Bicaudal-C associates with a Trailer Hitch/Me31B complex and is required for efficient Gurken secretion.
Bicaudal-C (Bic-C) is a multiple KH-domain RNA-binding protein required for Drosophila oogenesis and, maternally, for embryonic patterning. In early oogenesis, Bic-C negatively regulates target mRNAs, including Bic-C, by recruiting the CCR4 deadenylase through a direct association with its NOT3 subunit. Here, we identify a novel function for Bic-C in secretion of the TGF-alpha homolog Gurken (Grk). In Bic-C mutant egg chambers, Grk is sequestered within actin-coated structures during mid-oogenesis. As a consequence, Egfr signalling is not efficiently activated in the dorsal-anterior follicle cells. This phenotype is strikingly similar to that of trailer hitch (tral) mutants. Consistent with the idea that Bic-C and Tral act together in Grk secretion, Bic-C co-localizes with Tral within cytoplasmic granules, and can be co-purified with multiple protein components of a Tral mRNP complex. Taken together, our results implicate translational regulation by Bic-C and Tral in the secretory pathway.
Kugler
Jan-Michael
JM
Department of Biology, McGill University, 1205 Avenue Docteur Penfield, Montréal, Québec, Canada H3A 1B1.
Chicoine
Jarred
J
Lasko
Paul
P
D000818:Animals; D053487:DEAD-box RNA Helicases / Q000378:metabolism*; D004330:Drosophila / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D004625:Embryo, Nonmammalian; D009154:Mutation; D009866:Oogenesis / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012261:Ribonucleoproteins / Q000378:metabolism*; D016211:Transforming Growth Factor alpha / Q000378:metabolism*
C113767:BicC protein, Drosophila; D029721:Drosophila Proteins; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; C516259:TRAL protein, Drosophila; D016211:Transforming Growth Factor alpha; C083730:grk protein, Drosophila; C532748:Me31B protein, Drosophila; D053487:DEAD-box RNA Helicases