A mechanism of Munc18b-syntaxin 3-SNAP25 complex assembly in regulated epithelial secretion.
A mechanism of Munc18b-syntaxin 3-SNAP25 complex assembly in regulated epithelial secretion.
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Munc18b-syntaxin 3-SNAP25 复合物组装在调节上皮分泌中的机制。
DOI：
10.1016/j.febslet.2007.07.083
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发表时间：
2007
期刊：
影响因子：
3.5
通讯作者：
Yao,Xuebiao
中科院分区：
文献类型：
--
作者：
Liu,Ya;Ding,Xia;Wang,Dongmei;Deng,Hui;Feng,Mingye;Wang,Min;Yu,Xue;Jiang,Kai;Ward,Tarsha;Aikhionbare,Felix;Guo,Zhen;Forte,JohnG;Yao,Xuebiao
Syntaxin 和 Munc18 对于所有真核生物中胞吐作用的调节至关重要。结果表明，Munc18 对神经元突触蛋白 1 的抑制可以通过 CDK5 磷酸化来克服，表明结构变化破坏了突触蛋白与 Munc18 的相互作用。在这里，我们证明这种磷酸化促进了 Munc18b-syntaxin 3-SNAP25 三联复合物和膜融合机制 SNARE 的组装。使用 siRNA 筛选调节上皮分泌所需的基因，我们确定了 CDK5 和 Munc18b 在 cAMP 依赖性胃酸分泌中的需求。生化表征表明，Munc18b 在其最 C 端 53 个氨基酸处具有突触融合蛋白 3 选择性结合位点。值得注意的是，CDK5 对 Thr572 的磷酸化减弱了 Munc18b-syntaxin 3 相互作用，并促进 Munc18b-syntaxin 3-SNAP25 三联复合物的形成，从而导致功能性 Munc18b-syntaxin 3-SNAP25-VAMP2 膜融合机制的组装。因此，我们的研究提出了一种新的调节机制，其中 Munc18b 的磷酸化在受调节的胞吐作用中操作囊泡对接和融合。
Syntaxin and Munc18 are essential for regulated exocytosis in all eukaryotes. It was shown that Munc18 inhibition of neuronal syntaxin 1 can be overcome by CDK5 phosphorylation, indicating that structural change disrupts the syntaxin–Munc18 interaction. Here, we show that this phosphorylation promotes the assembly of Munc18b–syntaxin 3–SNAP25 tripartite complex and membrane fusion machinery SNARE. Using siRNAs to screen for genes required for regulated epithelial secretion, we identified the requirements of CDK5 and Munc18b in cAMP-dependent gastric acid secretion. Biochemical characterization revealed that Munc18b bears a syntaxin 3-selective binding site located at its most C-terminal 53 amino acids. Significantly, the phosphorylation of Thr572 by CDK5 attenuates Munc18b–syntaxin 3 interaction and promotes formation of Munc18b–syntaxin 3–SNAP25 tripartite complex, leading to an assembly of functional Munc18b–syntaxin 3–SNAP25–VAMP2 membrane fusion machinery. Thus, our studies suggest a novel regulatory mechanism in which phosphorylation of Munc18b operates vesicle docking and fusion in regulated exocytosis.