Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
XB-ART-54628
Acta Physiol (Oxf) February 28, 2018; e13060.

Plasma kallikrein activates the epithelial sodium channel in vitro but is not essential for volume retention in nephrotic mice.

Haerteis S , Schork A , Dörffel T , Bohnert BN , Nacken R , Wörn M , Xiao M , Essigke D , Janessa A , Schmaier AH , Feener EP , Häring HU , Bertog M , Korbmacher C , Artunc F .


Abstract
AIM: Recent work has demonstrated that activation of the epithelial sodium channel (ENaC) by aberrantly filtered serine proteases causes sodium retention in nephrotic syndrome. The aim of this study was to elucidate a potential role of plasma kallikrein (PKLK) as a candidate serine protease in this context. METHODS: We analysed PKLK in the urine of patients with chronic kidney disease (CKD, n = 171) and investigated its ability to activate human ENaC expressed in Xenopus laevis oocytes. Moreover, we studied sodium retention in PKLK-deficient mice (klkb1 -/- ) with experimental nephrotic syndrome induced by doxorubicin injection. RESULTS: In patients with CKD, we found that PKLK is excreted in the urine up to a concentration of 2 μg mL -1 which was correlated with albuminuria (r = .71) and overhydration as assessed by bioimpedance spectroscopy (r = .44). PKLK increased ENaC-mediated whole-cell currents, which was associated with the appearance of a 67 kDa γ-ENaC cleavage product at the cell surface consistent with proteolytic activation. Mutating a putative prostasin cleavage site in γ-ENaC prevented channel stimulation by PKLK. In a mouse model for nephrotic syndrome, active PKLK was present in nephrotic urine of klkb1 +/+ but not of klkb1 -/- mice. However, klkb1 -/- mice were not protected from ENaC activation and sodium retention compared to nephrotic klkb1 +/+ mice. CONCLUSION: Plasma kallikrein is detected in the urine of proteinuric patients and mice and activates ENaC in vitro involving the putative prostasin cleavage site. However, PKLK is not essential for volume retention in nephrotic mice.

PubMed ID: 29489063
Article link: Acta Physiol (Oxf)



External Resources:

Xenbase: The Xenopus laevis and X. tropicalis resource.
Version: 4.9.2
Major funding for Xenbase is provided by the National Institute of Child Health and Human Development, grant P41 HD064556