Polyák Erzsébet, Boopathi Ettickan, Mohanan Sunish, Deng Maoxian, Zderic Stephen A, Wein Alan J, Chacko Samuel
Department of Pathobiology, University of Pennsylvania, Philadelphia, Pennsylvania 19036, USA.
J Urol. 2009 Nov;182(5):2497-503. doi: 10.1016/j.juro.2009.07.011. Epub 2009 Sep 17.
Partial bladder outlet obstruction in male rabbits causes detrusor smooth muscle hypertrophy and voiding dysfunction similar to that observed in men with benign prostate hyperplasia. Using this model, we analyzed the protein expression and ultrastructure of caveolae and the intermediate size filament in detrusor smooth muscle following partial bladder outlet obstruction induced hypertrophy.
Detrusor smooth muscle sections from bladder body were processed for immunofluorescence and electron microscopy. Western analysis was performed to determine the expression of caveolin isoform-1, 2 and 3, and intermediate size filament proteins.
Detrusor smooth muscle cells from both normal and hypertrophied bladders contain orderly arrays of thick and thin myofilaments, interspersed with dense bodies. In addition, there was an increase in intermediate size filaments in the hypertrophic detrusor smooth muscle cells. The dense plaques in the inner membrane of hypertrophied detrusor smooth muscle were longer than those of the control. Detrusor smooth muscle from hypertrophied bladder revealed a decreased number of caveolae and a lack of their orderly distribution at the plasma membrane. Western blotting showed decreased expression of caveolin-1, 2 and 3 in hypertrophied detrusor smooth muscle.
Caveolae serve as platforms for proteins and receptors that have a role in signal transduction. The decreased number of caveolae and caveolin protein expression in hypertrophied detrusor smooth muscle might contribute to alterations in signal transduction pathways that regulate the downstream effects of agonist induced contraction, including calcium sensitization, observed in obstructed bladder. In addition, the increased number of intermediate size filaments in the hypertrophied detrusor smooth muscle is likely to alter the cytoskeletal structure and affect the cellular transmission of passive and/or active force.
雄性兔的部分膀胱出口梗阻会导致逼尿肌平滑肌肥大和排尿功能障碍，这与良性前列腺增生男性患者中观察到的情况相似。利用该模型，我们分析了部分膀胱出口梗阻诱导肥大后逼尿肌平滑肌中小窝和中间丝的蛋白表达及超微结构。
对膀胱体的逼尿肌平滑肌切片进行免疫荧光和电子显微镜处理。进行蛋白质印迹分析以确定小窝蛋白亚型1、2和3以及中间丝蛋白的表达。
正常和肥大膀胱的逼尿肌平滑肌细胞均含有排列有序的粗细肌丝，其间散布着致密体。此外，肥大的逼尿肌平滑肌细胞中的中间丝数量增加。肥大的逼尿肌平滑肌内膜中的致密斑比对照组的更长。肥大膀胱的逼尿肌平滑肌显示小窝数量减少且在质膜上缺乏有序分布。蛋白质印迹显示肥大的逼尿肌平滑肌中小窝蛋白-1、2和3的表达降低。
小窝作为蛋白质和受体的平台，在信号转导中发挥作用。肥大的逼尿肌平滑肌中小窝数量减少和小窝蛋白表达降低可能导致信号转导途径的改变，这些途径调节激动剂诱导收缩的下游效应，包括在梗阻膀胱中观察到的钙敏化。此外，肥大的逼尿肌平滑肌中中间丝数量增加可能会改变细胞骨架结构并影响被动和/或主动力的细胞传递。
