Effects of aldosterone on the protein expressions and the urea transport activity of UT-A1 and UT-A3 / 中华肾脏病杂志

ABSTRACT

Objective To investigate the effects of protein expressions and the urea transport activity of aldosterone on urea transporter A1 (UT-A1) and urea transporter A3 (UT-A3) in HEK293 cells and Xenopus laevis oocytes.Methods (1) Western Blot was used to investigate the protein expressions of UT-A1 and UT-A3.(2) Cell surface biotinylation was used to investigate the protein expressions of UT-A1 and UT-A3 on the cell surface of Xenopus laevis oocytes.(3) 14C-urea transport experiment was conducted to investigate the transport activity of UT-A1 and UT-A3 in Xenopus laevis oocytes.Results (1) Compared with UT-A1 or UT-A3 high expression groups,the total protein levels of UT-A 1 and UT-A3 were all significantly reduced in aldosterone treatment groups (all P ＜ 0.01).(2) Compared with UT-A1 or UT-A3 high expression groups,the levels of protein expression on cell surface were all significantly reduced in aldosterone groups (all P ＜ 0.01).(3) Compared with UT-A1 or UT-A3 high expression groups,14C-urea transport experiment results showed that aldosterone treatment groups had significantly reduced the urea transporter activity of UT-A1 (1 min94.32±9.044vs 40.68±4.274,P＜0.01,n=6;3 min165.0±4.7 vs 80.3±0.6,P＜0.01,n=6),and UT-A3 (1 min204.6± 3.1 vs 176.7± 9.1,P＜0.05,n=6;3 min371.4 ± 14.9 vs 318.8 ± 12.0,P＜0.05,n=6).Conclusion Aldosterone can directly down-regulate the protein expressions of UT-A1 and UT-A3 in both total protein and cell surface level,which reduces their urea transport activity.