scholarly journals A Role for Actin, Cdc1p, and Myo2p in the Inheritance of Late Golgi Elements in Saccharomyces cerevisiae

2001 ◽  
Vol 153 (1) ◽  
pp. 47-62 ◽  
Author(s):  
Olivia W. Rossanese ◽  
Catherine A. Reinke ◽  
Brooke J. Bevis ◽  
Adam T. Hammond ◽  
Irina B. Sears ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Fluorescence Microscopy ◽  
Actin Cytoskeleton ◽  
Polarized Growth ◽  
Independent Manner ◽  
Multiple Alleles ◽  
Actin Cables ◽  
Type V

In Saccharomyces cerevisiae, Golgi elements are present in the bud very early in the cell cycle. We have analyzed this Golgi inheritance process using fluorescence microscopy and genetics. In rapidly growing cells, late Golgi elements show an actin-dependent concentration at sites of polarized growth. Late Golgi elements are apparently transported into the bud along actin cables and are also retained in the bud by a mechanism that may involve actin. A visual screen for mutants defective in the inheritance of late Golgi elements yielded multiple alleles of CDC1. Mutations in CDC1 severely depolarize the actin cytoskeleton, and these mutations prevent late Golgi elements from being retained in the bud. The efficient localization of late Golgi elements to the bud requires the type V myosin Myo2p, further suggesting that actin plays a role in Golgi inheritance. Surprisingly, early and late Golgi elements are inherited by different pathways, with early Golgi elements localizing to the bud in a Cdc1p- and Myo2p-independent manner. We propose that early Golgi elements arise from ER membranes that are present in the bud. These two pathways of Golgi inheritance in S. cerevisiae resemble Golgi inheritance pathways in vertebrate cells.

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.

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.

The lethality of p60v-src in Saccharomyces cerevisiae and the activation of p34CDC28 kinase are dependent on the integrity of the SH2 domain

1993 ◽  
Vol 105 (2) ◽  
pp. 519-528
Author(s):  
F. Boschelli ◽  
S.M. Uptain ◽  
J.J. Lightbody
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Protein Tyrosine Kinase ◽  
Kinase Activity ◽  
Cell Cycle Control ◽  
Sh2 Domain ◽  
Wild Type ◽  
Type V ◽  
Cdc28 Kinase ◽  
In Cells

The lethal effects of the expression of the oncogenic protein tyrosine kinase p60v-src in Saccharomyces cerevisiae are associated with a loss of cell cycle control at the G1/S and G2/M checkpoints. Results described here indicate that the ability of v-Src to kill yeast is dependent on the integrity of the SH2 domain, a region of the Src protein involved in recognition of proteins phosphorylated on tyrosine. Catalytically active v-Src proteins with deletions in the SH2 domain have little effect on yeast growth, unlike wild-type v-Src protein, which causes accumulation of large-budded cells, perturbation of spindle microtubules and increased DNA content when expressed. The proteins phosphorylated on tyrosine in cells expressing v-Src differ from those in cells expressing a Src protein with a deletion in the SH2 domain. Also, unlike the wild-type v-Src protein, which drastically increases histone H1-associated Cdc28 kinase activity, c-Src and an altered v-Src protein have no effect on Cdc28 kinase activity. These results indicate that the SH2 domain is functionally important in the disruption of the yeast cell cycle by v-Src.

Search, capture and signal: games microtubules and centrosomes play

2001 ◽  
Vol 114 (2) ◽  
pp. 247-255 ◽  
Author(s):  
S.C. Schuyler ◽  
D. Pellman
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Cytoplasmic Dynein ◽  
Cell Cycle Checkpoint ◽  
Cellular Polarity ◽  
Cycle Progression ◽  
Cycle Checkpoint ◽  
Dividing Cells ◽  
Actin Cables ◽  
Type V

Accurate distribution of the chromosomes in dividing cells requires coupling of cellular polarity cues with both the orientation of the mitotic spindle and cell cycle progression. Work in budding yeast has demonstrated that cytoplasmic dynein and the kinesin Kip3p define redundant pathways that ensure proper spindle orientation. Furthermore, it has been shown that the Kip3p pathway components Kar9p and Bim1p (Yeb1p) form a complex that provides a molecular link between cortical polarity cues and spindle microtubules. Recently, other studies indicated that the cortical localization of Kar9p depends upon actin cables and Myo2p, a type V myosin. In addition, a BUB2-dependent cell cycle checkpoint has been described that inhibits the mitotic exit network and cytokinesis until proper centrosome position is achieved. Combined, these studies provide molecular insight into how cells link cellular polarity, spindle position and cell cycle progression.

scholarly journals The Saccharomyces cerevisiae SDA1 gene is required for actin cytoskeleton organization and cell cycle progression

2000 ◽  
Vol 113 (7) ◽  
pp. 1199-1211
Author(s):  
G. Buscemi ◽  
F. Saracino ◽  
D. Masnada ◽  
M.L. Carbone
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Dna Replication ◽  
Actin Cytoskeleton ◽  
Cell Cycle Progression ◽  
Temperature Sensitive ◽  
Permissive Temperature ◽  
Cycle Progression ◽  
Cytoskeleton Organization ◽  
Actin Cytoskeleton Organization

The organization of the actin cytoskeleton is essential for several cellular processes. Here we report the characterization of a Saccharomyces cerevisiae novel gene, SDA1, encoding a highly conserved protein, which is essential for cell viability and is localized in the nucleus. Depletion or inactivation of Sda1 cause cell cycle arrest in G(1) by blocking both budding and DNA replication, without loss of viability. Furthermore, sda1-1 temperature-sensitive mutant cells arrest at the non-permissive temperature mostly without detectable structures of polymerized actin, although a normal actin protein level is maintained, indicating that Sda1 is required for proper organization of the actin cytoskeleton. To our knowledge, this is the first mutation shown to cause such a phenotype. Recovery of Sda1 activity restores proper assembly of actin structures, as well as budding and DNA replication. Furthermore we show that direct actin perturbation, either in sda1-1 or in cdc28-13 cells released from G(1) block, prevents recovery of budding and DNA replication. We also show that the block in G(1) caused by loss of Sda1 function is independent of Swe1. Altogether our results suggest that disruption of F-actin structure can block cell cycle progression in G(1) and that Sda1 is involved in the control of the actin cytoskeleton.

scholarly journals Cell Cycle Progression and Cell Polarity Require Sphingolipid Biosynthesis in Aspergillus nidulans

2001 ◽  
Vol 21 (18) ◽  
pp. 6198-6209 ◽  
Author(s):  
Jijun Cheng ◽  
Tae-Sik Park ◽  
Anthony S. Fischl ◽  
Xiang S. Ye
Keyword(s):  
Cell Cycle ◽  
Actin Cytoskeleton ◽  
Aspergillus Nidulans ◽  
Cell Polarity ◽  
Cell Cycle Progression ◽  
Polarized Growth ◽  
Serine Palmitoyltransferase ◽  
Cycle Progression ◽  
Marked Accumulation ◽  
Sphingolipid Biosynthesis

ABSTRACT Sphingolipids are major components of the plasma membrane of eukaryotic cells and were once thought of merely as structural components of the membrane. We have investigated effects of inhibiting sphingolipid biosynthesis, both in germinating spores and growing hyphae of Aspergillus nidulans. In germinating spores, genetic or pharmacological inactivation of inositol phosphorylceramide (IPC) synthase arrests the cell cycle in G1 and also prevents polarized growth during spore germination. However, inactivation of IPC synthase not only eliminates sphingolipid biosynthesis but also leads to a marked accumulation of ceramide, its upstream intermediate. We therefore inactivated serine palmitoyltransferase, the first enzyme in the sphingolipid biosynthesis pathway, to determine effects of inhibiting sphingolipid biosynthesis without an accumulation of ceramide. This inactivation also prevented polarized growth but did not affect nuclear division of germinating spores. To see if sphingolipid biosynthesis is required to maintain polarized growth, and not just to establish polarity, we inhibited sphingolipid biosynthesis in cells in which polarity was already established. This inhibition rapidly abolished normal cell polarity and promoted cell tip branching, which normally never occurs. Cell tip branching was closely associated with dramatic changes in the normally highly polarized actin cytoskeleton and found to be dependent on actin function. The results indicate that sphingolipids are essential for the establishment and maintenance of cell polarity via control of the actin cytoskeleton and that accumulation of ceramide is likely responsible for arresting the cell cycle in G1.

Depolarization of the actin cytoskeleton is a specific phenotype in Saccharomyces cerevisiae

1998 ◽  
Vol 111 (17) ◽  
pp. 2689-2696 ◽  
Author(s):  
T.S. Karpova ◽  
S.L. Moltz ◽  
L.E. Riles ◽  
U. Guldener ◽  
J.H. Hegemann ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Environmental Factors ◽  
Actin Cytoskeleton ◽  
Slow Growth ◽  
Specific Response ◽  
Number Of Genes ◽  
Chromosome I ◽  
Harsh Conditions

The yeast actin cytoskeleton is polarized during most of the cell cycle. Certain environmental factors and mutations are associated with depolarization of the actin cytoskeleton. Is depolarization of the actin cytoskeleton a specific response, or is it a nonspecific reaction to harsh conditions or poor metabolism? If depolarization is a nonspecific response, then any mutation that slows growth should induce depolarization. In addition, the number of genes with the depolarization phenotype should constitute a relatively large part of the genome. To address this question, we determined the effect of slow growth on the actin cytoskeleton, and we determined the frequency of mutations that affect the actin cytoskeleton. Eight mutants with slow growth showed no defect in actin polarization, indicating that slow growth alone is not sufficient to cause depolarization. Among 273 viable haploids disrupted for ORFs of chromosome I and VIII and 950 viable haploids with random genome disruptions, none had depolarization of the cytoskeleton. We conclude that depolarization of the actin cytoskeleton is a specific phenotype.

SRO9, a Multicopy Suppressor of the Bud Gpowth Defect in the Saccharomyces cerevisiae rho3-Deficient Cells, Shows Strong Genetic Interactions With Tropomyosin Genes, Suggesting Its Role in Organization of the Actin Cytoskeleton

Genetics ◽  
1997 ◽  
Vol 147 (3) ◽  
pp. 1003-1016
Author(s):  
Mitsuhiro Kagami ◽  
Akio Toh-e ◽  
Yasushi Matsui
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Actin Cytoskeleton ◽  
Actin Filaments ◽  
Rna Binding ◽  
Small Gtpase ◽  
Growth Defect ◽  
Cortical Actin ◽  
Cytoplasmic Factor ◽  
Multicopy Suppressor ◽  
Actin Cables

RHO3 encodes a Rho-type small GTPase in the yeast Saccharomyces cerevisiae and is involved in the proper organization of the actin cytoskeleton required for bud growth. SRO9 (YCL37c) was isolated as a multicopy suppressor of a rho3Δ mutation. An Sro9p domain required for function is similar to a domain in the La protein (an RNA-binding protein). Disruption of SRO9 did not affect vegetative growth, even with the simultaneous disruption of an SRO9 homologue, SRO99. However, sro9Δ was synthetically lethal with a disruption of TPM1, which encodes tropomyosin; sro9Δ tpm1Δ cells did not distribute cortical actin patches properly and lysed. We isolated TPM2, the other gene for tropomyosin, as a multicopy suppressor of a tpm1Δ sro9Δ double mutant. Genetic analysis suggests that TPM2 is functionally related to TPM1 and that tropomyosin is important but not essential for cell growth. Overexpression of SRO9 suppressed the growth defect in tpm1Δ tpm2Δ cells, disappearance of cables of actin filaments in both rho3Δ cells and tpm1Δ cells, and temperature sensitivity of actin mutant cells (act1-1 cells), suggesting that Sro9p has a function that overlaps or is related to tropomyosin function. Unlike tropomyosin, Sro9p does not colocalize with actin cables but is diffusely cytoplasmic. These results suggest that Sro9p is a new cytoplasmic factor involved in the organization of actin filaments.

scholarly journals The Role of Actin in Spindle Orientation Changes during the Saccharomyces cerevisiae Cell Cycle

1999 ◽  
Vol 146 (5) ◽  
pp. 1019-1032 ◽  
Author(s):  
Chandra L. Theesfeld ◽  
Javier E. Irazoqui ◽  
Kerry Bloom ◽  
Daniel J. Lew
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Spindle Orientation ◽  
Cortical Actin ◽  
Yeast Saccharomyces Cerevisiae ◽  
Daughter Cells ◽  
M Phase ◽  
Actin Cables

In the budding yeast Saccharomyces cerevisiae, the mitotic spindle must align along the mother-bud axis to accurately partition the sister chromatids into daughter cells. Previous studies showed that spindle orientation required both astral microtubules and the actin cytoskeleton. We now report that maintenance of correct spindle orientation does not depend on F-actin during G2/M phase of the cell cycle. Depolymerization of F-actin using Latrunculin-A did not perturb spindle orientation after this stage. Even an early step in spindle orientation, the migration of the spindle pole body (SPB), became actin-independent if it was delayed until late in the cell cycle. Early in the cell cycle, both SPB migration and spindle orientation were very sensitive to perturbation of F-actin. Selective disruption of actin cables using a conditional tropomyosin double-mutant also led to de- fects in spindle orientation, even though cortical actin patches were still polarized. This suggests that actin cables are important for either guiding astral microtubules into the bud or anchoring them in the bud. In addition, F-actin was required early in the cell cycle for the development of the actin-independent spindle orientation capability later in the cell cycle. Finally, neither SPB migration nor the switch from actin-dependent to actin-independent spindle behavior required B-type cyclins.

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.

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