Kir5.1 regulates Nedd4-2-mediated ubiquitination of Kir4.1 in distal nephron.

Kir5.1 regulates Nedd4-2-mediated ubiquitination of Kir4.1 in distal nephron. Am J Physiol Renal Physiol. 2018 Jun 13;: Authors: Wang MX, Su XT, Wu P, Gao ZX, Wang WH, Staub O, Lin DH Abstract Kir4.1/5.1 heterotetramer participates in generating the negative cell membrane potential in distal convoluted tubule (DCT) and plays a critical role in determining the activity of Na-Cl co-transporter (NCC). Kir5.1 contains a phosphothreonine-motif at its c-terminus (AA249-252). Co-immunoprecipitation showed that Nedd4-2 was associated with Kir5.1 in HEK293 cells cotransfected with Kir5.1 or Kir4.1/Kir5.1. GST-pull-down further confirmed the association between Nedd4-2 and Kir5.1. Ubiquitination assay showed that Nedd4-2 increased the ubiquitination of Kir4.1/Kir5.1 heterotetramer in the cells co-transfected with Kir4.1/Kir5.1 but it has no effect on Kir4.1 or Kir5.1 alone. Patch-clamp and western blot also demonstrated that co-expression of Nedd4-2 but not Nedd4-1 decreased K currents and Kir4.1 expression in the cells cotransfected with Kir4.1 and Kir5.1. In contrast, Nedd4-2 fails to inhibit Kir4.1 in the absence of Kir5.1 or in the cells transfected with the inactivated form of Nedd4-2 (Nedd4-2C821A). Moreover, the mutation of TPVT motif in the C-terminus of Kir5.1 largely abolished the association of Nedd4-2 with Kir5.1 and abolished the inhibitory effect of Nedd4-2 on K currents in HEK293 cells transfected with Kir4.1 and Kir5.1 mutant (...
Source: Am J Physiol Renal P... - Category: Urology & Nephrology Authors: Tags: Am J Physiol Renal Physiol Source Type: research