Rab17 regulates apical delivery of hepatic transcytotic vesicles.
Rab17 regulates apical delivery of hepatic transcytotic vesicles.
复制标题
DOI：
10.1091/mbc.e18-07-0433
复制
发表时间：
2018-11-15
影响因子：
3.3
通讯作者：
Tuma PL
中科院分区：
文献类型：
--
作者：
Striz AC;Stephan AP;López-Coral A;Tuma PL
我们实验室的一个主要关注点是确定调节极化肝细胞基底侧到顶端跨细胞作用的分子和机制。我们最近的研究主要集中在表征小的Rab17 GTP酶的生化和功能特性。利用极化的肝脏WIF-B细胞外源表达野生型、显性活性/三磷酸鸟苷(GTP)结合、显性负性/鸟苷二磷酸(GDP)结合、或苏甲基化缺陷/K68R rab17蛋白，我们证实了Rab17调节基侧-顶端跨细胞小泡对接和与顶端表面的融合。我们进一步证实，从根尖下室到根尖表面，跨细胞作用受到损害，GTP结合和SUMoyl化的Rab17很可能是根尖小泡对接所必需的。由于与GTP结合的Rab17的表达导致跨细胞作用受损，而野生型则没有作用，我们进一步认为Rab17 GTP的水解是囊泡递送所必需的。我们还确定了三类新合成的顶端居民的跨细胞反应对Rab17突变表达的反应相似，表明Rab17是顶端预定的囊泡对接和融合所需的跨细胞机械的一般组成部分。
A major focus for our laboratory is identifying the molecules and mechanisms that regulate basolateral-to-apical transcytosis in polarized hepatocytes. Our most recent studies have focused on characterizing the biochemical and functional properties of the small rab17 GTPase. We determined that rab17 is a monosumoylated protein and that this modification likely mediates selective interactions with the apically located syntaxin 2. Using polarized hepatic WIF-B cells exogenously expressing wild-type, dominant active/guanosine triphosphate (GTP)-bound, dominant negative/guanosine diphosphate (GDP)-bound, or sumoylation-deficient/K68R rab17 proteins, we confirmed that rab17 regulates basolateral-to-apical transcytotic vesicle docking and fusion with the apical surface. We further confirmed that transcytosis is impaired from the subapical compartment to the apical surface and that GTP-bound and sumoylated rab17 are likely required for apical vesicle docking. Because expression of the GTP-bound rab17 led to impaired transcytosis, whereas wild type had no effect, we further propose that rab17 GTP hydrolysis is required for vesicle delivery. We also determined that transcytosis of three classes of newly synthesized apical residents showed similar responses to rab17 mutant expression, indicating that rab17 is a general component of the transcytotic machinery required for apically destined vesicle docking and fusion.