Influence of PKD1-Mediated Apoptosis on Proliferation and Autophagy in Human Embryonic Kidney Cells

Background: Polycystic Kidney Disease (PKD) is the most common genetic cause of chronic kidney disease, affecting millions globally. The condition is characterized by kidney cysts, excessive proliferation, apoptosis, and fibrosis. PKD arises from a mutation in the PKD1 gene, encoding polycystin-1 (PC1), a transmembrane protein. Loss of PC1 is linked to centrosome amplification, genomic instability, and excessive proliferation, but the underlying mechanisms are unclear. This study examines the consequences of PC1 loss, focusing on apoptosis and its effects on proliferation and autophagy. It also investigates the potential therapeutic impact of apoptosis-inhibitory small molecules (Z-DEVD-FMK and Z-VAD-FMK) on reversing the condition in PKD1-silenced Human Embryonic Kidney Cells (HEK293T). Methods: We silenced PKD1 and verified knockdown by sequencing. Cell viability was measured by MTT assay. Apoptosis, proliferation, and autophagy were examined by immunostaining and western blot. Apoptosis inhibitors were used to rescue PKD1-silenced cells. Lastly, we generated spheroids for the control and PKD1 silenced cells embedded in Matrigel, collagen, and ECM hydrogel to assess the effect of PKD1 deletion and apoptosis inhibition in three-dimensional cultures. Results: PKD1 loss significantly reduced cell viability to 56.8% (p=0.0394), indicating its importance in metabolic activity. This was not due to changes in proliferation but rather due to a significant induction of apoptosis (p=0.0131) comparable to the potent apoptosis-inducer staurosporine. PKD1 silencing also reduced autophagy, decreasing LC3B expression to 2.781% (p=0.0058) of controls (10.77%). The caspase-3 inhibitor (Z-DEVD-FMK) and pan-caspase inhibitor (Z-VAD-FMK) both reduced caspase-3 expression, but the latter was more effective at reducing cleaved PARP (p=0.0257). These results highlight PKD1's critical role in regulating apoptosis and autophagy. Conclusion: We uncover PKD1's critical role in controlling apoptosis and offer a potential therapeutic avenue to mitigate disease progression.