Targeting of SNAP-23 and SNAP-25 in polarized epithelial cells
Targeting of SNAP-23 and SNAP-25 in polarized epithelial cells
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DOI：
10.1074/jbc.273.6.3422
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发表时间：
1998-02-06
影响因子：
4.8
通讯作者：
Weimbs, T
中科院分区：
文献类型：
--
作者：
Low, SH;Roche, PA;Weimbs, T
SNAP-23是神经元SNAP-25的广泛表达的同源物，其在突触囊泡融合中起作用。我们已经研究了SNAP-23在极化上皮细胞中的亚细胞定位。在肝细胞衍生的HepG 2细胞和Madin-Darby犬肾（MDCK）细胞中，大多数SNAP-23存在于基底外侧和顶端质膜结构域，几乎没有细胞内定位，这表明SNAP-23在细胞内融合事件中不起作用，而是作为一般质膜t-SNARE。犬SNAP-23被肉毒杆菌神经毒素E有效切割，表明它是先前发现参与MDCK细胞中质膜融合的毒素敏感因子，为了比较，研究了SNAP-25在转染的MDCK细胞中的定位，发现与SNAP-23相同，除了SNAP-25被转运到从顶端质膜突出的初级纤毛，这表明两种蛋白质的靶向信号存在细微差异。与其在神经元中的行为相反，SNAP-25在MDCK细胞中的分布通过用二丁酰cAMP或毛喉素处理而保持不变，然而，这引起初级纤毛的生长增加。最后，我们发现SNAP-23/25和突触融合蛋白1A在MDCK细胞中共表达时，不稳定地相互作用，而是分别独立地靶向质膜和溶酶体。
SNAP-23 is the ubiquitously expressed homologue of the neuronal SNAP-25, which functions in synaptic vesicle fusion, We have investigated the subcellular localization of SNAP-23 in polarized epithelial cells, In hepatocyte-derived HepG2 cells and in Madin-Darby canine kidney (MDCK) cells, the majority of SNAP-23 was present at both the basolateral and apical plasma membrane domains with little intracellular localization, This suggests that SNAP-23 does not function in intracellular fusion events but rather as a general plasma membrane t-SNARE, Canine SNAP-23 is efficiently cleaved by the botulinum neurotoxin E, suggesting that it is the toxin-sensitive factor previously found to be involved in plasma membrane fusion in MDCK cells, The localization of SNAP-25 in transfected MDCK cells was studied for comparison and was found to be identical to SNAP-23 with the exception that SNAP-25 was transported to the primary cilia protruding from the apical plasma membrane, which suggests that subtle differences in the targeting signals of both proteins exist. In contrast to its behavior in neurons, the distribution of SNAP-25 in MDCK cells remained unaltered by treatment with dibutyryl cAMP or forskolin, which, however, caused an increased growth of the primary cilia, Finally, we found that SNAP-23/25 and syntaxin 1A, when coexpressed in MDCK cells, do not stably interact with each other but are independently targeted to the plasma membrane and lysosomes, respectively.