Haefliger Jacques-Antoine, Tissières Pierre, Tawadros Thomas, Formenton Andrea, Bény Jean-Louis, Nicod Pascal, Frey Peter, Meda Paolo
Department of Internal Medicine, University Hospital, Lausanne, CHUV-1011, Switzerland.
Exp Cell Res. 2002 Apr 1;274(2):216-25. doi: 10.1006/excr.2001.5465.
To evaluate the regulation of connexin expression by fluid pressure, we have studied the effects of elevated transmural urine pressure on Connexin43 (Cx43) and Cx26. We chose to focus on these two proteins out of the five connexins (Cx26, 43, 40, 37, and 45) which we found by RT-PCR to be expressed in the rat bladder, since in situ hybridization and immunofluorescence showed that Cx43 is the predominant connexin expressed by smooth muscle cells (SMC), whereas Cx26 is abundantly expressed only in the latter cell type. To evaluate whether these connexins are affected by changes in transmural urine pressure, we used a rat model of bladder outlet obstruction, in which a ligature is placed around the urethra. Under conditions of increased fluid pressure due to urine retention, we observed that the expression of both Cx43 and Cx26 increased at both transcript and protein levels, reaching a maximum 7-9 h after the ligature. Further analysis revealed that these changes were accounted for by a fourfold increase in Cx43 mRNA of SMC but not urothelial cell and by a fivefold increase in Cx26 mRNA of urothelium. Scrape-loading of propidium iodide showed that the latter change was paralleled by a twofold increase in coupling between urothelial cells. The data show that Cx43 and Cx26 are differentially regulated during bladder outlet obstruction and contribute to the response of the bladder wall to increased voiding pressure, possibly to control its elasticity.
为了评估流体压力对连接蛋白表达的调节作用，我们研究了跨壁尿压升高对连接蛋白43（Cx43）和Cx26的影响。我们从通过逆转录聚合酶链反应（RT-PCR）发现的大鼠膀胱中表达的五种连接蛋白（Cx26、43、40、37和45）中选择重点研究这两种蛋白，因为原位杂交和免疫荧光显示Cx43是平滑肌细胞（SMC）表达的主要连接蛋白，而Cx26仅在后者这种细胞类型中大量表达。为了评估这些连接蛋白是否受跨壁尿压变化的影响，我们使用了膀胱出口梗阻的大鼠模型，即在尿道周围放置结扎线。在因尿液潴留导致流体压力增加的情况下，我们观察到Cx43和Cx26在转录水平和蛋白水平的表达均增加，在结扎后7 - 9小时达到最大值。进一步分析表明，这些变化是由于SMC中Cx43 mRNA增加了四倍，但尿路上皮细胞中未增加，以及尿路上皮中Cx26 mRNA增加了五倍所致。碘化丙啶刮取加载显示，后一种变化伴随着尿路上皮细胞之间耦联增加了两倍。数据表明，在膀胱出口梗阻期间，Cx43和Cx26受到不同的调节，并有助于膀胱壁对排尿压力增加的反应，可能是为了控制其弹性。
