SNAP25, but not syntaxin ARF6-regulated pathway in 1A, recycles via an neuroendocrine cells
SNAP25, but not syntaxin ARF6-regulated pathway in 1A, recycles via an neuroendocrine cells
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DOI：
10.1091/mbc.e05-05-0382
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发表时间：
2006-02-01
影响因子：
3.3
通讯作者：
Martin, TFJ
中科院分区：
文献类型：
--
作者：
Aikawa, Y;Xia, XF;Martin, TFJ
可溶性N-乙基马来酰亚胺敏感性融合蛋白附着蛋白受体（SNARE）蛋白介导细胞膜融合事件，并为供体-受体膜相互作用提供一定水平的特异性。然而，个别SNARE蛋白被靶向特定的膜隔室的运输途径还没有很好地理解。在神经内分泌细胞中，25 kDa的突触体相关蛋白（SNAP 25）定位于质膜，在那里它在受调节的分泌囊泡胞吐中起作用，但它也存在于细胞内膜上。我们确定了SNAP 25在PC 12细胞中的动态再循环途径，通过该途径，质膜SNAP 25在类似于3 h的时间内再循环。大约20%的SNAP 25存在于核周再循环内体-反式-高尔基体网络（TGN）区室中，其从该区室再循环回到质膜。SNAP 25内化通过组成型、动力蛋白非依赖性内吞作用发生，其不同于在胞吐作用后取回分泌囊泡成分的动力蛋白依赖性内吞作用。SNAP 25的内吞作用受ADP-核糖基化因子（ARF）6（通过磷脂酰肌醇二磷酸合成）调节，并依赖于F-肌动蛋白。SNAP 25内体，不包括质膜SNARE突触融合蛋白1A，与那些来自网格蛋白依赖性内吞含有内体突触融合蛋白13。我们的研究结果表征了一种强大的ARF 6依赖性内化机制，该机制维持了SNAP 25的细胞内池，这与SNAP 25在神经内分泌细胞中可能的细胞内作用是相容的。
Soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor (SNARE) proteins mediate cellular membrane fusion events and provide a level of specificity to donor-acceptor membrane interactions. However, the trafficking pathways by which individual SNARE proteins are targeted to specific membrane compartments are not well understood. In neuroendocrine cells, synaptosome-associated protein of 25 kDa (SNAP25) is localized to the plasma membrane where it functions in regulated secretory vesicle exocytosis, but it is also found on intracellular membranes. We identified a dynamic recycling pathway for SNAP25 in PC12 cells through which plasma membrane SNAP25 recycles in similar to 3 h. Approximately 20% of the SNAP25 resides in a perinuclear recycling endosome-trans-Golgi network (TGN) compartment from which it recycles back to the plasma membrane. SNAP25 internalization occurs by constitutive, dynamin-independent endocytosis that is distinct from the dynamin-dependent endocytosis that retrieves secretory vesicle constituents after exocytosis. Endocytosis of SNAP25 is regulated by ADP-ribosylation factor (ARF)6 (through phosphatidylinositol bisphosphate synthesis) and is dependent upon F-actin. SNAP25 endosomes, which exclude the plasma membrane SNARE syntaxin 1A, merge with those derived from clathrin-dependent endocytosis containing endosomal syntaxin 13. Our results characterize a robust ARF6-dependent internalization mechanism that maintains an intracellular pool of SNAP25, which is compatible with possible intracellular roles for SNAP25 in neuroendocrine cells.