title: Dorso-ventral axis formation of the Drosophila oocyte requires Cyclin G.
abstract: In general, cyclins control the cell cycle. Not so the atypical cyclins, which are required for diverse cellular functions such as for genome stability or for the regulation of transcription and translation. The atypical Cyclin G (CycG) gene of Drosophila has been involved in the epigenetic regulation of abdominal segmentation, cell proliferation and growth, based on overexpression and RNAi studies, but detailed analyses were hampered by the lack of a cycG mutant. For further investigations, we subjected the cycG locus to a detailed molecular analysis. Moreover, we studied a cycG null mutant that we recently established. The mutant flies are homozygous viable, however, the mutant females are sterile and produce ventralized eggs. Here we show that this egg phenotype is primarily a consequence of a defective Epidermal Growth Factor Receptor (EGFR) signalling pathway. By using different read outs, we demonstrate that cycG loss is tantamount to lowered EGFR signalling. Inferred from epistasis experiments, we conclude that CycG promotes the Grk signal in the oocyte. Abnormal accumulation but regular secretion of the Grk protein suggests defects of Grk translation in cycG mutants rather than transcriptional regulation. Accordingly, protein accumulation of Vasa, which acts as an oocyte specific translational regulator of Grk in the oocyte is abnormal. We propose a role of cycG in processes that regulate translation of Grk and hence, influence EGFR-mediated patterning processes during oogenesis.
authors.affiliation: Institut für Genetik, Universität Hohenheim, DE-70599 Stuttgart, Germany.
authors.forename: Anja C
authors.initials: AC
authors.lastname: Nagel
authors.forename: Jutta
authors.initials: J
authors.lastname: Szawinski
authors.forename: Patrick
authors.initials: P
authors.lastname: Fischer
authors.forename: Dieter
authors.initials: D
authors.lastname: Maier
authors.forename: Irmgard
authors.initials: I
authors.lastname: Wech
authors.forename: Anette
authors.initials: A
authors.lastname: Preiss
mesh_terms: D000818:Animals; D019521:Body Patterning; D059006:Chromosomes, Insect / Q000235:genetics / Q000378:metabolism; D056746:Cyclin G / Q000235:genetics / Q000378:metabolism*; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D005260:Female; D056426:Genetic Loci; D009154:Mutation; D009865:Oocytes / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D009866:Oogenesis; D010641:Phenotype; D014176:Protein Biosynthesis; D018010:Receptors, Invertebrate Peptide / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014158:Transcription, Genetic; D016211:Transforming Growth Factor alpha / Q000235:genetics / Q000378:metabolism
chemical_list: D056746:Cyclin G; D029721:Drosophila Proteins; D018010:Receptors, Invertebrate Peptide; D016211:Transforming Growth Factor alpha; C083730:grk protein, Drosophila; C066532:Egfr protein, Drosophila; D066246:ErbB Receptors; C088269:vas protein, Drosophila; D053487:DEAD-box RNA Helicases