Aneuploidy, a chromosome content that is not a multiple of the haploid karyotype, is associated with reduced fitness in all organisms analyzed to date. In budding yeast aneuploidy causes cell prolifer Show more
Aneuploidy, a chromosome content that is not a multiple of the haploid karyotype, is associated with reduced fitness in all organisms analyzed to date. In budding yeast aneuploidy causes cell proliferation defects, with many different aneuploid strains exhibiting a delay in G1, a cell cycle stage governed by extracellular cues, growth rate, and cell cycle events. Here we characterize this G1 delay. We show that 10 of 14 aneuploid yeast strains exhibit a growth defect during G1. Furthermore, 10 of 14 aneuploid strains display a cell cycle entry delay that correlates with the size of the additional chromosome. This cell cycle entry delay is due to a delayed accumulation of G1 cyclins that can be suppressed by supplying cells with high levels of a G1 cyclin. Our results indicate that aneuploidy frequently interferes with the ability of cells to grow and, as with many other cellular stresses, entry into the cell cycle. Show less
A Amon · 1997 · The EMBO journal · Oxford University Press · added 2026-04-24
In budding yeast, stability of the mitotic B-type cyclin Clb2 is tightly cell cycle-regulated. B-type cyclin proteolysis is initiated during anaphase and persists throughout the G1 phase. Cln-Cdc28 ki Show more
In budding yeast, stability of the mitotic B-type cyclin Clb2 is tightly cell cycle-regulated. B-type cyclin proteolysis is initiated during anaphase and persists throughout the G1 phase. Cln-Cdc28 kinase activity at START is required to repress B-type cyclin-specific proteolysis. Here, we show that Clb-dependent kinases, when expressed during G1, are also capable of repressing the B-type cyclin proteolysis machinery. Furthermore, we find that inactivation of Cln- and Clb-Cdc28 kinases is sufficient to trigger Clb2 proteolysis and sister-chromatid separation in G2/M phase-arrested cells, where the B-type cyclin-specific proteolysis machinery is normally inactive. Our results suggest that Cln- and Clb-dependent kinases are both capable of repressing B-type cyclin-specific proteolysis and that they are required to maintain the proteolysis machinery in an inactive state in S and G2/M phase-arrested cells. We propose that in yeast, as cells pass through START, Cln-Cdc28-dependent kinases inactivate B-type cyclin proteolysis. As Cln-Cdc28-dependent kinases decline during G2, Clb-Cdc28-dependent kinases take over this role, ensuring that B-type cyclin proteolysis is not activated during S phase and early mitosis. Show less