title: G1 cyclins block the Ime1 pathway to make mitosis and meiosis incompatible in budding yeast.
abstract: Diploid yeast cells switch from mitosis to meiosis when starved of essential nutrients. While G1 cyclins play a key role in initiating the mitotic cell cycle, entry into meiosis depends on Ime1, a transcriptional activator regulated by both nutritional and cell-type signals. We show here that G1 cyclins downregulate IME1 transcription and prevent the accumulation of the Ime1 protein within the nucleus, which results in repression of early-meiotic gene expression. As G1-cyclin deficient cells do not require nutrient starvation to undergo meiosis, G1 cyclin would exert its role by transmitting essential nutritional signals to Ime1 function. The existence of a negative cross-talk mechanism between mitosis and meiosis may help explain why these two developmental options are incompatible in budding yeast.
authors.affiliation: Departament de Ciències Mèdiques Bàsiques, Universitat de Lleida, Rovira Roure 44, 25198 Lleida, Catalunya, Spain.
authors.forename: N
authors.initials: N
authors.lastname: Colomina
authors.forename: E
authors.initials: E
authors.lastname: Garí
authors.forename: C
authors.initials: C
authors.lastname: Gallego
authors.forename: E
authors.initials: E
authors.lastname: Herrero
authors.forename: M
authors.initials: M
authors.lastname: Aldea
mesh_terms: D002467:Cell Nucleus / Q000502:physiology; D003470:Culture Media; D016213:Cyclins / Q000235:genetics / Q000502:physiology*; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D016193:G1 Phase / Q000235:genetics / Q000502:physiology*; D015870:Gene Expression; D005800:Genes, Fungal; D008540:Meiosis / Q000235:genetics / Q000502:physiology*; D008938:Mitosis / Q000235:genetics / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology*; D016196:S Phase / Q000235:genetics / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors
chemical_list: C082719:CLN1 protein, S cerevisiae; C082721:CLN2 protein, S cerevisiae; C079895:CLN3 protein, S cerevisiae; D003470:Culture Media; D016213:Cyclins; D005656:Fungal Proteins; C080326:IME1 protein, S cerevisiae; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors