Deletion of dicer in smooth muscle affects voiding pattern and reduces detrusor contractility and neuroeffector

MicroRNAs have emerged as important regulators of smooth muscle phenotype and may play important roles in pathogenesis of various smooth muscle related disease states. The aim of this study was to investigate the role of miRNAs for urinary bladder function. We used an inducible and smooth muscle specific Dicer knockout (KO) mouse which resulted in significantly reduced levels of miRNAs, including miR-145, miR-143, miR-22, miR125b-5p and miR-27a, from detrusor preparations without mucosa. Deletion of Dicer resulted in a disturbed micturition pattern in vivo and reduced depolarization-induced pressure development in the isolated detrusor. Furthermore, electrical field stimulation revealed a decreased cholinergic but maintained purinergic component of neurogenic activation in Dicer KO bladder strips. The ultrastructure of detrusor smooth muscle cells was well maintained, and the density of nerve terminals was similar. Western blotting demonstrated reduced contents of calponin and desmin. Smooth muscle a-actin, SM22a and myocardin were unchanged. Activation of strips with exogenous agonists showed that depolarization-induced contraction was preferentially reduced; ATPand calyculin A-induced contractions were unchanged. Quantitative real time PCR and western blotting demonstrated reduced expression of Cav1.2 (Cacna1c). It is concluded that smooth muscle miRNAs play an important role for detrusor contractility and voiding pattern of unrestrained mice. This is mediated in part via effects on expression of smooth muscle differentiation markers and L-type Ca channels in the detrusor. Citation: Sadegh MK, Ekman M, Rippe C, Uvelius B, Swärd K, et al. (2012) Deletion of Dicer in Smooth Muscle Affects Voiding Pattern and Reduces Detrusor Contractility and Neuroeffector Transmission. PLoS ONE 7(4): e35882. doi:10.1371/journal.pone.0035882 Editor: Partha Mukhopadhyay, National Institutes of Health, United States of America Received February 21, 2012; Accepted March 23, 2012; Published April 27, 2012 Copyright: 2012 Sadegh et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported by the Swedish Research Council (K2009-65X-4955-01-3, K2011-67P-20608-02-4, and repatriation grant), the Swedish Heart and Lung Foundation, The Crafoord Foundation, The Royal Physiographic Society, The Åke Wiberg Foundation, The Tore Nilson Foundation, The Greta and Johan Kock Foundation, The Magnus Bergvall Foundation, regional health care grants (ALF), and the faculty of Medicine at Lund University. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: [email protected] . These authors contributed equally to this work.