TMCC3 localizes at the three-way junctions for the proper tubular network of the endoplasmic reticulum.
TMCC3 localizes at the three-way junctions for the proper tubular network of the endoplasmic reticulum.
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DOI：
10.1042/bcj20190359
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发表时间：
2019-11
期刊：
影响因子：
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通讯作者：
Sindhu Wisesa;Yasunori Yamamoto;T. Sakisaka
中科院分区：
文献类型：
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作者：
Sindhu Wisesa;Yasunori Yamamoto;T. Sakisaka
内质网(ER)的管状网络是由内质网小管通过三向连接形成的。到目前为止，已发现两类保守的内质网膜蛋白：atlastins和Lunpark，它们存在于三向连接，参与了三向连接的产生和稳定。在这项研究中，我们报道了TEX28家族的成员TMCC3(跨膜和螺旋结构域家族3)，它是另一种存在于哺乳动物细胞三向连接的内质膜蛋白。将TEX28家族成员导入U2OS细胞后，TMCC3特异性定位于外周内质网的三向连接。TMCC3通过C端跨膜结构域与atlastins结合。一个缺失N-末端螺旋线圈结构域的TMCC3突变体取消了对三向连接的定位，这表明TMCC3的定位独立于与atlastins的结合。TMCC3基因敲除导致U2OS细胞内三向连接数目减少，内质网扩张，导致小管状内质网减少。TMCC3基因敲除表型部分被atlastin-2的过表达所挽救，提示TMCC3基因敲除会降低atlastins的活性。这些结果表明，TMCC3定位于合适的管状ER网络的三向连接。
The tubular network of the endoplasmic reticulum (ER) is formed by connecting ER tubules through three-way junctions. Two classes of the conserved ER membrane proteins, atlastins and lunapark, have been shown to reside at the three-way junctions so far and be involved in the generation and stabilization of the three-way junctions. In this study, we report TMCC3 (transmembrane and coiled-coil domain family 3), a member of the TEX28 family, as another ER membrane protein that resides at the three-way junctions in mammalian cells. When the TEX28 family members were transfected into U2OS cells, TMCC3 specifically localized at the three-way junctions in the peripheral ER. TMCC3 bound to atlastins through the C-terminal transmembrane domains. A TMCC3 mutant lacking the N-terminal coiled-coil domain abolished localization to the three-way junctions, suggesting that TMCC3 localized independently of binding to atlastins. TMCC3 knockdown caused a decrease in the number of three-way junctions and expansion of ER sheets, leading to a reduction of the tubular ER network in U2OS cells. The TMCC3 knockdown phenotype was partially rescued by the overexpression of atlastin-2, suggesting that TMCC3 knockdown would decrease the activity of atlastins. These results indicate that TMCC3 localizes at the three-way junctions for the proper tubular ER network.