scholarly journals Cell cycle entry triggers a switch between two modes of Cdc42 activation during yeast polarization

2017 ◽  
Author(s):  
Kristen Witte ◽  
Devin Strickland ◽  
Michael Glotzer
Keyword(s):  
Cell Cycle ◽  
Positive Feedback ◽  
Budding Yeast ◽  
Induce Polarization ◽  
Cell Polarization ◽  
Cell Cycle Stage ◽  
Cell Cycle Entry ◽  
Local Perturbations ◽  
Polarity Establishment ◽  
Local Recruitment

AbstractCell polarization underlies many cellular and organismal functions. The GTPase Cdc42 orchestrates polarization in many contexts. In budding yeast, polarization is associated with a focus of Cdc42•GTP which is thought to self sustain by recruiting a complex containing Cla4, a Cdc42-binding effector, Bem1, a scaffold and Cdc24, a Cdc42 GEF. Using optogenetics, we probe yeast polarization and find that local recruitment of Cdc24 or Bem1 is sufficient to induce polarization by triggering self-sustaining Cdc42 activity. However, the response to these perturbations depends on the recruited molecule, the cell cycle stage, and existing polarization sites. Before cell cycle entry, recruitment of Cdc24, but not Bem1, induces a metastable pool of Cdc42 that is sustained by positive feedback. Upon Cdk1 activation, recruitment of either Cdc24 or Bem1 creates a stable site of polarization that induces budding and inhibits formation of competing sites. Local perturbations have therefore revealed unexpected features of polarity establishment.

scholarly journals Cell cycle entry triggers a switch between two modes of Cdc42 activation during yeast polarization

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Kristen Witte ◽  
Devin Strickland ◽  
Michael Glotzer
Keyword(s):  
Cell Cycle ◽  
Positive Feedback ◽  
Budding Yeast ◽  
Induce Polarization ◽  
Cell Polarization ◽  
Cell Cycle Stage ◽  
Cell Cycle Entry ◽  
Local Perturbations ◽  
Polarity Establishment ◽  
Local Recruitment

Cell polarization underlies many cellular and organismal functions. The GTPase Cdc42 orchestrates polarization in many contexts. In budding yeast, polarization is associated with a focus of Cdc42•GTP which is thought to self sustain by recruiting a complex containing Cla4, a Cdc42-binding effector, Bem1, a scaffold, and Cdc24, a Cdc42 GEF. Using optogenetics, we probe yeast polarization and find that local recruitment of Cdc24 or Bem1 is sufficient to induce polarization by triggering self-sustaining Cdc42 activity. However, the response to these perturbations depends on the recruited molecule, the cell cycle stage, and existing polarization sites. Before cell cycle entry, recruitment of Cdc24, but not Bem1, induces a metastable pool of Cdc42 that is sustained by positive feedback. Upon Cdk1 activation, recruitment of either Cdc24 or Bem1 creates a stable site of polarization that induces budding and inhibits formation of competing sites. Local perturbations have therefore revealed unexpected features of polarity establishment.

scholarly journals Positive feedback of G1 cyclins ensures coherent cell cycle entry

Nature ◽  
2008 ◽  
Vol 454 (7202) ◽  
pp. 291-296 ◽  
Author(s):  
Jan M. Skotheim ◽  
Stefano Di Talia ◽  
Eric D. Siggia ◽  
Frederick R. Cross
Keyword(s):  
Cell Cycle ◽  
Positive Feedback ◽  
G1 Cyclins ◽  
Cell Cycle Entry

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

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.

scholarly journals The duration of mitosis and daughter cell size are modulated by nutrients in budding yeast

2017 ◽  
Vol 216 (11) ◽  
pp. 3463-3470 ◽  
Author(s):  
Ricardo M. Leitao ◽  
Douglas R. Kellogg
Keyword(s):  
Cell Cycle ◽  
Cell Size ◽  
Daughter Cell ◽  
Slow Growth ◽  
Budding Yeast ◽  
Size Control ◽  
G1 Phase ◽  
Large Reduction ◽  
Duration Of Mitosis ◽  
Cell Cycle Entry

The size of nearly all cells is modulated by nutrients. Thus, cells growing in poor nutrients can be nearly half the size of cells in rich nutrients. In budding yeast, cell size is thought to be controlled almost entirely by a mechanism that delays cell cycle entry until sufficient growth has occurred in G1 phase. Here, we show that most growth of a new daughter cell occurs in mitosis. When the rate of growth is slowed by poor nutrients, the duration of mitosis is increased, which suggests that cells compensate for slow growth in mitosis by increasing the duration of growth. The amount of growth required to complete mitosis is reduced in poor nutrients, leading to a large reduction in cell size. Together, these observations suggest that mechanisms that control the extent of growth in mitosis play a major role in cell size control in budding yeast.

scholarly journals Huxley's Revenge: Cell-Cycle Entry, Positive Feedback, and the G1 Cyclins

2008 ◽  
Vol 31 (3) ◽  
pp. 307-308
Author(s):  
Lucas B. Carey ◽  
Janet K. Leatherwood ◽  
Bruce Futcher
Keyword(s):  
Cell Cycle ◽  
Positive Feedback ◽  
G1 Cyclins ◽  
Cell Cycle Entry

scholarly journals The Rsr1/Bud1 GTPase Interacts with Itself and the Cdc42 GTPase during Bud-Site Selection and Polarity Establishment in Budding Yeast

2010 ◽  
Vol 21 (17) ◽  
pp. 3007-3016 ◽  
Author(s):  
Pil Jung Kang ◽  
Laure Béven ◽  
Seethalakshmi Hariharan ◽  
Hay-Oak Park
Keyword(s):  
Budding Yeast ◽  
Cell Polarization ◽  
Spatial Cues ◽  
Division Site ◽  
Heterotypic Interactions ◽  
Polarity Establishment ◽  
Set Up ◽  
Bud Site

Cell polarization occurs along a single axis that is generally determined in response to spatial cues. In budding yeast, the Rsr1 GTPase and its regulators direct the establishment of cell polarity at the proper cortical location in response to cell type–specific cues. Here we use a combination of in vivo and in vitro approaches to understand how Rsr1 polarization is established. We find that Rsr1 associates with itself in a spatially and temporally controlled manner. The homotypic interaction and localization of Rsr1 to the mother-bud neck and to the subsequent division site are dependent on its GDP-GTP exchange factor Bud5. Analyses of rsr1 mutants suggest that Bud5 recruits Rsr1 to these sites and promotes the homodimer formation. Rsr1 also exhibits heterotypic interaction with the Cdc42 GTPase in vivo. We show that the polybasic region of Rsr1 is necessary for the efficient homotypic and heterotypic interactions, selection of a proper growth site, and polarity establishment. Our findings thus suggest that dimerization of GTPases may be an efficient mechanism to set up cellular asymmetry.

scholarly journals The duration of mitosis and daughter cell size are modulated by nutrients in budding yeast

2016 ◽  
Author(s):  
Ricardo M. Leitao ◽  
Douglas R. Kellogg
Keyword(s):  
Cell Cycle ◽  
Cell Size ◽  
Daughter Cell ◽  
Slow Growth ◽  
Budding Yeast ◽  
Size Control ◽  
G1 Phase ◽  
Large Reduction ◽  
Duration Of Mitosis ◽  
Cell Cycle Entry

AbstractThe size of nearly all cells is modulated by nutrients. Thus, cells growing in poor nutrients can be nearly half the size of cells in rich nutrients. In budding yeast, cell size is thought to be controlled almost entirely by a mechanism that delays cell cycle entry until sufficient growth has occurred in G1 phase. Here, we show that most growth of a new daughter cell occurs in mitosis. When the rate of growth is slowed by poor nutrients, the duration of mitosis is increased, which suggests that cells compensate for slow growth in mitosis by increasing the duration of growth. The amount of growth required to complete mitosis is reduced in poor nutrients, leading to a large reduction in cell size. Together, these observations suggest that mechanisms that control the extent of growth in mitosis play a major role in cell size control in budding yeast.

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

eLife ◽  
2021 ◽  
Vol 10 ◽  
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

Entry into the cell cycle occurs only when sufficient growth has occurred. In budding yeast, the cyclin Cln3 is thought to initiate 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 control cell growth and size. Together, the data are consistent with models in which Cln3 is a crucial link between cell growth and the cell cycle.

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