Stimulation of endocytosis and actin dynamics by Oskar polarizes the Drosophila oocyte.
In Drosophila, localized activity of oskar at the posterior pole of the oocyte induces germline and abdomen formation in the embryo. Oskar has two isoforms, a short isoform encoding the patterning determinant and a long isoform of unknown function. Here, we show by immuno-electron microscopy that the two Oskar isoforms have different subcellular localizations in the oocyte: Short Oskar mainly localizes to polar granules, and Long Oskar is specifically associated with endocytic membranes along the posterior cortex. Our cell biological and genetic analyses reveal that Oskar stimulates endocytosis, and that its two isoforms are required to regulate this process. Furthermore, we describe long F-actin projections at the oocyte posterior pole that are induced by and intermingled with Oskar protein. We propose that Oskar maintains its localization at the posterior pole through dual functions in regulating endocytosis and F-actin dynamics.
Vanzo
Nathalie
N
Centre de Biologie du Développement, UMR 5547 CNRS/UPS, 118 Rte de Narbonne, 31062 Toulouse Cedex 04, France.
Oprins
Adrian
A
Xanthakis
Despina
D
Ephrussi
Anne
A
Rabouille
Catherine
C
D000199:Actins / Q000378:metabolism*; D000818:Animals; D030801:Animals, Genetically Modified; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity; D002966:Clathrin / Q000378:metabolism / Q000502:physiology; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000378:metabolism* / Q000502:physiology; D004705:Endocytosis; D005260:Female; D066298:In Vitro Techniques; D016253:Microscopy, Immunoelectron; D008954:Models, Biological; D009865:Oocytes / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure; D020033:Protein Isoforms; D015854:Up-Regulation
D000199:Actins; D002966:Clathrin; D029721:Drosophila Proteins; D020033:Protein Isoforms; C091675:osk protein, Drosophila