RAB27B requirement for stretch-induced exocytosis in bladder umbrella cells
RAB27B requirement for stretch-induced exocytosis in bladder umbrella cells
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DOI：
10.1152/ajpcell.00218.2017
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发表时间：
2018-03-01
影响因子：
5.5
通讯作者：
Apodaca, Gerard
中科院分区：
文献类型：
--
作者：
Gallo, Luciana, I;Dalghi, Marianela G.;Apodaca, Gerard
伞细胞，这必须保持一个紧密的屏障，调节其顶端的西装ACE领域在膀胱tilling的一个丰富的，亚顶端池的盘状和/或梭形囊泡（DFV）的胞吐作用。尽管这种运输事件对膀胱功能的重要性，但促进DFV胞吐的途径仍有待确定。我们先前表明DFV胞吐部分依赖于RAB 11 A-RAB 8A-MYO 5 B网络，但也报道了RAB 27 B与DFV相关，并且缺乏RAB 27 B的敲除小鼠具有较少的DFV。然而，RAB 27 B对DFV胞吐的需求以及RAB 27 B与其他伞细胞表达的RAB之间的关系仍不清楚。使用整个膀胱的准备，我们观察到，填充诱导的胞吐的人生长激素加载DFV显着抑制时，RAB 27 B的表达下调使用shRNA。RAB 27 A也在大鼠尿路上皮中表达;然而，RAB 27 A特异性shRNA并不抑制胞吐作用，并且RAB 27 A和RAB 27 B shRNA的组合并不比单独用RAB 27 B shRNA处理更显著地影响DFV胞吐作用。当使用Squassh分割软件定量时，RAB 27 B和RAB 11 A显示出较小程度的重叠，并且RAB 11 A或RAB 8A的显性活性或显性阴性突变体的表达，或RAB 11 A特异性shRNA的表达，对RAB 27 B阳性DFV的大小、数量或强度没有显著影响。同样，用RAB 27 B特异性shRNA处理对RAB 11 A阳性DFV参数没有影响。我们的结论是，RAB 27 B，而不是RAB 27 A，调节DFV胞吐在膀胱伞细胞的方式，可能是平行于先前描述的RAB 11 A-RAB 8AMO 5 B途径。
Umbrella cells, which must maintain a tight barrier, modulate their apical suit ace area during bladder tilling by exocytosis of an abundant, subapical pool of discoidal- and/or fusiform-shaped vesicles (DFVs). Despite the importance of this trafficking event for bladder function, the pathways that promote DFV exocytosis remain to be identified. We previously showed that DFV exocytosis depends in part on a RAB11A-RAB8A-MYO5B network, but RAB27B is also reported lo be associated with DFVs, and knockout mice lacking RAB27B have fewer DFVs. However, the RAB27B requirements for DFV exocytosis and the relationship between RAB27B and the other umbrella cell-expressed RABs remains unclear. Using a whole bladder preparation, we observed that filling-induced exocytosis of human growth hormone-loaded DFVs was significantly inhibited when RAB27B expression was downregulated using shRNA. RAB27A was also expressed in rat urothelium; however, RAB27A-specific shRNAs did not inhibit exocytosis, and the combination of RAB27A and RAB27B shRNAs did not significantly affect DFV exocytosis more than treatment with RAB27B shRNA alone. RAB27B and RAB11A showed a small degree of overlap when quantified using Squassh segmentation software, and expression of dominant-active or dominant-negative mutants of RAB11A or RAB8A, or expression of a RAB11A-specific shRNA, had no significant effect on the size, number, or intensity of RAB27B-positive DFVs. Likewise, treatment with RAB27B-specific shRNA had no effect on RAB11A-positive DFV parameters. We conclude that RAB27B, but not RAB27A, regulates DFV exocytosis in bladder umbrella cells in a manner that may be parallel to the previously described RAB11A-RAB8AMO5B pathway.