互作用，并将其与功能联系起来。此外，将研究外泌体DbpA对细胞增殖、促炎和纤维化细胞表型的贡献。(iii)我们将阐明DbpA基因消融如何影响肾脏疾病的炎症反应/结局。(iv)最后，初步数据表明，DbpA在白细胞中的表达水平是高度调节的，同时血清中含有大量的蛋白质。我们的目标是确定DbpA表达在循环免疫细胞中受哪些刺激调节。鉴于针对冷休克蛋白的自身免疫反应已经建立，我们将测试针对DbpA的自身抗体。该提案解决了关于冷休克蛋白DbpA在炎症性肾脏疾病发病机制中的功能作用的关键问题。鉴于在系膜和肾小管细胞中DbpA表达的修饰所观察到的显著细胞效应，我们的追求是利用这些发现来开发诊断和治疗策略。

DNA binding protein-A (DbpA) belongs to the human cold shock protein superfamily with known functions related to fibrogenesis, cancerogenesis and transcriptional/translational regulation. Evidences link DbpA with an activated, proliferative tubular cell phenotype. Beyond its participation in tight junction-related complex formation, our data suggest mitochondrial and exosomal functions. Furthermore, DbpA protein is actively secreted, e.g. in mesangioproliferative nephritis. The combined effects of two cold shock proteins, Y-box binding protein-1 (YB-1) and DbpA, results in an invasive, pro-migratory cell phenotype. The current proposal focuses on inflammatory kidney diseases (such as unilateral ureteral nephropathy, nephrotoxic nephritis and diabetic nephropathy) and aims to investigate the functional role(s) and participation of DbpA. We will determine (i) functions fulfilled by intra- and extracellular DbpA. For intracellular DbpA its participation in mitochondrial energy homeostasis will be clarified. Furthermore a search for cell surface receptors will be set up that may affect intracellular signaling/cell fate decision. (ii) Having identified an overlap in the interactome of DbpA and YB-1, we will characterize extra- and intracellular interactions of both proteins and relate these to functions. Additionally the contribution of exosomal DbpA to cell proliferation, pro-inflammatory and -fibrotic cell phenotypes will be investigated. (iii) We will clarify how genetic ablation of DbpA affects the inflammatory response/outcome of kidney diseases. (iv) Finally, preliminary data indicate that DbpA expression levels in leukocytes is highly regulated, at the same time serum contains significant protein amounts. Our quest is to determine by which stimuli the DbpA expression is regulated in circulating immune cells. Given autoimmune responses against cold shock proteins are established we will test for autoantibodies against DbpA.The proposal addresses pivotal questions on the functional role(s) of the cold shock protein DbpA in the pathogenesis of inflammatory kidney diseases. Given the marked cellular effects seen with modification of DbpA expression in mesangial and tubular cells our quest is to harness the findings to develop diagnostic and therapeutic strategies.