Regulation of podocyte BK(Ca) channels by synaptopodin, Rho, and actin microfilaments

2010; doi:10.1152/ajprenal.00206.2010.—Mechanosensitive large-conductance Ca2-activated K channels encoded by the Slo1 gene (BKCa channels) are expressed in podocytes. Here we show that BKCa channels reciprocally coimmunoprecipitate with synap-topodin (Synpo) in mouse glomeruli, in mouse podocytes, and in a heterologous expression system (HEK293T cells) in which these proteins are transiently expressed. Synpo and Slo1 colocalize along the surface of the glomerular basement membrane in mouse glo-meruli. Synpo interacts with BKCa channels at COOH-terminal domains that overlap with an actin-binding domain on the channel molecule that is necessary for trafficking of BKCa channels to the cell surface. Moreover, addition of exogenous -actin to mouse podocyte lysates reduces BKCa-Synpo interactions. Coexpression of Synpo increases steady-state surface expression of BKCa chan-nels in HEK293T cells. However, Synpo does not affect th