Targeting Myosin to Treat Polycystic Kidney Disease

项目摘要 该提案的目的是推进一种新的治疗方法，针对肌球蛋白多囊肾 疾病（PKD）。PKD是一种主要的危及生命的孟德尔疾病，影响12，000，000人， 这意味着约10亿美元的市场机会。在PKD中，肾脏，肝脏和其他器官中的小管 逐渐扩张成充满液体的囊肿，导致器官衰竭。PKD通常作为功能丧失遗传 PKD 1或PKD 2中的突变，分别编码多囊蛋白-1（PC 1）或多囊蛋白-2（PC 2）。一般治疗 包括管理慢性肾脏疾病的并发症，控制血压，并为肾脏疾病做好准备。 替代疗法托伐普坦是一种血管加压素受体拮抗剂，已被批准用于快速进展的 例，但其适度的疗效和偶尔严重的副作用使其不适合许多PKD患者。 囊肿如何形成机制仍然不完全清楚，这阻碍了药物开发。因此 迫切需要新的治疗方法和靶点来减缓或逆转PKD，并且存在市场。 为了更好地模拟人PKD并开发治疗策略，我们发明了PKD 1-/-和PKD 2-/-人PKD。 肾类器官，从肾小管发生PKD特异性囊肿形成，重建疾病表型 在培养皿中。类器官研究表明PKD囊肿形成对微环境高度敏感， blebbistatin，一种肌球蛋白II抑制剂，大大增加了囊肿形成。非肌肉肌球蛋白II（NMII），一种已知的 赋予细胞强度和形状的blebbistatin的靶标在肾小管上皮细胞中强烈表达， 在类器官囊肿中重新分布。相反，在初步研究中，我们发现了一种肌球蛋白II激活剂， 减少PKD囊肿形成，提示了一种新的治疗策略。这个化合物有一个公认的 在大型动物研究中的安全性和生物利用度。根据我们的初步数据和文献，我们 假设它直接激活NMII重链，以加强和修复肾脏的细胞骨架 小管，从而限制了它们变形为囊肿的趋势。本提案的主要目的是证明这一点 作为靶向药物开发的概念证明的作用机制。这将在独立的 目的是在体外和表型人类和动物模型中使用纯化的NMII。 目的#1：证明我们的命中化合物在适合药物优化的测定中激活NMII。 目标2。阐明匪II在类器官和体内PKD囊肿形成期间的靶向功能。 这两个目标的完成将连接我们的治疗击中化合物，NMII和PKD囊肿之间的点 从单分子到类器官规模的形成，阐明了治疗囊性癌的新作用机制。 疾病这将证明概念，进一步验证治疗效果，并为 II期更深入的药物开发工作（先导药物优化和临床前试验）。

PROJECT SUMMARY The goal of this proposal is to advance a new therapeutic approach targeting myosin for polycystic kidney disease (PKD). PKD is a major life-threatening Mendelian disorder that affects 12,000,000 individuals, representing a market opportunity of ~$1 billion. In PKD, tiny tubules in the kidneys, liver, and other organs gradually expand into fluid-filled cysts, leading to organ failure. PKD is commonly inherited as a loss-of-function mutation in PKD1 or PKD2, encoding polycystin-1 (PC1) or polycystin-2 (PC2), respectively. General treatment involves managing complications of chronic kidney disease, controlling blood pressure, and preparing for renal replacement therapy. Tolvaptan, a vasopressin receptor antagonist, is approved for use in rapidly progressing cases, but its modest efficacy and occasionally severe side effects make it unsuitable for many PKD patients. How cysts form mechanistically remains incompletely understood, which has hampered drug development. Thus a compelling need and market exists for new treatments and targets to slow or reverse PKD. To better model human PKD and develop therapeutic strategies, we have invented PKD1-/- and PKD2-/- human kidney organoids, which undergo PKD-specific cyst formation from tubules, reconstituting the disease phenotype in a petri dish. Organoid studies reveal that PKD cyst formation is highly sensitive to the microenvironment, and that blebbistatin, a myosin II inhibitor, greatly increases cystogenesis. Non-muscle myosin II (NMII), a known target of blebbistatin that confers strength and shape to cells, is strongly expressed in tubular epithelia and redistributed in organoid cysts. Conversely, in preliminary studies, we have discovered a myosin II activator that reduces PKD cystogenesis, suggesting a novel therapeutic strategy. This compound has a well-established safety and bioavailability profile in large animal studies. Based on our preliminary data and the literature, we hypothesize that it directly activates NMII heavy chains to strengthen and stiffen the cytoskeleton of kidney tubules, thus limiting their tendency to deform into cysts. The major goal of this proposal is to demonstrate this mechanism of action as proof of concept for targeted drug development. This will be achieved in independent aims using purified NMII in vitro and in phenotypic human and animal models. Aim #1: Demonstrate that our hit compound activates NMII in assays suitable for drug optimization. Aim #2. Elucidate the targetable function of NMII during PKD cyst formation in organoids and in vivo. Completion of these two aims will connect the dots between our therapeutic hit compound, NMII, and PKD cyst formation from the single molecule to organoid scale, elucidating a novel mechanism of action for treating cystic disease. This will demonstrate proof of concept, further validate the therapeutic hit, and lay the groundwork for deeper drug development efforts in Phase II (lead optimization and pre-clinical testing).