Podocyte cytoskeletal injury is characterized by dysregulation of Ca2+ signaling and increased podocyte motility, which correlate with podocyte foot process (FP) collapse and the emergence of albuminuria. Our laboratory showed that increased podocyte motility is mediated by TRPC5, an ion channel our laboratory introduced a few years ago as an important Ca2+ influx pathway in podocytes. Based on our recent work, TRPC5 channels play an important role in the emergence of albuminuria in acute models of disease. However, little is known about the role of podocyte TRPC5 signaling in the chronicity of acquired glomerular disease such as FSGS, which is the focus of this proposal. Understanding the mechanistic steps involving TRPC5 activity and how to block it is important for the many children and adults with de novo idiopathic Nephrotic Syndrome (such as FSGS), for the devastating cases of recurrence of FSGS post-transplantation and for the millions of patients with albuminuria and FSGS in the setting of diabetes and hypertension. Unfortunately, we presently lack effective treatment for these patients, so there is tremendous unmet need in this therapeutic area. Here we propose a series of detailed in vivo studies to test the hypothesis that blocking TRPC5 channels using a small molecule inhibitor can prevent progression to FSGS and kidney failure.