G1 cyclins block the Ime1 pathway to make mitosis and meiosis incompatible in budding yeast.
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.
Colomina
N
N
Departament de Ciències Mèdiques Bàsiques, Universitat de Lleida, Rovira Roure 44, 25198 Lleida, Catalunya, Spain.
Garí
E
E
Gallego
C
C
Herrero
E
E
Aldea
M
M
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
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