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Altered expression and modulation of the two-pore domain (K2p) mechano-gated potassium channel TREK-1 in overactive human detrusor

, , , , , ,

Renal Physiology

Published online on

Abstract

Background Detrusor overactivity (DO) is the abnormal response of the urinary bladder to physiological stretch during the filling phase of the micturition cycle. The mechanisms of bladder smooth muscle compliance upon the wall stretch are poorly understood. We previously reported that the function of normal detrusor is regulated by TREK-1, a member of the mechano-gated subfamily of two-pore domain potassium (K2P) channels. In the present study, we aimed to identify the changes in expression and function of TREK-1 channels under pathological conditions associated with DO, evaluate the potential relationship between TREK-1 channels and cytoskeletal proteins in the human bladder, and test the possibility of modulation of TREK-1 channel expression by small RNAs. Results Expression of TREK-1 channels in DO specimens was 2.7-fold decreased in comparison to control bladders, and was associated with a significant reduction of the recorded TREK-1 currents. Isolated DO muscle strips failed to relax when exposed to a TREK-1 channel opener. Immunocytochemical labeling revealed close association of TREK-1 channels with cell cytoskeletal proteins and caveolins, with caveolae microdomains being severely disrupted in DO specimens. Small activating RNA tested in vitro provided evidence that expression of TREK-1 protein could be partially up-regulated. Conclusions Our data confirmed a significant down-regulation of TREK-1 expression in human DO specimens, and provided evidence of close association between the channel, cell cytoskeleton and caveolins. Up-regulation of TREK-1 expression by saRNA could be a future step for the development of in vivo pharmacological and genetic approaches to treat DO in humans.