Centromeric signaling proteins boost G1 cyclin degradation and modulate cell size in budding yeast

Abstract How organelle biogenesis and inheritance is linked to cell division is poorly understood. In the budding yeast Saccharomyces cerevisiae the G1 cyclins Cln1,2,3p control initiation of cell division. Here we show that Cln3p controls vacuolar (lysosomal) biogenesis and segregation. First, loss of Cln3p, but not Cln1p or Cln2p, resulted in vacuolar fragmentation. Although the vacuoles of cln3Δ cells were fragmented, together they occupied a large space, which accounted for a significant fraction of the overall cell size increase in cln3Δ cells. Second, cytosol prepared from cells lacking Cln3p had reduced vacuolar homotypic fusion activity in cell-free assays. Third, vacuolar segregation was perturbed in cln3Δ cells. Our findings reveal a novel role for a eukaryotic G1 cyclin in cytoplasmic organelle biogenesis and segregation.

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Metabolic pathways further increase the complexity of cell size control in budding yeast

Microbial Cell ◽

10.15698/mic2014.09.167 ◽

2014 ◽

Vol 1 (9) ◽

pp. 276-278

Author(s):

Jorrit Enserink ◽

Keyword(s):

Cell Size ◽

Metabolic Pathways ◽

Budding Yeast ◽

Size Control ◽

Cell Size Control

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G2/M Arrest Caused by Actin Disruption Is a Manifestation of the Cell Size Checkpoint in Fission Yeast

Molecular Biology of the Cell ◽

10.1091/mbc.12.12.3892 ◽

2001 ◽

Vol 12 (12) ◽

pp. 3892-3903 ◽

Cited By ~ 42

Author(s):

Ivan Rupes̆ ◽

Bradley A. Webb ◽

Alan Mak ◽

Paul G. Young

Keyword(s):

Cell Size ◽

Budding Yeast ◽

Tyrosine Phosphatase ◽

Careful Analysis ◽

Cell Cycle Checkpoint ◽

Size Monitoring ◽

Inhibitory Tyrosine Phosphorylation ◽

Cycle Checkpoint ◽

Size Threshold ◽

Cdc25 Protein

In budding yeast, actin disruption prevents nuclear division. This has been explained as activation of a morphogenesis checkpoint monitoring the integrity of the actin cytoskeleton. The checkpoint operates through inhibitory tyrosine phosphorylation of Cdc28, the budding yeast Cdc2 homolog. Wild-type Schizosaccharomyces pombe cells also arrest before mitosis after actin depolymerization. Oversized cells, however, enter mitosis uninhibited. We carried out a careful analysis of the kinetics of mitotic initiation after actin disruption in undersized and oversized cells. We show that an inability to reach the mitotic size threshold explains the arrest in smaller cells. Among the regulators that control the level of the inhibitory Cdc2-Tyr15 phosphorylation, the Cdc25 protein tyrosine phosphatase is required to link cell size monitoring to mitotic control. This represents a novel function of the Cdc25 phosphatase. Furthermore, we demonstrate that this cell size-monitoring system fulfills the formal criteria of a cell cycle checkpoint.

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PP2ARts1 is a master regulator of pathways that control cell size

The Journal of Cell Biology ◽

10.1083/jcb.201309119 ◽

2014 ◽

Vol 204 (3) ◽

pp. 359-376 ◽

Cited By ~ 47

Author(s):

Jessica Zapata ◽

Noah Dephoure ◽

Tracy MacDonough ◽

Yaxin Yu ◽

Emily J. Parnell ◽

...

Keyword(s):

Cell Cycle ◽

Cell Growth ◽

Cell Size ◽

Control Cell ◽

Size Control ◽

Regulatory Subunit ◽

Delay Cell ◽

Cell Cycle Entry ◽

G1 Cyclin

Cell size checkpoints ensure that passage through G1 and mitosis occurs only when sufficient growth has occurred. The mechanisms by which these checkpoints work are largely unknown. PP2A associated with the Rts1 regulatory subunit (PP2ARts1) is required for cell size control in budding yeast, but the relevant targets are unknown. In this paper, we used quantitative proteome-wide mass spectrometry to identify proteins controlled by PP2ARts1. This revealed that PP2ARts1 controls the two key checkpoint pathways thought to regulate the cell cycle in response to cell growth. To investigate the role of PP2ARts1 in these pathways, we focused on the Ace2 transcription factor, which is thought to delay cell cycle entry by repressing transcription of the G1 cyclin CLN3. Diverse experiments suggest that PP2ARts1 promotes cell cycle entry by inhibiting the repressor functions of Ace2. We hypothesize that control of Ace2 by PP2ARts1 plays a role in mechanisms that link G1 cyclin accumulation to cell growth.

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Phosphorylation of Cdc28 and regulation of cell size by the protein kinase CKII in Saccharomyces cerevisiae

Biochemical Journal ◽

10.1042/bj3510143 ◽

2000 ◽

Vol 351 (1) ◽

pp. 143-150 ◽

Cited By ~ 7

Author(s):

Gian Luigi RUSSO ◽

Christian VAN DEN BOS ◽

Ann SUTTON ◽

Paola COCCETTI ◽

Maurizio D. BARONI ◽

...

Keyword(s):

Saccharomyces Cerevisiae ◽

Cell Division ◽

Protein Kinase ◽

Cell Size ◽

Peptide Mapping ◽

Budding Yeast ◽

Cell Division Cycle ◽

Yeast Saccharomyces Cerevisiae ◽

Protein Kinase Ckii

The CDK (cyclin-dependent kinase) family of enzymes is required for the G1-to-S-phase and G2-to-M-phase transitions during the cell-division cycle of eukaryotes. We have shown previously that the protein kinase CKII catalyses the phosphorylation of Ser-39 in Cdc2 during the G1 phase of the HeLa cell-division cycle [Russo, Vandenberg, Yu, Bae, Franza and Marshak (1992) J. Biol. Chem. 267, 20317–20325]. To identify a functional role for this phosphorylation, we have studied the homologous enzymes in the budding yeast Saccharomyces cerevisiae. The S. cerevisiae homologue of Cdc2, Cdc28, contains a consensus CKII site (Ser-46), which is homologous with that of human Cdc2. Using in vitro kinase assays, metabolic labelling, peptide mapping and phosphoamino acid analysis, we demonstrate that this site is phosphorylated in Cdc28 in vivo as well in vitro. In addition, S. cerevisiae cells in which Ser-46 has been mutated to alanine show a decrease in both cell volume and protein content of 33%, and this effect is most pronounced in the stationary phase. Because cell size in S. cerevisiae is regulated primarily at the G1 stage, we suggest that CKII contributes to the regulation of the cell cycle in budding yeast by phosphorylation of Cdc28 as a checkpoint for G1 progression.

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Daughter-Specific Transcription Factors Regulate Cell Size Control in Budding Yeast

PLoS Biology ◽

10.1371/journal.pbio.1000221 ◽

2009 ◽

Vol 7 (10) ◽

pp. e1000221 ◽

Cited By ~ 84

Author(s):

Stefano Di Talia ◽

Hongyin Wang ◽

Jan M. Skotheim ◽

Adam P. Rosebrock ◽

Bruce Futcher ◽

...

Keyword(s):

Transcription Factors ◽

Cell Size ◽

Budding Yeast ◽

Size Control ◽

Cell Size Control

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Cell size and growth rate are modulated by TORC2-dependent signals

10.1101/188698 ◽

2017 ◽

Cited By ~ 1

Author(s):

Rafael Lucena ◽

Maria Alcaide-Gavilán ◽

Katherine Schubert ◽

Maybo He ◽

Matthew Domnauer ◽

...

Keyword(s):

Growth Rate ◽

Cell Size ◽

Nutrient Availability ◽

Feedback Loop ◽

Budding Yeast ◽

Regulatory Subunit ◽

Underlying Mechanisms

SummaryThe size of all cells, from bacteria to vertebrates, is proportional to the growth rate set by nutrient availability, but the underlying mechanisms are unknown. Here, we show that nutrients modulate TORC2 signaling, and that cell size is proportional to TORC2 signaling in budding yeast. The TORC2 network controls production of ceramide lipids, which play roles in signaling. We discovered that ceramide-dependent signals control both growth rate and cell size. Thus, cells that can not make ceramides fail to modulate their growth rate or size in response to changes in nutrients. PP2A associated with the Rts1 regulatory subunit (PP2ARts1) is embedded in a feedback loop that controls TORC2 signaling and plays an important role in mechanisms that modulate TORC2 signaling in response to nutrients. Together, the data suggest a model in which growth rate and cell size are mechanistically linked by ceramide-dependent signals arising from the TORC2 network.

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Growth-dependent signals drive an increase in early G1 cyclin concentration to link cell cycle entry with cell growth

10.1101/2020.09.30.321182 ◽

2020 ◽

Author(s):

Robert A. Sommer ◽

Jerry T. DeWitt ◽

Raymond Tan ◽

Douglas R. Kellogg

Keyword(s):

Cell Cycle ◽

Cell Growth ◽

Budding Yeast ◽

Control Cell ◽

Transcriptional Repressor ◽

Cell Cycle Entry ◽

G1 Cyclin

AbstractEntry into the cell cycle occurs only when sufficient growth has occurred. In budding yeast, the cyclin Cln3 initiates cell cycle entry by inactivating a transcriptional repressor called Whi5. Growth-dependent changes in the concentrations of Cln3 or Whi5 have been proposed to link cell cycle entry to cell growth. However, there are conflicting reports regarding the behavior and roles of Cln3 and Whi5. Here, we found no evidence that changes in the concentration of Whi5 play a major role in controlling cell cycle entry. Rather, the data suggest that cell growth triggers cell cycle entry by driving an increase in the concentration of Cln3. We further found that accumulation of Cln3 is dependent upon homologs of mammalian SGK kinases that play roles in control of cell growth and size. Together, the data are consistent with models in which Cln3 serves as the crucial link between the cell cycle and signals that control cell growth and size.

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