Endolysosomal trafficking controls yolk granule biogenesis in vitellogenic < i > Drosophila < /i > oocytes

by Yue Yu, Dongsheng Chen, Stephen M. Farmer, Shiyu Xu, Beatriz Rios, Amanda Solbach, Xin Ye, Lili Ye, Sheng Zhang

Endocytosis and endolysosomal trafficking are essential for almost all aspects of physiological functions of eukaryotic cells. As our understanding on these membrane trafficking events are mostly from studies in yeast and cultured mammalian cells, one challenge is to systematically evaluate the findings from these cell-based studies in multicellular organisms under physiological settings. One potentially valuablein vivo system to address this challenge is the vitellogenic oocyte inDrosophila, which undergoes extensive endocytosis by Yolkless (Yl), a low-density lipoprotein receptor (LDLR), to uptake extracellular lipoproteins into oocytes and package them into a specialized lysosome, the yolk granule, for storage and usage during later development. However, by now there is still a lack of sufficient understanding on the molecular and cellular processes that control yolk granule biogenesis. Here, by creating genome-tagging lines for Yl receptor and analyzing its distribution in vitellogenic oocytes, we observed a close association of different endosomal structures with distinct phosphoinositides and actin cytoskeleton dynamics. We further showed that Rab5 and Rab11, but surprisingly not Rab4 and Rab7, are essential for yolk granules biogenesis. Instead, we uncovered evidence for a potential role of Rab7 in actin regulation and observed a notable overlap of Rab4 a...

Source: PLoS Genetics - February 5, 2024 Category: Genetics & Stem Cells Authors: Yue Yu Source Type: research