Figure 5

Inadequate 11β-HSD2 activity and glucocorticoid receptor protein expression in CAP2/Tmprss4 knockout mice under low K⁺ diet. (A) Plasma levels of corticosterone (nM) in CAP2/Tmprss4 wildtype (+/+, white circles, n = 6), heterozygous mutant (∆/+, grey circles, n = 5), and knockout (∆/∆, black circles, n = 5) mice under regular K⁺ (RK) and low K⁺ diet (LK). (B) 11β-HSD2 activity (fmol/µg protein/1 h) in CAP2/Tmprss4 wildtype (+/+, white circles, n = 6), heterozygous mutant (∆/+, grey circles, n = 5), and knockout (∆/∆, black circles, n = 5) mice under low K⁺ diet. (C) Representative (cropped) immunoblot for GR in kidney lysates from wildtype mice under regular K⁺ diet (RK) and under low K⁺ diet (LK) (n = 4 per condition) and (D) corresponding GR protein quantification (RK, triangles, and LK, diamonds); actin was used as loading control. The membrane was cut and GR and actin were blotted separately. (E) Representative (cropped) immunoblot for glucocorticoid receptor (GR) and pS220-GR in kidney lysates from CAP2/Tmprss4 wildtype (+/+, white circles) and knockout (∆/∆, black circles) mice (n = 6 per genotype) under low K⁺ diet. Actin was used as loading control. The membrane was cut, the lower part was blotted against actin, while the upper part was first blotted against pS220-GR, then stripped and blotted against GR. (F) Corresponding GR and pS220-GR protein quantification. (G) Representative (cropped) immunoblot of mineralocorticoid receptor (MR) in kidney lysates from CAP2/Tmprss4 wildtype (+/+) and knockout (∆/∆) mice (n = 6 per genotype) under low K⁺ diet, and (H) corresponding MR protein quantification; actin was used as loading control. The membrane was cut and MR and actin were blotted separately. A nephron-specific MR knockout⁷⁹ kidney lysate was used as negative control (ctrl KO) *p < 0.05, **p < 0.01, ***p < 0.001. For the sake of visual clarity, blots for GR and pS220-GR are shown with a higher contrast, quantifications were however performed on the original blots. Full-length original immunoblots can be found in the supplementary information.