Myosin Activation as a Novel Therapeutic Strategy for Polycystic Kidney Disease

点击翻译按钮获取中文摘要

ABSTRACT Autosomal dominant polycystic kidney disease (ADPKD) affects 1 in every 400-1000 people worldwide, causing progressive fluid-filled cyst production in the kidneys, liver, and other organs, resulting in organ failure. PKD is caused by mutations in the polycystin proteins polycystin-1 (PC1) or polycystin-2 (PC2). A clear understanding of how polycystin dysfunction leads to cysts mechanistically is still elusive, due, in part, to the lack of cyst producing model systems that accurately phenocopy the disease. Stem cell derived human kidney organoids model PKD cystogenesis in a specific way and have potential to accelerate drug discovery and development for PKD. Using these PKD organoids, a drug screen was performed identifying blebbistatin, a myosin inhibitor, as a potent cyst agonist. Subsequently, I discovered that EMD, a myosin activator, showed pre-clinical promise in treating PKD cystogenesis in PKD organoids at both early and late stages of disease. Based upon preliminary data and clues from the literature, I hypothesize that PC1 and PC2 positively regulate non-muscle myosin contractility within the tubular epithelium to prevent cystogenesis. Utilizing the unique kidney organoid in vitro system, I propose to analyze myosin modulator compounds and non-muscle myosin dynamics in organoids to pinpoint the myosin domain that governs cyst expansion to inform pre-clinical drug development. Second, I aim to optimize in vivo delivery and treatment strategies of EMD in a mouse model of PKD. Finally, I will utilize the insight that PC1 structurally resembles an atypical adhesion G-protein coupled receptor to analyze whether biochemically activating PC1 can stimulate organoid contraction to link polycystin function to myosin control. Together, these experiments will establish myosin activation as a therapeutic strategy to treat PKD and determine mechanisms of PC1 as a regulator of myosin contractility. The goal of this work is to expedite drug discovery for PKD by utilizing model systems that best represent the disease, and mechanistic studies that inform polycystin function in cystogenesis.