Rab3A/Rab27A System Silencing Ameliorates High Glucose-Induced Injury in Podocytes

SIMPLE SUMMARY: In diabetic nephropathy, the injury of renal cells such as podocytes worsens the glomerular filtration process due to the cells’ loss and detachment from the basal membrane. Intra- and intercellular communications in cells are partially mediated by the Rab3A/Rab27A system. We have observed that silencing the Rab3A/Rab27A system in podocytes experiencing glucose overload has a differential impact on differentiation, cytoskeleton organisation, apoptosis, CD63 distribution, and miRNA levels. Generally, when cells are subjected to glucose stress and the Rab system is silenced, we observed a reduction in the detrimental cell processes. These results suggest that the Rab3A/Rab27A system is a key participant in podocyte injury and vesicular traffic regulation in diabetic nephropathy. ABSTRACT: Diabetic nephropathy is a major complication in diabetic patients. Podocytes undergo loss and detachment from the basal membrane. Intra- and intercellular communication through exosomes are key processes for maintaining function, and the Rab3A/Rab27A system is an important counterpart. Previously, we observed significant changes in the Rab3A/Rab27A system in podocytes under glucose overload, demonstrating its important role in podocyte injury. We investigated the implication of silencing the Rab3A/Rab27A system in high glucose-treated podocytes and analysed the effect on differentiation, apoptosis, cytoskeletal organisation, vesicle distribution, and microRNA expression in cells and exosomes. For this, we subjected podocytes to high glucose and transfection through siRNAs, and we isolated extracellular vesicles and performed western blotting, transmission electron microscopy, RT-qPCR, immunofluorescence and flow cytometry assays. We found that silencing RAB3A and RAB27A generally leads to a decrease in podocyte differentiation and cytoskeleton organization and an increase in apoptosis. Moreover, CD63-positive vesicles experienced a pattern distribution change. Under high glucose, Rab3A/Rab27A silencing ameliorates some of these detrimental processes, suggesting a differential influence depending on the presence or absence of cellular stress. We also observed substantial expression changes in miRNAs that were relevant in diabetic nephropathy upon silencing and glucose treatment. Our findings highlight the Rab3A/Rab27A system as a key participant in podocyte injury and vesicular traffic regulation in diabetic nephropathy.