Department of Urology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
J Urol. 2011 Sep;186(3):1121-7. doi: 10.1016/j.juro.2011.04.107. Epub 2011 Jul 23.
TRPV4 (transient receptor potential vanilloid 4 channel) is a nonselective cation channel involved in different sensory functions that was recently implicated in bladder mechanosensation. We investigated the cellular site of TRPV4 in bladder urothelium and explored a molecular connection between TRPV4 and urothelial adherence junctions.
We obtained healthy tissues sections from cystectomy in humans due to cancer in 3 and noncancerous conditions in 2. Besides human biopsies tissues from 7 normal and 7 TRPV4-/-mice, and the urothelial cell line RT4 were also used. Experiments were done with polyclonal antibody against TRPV4 (against the N-terminus of rat TRPV4). A molecular connection between TRPV4 and different adherence junction components was investigated using immunofluorescence, Western blot and immunoprecipitation.
Results revealed TRPV4 on urothelial cell membranes near adherence junctions. Results were comparable in the urothelial cell line, human bladders and mouse bladders. Subsequent immunoprecipitation experiments established a molecular connection of TRPV4 to α-catenin, an integral part of the adherence junction that catenates E-cadherin to the actin-microfilament network.
Results provide evidence for the location of TRPV4 in human bladder urothelium. TRPV4 is molecularly connected to adherence junctions on the urothelial cell membrane. TRPV4 coupling to a rigid intracellular and intercellular structural network would agree with the hypothesis that TRPV4 can be activated by bladder stretch.
TRPV4（瞬时受体电位香草素 4 通道）是一种非选择性阳离子通道，参与多种感觉功能，最近被牵连到膀胱机械感觉中。我们研究了膀胱尿路上皮中 TRPV4 的细胞位置，并探索了 TRPV4 与尿路上皮黏附连接之间的分子联系。
我们从因癌症而进行膀胱切除术的 3 名患者和非癌症患者的 2 名患者中获得了健康的组织切片。此外，还使用了来自 7 只正常和 7 只 TRPV4-/-小鼠以及尿路上皮细胞系 RT4 的组织。实验使用了针对 TRPV4（针对大鼠 TRPV4 的 N 端）的多克隆抗体进行。使用免疫荧光、Western blot 和免疫沉淀研究了 TRPV4 与不同黏附连接成分之间的分子联系。
结果显示 TRPV4 位于靠近黏附连接的尿路上皮细胞膜上。在尿路上皮细胞系、人膀胱和鼠膀胱中得到了相似的结果。随后的免疫沉淀实验建立了 TRPV4 与黏附连接的α-连环蛋白（E-钙黏蛋白与肌动蛋白微丝网络连接的组成部分）之间的分子联系。
结果为 TRPV4 在人膀胱尿路上皮中的位置提供了证据。TRPV4 与尿路上皮细胞膜上的黏附连接在分子上相连。TRPV4 与刚性的细胞内和细胞间结构网络的偶联与 TRPV4 可以通过膀胱拉伸而被激活的假说一致。
