Department of Genetics and Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115.
Department of Cell Biology, Harvard Medical School, Boston, MA 02115.
Mol Biol Cell. 2018 Aug 15;29(17):2045-2054. doi: 10.1091/mbc.E18-05-0282. Epub 2018 Jun 27.
Rab GTPases recruit peripheral membrane proteins and can define organelle identity. Rab18 localizes to the endoplasmic reticulum (ER) but also to lipid droplets (LDs), where it has been implicated in effector protein recruitment and in defining LD identity. Here, we studied Rab18 localization and function in a human mammary carcinoma cell line. Rab18 localized to the ER and to LD membranes on LD induction, with the latter depending on the Rab18 activation state. In cells lacking Rab18, LDs were modestly reduced in size and numbers, but we found little evidence for Rab18 function in LD formation, LD turnover on cell starvation, or the targeting of several proteins to LDs. We conclude that Rab18 is not a general, necessary component of the protein machinery involved in LD biogenesis or turnover.
Rab GTPases 招募外周膜蛋白，并可以定义细胞器的身份。Rab18 定位于内质网 (ER)，但也定位于脂滴 (LD)，在那里它被牵连到效应蛋白的招募和定义 LD 身份。在这里，我们研究了 Rab18 在人乳腺癌细胞系中的定位和功能。Rab18 在 ER 上定位，并在 LD 诱导时定位在 LD 膜上，后者取决于 Rab18 的激活状态。在缺乏 Rab18 的细胞中，LD 的大小和数量略有减少，但我们几乎没有发现 Rab18 在 LD 形成、细胞饥饿时 LD 周转或几种蛋白质靶向 LD 方面的功能证据。我们的结论是，Rab18 不是参与 LD 生物发生或周转的蛋白质机制的一般必需成分。
