Dysfunction of the Klotho-miR-30s/TRPC6 axis confers podocyte injury

Klotho deficiency was observed in virtually all kinds of kidney disease and is thought to play a critical role in podocyte injury. However, the underline mechanisms involved in podocyte injury remain unknown. miRNAs have diverse regulatory roles, and miR-30 family members were essential for podocyte homeostasis. Our study revealed that Klotho and miR-30s were downregulated in PAN-treated podocytes. The ectopic expression of Klotho ameliorates PAN induced podocyte apoptosis through upregulating miR-30a and downregulating Ppp3ca, Ppp3cb, Ppp3r1, and Nfact3 expression, which are the known targets of miR-30s. We also found that Klotho regulates TRPC6 via miR-30a to activate calcium/calcineurin signaling. Further, glucocorticoid (Dexamethasone, DEX) was found to sustain Klotho and miR-30a levels during PAN treatment in vitro. Eventually, in rats, PAN treatment substantially downregulated Klotho and miR-30a levels, lead to podocyte injury and increased proteinuria. The transfer of exogenous Klotho to podocytes of PAN-treated rats could increase miR-30a expression, reduce TRPC6 expression, and also ameliorated podocyte injury and proteinuria. In conclusion, Klotho, acting on miR-30s, which directly regulates its target genes, contributes to podocyte apoptosis induced by PAN. It is a novel mechanism underlying PAN-induced podocyte injury.