Microtubules Orient the Mitotic Spindle in Yeast through Dynein-dependent Interactions with the Cell Cortex

Carminati, Janet L.; Stearns, Tim

doi:10.1083/jcb.138.3.629

Cited by 455 publications

(447 citation statements)

References 69 publications

Supporting

Mentioning

404

Contrasting

Unclassified

Order By: Relevance

“…The structures looked very similar to those seen in S. cerevisiae (Kilmartin and Adams, 1984;Carminati and Stearns, 1997) and were named accordingly. A spindle pole body (SPB) was observed as a very faint spot that colocalized with the nucleus ( Figure 1A, a).…”

Section: Hyphal Germ Tube Emergence Can Occur Before Cell Cycle Eventmentioning

confidence: 78%

Hyphal Elongation Is Regulated Independently of Cell Cycle inCandida albicans

Hazan

Sepulveda-Becerra

Liu

2002

MBoC

105

138

View full text Add to dashboard Cite

The mechanism for apical growth during hyphal morphogenesis in Candida albicans is unknown. Studies from Saccharomyces cerevisiae indicate that cell morphogenesis may involve cell cycle regulation by cyclin-dependent kinase. To examine whether this is the mechanism for hyphal morphogenesis, the temporal appearance of different spindle pole body and spindle structures, the cell cycle-regulated rearrangements of the actin cytoskeleton, and the phosphorylation state of the conserved Tyr19 of Cdc28 during the cell cycle were compared and found to be similar between yeast and serum-induced hyphal apical cells. These data suggest that hyphal elongation is not mediated by altering cell cycle progression or through phosphorylation of Tyr19 of Cdc28. We have also shown that germ tubes can evaginate before spindle pole body duplication, chitin ring formation, and DNA replication. Similarly, tip-associated actin polarization in each hypha occurs before the events of the G 1 /S transition and persists throughout the cell cycle, whereas cell cycle-regulated actin assemblies come and go. We have also shown that cells in phases other than G 1 can be induced to form hyphae. Hyphae induced from G 1 cells have no constrictions, and the first chitin ring is positioned in the germ tube at various distances from the base. Hyphae induced from budded cells have a constriction and a chitin ring at the bud neck, beyond which the hyphae continue to elongate with no further constrictions. Our data suggest that hyphal elongation and cell cycle morphogenesis programs are uncoupled, and each contributes to different aspects of cell morphogenesis. INTRODUCTIONCandida albicans is a polymorphic fungal pathogen that undergoes reversible morphogenetic transitions among budding, pseudohyphal, and hyphal growth forms (Odds, 1985). Its ability to switch between yeast and hyphal growth forms is directly related to its virulence, because mutants defective in hyphal growth are less virulent in mouse models than are their wild-type counterparts (Leberer et al., 1997;Lo et al., 1997;Gale et al., 1998). Hyphae may be suited to breach barriers in the host, whereas the yeast form is more easily disseminated within the host. Therefore, understanding the mechanisms for this morphogenetic switch should provide insight into the pathogenicity of this fungus.During hyphal growth in C. albicans, cell surface expansion is restricted to a small region at the hyphal tip. This apical growth zone is active during the entire hyphal growth period (Staebell and Soll, 1985). In contrast, yeast-form cells expand from a small area in a mostly apical manner only at the initial stage of budding. When the bud has reached a critical size, apical growth shuts down and general (isotropic) expansion takes place (Staebell and Soll, 1985). The localization of the actin cytoskeleton in yeast and hyphal cells reflects these differences in morphogenesis. Polarization of the actin cytoskeleton to the hyphal tip is observed in all hyphal cells (Anderson and Soll, 1986). However, in yeast-...

show abstract

Section: Hyphal Germ Tube Emergence Can Occur Before Cell Cycle Eventmentioning

confidence: 78%

Hyphal Elongation Is Regulated Independently of Cell Cycle inCandida albicans

Hazan

Sepulveda-Becerra

Liu

2002

MBoC

105

138

View full text Add to dashboard Cite

show abstract

“…The nuclear microtubules form the bipolar spindle and are required for chromosome segregation. It has been proposed that the highly dynamic nature of microtubules contributes to a search and capture mechanism of cytoplasmic microtubules at the site of bud growth during G1 (Carminati and Stearns, 1997;Shaw et al, 1997b) and of nuclear microtubules at the kinetochores before chromosome segregation (Holy and Leibler, 1994;Winey et al, 1995;O'Toole et al, 1999;Maddox et al, 2000). However, it has not been possible to distinguish the role of microtubule dynamics from the essential role of microtubules for cellular viability.…”

Section: Introductionmentioning

confidence: 98%

“…In contrast, tub2-C354 mutant cells contained one stable and persistent cytoplasmic microtubule throughout the entire unbudded phase of cell growth. Microtubule localization to the bud is believed to involve a search and capture mechanism, which relies on microtubule dynamic instability to effectively probe the entire cell cortex (Carminati and Stearns, 1997). This dynamic property of microtubules has been shown to be an efficient mechanism for probing intracellular space (Holy and Leibler, 1994).…”

Section: In Tub2-c354 Mutants a Single Stable Cytoplasmic Microtubulementioning

confidence: 99%

β-Tubulin C354 Mutations that Severely Decrease Microtubule Dynamics Do Not Prevent Nuclear Migration in Yeast

Gupta

Bode

Thrower

et al. 2002

MBoC

View full text Add to dashboard Cite

Microtubule dynamics are influenced by interactions of microtubules with cellular factors and by changes in the primary sequence of the tubulin molecule. Mutations of yeast ␤-tubulin C354, which is located near the binding site of some antimitotic compounds, reduce microtubule dynamicity greater than 90% in vivo and in vitro. The resulting intrinsically stable microtubules allowed us to determine which, if any, cellular processes are dependent on dynamic microtubules. The average number of cytoplasmic microtubules decreased from 3 in wild-type to 1 in mutant cells. The single microtubule effectively located the bud site before bud emergence. Although spindles were positioned near the bud neck at the onset of anaphase, the mutant cells were deficient in preanaphase spindle alignment along the mother-bud axis. Spindle microtubule dynamics and spindle elongation rates were also severely depressed in the mutants. The pattern and extent of cytoplasmic microtubule dynamics modulation through the cell cycle may reveal the minimum dynamic properties required to support growth. The ability to alter intrinsic microtubule dynamics and determine the in vivo phenotype of cells expressing the mutant tubulin provides a critical advance in assessing the dynamic requirements of an essential gene function.

show abstract

“…In budding yeast, the EB1 homologue Bim1 and APC-like protein Kar9 are microtubule plus-end (ϩend)-interacting proteins (ϩTIP) that link astral microtubules to the cortex and facilitate spindle placement at the bud neck before anaphase (Carminati and Stearns, 1997;Tirnauer et al, 1999;Beach et al, 2000;Lee et al, 2000;Miller et al, 2000;Yin et al, 2000;Liakopoulos et al, 2003;Maekawa et al, 2003). Paradoxically, EB1/Bim1 and APC/Kar9 can also localize to microtubule-organizing centers; centrosomes or spindle pole bodies (SPBs) in yeast, independently of astral microtubules (Liakopoulos et al, 2003;Louie et al, 2004;Maekawa and Schiebel, 2004).…”

Section: Introductionmentioning

confidence: 99%

γ-Tubulin Is Required for Proper Recruitment and Assembly of Kar9–Bim1 Complexes in Budding Yeast

Cuschieri

Miller

Vogel

2006

MBoC

View full text Add to dashboard Cite

Microtubule plus-end-interacting proteins (؉TIPs) promote the dynamic interactions between the plus ends (؉ends) of astral microtubules and cortical actin that are required for preanaphase spindle positioning. Paradoxically, ؉TIPs such as the EB1 orthologue Bim1 and Kar9 also associate with spindle pole bodies (SPBs), the centrosome equivalent in budding yeast. Here, we show that deletion of four C-terminal residues of the budding yeast ␥-tubulin Tub4 (tub4-⌬dsyl) perturbs Bim1 and Kar9 localization to SPBs and Kar9-dependant spindle positioning. Surprisingly, we find Kar9 localizes to microtubule ؉ends in tub4-⌬dsyl cells, but these microtubules fail to position the spindle when targeted to the bud. Using cofluorescence and coaffinity purification, we show Kar9 complexes in tub4-⌬dsyl cells contain reduced levels of Bim1. Astral microtubule dynamics is suppressed in tub4-⌬dsyl cells, but it are restored by deletion of Kar9. Moreover, Myo2-and F-actin-dependent dwelling of Kar9 in the bud is observed in tub4-⌬dsyl cells, suggesting defective Kar9 complexes tether microtubule ؉ends to the cortex. Overproduction of Bim1, but not Kar9, restores Kar9-dependent spindle positioning in the tub4-⌬dsyl mutant, reduces cortical dwelling, and promotes Bim1-Kar9 interactions. We propose that SPBs, via the tail of Tub4, promote the assembly of functional ؉TIP complexes before their deployment to microtubule ؉ends.

show abstract

Microtubules Orient the Mitotic Spindle in Yeast through Dynein-dependent Interactions with the Cell Cortex

Cited by 455 publications

References 69 publications

Hyphal Elongation Is Regulated Independently of Cell Cycle inCandida albicans

Hyphal Elongation Is Regulated Independently of Cell Cycle inCandida albicans

β-Tubulin C354 Mutations that Severely Decrease Microtubule Dynamics Do Not Prevent Nuclear Migration in Yeast

γ-Tubulin Is Required for Proper Recruitment and Assembly of Kar9–Bim1 Complexes in Budding Yeast

Contact Info

Product

Resources

About