Iinuma Takayuki, Aoki Takehiro, Arasaki Kohei, Hirose Hidenori, Yamamoto Akitsugu, Samata Rie, Hauri Hans-Peter, Arimitsu Nagisa, Tagaya Mitsuo, Tani Katsuko
School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan.
J Cell Sci. 2009 May 15;122(Pt 10):1680-90. doi: 10.1242/jcs.036103. Epub 2009 Apr 28.
The presence of subdomains in the endoplasmic reticulum (ER) enables this organelle to perform a variety of functions, yet the mechanisms underlying their organization are poorly understood. In the present study, we show that syntaxin 18, a SNAP (soluble NSF attachment protein) receptor localized in the ER, is important for the organization of two ER subdomains, smooth/rough ER membranes and ER exit sites. Knockdown of syntaxin 18 caused a global change in ER membrane architecture, leading to the segregation of the smooth and rough ER. Furthermore, the organization of ER exit sites was markedly changed concomitantly with dispersion of the ER-Golgi intermediate compartment and the Golgi complex. These morphological changes in the ER were substantially recovered by treatment of syntaxin-18-depleted cells with brefeldin A, a reagent that stimulates retrograde membrane flow to the ER. These results suggest that syntaxin 18 has an important role in ER subdomain organization by mediating the fusion of retrograde membrane carriers with the ER membrane.
内质网（ER）中存在的亚结构域使该细胞器能够执行多种功能，但其组织背后的机制仍知之甚少。在本研究中，我们表明Syntaxin 18，一种定位于内质网的SNAP（可溶性NSF附着蛋白）受体，对于两个内质网亚结构域的组织很重要，即光滑/粗糙内质网膜和内质网出口位点。Syntaxin 18的敲低导致内质网膜结构的整体变化，导致光滑内质网和粗糙内质网的分离。此外，内质网出口位点的组织随着内质网-高尔基体中间腔室和高尔基体复合体的分散而显著改变。通过用布雷菲德菌素A处理Syntaxin-18缺失的细胞，内质网的这些形态变化得到了实质性恢复，布雷菲德菌素A是一种刺激逆行膜流向内质网的试剂。这些结果表明，Syntaxin 18通过介导逆行膜载体与内质网膜的融合在内质网亚结构域组织中起重要作用。
