scholarly journals Pak-Family Kinases Regulate Cell and Actin Polarization Throughout the Cell Cycle of Saccharomyces cerevisiae

1999 ◽  
Vol 147 (4) ◽  
pp. 845-856 ◽  
Author(s):  
Stephen P. Holly ◽  
Kendall J. Blumer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Surface ◽  
Actin Cytoskeleton ◽  
Yeast Cell ◽  
Fluorescent Protein ◽  
Surface Growth ◽  
Yeast Cell Cycle ◽  
Cortical Actin ◽  
Bud Emergence

During the cell cycle of the yeast Saccharomyces cerevisiae, the actin cytoskeleton and cell surface growth are polarized, mediating bud emergence, bud growth, and cytokinesis. We have determined whether p21-activated kinase (PAK)-family kinases regulate cell and actin polarization at one or several points during the yeast cell cycle. Inactivation of the PAK homologues Ste20 and Cla4 at various points in the cell cycle resulted in loss of cell and actin cytoskeletal polarity, but not in depolymerization of F-actin. Loss of PAK function in G1 depolarized the cortical actin cytoskeleton and blocked bud emergence, but allowed isotropic growth and led to defects in septin assembly, indicating that PAKs are effectors of the Rho–guanosine triphosphatase Cdc42. PAK inactivation in S/G2 resulted in depolarized growth of the mother and bud and a loss of actin polarity. Loss of PAK function in mitosis caused a defect in cytokinesis and a failure to polarize the cortical actin cytoskeleton to the mother-bud neck. Cla4–green fluorescent protein localized to sites where the cortical actin cytoskeleton and cell surface growth are polarized, independently of an intact actin cytoskeleton. Thus, PAK family kinases are primary regulators of cell and actin cytoskeletal polarity throughout most or all of the yeast cell cycle. PAK-family kinases in higher organisms may have similar functions.

scholarly journals Morphogenesis in the yeast cell cycle: regulation by Cdc28 and cyclins.

1993 ◽  
Vol 120 (6) ◽  
pp. 1305-1320 ◽  
Author(s):  
D J Lew ◽  
S I Reed
Keyword(s):  
Cell Cycle ◽  
Actin Cytoskeleton ◽  
Yeast Cell ◽  
Cell Cycle Regulation ◽  
Regulatory Protein ◽  
Yeast Cell Cycle ◽  
Actin Binding ◽  
Cortical Actin ◽  
Bud Site ◽  
Cycle Regulation

Analysis of cell cycle regulation in the budding yeast Saccharomyces cerevisiae has shown that a central regulatory protein kinase, Cdc28, undergoes changes in activity through the cell cycle by associating with distinct groups of cyclins that accumulate at different times. The various cyclin/Cdc28 complexes control different aspects of cell cycle progression, including the commitment step known as START and mitosis. We found that altering the activity of Cdc28 had profound effects on morphogenesis during the yeast cell cycle. Our results suggest that activation of Cdc28 by G1 cyclins (Cln1, Cln2, or Cln3) in unbudded G1 cells triggers polarization of the cortical actin cytoskeleton to a specialized pre-bud site at one end of the cell, while activation of Cdc28 by mitotic cyclins (Clb1 or Clb2) in budded G2 cells causes depolarization of the cortical actin cytoskeleton and secretory apparatus. Inactivation of Cdc28 following cyclin destruction in mitosis triggers redistribution of cortical actin structures to the neck region for cytokinesis. In the case of pre-bud site assembly following START, we found that the actin rearrangement could be triggered by Cln/Cdc28 activation in the absence of de novo protein synthesis, suggesting that the kinase may directly phosphorylate substrates (such as actin-binding proteins) that regulate actin distribution in cells.

scholarly journals Identification of Genes Controlling Growth Polarity in the Budding Yeast Saccharomyces cerevisiae: A Possible Role of N-Glycosylation and Involvement of the Exocyst Complex

Genetics ◽  
1997 ◽  
Vol 147 (2) ◽  
pp. 421-434 ◽  
Author(s):  
G Mondésert ◽  
D J Clarke ◽  
S I Reed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Surface ◽  
Actin Cytoskeleton ◽  
Cell Cycle Progression ◽  
Cellular Systems ◽  
Surface Growth ◽  
Polarized Growth ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cycle Progression

The regulation of secretion polarity and cell surface growth during the cell cycle is critical for proper morphogenesis and viability of Saccharomyces cerevisiae. A shift from isotropic cell surface growth to polarized growth is necessary for bud emergence and a repolarization of secretion to the bud neck is necessary for cell separation. Although alterations in the actin cytoskeleton have been implicated in these changes in secretion polarity, clearly other cellular systems involved in secretion are likely to be targets of cell cycle regulation. To investigate mechanisms coupling cell cycle progression to changes in secretion polarity in parallel with and downstream of regulation of actin polarization, we implemented a screen for mutants defective specifically in polarized growth but with normal actin cytoskeleton structure. These mutants fell into three classes: those partially defective in N-glycosylation, those linked to specific defects in the exocyst, and a third class neither defective in glycosylation nor linked to the exocyst. These results raise the possibility that changes in N-linked glycosylation may be involved in a signal linking cell cycle progression and secretion polarity and that the exocyst may have regulatory functions in coupling the secretory machinery to the polarized actin cytoskeleton.

scholarly journals Saccharomyces cerevisiae Cdc42p GTPase Is Involved in Preventing the Recurrence of Bud Emergence during the Cell Cycle

2000 ◽  
Vol 20 (22) ◽  
pp. 8548-8559 ◽  
Author(s):  
Tamara J. Richman ◽  
Douglas I. Johnson
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Fluorescent Protein ◽  
Mutant Protein ◽  
Cortical Actin ◽  
Effector Domain ◽  
Septin Ring ◽  
Bud Emergence ◽  
Downstream Effectors ◽  
Green Fluorescent

ABSTRACT The Saccharomyces cerevisiae Cdc42p GTPase interacts with multiple regulators and downstream effectors through an ∼25-amino-acid effector domain. Four effector domain mutations, Y32K, F37A, D38E, and Y40C, were introduced into Cdc42p and characterized for their effects on these interactions. Each mutant protein showed differential interactions with a number of downstream effectors and regulators and various levels of functionality. Specifically, Cdc42D38Ep showed reduced interactions with the Cla4p p21-activated protein kinase and the Bem3p GTPase-activating protein and cdc42 D38E was the only mutant allele able to complement the Δcdc42 null mutant. However, the mutant protein was only partially functional, as indicated by a temperature-dependent multibudded phenotype seen in conjunction with defects in both septin ring localization and activation of the Swe1p-dependent morphogenetic checkpoint. Further analysis of this mutant suggested that the multiple buds emerged consecutively with a premature termination of bud enlargement preceding the appearance of the next bud. Cortical actin, the septin ring, Cla4p-green fluorescent protein (GFP), and GFP-Cdc24p all predominantly localized to one bud at a time per multibudded cell. These data suggest that Cdc42D38Ep triggers a morphogenetic defect post-bud emergence, leading to cessation of bud growth and reorganization of the budding machinery to another random budding site, indicating that Cdc42p is involved in prevention of the initiation of supernumerary buds during the cell cycle.

scholarly journals BED1, a gene encoding a galactosyltransferase homologue, is required for polarized growth and efficient bud emergence in Saccharomyces cerevisiae.

1996 ◽  
Vol 132 (1) ◽  
pp. 137-151 ◽  
Author(s):  
G Mondésert ◽  
S I Reed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Actin Cytoskeleton ◽  
Dependent Manner ◽  
Polarized Growth ◽  
Checkpoint Control ◽  
Wild Type ◽  
Ellipsoidal Shape ◽  
Bud Emergence ◽  
Morphogenesis Checkpoint

The ellipsoidal shape of the yeast Saccharomyces cerevisiae is the result of successive isotropic/apical growth switches that are regulated in a cell cycle-dependent manner. It is thought that growth polarity is governed by the remodeling of the actin cytoskeleton that is itself under the control of the cell cycle machinery. The cell cycle and the morphogenesis cycle are tightly coupled and it has been recently suggested that a morphogenesis/polarity checkpoint control monitors bud emergence in order to maintain the coupling of these two events (Lew, D. J., and S. I. Reed. 1995. J. Cell Biol. 129:739-749). During a screen based on the inability of cells impaired in the budding process to survive when the morphogenesis checkpoint control is abolished, we identified and characterized BED1, a new gene that is required for efficient budding. Cells carrying a disrupted allele of BED1 no longer have the wild-type ellipsoidal shape characteristic of S. cerevisiae, are larger than wild-type cells, are deficient in bud emergence, and depend upon an intact morphogenesis checkpoint control to survive. These cells show defects in polarized growth despite the fact that the actin cytoskeleton appears normal. Our results suggest that Bed1 is a type II membrane protein localized in the endoplasmic reticulum. BED1 is significantly homologous to gma12+, a S. pombe gene coding for an alpha-1,2,-galactosyltransferase, suggesting that glycosylation of specific proteins or lipids could be important for signaling in the switch to polarized growth and in bud emergence.

Towards a yeast cell cycle Sys-bio model: CK2 activity is modulated by growth rate in Saccharomyces cerevisiae

2010 ◽  
Vol 150 ◽  
pp. 519-519
Author(s):  
C. Cirulli ◽  
F. Tripodi ◽  
V. Reghellin ◽  
L. Brambilla ◽  
P. Coccetti ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Growth Rate ◽  
Yeast Cell ◽  
Yeast Cell Cycle

scholarly journals CDC42 and CDC43, two additional genes involved in budding and the establishment of cell polarity in the yeast Saccharomyces cerevisiae.

1990 ◽  
Vol 111 (1) ◽  
pp. 131-142 ◽  
Author(s):  
A E Adams ◽  
D I Johnson ◽  
R M Longnecker ◽  
B F Sloat ◽  
J R Pringle
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Surface ◽  
Actin Cytoskeleton ◽  
Cell Polarity ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Mitotic Spindles ◽  
Yeast Saccharomyces Cerevisiae ◽  
Continue Growth

Budding in the yeast Saccharomyces cerevisiae involves a polarized deposition of new cell surface material that is associated with a highly asymmetric disposition of the actin cytoskeleton. Mutants defective in gene CDC24, which are unable to bud or establish cell polarity, have been of great interest with regard to both the mechanisms of cellular morphogenesis and the mechanisms that coordinate cell-cycle events. To gain further insights into these problems, we sought additional mutants with defects in budding. We report here that temperature-sensitive mutants defective in genes CDC42 and CDC43, like cdc24 mutants, fail to bud but continue growth at restrictive temperature, and thus arrest as large unbudded cells. Nearly all of the arrested cells appear to begin nuclear cycles (as judged by the occurrence of DNA replication and the formation and elongation of mitotic spindles), and many go on to complete nuclear division, supporting the hypothesis that the events associated with budding and those of the nuclear cycle represent two independent pathways within the cell cycle. The arrested mutant cells display delocalized cell-surface deposition associated with a loss of asymmetry of the actin cytoskeleton. CDC42 maps distal to the rDNA on chromosome XII and CDC43 maps near lys5 on chromosome VII.

Sign in / Sign up

Export Citation Format

Share Document