title: Starvation induces FoxO-dependent mitotic-to-endocycle switch pausing during Drosophila oogenesis.
abstract: When exposed to nutrient challenge, organisms have to adapt their physiology in order to balance reproduction with adult fitness. In mammals, ovarian follicles enter a massive growth phase during which they become highly dependent on gonadotrophic factors and nutrients. Somatic tissues play a crucial role in integrating these signals, controlling ovarian follicle atresia and eventually leading to the selection of a single follicle for ovulation. We used Drosophila follicles as a model to study the effect of starvation on follicle maturation. Upon starvation, Drosophila vitellogenic follicles adopt an 'atresia-like' behavior, in which some slow down their development whereas others enter degeneration. The mitotic-to-endocycle (M/E) transition is a critical step during Drosophila oogenesis, allowing the entry of egg chambers into vitellogenesis. Here, we describe a specific and transient phase during M/E switching that is paused upon starvation. The Insulin pathway induces the pausing of the M/E switch, blocking the entry of egg chambers into vitellogenesis. Pausing of the M/E switch involves a previously unknown crosstalk between FoxO, Cut and Notch that ensures full reversion of the process and rapid resumption of oogenesis upon refeeding. Our work reveals a novel genetic mechanism controlling the extent of the M/E switch upon starvation, thus integrating metabolic cues with development, growth and reproduction.
authors.affiliation: Université Nice Sophia Antipolis, Institut de Biologie Valrose, iBV, Nice 06100, France CNRS, Institut de Biologie Valrose, iBV, UMR 7277, Nice 06100, France INSERM, Institut de Biologie Valrose, iBV, U1091, Nice 06100, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Jouandin
authors.affiliation: Université Nice Sophia Antipolis, Institut de Biologie Valrose, iBV, Nice 06100, France CNRS, Institut de Biologie Valrose, iBV, UMR 7277, Nice 06100, France INSERM, Institut de Biologie Valrose, iBV, U1091, Nice 06100, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Ghiglione
authors.affiliation: Université Nice Sophia Antipolis, Institut de Biologie Valrose, iBV, Nice 06100, France CNRS, Institut de Biologie Valrose, iBV, UMR 7277, Nice 06100, France INSERM, Institut de Biologie Valrose, iBV, U1091, Nice 06100, France noselli@unice.fr.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Noselli
mesh_terms: D000818:Animals; D002453:Cell Cycle; D003593:Cytoplasm / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000502:physiology*; D004331:Drosophila melanogaster / Q000502:physiology*; D005260:Female; D005508:Food Deprivation; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000502:physiology*; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008938:Mitosis; D009865:Oocytes / Q000166:cytology; D009866:Oogenesis / Q000502:physiology*; D006080:Ovarian Follicle / Q000378:metabolism; D010060:Ovulation; D011003:Ploidies; D051880:Receptors, Notch / Q000378:metabolism; D015398:Signal Transduction; D014818:Vitellogenesis
chemical_list: D029721:Drosophila Proteins; C477334:FOXO protein, Drosophila; D051858:Forkhead Transcription Factors; D051880:Receptors, Notch; D049452:Green Fluorescent Proteins
keywords: Drosophila; Follicle; M/E switch; Oogenesis; dFoxO