Interplay between skeletal muscle catabolism and remodeling of arteriovenous fistulae via YAP1/TAZ signaling

摘要 动静脉瘘(AVF)，一种人工创建的动脉和血管之间的直接连接 静脉是慢性肾脏病(CKD)血液透析患者的生命线。 然而，60%-65%的AVF在创建后1年内失败，导致严重的健康风险和 给患者带来沉重的经济负担。放置或维护血管通道的成本超过2.8美元 十亿/年。尽管已经进行了多项临床试验，但没有可行的治疗方案。 已经被发现了。我们的长期目标是确定细胞和分子机制 AVF成熟失败，因此可以开发治疗策略来预防和治疗aVF 失败了。早期研究表明，CKD诱导的新生内膜(内血管增厚) 层)形成和血管纤维化是导致AVF成熟失败的主要危险因素。 最近，我们发现尿毒症小鼠骨骼肌分解代谢之间的串扰可能是 与AVF功能故障相关。我们的初步结果表明，肌肉生长抑制素在 尿毒症小鼠骨骼肌刺激转录调节因子YAP1/TAZ的表达 参与细胞增殖的基因)可以促进血管平滑肌的激活 血管平滑肌细胞与外膜间充质干细胞向成骨细胞的分化 肌成纤维细胞。这些反应导致细胞外基质蛋白的增加和进行性 血管纤维化。细胞外基质的刚性激活了YAP1/TAZ，形成了“前向” 反馈环“。其结果是促进了增殖、迁移和炎症，从而导致 至AVF成熟失败。因此，我们假设抑制Myostatin或YAP1/TAZ 将阻断VSMC的激活和MSC向肌成纤维细胞的分化，从而改善AVF 功能。在这项申请中提出的具体目标将调查这一假设的有效性。 在目标1中，我们将研究使用中和多肽抑制肌肉生长抑素的作用。 慢性肾脏病小鼠血管内膜细胞与动静脉瘘纤维化目标2和目标3将分析YAP1和 Taz基因敲除Myostatin诱导的VSMC激活和MSC转分化 在体内，并评估FDA批准的药物维替普芬是否局部抑制YAP1激活 抑制CKD诱导的小鼠AVF衰竭。成功完成这些研究将导致 开发新的治疗策略来预防和治疗透析中的AVF失败 病人。

Summary Arteriovenous fistula (AVF), an artificially created direct connection between an artery and vein, is the life line for hemodialysis patients suffering from chronic kidney disease (CKD). However, 60-65% of AVFs fail within 1 year of their creation resulting in serious health risks and heavy financial burden to patients. The costs of placing or caring for vascular access exceed $2.8 billion/year. Although, multiple clinical trials have been performed, no viable treatment options have been uncovered. Our long term goal is to identify the cellular and molecular mechanisms of AVF maturation failure so that therapeutic strategies can be developed to prevent and treat AVF failure. Earlier studies demonstrated that CKD-induced neointima (thickening of inner vascular layer) formation and vascular fibrosis are the leading risk factors causing AVF maturation failure. Recently, we found the crosstalk between skeletal muscle catabolism in uremic mice could be related with AVF function failure. Our Preliminary results indicated that myostatin generated in skeletal muscle in uremic mice stimulated the expression of YAP1/TAZ (transcriptional regulators of genes involved in cellular proliferation) which can promote activation of vascular smooth muscle cells (VSMCs) and differentiation of adventitial mesenchymal stem cells (MSCs) into myofibroblasts. These responses result in increased extracellular matrix proteins and progressive vascular fibrosis. The stiffness of extracellular matrix activates YAP1/TAZ which forms a “forward feedback loop”. The result is the enhanced proliferation, migration, and inflammation which lead to AVF maturation failure. We therefore hypothesize that inhibition of myostatin or of YAP1/TAZ will block VSMC activation and MSC differentiation into myofibroblasts resulting in improved AVF functions. Specific Aims proposed in this application will investigate the validity of this hypothesis. In Aim 1 we will examine the effects of myostatin inhibition using a neutralizing peptibody on neointima cells and AVF fibrosis in CKD mice. Aim 2 and 3 will analyze the effects of YAP1 and TAZ knock down on myostatin induced VSMC activation and MSC transdifferentiation in vitro and in vivo, and evaluate if local inhibition of YAP1 activation by FDA-approved drug, Verteporfin suppresses CKD–induced AVF failure in mice. Successful completion of these studies will lead to the development of new therapeutic strategies to prevent and treat AVF failure in dialysis patients.