scholarly journals LIN-5 Is a Novel Component of the Spindle Apparatus Required for Chromosome Segregation and Cleavage Plane Specification in Caenorhabditis elegans

2000 ◽  
Vol 148 (1) ◽  
pp. 73-86 ◽  
Author(s):  
Monique A. Lorson ◽  
H. Robert Horvitz ◽  
Sander van den Heuvel
Keyword(s):  
Cell Cycle ◽  
Caenorhabditis Elegans ◽  
Dna Replication ◽  
Chromosome Segregation ◽  
Cleavage Plane ◽  
Coiled Coil ◽  
Metaphase Plate ◽  
Dependent Manner ◽  
Spindle Apparatus ◽  
Cytoplasmic Cleavage

Successful divisions of eukaryotic cells require accurate and coordinated cycles of DNA replication, spindle formation, chromosome segregation, and cytoplasmic cleavage. The Caenorhabditis elegans gene lin-5 is essential for multiple aspects of cell division. Cells in lin-5 null mutants enter mitosis at the normal time and form bipolar spindles, but fail chromosome alignment at the metaphase plate, sister chromatid separation, and cytokinesis. Despite these defects, cells exit from mitosis without delay and progress through subsequent rounds of DNA replication, centrosome duplication, and abortive mitoses. In addition, early embryos that lack lin-5 function show defects in spindle positioning and cleavage plane specification. The lin-5 gene encodes a novel protein with a central coiled-coil domain. This protein localizes to the spindle apparatus in a cell cycle- and microtubule-dependent manner. The LIN-5 protein is located at the centrosomes throughout mitosis, at the kinetochore microtubules in metaphase cells, and at the spindle during meiosis. Our results show that LIN-5 is a novel component of the spindle apparatus required for chromosome and spindle movements, cytoplasmic cleavage, and correct alternation of the S and M phases of the cell cycle.

scholarly journals Distinct Developmental Function of Two Caenorhabditis elegans Homologs of the Cohesin Subunit Scc1/Rad21

2003 ◽  
Vol 14 (6) ◽  
pp. 2399-2409 ◽  
Author(s):  
Yoshiko Mito ◽  
Asako Sugimoto ◽  
Masayuki Yamamoto
Keyword(s):  
Cell Cycle ◽  
Caenorhabditis Elegans ◽  
Chromosome Segregation ◽  
Mitotic Chromosome ◽  
Dependent Manner ◽  
C Elegans ◽  
Late Embryogenesis ◽  
A Cell ◽  
Cohesin Subunit ◽  
Cycle Dependent

Cohesin, which mediates sister chromatid cohesion, is composed of four subunits, named Scc1/Rad21, Scc3, Smc1, and Smc3 in yeast. Caenorhabditis elegans has a single homolog for each of Scc3, Smc1, and Smc3, but as many as four for Scc1/Rad21 (COH-1, SCC-1/COH-2, COH-3, and REC-8). Except for REC-8 required for meiosis, function of these C. elegans proteins remains largely unknown. Herein, we examined their possible involvement in mitosis and development. Embryos depleted of the homolog of either Scc3, or Smc1, or Smc3 by RNA interference revealed a defect in mitotic chromosome segregation but not in chromosome condensation and cytokinesis. Depletion of SCC-1/COH-2 caused similar phenotypes. SCC-1/COH-2 was present in cells destined to divide. It localized to chromosomes in a cell cycle-dependent manner. Worms depleted of COH-1 arrested at either the late embryonic or the larval stage, with no indication of mitotic dysfunction. COH-1 associated chromosomes throughout the cell cycle in all somatic cells undergoing late embryogenesis or larval development. Thus, SCC-1/COH-2 and the homologs of Scc3, Smc1, and Smc3 facilitate mitotic chromosome segregation during the development, presumably by forming a cohesin complex, whereas COH-1 seems to play a role important for development but unrelated to mitosis.

scholarly journals A Spindle Checkpoint Functions during Mitosis in the Early Caenorhabditis elegans Embryo

2005 ◽  
Vol 16 (3) ◽  
pp. 1056-1070 ◽  
Author(s):  
Sandra E. Encalada ◽  
John Willis ◽  
Rebecca Lyczak ◽  
Bruce Bowerman
Keyword(s):  
Caenorhabditis Elegans ◽  
Chromosome Segregation ◽  
Spindle Checkpoint ◽  
Metaphase Plate ◽  
Time Lapse ◽  
Cell Types ◽  
Embryonic Cells ◽  
Mitotic Spindles ◽  
Animal Cells ◽  
Dividing Cells

During mitosis, chromosome segregation is regulated by a spindle checkpoint mechanism. This checkpoint delays anaphase until all kinetochores are captured by microtubules from both spindle poles, chromosomes congress to the metaphase plate, and the tension between kinetochores and their attached microtubules is properly sensed. Although the spindle checkpoint can be activated in many different cell types, the role of this regulatory mechanism in rapidly dividing embryonic animal cells has remained controversial. Here, using time-lapse imaging of live embryonic cells, we show that chemical or mutational disruption of the mitotic spindle in early Caenorhabditis elegans embryos delays progression through mitosis. By reducing the function of conserved checkpoint genes in mutant embryos with defective mitotic spindles, we show that these delays require the spindle checkpoint. In the absence of a functional checkpoint, more severe defects in chromosome segregation are observed in mutants with abnormal mitotic spindles. We also show that the conserved kinesin CeMCAK, the CENP-F-related proteins HCP-1 and HCP-2, and the core kinetochore protein CeCENP-C all are required for this checkpoint. Our analysis indicates that spindle checkpoint mechanisms are functional in the rapidly dividing cells of an early animal embryo and that this checkpoint can prevent chromosome segregation defects during mitosis.

scholarly journals Dynamic SUMO modification regulates mitotic chromosome assembly and cell cycle progression in Caenorhabditis elegans

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Federico Pelisch ◽  
Remi Sonneville ◽  
Ehsan Pourkarimi ◽  
Ana Agostinho ◽  
J. Julian Blow ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Caenorhabditis Elegans ◽  
Cell Cycle Progression ◽  
Metaphase Plate ◽  
Gene Encoding ◽  
Cycle Progression ◽  
Sumo Protease ◽  
Sumo Conjugation ◽  
Centromeric Protein ◽  
Cycle Regulation

Abstract The small ubiquitin-like modifier (SUMO), initially characterized as a suppressor of a mutation in the gene encoding the centromeric protein MIF2, is involved in many aspects of cell cycle regulation. The dynamics of conjugation and deconjugation and the role of SUMO during the cell cycle remain unexplored. Here we used Caenorhabditis elegans to establish the contribution of SUMO to a timely and accurate cell division. Chromatin-associated SUMO conjugates increase during metaphase but decrease rapidly during anaphase. Accumulation of SUMO conjugates on the metaphase plate and proper chromosome alignment depend on the SUMO E2 conjugating enzyme UBC-9 and SUMO E3 ligase PIASGEI-17. Deconjugation is achieved by the SUMO protease ULP-4 and is crucial for correct progression through the cell cycle. Moreover, ULP-4 is necessary for Aurora BAIR-2 extraction from chromatin and relocation to the spindle mid-zone. Our results show that dynamic SUMO conjugation plays a role in cell cycle progression.

scholarly journals Cyclin F-Chk1 synthetic lethality mediated by E2F1 degradation

2019 ◽  
Author(s):  
Kamila Burdova ◽  
Hongbin Yang ◽  
Roberta Faedda ◽  
Samuel Hume ◽  
Daniel Ebner ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Cell Cycle Progression ◽  
Kinase Inhibitors ◽  
Synthetic Lethality ◽  
Checkpoint Inhibitors ◽  
Dependent Manner ◽  
Cycle Progression ◽  
Multiple Substrates ◽  
Cyclin F

SummaryCyclins are central engines of cell cycle progression when partnered with Cyclin Dependent Kinases (CDKs). Among the different cyclins controlling cell cycle progression, cyclin F does not partner with a CDK, but forms an E3 ubiquitin ligase, assembling through the F-box domain, an Skp1-Cul1-F-box (SCF) module. Although multiple substrates of cyclin F have been identified the vulnerabilities of cells lacking cyclin F are not known. Thus, we assessed viability of cells lacking cyclin F upon challenging cells with more than 200 kinase inhibitors. The screen revealed a striking synthetic lethality between Chk1 inhibition and cyclin F loss. Chk1 inhibition in cells lacking cyclin F leads to DNA replication catastrophe. The DNA replication catastrophe depends on the accumulation of E2F1 in cyclin F depleted cells. We observe that SCFcyclin F promotes E2F1 degradation after Chk1 inhibitors in a CDK dependent manner. Thus, Cyclin F restricts E2F1 activity during cell cycle and upon checkpoint inhibition to prevent DNA replication stress. Our findings pave the way for patient selection in the clinical use of checkpoint inhibitors.

scholarly journals Cdc14 phosphatase directs centrosome re-duplication at the meiosis I to meiosis II transition in budding yeast

2017 ◽  
Vol 2 ◽  
pp. 2 ◽  
Author(s):  
Colette Fox ◽  
Juan Zou ◽  
Juri Rappsilber ◽  
Adele L. Marston
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Chromosome Segregation ◽  
Budding Yeast ◽  
Spindle Pole Body ◽  
Initial Step ◽  
Mitotic Cell ◽  
Spindle Pole ◽  
Fluorescence And Electron Microscopy ◽  
Meiosis I

Background Gametes are generated through a specialized cell division called meiosis, in which ploidy is reduced by half because two consecutive rounds of chromosome segregation, meiosis I and meiosis II, occur without intervening DNA replication. This contrasts with the mitotic cell cycle where DNA replication and chromosome segregation alternate to maintain the same ploidy. At the end of mitosis, CDKs are inactivated. This low CDK state in late mitosis/G1 allows for critical preparatory events for DNA replication and centrosome/spindle pole body (SPB) duplication. However, their execution is inhibited until S phase, where further preparatory events are also prevented. This “licensing” ensures that both the chromosomes and the centrosomes/SPBs replicate exactly once per cell cycle, thereby maintaining constant ploidy. Crucially, between meiosis I and meiosis II, centrosomes/SPBs must be re-licensed, but DNA re-replication must be avoided. In budding yeast, the Cdc14 protein phosphatase triggers CDK down regulation to promote exit from mitosis. Cdc14 also regulates the meiosis I to meiosis II transition, though its mode of action has remained unclear. Methods Fluorescence and electron microscopy was combined with proteomics to probe SPB duplication in cells with inactive or hyperactive Cdc14. Results We demonstrate that Cdc14 ensures two successive nuclear divisions by re-licensing SPBs at the meiosis I to meiosis II transition. We show that Cdc14 is asymmetrically enriched on a single SPB during anaphase I and provide evidence that this enrichment promotes SPB re-duplication. Cells with impaired Cdc14 activity fail to promote extension of the SPB half-bridge, the initial step in morphogenesis of a new SPB. Conversely, cells with hyper-active Cdc14 duplicate SPBs, but fail to induce their separation. Conclusion Our findings implicate reversal of key CDK-dependent phosphorylations in the differential licensing of cyclical events at the meiosis I to meiosis I transition.

scholarly journals A dependent pathway of gene functions leading to chromosome segregation in Saccharomyces cerevisiae.

1982 ◽  
Vol 94 (3) ◽  
pp. 718-726 ◽  
Author(s):  
J S Wood ◽  
L H Hartwell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Chromosome Segregation ◽  
Nuclear Division ◽  
Mitotic Cell ◽  
Mitotic Cell Cycle ◽  
Gene Products ◽  
Dependent Pathway

Methyl-benzimidazole-2-ylcarbamate (MBC) inhibits the mitotic cell cycle of Saccharomyces cerevisiae at a stage subsequent to DNA synthesis and before the completion of nuclear division (Quinlan, R. A., C. I. Pogson, and K, Gull, 1980, J Cell Sci., 46: 341-352). The step in the cell cycle that is sensitive to MBC inhibition was ordered to reciprocal shift experiments with respect to the step catalyzed by cdc gene products. Execution of the CDC7 step is required for the initiation of DNA synthesis and for completion of the MBC-sensitive step. Results obtained with mutants (cdc2, 6, 8, 9, and 21) defective in DNA replication and with an inhibitor of DNA replication (hydroxyurea) suggest that some DNA replication required for execution of the MBC-sensitive step but that the completion of replication is not. Of particular interest were mutants (cdc5, 13, 14, 15, 16, 17, and 23) that arrest cell division after DNA replication but before nuclear division since previous experiments had not been able to resolve the pathway of events in this part of the cell cycle. Execution of the CDC17 step was found to be a prerequisite for execution of the MBC-sensitive step; the CDC13, 16 and 23 steps are executed independently of the MBC-sensitive step; execution of the MBC-sensitive step is prerequisite for execution of the MBC-sensitive step; execution of the MBC-sensitive step is prerequisite for execution of the CDC14 and 23 steps. These results considerably extend the dependent pathway of events that constitute the cell cycle of S. cerevisiae.

scholarly journals Targeting and functional mechanisms of the cytokinesis‑related F‑BAR protein Hof1 during the cell cycle

2013 ◽  
Vol 24 (9) ◽  
pp. 1305-1320 ◽  
Author(s):  
Younghoon Oh ◽  
Jennifer Schreiter ◽  
Ryuichi Nishihama ◽  
Carsten Wloka ◽  
Erfei Bi
Keyword(s):  
Cell Cycle ◽  
Budding Yeast ◽  
Coiled Coil ◽  
Dependent Manner ◽  
Polarized Growth ◽  
Yeast Saccharomyces Cerevisiae ◽  
Septum Formation ◽  
Primary Septum ◽  
Bud Neck ◽  
Ring Constriction

F-BAR proteins are membrane‑associated proteins believed to link the plasma membrane to the actin cytoskeleton in cellular processes such as cytokinesis and endocytosis. In the budding yeast Saccharomyces cerevisiae, the F‑BAR protein Hof1 localizes to the division site in a complex pattern during the cell cycle and plays an important role in cytokinesis. However, the mechanisms underlying its localization and function are poorly understood. Here we show that Hof1 contains three distinct targeting domains that contribute to cytokinesis differentially. The N‑terminal half of Hof1 localizes to the bud neck and the sites of polarized growth during the cell cycle. The neck localization is mediated mainly by an interaction between the second coiled‑coil region in the N‑terminus and the septin Cdc10, whereas the localization to the sites of polarized growth is mediated entirely by the F‑BAR domain. In contrast, the C‑terminal half of Hof1 interacts with Myo1, the sole myosin‑II heavy chain in budding yeast, and localizes to the bud neck in a Myo1‑dependent manner from the onset to the completion of cytokinesis. We also show that the SH3 domain in the C‑terminus plays an important role in maintaining the symmetry of Myo1 ring constriction during cytokinesis and that Hof1 interacts with Chs2, a chitin synthase that is required for primary septum formation. Together these data define a mechanism that accounts for the localization of Hof1 during the cell cycle and suggest that Hof1 may function in cytokinesis by coupling actomyosin ring constriction to primary septum formation through interactions with Myo1 and Chs2.

scholarly journals Banp regulates DNA damage response and chromosome segregation during the cell cycle in zebrafish retina

2021 ◽  
Author(s):  
Swathy Babu ◽  
Yuki Takeuchi ◽  
Ichiro Masai
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Replication ◽  
Dna Damage Response ◽  
Chromosome Segregation ◽  
Cell Cycle Progression ◽  
Target Genes ◽  
Damage Response ◽  
Dna Damage Responses

Btg3-associated nuclear protein (Banp) was originally identified as a nuclear matrix-associated protein and it functions as a tumor suppressor. At molecular level, Banp regulates transcription of metabolic genes via a CGCG-containing motif called the Banp motif. However, its physiological roles in embryonic development are unknown. Here we report that Banp is indispensable for DNA damage response and chromosome segregation during mitosis. Zebrafish banp mutants show mitotic arrest and apoptosis in developing retina. We found that DNA replication stress and tp53-dependent DNA damage responses were activated to induce apoptosis in banp mutants, suggesting that Banp is required for integrity of DNA replication and DNA damage repair. Furthermore, in banp mutants, chromosome segregation was not smoothly processed from prometaphase to anaphase, leading to a prolonged M-phase. Our RNA- and ATAC-sequencing identified 31 candidates for direct Banp target genes that carry the Banp motif. Interestingly, two chromosome segregation regulators, cenpt and ncapg, are included in this list. Thus, Banp directly regulates transcription of cenpt and ncapg to promote chromosome segregation during mitosis. Our findings provide the first in vivo evidence that Banp is required for cell-cycle progression and cell survival by regulating DNA damage responses and chromosome segregation during mitosis.

scholarly journals Activation of a signaling pathway by the physical translocation of a chromosome

2021 ◽  
Author(s):  
Mathilde Guzzo ◽  
Allen G. Sanderlin ◽  
Lennice K. Castro ◽  
Michael T. Laub
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Replication ◽  
Signaling Pathway ◽  
Chromosome Segregation ◽  
Caulobacter Crescentus ◽  
Replication Initiation ◽  
Dna Replication Initiation ◽  
Cellular Processes ◽  
Initiation Of Dna Replication

AbstractIn every organism, the cell cycle requires the execution of multiple cellular processes in a strictly defined order. However, the mechanisms used to ensure such order remain poorly understood, particularly in bacteria. Here, we show that the activation of the essential CtrA signaling pathway that triggers cell division in Caulobacter crescentus is intrinsically coupled to the successful initiation of DNA replication via the physical translocation of a newly-replicated chromosome, powered by the ParABS system. We demonstrate that ParA accumulation at the new cell pole during chromosome segregation recruits ChpT, an intermediate component of the CtrA signaling pathway. ChpT is normally restricted from accessing the selective PopZ polar microdomain until the new chromosome and ParA arrive. Consequently, any disruption to DNA replication initiation prevents the recruitment of ChpT and, in turn, cell division. Collectively, our findings reveal how major cell-cycle events are coordinated in Caulobacter and, importantly, how the physical translocation of a chromosome triggers an essential signaling pathway.

scholarly journals Cep57 and Cep57L1 maintain centriole engagement in interphase to ensure centriole duplication cycle

2021 ◽  
Vol 220 (3) ◽  
Author(s):  
Kei K. Ito ◽  
Koki Watanabe ◽  
Haruki Ishida ◽  
Kyohei Matsuhashi ◽  
Takumi Chinen ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Copy Number ◽  
Cell Cycle Progression ◽  
Dependent Manner ◽  
Tight Control ◽  
Cycle Progression ◽  
Centriole Duplication ◽  
Duplication Cycle

Centrioles duplicate in interphase only once per cell cycle. Newly formed centrioles remain associated with their mother centrioles. The two centrioles disengage at the end of mitosis, which licenses centriole duplication in the next cell cycle. Therefore, timely centriole disengagement is critical for the proper centriole duplication cycle. However, the mechanisms underlying centriole engagement during interphase are poorly understood. Here, we show that Cep57 and Cep57L1 cooperatively maintain centriole engagement during interphase. Codepletion of Cep57 and Cep57L1 induces precocious centriole disengagement in interphase without compromising cell cycle progression. The disengaged daughter centrioles convert into centrosomes during interphase in a Plk1-dependent manner. Furthermore, the centrioles reduplicate and the centriole number increases, which results in chromosome segregation errors. Overall, these findings demonstrate that the maintenance of centriole engagement by Cep57 and Cep57L1 during interphase is crucial for the tight control of centriole copy number and thus for proper chromosome segregation.

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