Leveraging cellular models of polycystic kidney disease for mechanistic discovery and therapeutic development

Abstract

Polycystic kidney disease (PKD) is a life-threatening disorder characterized by the progressive expansion of fluid-filled cysts originating from kidney tubules. As the leading monogenic cause of renal failure, PKD affects 1 in ~1,000 people with 50% of patients meeting criteria for end-stage renal disease by age 60. PKD is most commonly caused my loss-of-function mutations in PKD1 or PKD2 encoding the proteins polycystin-1 (PC1) and polycystin-2 (PC2), respectively. Despite significant advances in our understanding of the genes and proteins underlying PKD, there remains an unmet clinical need for optimized treatment in these patients. This has largely been hindered by limitations in currently available research models. Here we develop gene-edited clonal tubular epithelial cells and multi-cellular kidney organoids for mechanistic and therapeutic studies of PKD. In our kidney organoid model, we utilize CRISPR base editing to generate human pluripotent stem cells with specific clinically documented patient mutations. This system elicits a robust cystic phenotype and allows evaluation of therapeutic interventions. We show that partial restoration of polycystin expression, either by treatment with small molecule read-through compounds or through gene therapy approaches, is sufficient to drastically reduce PKD cystogenesis. In our PKD tubular epithelial cell model, we find dynamic regulation of PC1 that is dependent on both PC2 and confluence. Using RNA-sequencing, we identify instability of primary cilia, where the polycystins co-localize, that ultimately drives aberrant cell cycle re-entry in PKD cells. Stabilization of primary cilia, through inhibition of histone deacetylase 6-mediated ciliary disassembly, reduces PKD cystogenesis in human kidney organoids. Together, leveraging complementary approaches in our cellular and organoid based models advances our understanding of PKD mechanisms and supports further development of targeted therapeutics.