Drosophila RalA is essential for the maintenance of Jak/Stat signalling in ovarian follicles.
Small GTPases of the Ras-like (Ral) family are crucial for signalling functions in both normal and cancer cells; however, their role in a developing organism is poorly understood. Here, we identify the Drosophila Ral homologue RalA as a new key regulator of polar-cell differentiation during oogenesis. Polar cells have a crucial role in patterning the egg chamber and in recruiting border cells, which undergo collective and guided migration. We show that RalA function is essential for the maintenance of anterior and posterior polar-cell fate and survival. RalA is required cell autonomously to control the expression of polar-cell-specific markers, including the Jak/Stat ligand Unpaired. The loss of RalA also causes a cell non-autonomous phenotype owing to reduced Jak/Stat signalling in neighbouring follicle cells. As a result, border-cell assembly and migration as well as the polarization of the oocyte are defective. Thus, RalA is required in organizing centres to control proper patterning and migration in vivo.
Institute of Developmental Biology and Cancer, University of Nice Sophia-Antipolis, UMR6543-CNRS, Parc Valrose, 06108 Nice cedex 2, France.
Christian
C
Ghiglione
Olivier
O
Devergne
Delphine
D
Cerezo
Stéphane
S
Noselli
D000818:Animals; D002454:Cell Differentiation; D002465:Cell Movement; D016764:Cell Polarity; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology / Q000201:enzymology*; D005260:Female; D053612:Janus Kinases / Q000378:metabolism*; D020559:Monomeric GTP-Binding Proteins / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D006080:Ovarian Follicle / Q000166:cytology / Q000201:enzymology*; D021381:Protein Transport; D050791:STAT Transcription Factors / Q000378:metabolism*; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism
D029721:Drosophila Proteins; D050791:STAT Transcription Factors; D053612:Janus Kinases; D020559:Monomeric GTP-Binding Proteins; C531458:RalA protein, Drosophila