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G 1 cyclins block the Ime1 pathway to make mitosis and meiosis incompatible in budding yeast
Author(s) -
Colomieus,
Garí Eloi,
Gallego Carme,
Herrero Enrique,
Aldea Martí
Publication year - 1999
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/18.2.320
Subject(s) - block (permutation group theory) , computer science , combinatorics , mathematics
Diploid yeast cells switch from mitosis to meiosis when starved of essential nutrients. While G 1 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 G 1 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 G 1 ‐cyclin deficient cells do not require nutrient starvation to undergo meiosis, G 1 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.