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The Disruption of the Mitotic Cell Cycle Exit by Inositolless Death in S. cerevisiae

2013; Wiley; Volume: 27; Issue: S1 Linguagem: Inglês

10.1096/fasebj.27.1_supplement.1027.4

1530-6860

Barbara A. Hanson, Paul O’Connor, John Frandina, Joseph Pittari, Jean Munezero, Vincent Croglio,

Microtubule and mitosis dynamics

A rapid decline in cell viability and in Clb2 cyclin are the early changes that occur when an inositol‐requiring mutant of S. cerevisiae ( MC6A ) undergoes inositolless death. Another change is the appearance of polymerized tubulin in nonbudding cells. One explanation for the presence of polymerized tubulin is that the cells enter the cell cycle but do not progress through anaphase to the depolymerization of the spindle microtubules. This may be due to the decline in Clb2p and other key regulatory cell cycle proteins. In this study, the levels of mRNA for the genes: Securin (Pds1), Separin (Esp1) and a major subunit (Apc1) of the Anaphase‐promoting complex, were measured by RT‐PCR using RNA extracted from cells grown with and without inositol for 0, 3, 6, and 24 h after the start of inositolless death. The proteins also were measured by western blots of protein extracts from these cells. The mRNA levels for Pds1 and Apc1 declined to 55% and 60% of control levels at 3 h and 38% and 45% at 24h. The mRNA levels for Esp1 declined the most rapidly to to 40% of control levels at 3h and to 15% at 24h. It may be the rapid reduction in Esp1 mRNAs and the resulting low levels of the Esp1 protease prevent the sister chromatid separation and the progression through anaphase to spindle microtubule depolymerization. (Funded by Canisius College)