MCC regulator of WNT signaling pathway (MCC) is a podocyte essential gene

Podocytes are an integral part of the glomerular infiltration barrier. At present, many genes are known essential for podocyte survival and structural and functional homeostasis; however, there are more such genes to be uncovered. By single-cell RNA-seq of mouse podocytes, we detected the expression of gene encoding MCC regulator of WNT signaling pathway (MCC) in majority of the single podocytes and speculated that MCC may be essential for podocytes. We confirmed MCC expression in mouse podocytes and further showed its expression in human podocytes. To experimentally prove the essentiality of MCC for podocytes, we knocked down MCC in cultured podocytes, resulting in marked morphological change of cell shape, cytoskeletal stress fiber disruption, increased apoptosis, and downregulation of podocyte essential genes, CD2AP and WT1, demonstrating that MCC is essential for podocytes. To investigate the mechanism underlying the role of MCC in podocytes, we performed RNA-seq analysis of the podocytes in culture 24 hours after transfection of siRNA against MCC, followed by bioinformatics analysis of the genes with altered expression, and found some mechanistic clues. Lastly, we found that MCC is downregulated in podocytes treated with puromycin aminonucleosides and in glomeruli of diabetic mice and FSGS patients, implicating MCC in the development of podocytopathy and proteinuria. In conclusion, MCC is essential for podocytes and its deficiency may be involved in podocytopathy. Overall design: Immortalized human podocytes from Dr. Saleem M's laboratory (University of Bristol, Bristol, UK) were cultured with RPMI1640 medium supplemented with 10% FBS, 1% Pen/Strep and 1% ITS at 33°C in 5% CO2 incubator for growth, followed by trypsinization, replating and culture at 37°C for 10 days to obtain differentiated cells. Then the differentiated podocytes were transfected with siRNA against MCC or left untreated with only vehicle for 24 hours. The cells were homogenized with Trizol (Invitrogen) and the total RNA was extracted following the manual instruction. The RNA was then subject to RNA-seq.