Analysis of expression and function of vacuolar-type H^+-ATPase at bladder

空泡型H^-ATPase存在于包括人类在内的哺乳动物膀胱表面细胞的管腔细胞膜中，分泌质子使膀胱内的尿液酸化。为了研究它们的表达过程，我们建立了小鼠膀胱表面细胞再生的实验模型。在该模型中，用胰酶处理的表层细胞剥离3h后，用V-ATPase蛋白脂基因的Northern印迹杂交检测到的V-ATPase mRNA的表达水平显著升高。另一方面，用三种不同的细胞组分，即浅层细胞丰富部分、中间和基底细胞丰富部分和完整细胞进行免疫印迹显示，V-ATPase蛋白的表达水平几乎相同。这些结果表明，在细胞从中间细胞向表面细胞分化的过程中，存在于内膜系统中的V-ATPase进入了膀胱表面细胞的腔内细胞膜。我们还研究了V-ATPase在建立抵抗感染的粘膜屏障和血尿屏障中的作用。

Vacuolar-type H^+-ATPases were present in luminal cytoplasmic membrane of bladder superficial cells in mammals including human ; which secrete protons to acidify the urine in the bladder. In order to study their expression process, we have developed an experimental model for regeneration of superficial cells of mouse bladder. In this model, the expression level of V-ATPase mRNA,which was measured by Northern blot hybridization using cDNA of V-ATPase proteolipid gene, increased significantly 3 hours after exfoliation of superficial cells by trypsin treatment. On the other hand, western blotting using three different cells fractions, superficial cells rich fraction, intermediate and basal cells rich fraction, and whole cells, revealed almost same levels of V-ATPase protein expression. These results suggested that V-ATPases present in endomembrane systems moved into luminal cytoplasmic membrane of bladder superficial cells during cell differentiation from intermediate to superficial cells. We also examined the role of V-ATPase in establishing mucosal barrier against infection as well as blood-urine barrier.