scholarly journals Mitotic Spindle Positioning in Saccharomyces cerevisiae Is Accomplished by Antagonistically Acting Microtubule Motor Proteins

1997 ◽  
Vol 138 (5) ◽  
pp. 1041-1053 ◽  
Author(s):  
Frank R. Cottingham ◽  
M. Andrew Hoyt
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Mitotic Spindle ◽  
Asymmetric Cell Division ◽  
Wild Type ◽  
Yeast Saccharomyces Cerevisiae ◽  
Spindle Positioning ◽  
Dynein Motor ◽  
Bud Neck ◽  
Microtubule Motor

Proper positioning of the mitotic spindle is often essential for cell division and differentiation processes. The asymmetric cell division characteristic of budding yeast, Saccharomyces cerevisiae, requires that the spindle be positioned at the mother–bud neck and oriented along the mother–bud axis. The single dynein motor encoded by the S. cerevisiae genome performs an important but nonessential spindle-positioning role. We demonstrate that kinesin-related Kip3p makes a major contribution to spindle positioning in the absence of dynein. The elimination of Kip3p function in dyn1Δ cells severely compromised spindle movement to the mother–bud neck. In dyn1Δ cells that had completed positioning, elimination of Kip3p function caused spindles to mislocalize to distal positions in mother cell bodies. We also demonstrate that the spindle-positioning defects exhibited by dyn1 kip3 cells are caused, to a large extent, by the actions of kinesin- related Kip2p. Microtubules in kip2Δ cells were shorter and more sensitive to benomyl than wild-type, in contrast to the longer and benomyl-resistant microtubules found in dyn1Δ and kip3Δ cells. Most significantly, the deletion of KIP2 greatly suppressed the spindle localization defect and slow growth exhibited by dyn1 kip3 cells. Likewise, induced expression of KIP2 caused spindles to mislocalize in cells deficient for dynein and Kip3p. Our findings indicate that Kip2p participates in normal spindle positioning but antagonizes a positioning mechanism acting in dyn1 kip3 cells. The observation that deletion of KIP2 could also suppress the inviability of dyn1Δ kar3Δ cells suggests that kinesin-related Kar3p also contributes to spindle positioning.

scholarly journals Cytoplasmic dynein is required for normal nuclear segregation in yeast

1993 ◽  
Vol 90 (23) ◽  
pp. 11172-11176 ◽  
Author(s):  
D Eshel ◽  
L A Urrestarazu ◽  
S Vissers ◽  
J C Jauniaux ◽  
J C van Vliet-Reedijk ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Heavy Chain ◽  
Mitotic Spindle ◽  
Cytoplasmic Dynein ◽  
Predicted Amino Acid Sequence ◽  
Yeast Saccharomyces Cerevisiae ◽  
Abnormal Distribution ◽  
Bud Neck ◽  
Cytoplasmic Microtubules

We have identified the gene DYN1, which encodes the heavy chain of cytoplasmic dynein in the yeast Saccharomyces cerevisiae. The predicted amino acid sequence (M(r) 471,305) reveals the presence of four P-loop motifs, as in all dyneins known so far, and has 28% overall identity to the dynein heavy chain of Dictyostelium [Koonce, M. P., Grissom, P. M. & McIntosh, J. R. (1992) J. Cell Biol. 119, 1597-1604] with 40% identity in the putative motor domain. Disruption of DYN1 causes misalignment of the spindle relative to the bud neck during cell division and results in abnormal distribution of the dividing nuclei between the mother cell and the bud. Cytoplasmic dynein, by generating force along cytoplasmic microtubules, may play an important role in the proper alignment of the mitotic spindle in yeast.

scholarly journals Cortical dynein pulling mechanism is regulated by differentially targeted attachment molecule Num1

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Safia Omer ◽  
Samuel R Greenberg ◽  
Wei-Lih Lee
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Spatial Distribution ◽  
Direct Evidence ◽  
Critical Factor ◽  
Spindle Positioning ◽  
Dynein Motor ◽  
Independent Population ◽  
Bud Neck ◽  
Pulling Forces ◽  
Pulling Force

Cortical dynein generates pulling forces via microtubule (MT) end capture-shrinkage and lateral MT sliding mechanisms. In Saccharomyces cerevisiae, the dynein attachment molecule Num1 interacts with endoplasmic reticulum (ER) and mitochondria to facilitate spindle positioning across the mother-bud neck, but direct evidence for how these cortical contacts regulate dynein-dependent pulling forces is lacking. We show that loss of Scs2/Scs22, ER tethering proteins, resulted in defective Num1 distribution and loss of dynein-dependent MT sliding, the hallmark of dynein function. Cells lacking Scs2/Scs22 performed spindle positioning via MT end capture-shrinkage mechanism, requiring dynein anchorage to an ER- and mitochondria-independent population of Num1, dynein motor activity, and CAP-Gly domain of dynactin Nip100/p150Glued subunit. Additionally, a CAAX-targeted Num1 rescued loss of lateral patches and MT sliding in the absence of Scs2/Scs22. These results reveal distinct populations of Num1 and underline the importance of their spatial distribution as a critical factor for regulating dynein pulling force.

Mating-defective ste mutations are suppressed by cell division cycle start mutations in Saccharomyces cerevisiae

1982 ◽  
Vol 2 (9) ◽  
pp. 1052-1063
Author(s):  
J R Shuster
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Temperature Characteristic ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Gene Products ◽  
Wild Type ◽  
Mating Pheromone ◽  
Yeast Saccharomyces Cerevisiae ◽  
Mating Pheromones

Temperature-sensitive mutants which arrest in the G1 phase of the cell cycle have been described for the yeast Saccharomyces cerevisiae. One class of these mutants (carrying cdc28, cdc36, cdc37, or cdc39) forms a shmoo morphology at restrictive temperature, characteristic of mating pheromone-arrested wild-type cells. Therefore, one hypothesis to explain the control of cell division by mating factors states that mating pheromones arrest wild-type cells by inactivating one or more of these CDC gene products. A class of mutants (carrying ste4, ste5, ste7, ste11, or ste12) which is insensitive to mating pheromone and sterile has also been described. One possible function of the STE gene products is the inactivation of the CDC gene products in the presence of a mating pheromone. A model incorporating these two hypotheses predicts that such STE gene products will not be required for mating in strains carrying an appropriate cdc lesion. This prediction was tested by assaying the mating abilities of double mutants for all of the pairwise combinations of cdc and ste mutations. Lesions in either cdc36 or cdc39 suppressed the mating defect due to ste4 and ste5. Allele specificity was observed in the suppression of both ste4 and ste5. The results indicate that the CDC36, CDC39, STE4, and STE5 gene products interact functionally or physically or both in the regulation of cell division mediated by the presence or absence of mating pheromones. The cdc36 and cdc39 mutations did not suppress ste7, ste11, or ste12. Lesions in cdc28 or cdc37 did not suppress any of the ste mutations. Other models of CDC and STE gene action which predicted that some of the cdc and ste mutations would be alleles of the same locus were tested. None of the cdc mutations was allelic to the ste mutations and, therefore, these models were eliminated.

scholarly journals Polo-like kinase acts as a molecular timer that safeguards the asymmetric fate of spindle microtubule-organizing centers

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Laura Matellán ◽  
Javier Manzano-López ◽  
Fernando Monje-Casas
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Neurodegenerative Disorders ◽  
Mitotic Spindle ◽  
Asymmetric Cell Division ◽  
Cellular Aging ◽  
Spindle Microtubule ◽  
Microtubule Organizing Centers ◽  
Complex Receptor ◽  
Stem Cell Division

The microtubules that form the mitotic spindle originate from microtubule-organizing centers (MTOCs) located at either pole. After duplication, spindle MTOCs can be differentially inherited during asymmetric cell division in organisms ranging from yeast to humans. Problems with establishing predetermined spindle MTOC inheritance patterns during stem cell division have been associated with accelerated cellular aging and the development of both cancer and neurodegenerative disorders. Here, we expand the repertoire of functions Polo-like kinase family members fulfill in regulating pivotal cell cycle processes. We demonstrate that the Plk1 homolog Cdc5 acts as a molecular timer that facilitates the timely and sequential recruitment of two key determinants of spindle MTOCs distribution, that is the γ-tubulin complex receptor Spc72 and the protein Kar9, and establishes the fate of these structures, safeguarding their asymmetric inheritance during Saccharomyces cerevisiae mitosis.

scholarly journals Pericentromere tension is self-regulated by spindle structure in metaphase

2014 ◽  
Vol 205 (3) ◽  
pp. 313-324 ◽  
Author(s):  
Jeremy M. Chacón ◽  
Soumya Mukherjee ◽  
Breanna M. Schuster ◽  
Duncan J. Clarke ◽  
Melissa K. Gardner
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Chromosome Structure ◽  
Wild Type ◽  
Checkpoint Signaling ◽  
Daughter Cells ◽  
Fluorescent Markers ◽  
Spindle Structure

During cell division, a mitotic spindle is built by the cell and acts to align and stretch duplicated sister chromosomes before their ultimate segregation into daughter cells. Stretching of the pericentromeric chromatin during metaphase is thought to generate a tension-based signal that promotes proper chromosome segregation. However, it is not known whether the mitotic spindle actively maintains a set point tension magnitude for properly attached sister chromosomes to facilitate robust mechanochemical checkpoint signaling. By imaging and tracking the thermal movements of pericentromeric fluorescent markers in Saccharomyces cerevisiae, we measured pericentromere stiffness and then used the stiffness measurements to quantitatively evaluate the tension generated by pericentromere stretch during metaphase in wild-type cells and in mutants with disrupted chromosome structure. We found that pericentromere tension in yeast is substantial (4–6 pN) and is tightly self-regulated by the mitotic spindle: through adjustments in spindle structure, the cell maintains wild-type tension magnitudes even when pericentromere stiffness is disrupted.

scholarly journals Dynein-Driven Mitotic Spindle Positioning Restricted to Anaphase by She1p Inhibition of Dynactin Recruitment

2009 ◽  
Vol 20 (13) ◽  
pp. 3003-3011 ◽  
Author(s):  
Jeffrey B. Woodruff ◽  
David G. Drubin ◽  
Georjana Barnes
Keyword(s):  
Cell Cycle ◽  
Mitotic Spindle ◽  
Cell Cycle Regulation ◽  
Regulatory Mechanism ◽  
Present Evidence ◽  
Spindle Positioning ◽  
Dynein Motor ◽  
Microtubule Motor ◽  
Cycle Regulation ◽  
Dynactin Complex

Dynein is a minus-end–directed microtubule motor important for mitotic spindle positioning. In budding yeast, dynein activity is restricted to anaphase when the nucleus enters the bud neck, yet the nature of the underlying regulatory mechanism is not known. Here, the microtubule-associated protein She1p is identified as a novel regulator of dynein activity. In she1Δ cells, dynein is activated throughout the cell cycle, resulting in aberrant spindle movements that misposition the spindle. We also found that dynactin, a cofactor essential for dynein motor function, is a dynamic complex whose recruitment to astral microtubules (aMTs) increases dramatically during anaphase. Interestingly, loss of She1p eliminates the cell-cycle regulation of dynactin recruitment and permits enhanced dynactin accumulation on aMTs throughout the cell cycle. Furthermore, localization of the dynactin complex to aMTs requires dynein, suggesting that dynactin is recruited to aMTs via interaction with dynein and not the microtubule itself. Lastly, we present evidence supporting the existence of an incomplete dynactin subcomplex localized at the SPB, and a complete complex that is loaded onto aMTs from the cytoplasm. We propose that She1p restricts dynein-dependent spindle positioning to anaphase by inhibiting the association of dynein with the complete dynactin complex.

scholarly journals Spindle position dictates division site during asymmetric cell division in moss

2020 ◽  
Author(s):  
Elena Kozgunova ◽  
Mari W. Yoshida ◽  
Gohta Goshima
Keyword(s):  
Cell Division ◽  
Mitotic Spindle ◽  
Actin Filaments ◽  
Asymmetric Cell Division ◽  
Physcomitrella Patens ◽  
Plant Cells ◽  
Spindle Positioning ◽  
Division Site ◽  
Multicellular Organisms ◽  
Spindle Position

AbstractAsymmetric cell division (ACD) underlies the development of multicellular organisms. The division site in plant cells is predetermined prior to mitosis and the localization of the mitotic spindle is considered static, unlike in animal ACD, where the cell division site is defined by active spindle-positioning mechanisms. Here, we isolated a novel mutant of the microtubule-associated protein TPX2 in the moss Physcomitrella patens and observed abnormal spindle motility, which led to inverted asymmetric division during organ development. This phenotype was rescued by restoring endogenous TPX2 function and, unexpectedly, by depolymerizing actin filaments. Thus, we identify an active spindle-positioning mechanism involving microtubules and actin filaments that sets the division site in plants, which is reminiscent of the acentrosomal ACD in animals, and suggests the existence of a common ancestral mechanism.

scholarly journals Loss of spatial control of the mitotic spindle apparatus in a Chlamydomonas reinhardtii mutant strain lacking basal bodies.

Genetics ◽  
1995 ◽  
Vol 141 (3) ◽  
pp. 945-960 ◽  
Author(s):  
L L Ehler ◽  
J A Holmes ◽  
S K Dutcher
Keyword(s):  
Cell Division ◽  
Chlamydomonas Reinhardtii ◽  
Mitotic Spindle ◽  
Basal Bodies ◽  
Cleavage Furrow ◽  
Wild Type ◽  
Spindle Positioning ◽  
Spindle Apparatus ◽  
Variable Distribution ◽  
Spindle Position

Abstract The bld2-1 mutation in the green alga Chlamydomonas reinhardtii is the only known mutation that results in the loss of centrioles/basal bodies and the loss of coordination between spindle position and cleavage furrow position during cell division. Based on several different assays, bld2-1 cells lack basal bodies in > 99% of cells. The stereotypical cytoskeletal morphology and precise positioning of the cleavage furrow observed in wild-type cells is disrupted in bld2-1 cells. The positions of the mitotic spindle and of the cleavage furrow are not correlated with respect to each other or with a specific cellular landmark during cell division in bld2-1 cells. Actin has a variable distribution during mitosis in bld2-1 cells, but this aberrant distribution is not correlated with the spindle positioning defect. In both wild-type and bld2-1 cells, the position of the cleavage furrow is coincident with a specialized set of microtubules found in green algae known as the rootlet microtubules. We propose that the rootlet microtubules perform the functions of astral microtubules and that functional centrioles are necessary for the organization of the cytoskeletal superstructure critical for correct spindle and cleavage furrow placement in Chlamydomonas.

scholarly journals Mating-defective ste mutations are suppressed by cell division cycle start mutations in Saccharomyces cerevisiae.

1982 ◽  
Vol 2 (9) ◽  
pp. 1052-1063 ◽  
Author(s):  
J R Shuster
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Temperature Characteristic ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Gene Products ◽  
Wild Type ◽  
Mating Pheromone ◽  
Yeast Saccharomyces Cerevisiae ◽  
Mating Pheromones

Temperature-sensitive mutants which arrest in the G1 phase of the cell cycle have been described for the yeast Saccharomyces cerevisiae. One class of these mutants (carrying cdc28, cdc36, cdc37, or cdc39) forms a shmoo morphology at restrictive temperature, characteristic of mating pheromone-arrested wild-type cells. Therefore, one hypothesis to explain the control of cell division by mating factors states that mating pheromones arrest wild-type cells by inactivating one or more of these CDC gene products. A class of mutants (carrying ste4, ste5, ste7, ste11, or ste12) which is insensitive to mating pheromone and sterile has also been described. One possible function of the STE gene products is the inactivation of the CDC gene products in the presence of a mating pheromone. A model incorporating these two hypotheses predicts that such STE gene products will not be required for mating in strains carrying an appropriate cdc lesion. This prediction was tested by assaying the mating abilities of double mutants for all of the pairwise combinations of cdc and ste mutations. Lesions in either cdc36 or cdc39 suppressed the mating defect due to ste4 and ste5. Allele specificity was observed in the suppression of both ste4 and ste5. The results indicate that the CDC36, CDC39, STE4, and STE5 gene products interact functionally or physically or both in the regulation of cell division mediated by the presence or absence of mating pheromones. The cdc36 and cdc39 mutations did not suppress ste7, ste11, or ste12. Lesions in cdc28 or cdc37 did not suppress any of the ste mutations. Other models of CDC and STE gene action which predicted that some of the cdc and ste mutations would be alleles of the same locus were tested. None of the cdc mutations was allelic to the ste mutations and, therefore, these models were eliminated.

The spindle position checkpoint: how to deal with spindle misalignment during asymmetric cell division in budding yeast

2008 ◽  
Vol 36 (3) ◽  
pp. 416-420 ◽  
Author(s):  
Roberta Fraschini ◽  
Marianna Venturetti ◽  
Elena Chiroli ◽  
Simonetta Piatti
Keyword(s):  
Cell Division ◽  
Genome Stability ◽  
Asymmetric Cell Division ◽  
Budding Yeast ◽  
Spindle Positioning ◽  
Bud Neck ◽  
Mother And Daughter ◽  
Division Spindle ◽  
Division Axis ◽  
Spindle Position

During asymmetric cell division, spindle positioning is critical to ensure the unequal segregation of polarity factors and generate daughter cells with different sizes or fates. In budding yeast the boundary between mother and daughter cell resides at the bud neck, where cytokinesis takes place at the end of the cell cycle. Since budding and bud neck formation occur much earlier than bipolar spindle formation, spindle positioning is a finely regulated process. A surveillance device called the SPOC (spindle position checkpoint) oversees this process and delays mitotic exit and cytokinesis until the spindle is properly oriented along the division axis, thus ensuring genome stability.

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