Röper Katja
Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK.
J Cell Sci. 2007 Mar 15;120(Pt 6):1081-92. doi: 10.1242/jcs.03407. Epub 2007 Feb 27.
During oogenesis in Drosophila an organelle called the fusome plays a crucial role in germline cyst development and oocyte selection. The fusome consists of cytoskeletal proteins and intracellular membranes and, whereas many cytoskeletal components have been characterized, the nature and function of the membrane component is poorly understood. I have found the reticulon-like 1 (Rtnl1) protein, a membrane protein resident in the endoplasmic reticulum (ER), to be highly enriched in the fusome. In other Drosophila tissues Rtnl1 marks a subset of ER membranes often derived from smooth ER. During oogenesis, Rtnl1-containing membranes are recruited to the fusome by the cytoskeletal components and become concentrated into the forming oocyte. On the central part of the fusome, which is contained within the future oocyte and also at later stages in the growing oocyte and the nurse cells, Rtnl1-containing membranes colocalize with components of ribonucleoprotein complexes that store translationally repressed mRNAs. As the ER is actively transported into the oocyte, this colocalization suggests a role for the Rtnl1-containing subdomain in anchoring the ribonucleoprotein complexes within and/or transporting them into the oocyte.
在果蝇的卵子发生过程中，一种名为融合体的细胞器在生殖系囊肿发育和卵母细胞选择中起着关键作用。融合体由细胞骨架蛋白和细胞内膜组成，虽然许多细胞骨架成分已被鉴定，但膜成分的性质和功能却知之甚少。我发现内质网（ER）中的一种膜蛋白——类网织蛋白1（Rtnl1）在融合体中高度富集。在果蝇的其他组织中，Rtnl1标记了通常源自滑面内质网的一部分内质网膜。在卵子发生过程中，含Rtnl1的膜被细胞骨架成分招募到融合体中，并集中到正在形成的卵母细胞中。在融合体的中央部分，即未来的卵母细胞内以及生长中的卵母细胞和滋养细胞的后期阶段，含Rtnl1的膜与储存翻译抑制mRNA的核糖核蛋白复合物的成分共定位。由于内质网被主动运输到卵母细胞中，这种共定位表明含Rtnl1的亚结构域在将核糖核蛋白复合物锚定在卵母细胞内和/或将它们运输到卵母细胞中发挥作用。
