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Cytoskeleton (Hoboken, N.J.) Nov 2019Chromosome segregation is mediated by spindle microtubules that attach to the kinetochore via dynamic protein complexes, such as Ndc80, Ska, Cdt1 and ch-TOG during...
Chromosome segregation is mediated by spindle microtubules that attach to the kinetochore via dynamic protein complexes, such as Ndc80, Ska, Cdt1 and ch-TOG during mitotic metaphase. While experimental studies have previously shown that these proteins and protein complexes are all essential for maintaining a stable kinetochore-microtubule (kMT) interface, their exact roles in the mitotic metaphase remains elusive. In this study, we employed experimental and computational methods in order to characterize how these proteins can strengthen kMT attachments in both nonload-bearing and load-bearing conditions, typical of prometaphase and metaphase, respectively. Immunofluorescence staining of HeLa cells showed that the levels of Ska and Cdt1 significantly increased from prometaphase to metaphase, while levels of the Ndc80 complex remained unchanged. Our new computational model showed that by incorporating binding and unbinding of each protein complex coupled with a biased diffusion mechanism, the displacement of a possible complex formed by Ndc80-Ska-Cdt1 is significantly higher than that of Ndc80 alone or Ndc80-Ska. In addition, when we incorporate Ndc80/ch-TOG in the model, rupture force and time of attachment of the kMT interface increases. These results support the hypothesis that Ndc80-associated proteins strengthen kMT attachments, and that the interplay between kMT protein complexes in metaphase ensures stable attachments.
Topics: Cell Cycle Proteins; Chromosomal Proteins, Non-Histone; Computer Simulation; Cytoskeletal Proteins; HeLa Cells; Humans; Kinetochores; Metaphase; Microtubules; Mitosis; Protein Binding
PubMed: 31525284
DOI: 10.1002/cm.21562 -
Molecular Cell Dec 2011The spindle assembly checkpoint (SAC) restricts mitotic exit to cells that have completed chromosome-microtubule attachment. Cdc20 is a bifunctional protein. In complex...
The spindle assembly checkpoint (SAC) restricts mitotic exit to cells that have completed chromosome-microtubule attachment. Cdc20 is a bifunctional protein. In complex with SAC proteins Mad2, BubR1, and Bub3, Cdc20 forms the mitotic checkpoint complex (MCC), which binds the anaphase-promoting complex (APC/C) and inhibits its mitotic exit-promoting activity. When devoid of SAC proteins, Cdc20 serves as an APC/C coactivator and promotes mitotic exit. During mitotic arrest, Cdc20 is continuously degraded via ubiquitin-dependent proteolysis and resynthesized. It is believed that this cycle keeps the levels of Cdc20 below a threshold above which Cdc20 would promote mitotic exit. We report that p31(comet), a checkpoint antagonist, is necessary for mitotic destabilization of Cdc20. p31(comet) depletion stabilizes the MCC, super-inhibits the APC/C, and delays mitotic exit, indicating that Cdc20 proteolysis in prometaphase opposes the checkpoint. Our studies reveal a homeostatic network in which checkpoint-sustaining and -repressing forces oppose each other during mitotic arrest and suggest ways for enhancing the sensitivity of cancer cells to antitubulin chemotherapeutics.
Topics: Adaptor Proteins, Signal Transducing; Anaphase-Promoting Complex-Cyclosome; Cdc20 Proteins; Cell Cycle Proteins; HeLa Cells; Homeostasis; Humans; M Phase Cell Cycle Checkpoints; Mitosis; Nocodazole; Nuclear Proteins; Prometaphase; Ubiquitin-Protein Ligase Complexes
PubMed: 22152475
DOI: 10.1016/j.molcel.2011.11.014 -
BMC Psychiatry Mar 2022The World Health Organization (WHO) proposed COVID-19 vaccination as an emergent and important method to end the COVID-19 pandemic. Since China started vaccination...
Subjective health status: an easily available, independent, robust and significant predictive factor at the prometaphase of vaccination programs for the vaccination behavior of Chinese adults.
BACKGROUND
The World Health Organization (WHO) proposed COVID-19 vaccination as an emergent and important method to end the COVID-19 pandemic. Since China started vaccination programs in December 2020, vaccination has spread to provinces and municipalities nationwide. Previous research has focused on people's vaccination willingness and its influencing factors but has not examined vaccination behavior. We examine the effectiveness of psychosocial factors in predicting vaccination behavior.
METHODS
A cross-sectional online survey was performed among Chinese adults on 8 May and 4 June 2021. The statistical analysis of the data included univariate analysis, receiver operator characteristics (ROC) analysis and ordinal multiclassification logistic regression model analysis.
RESULTS
Of the 1300 respondents, 761 (58.5%) were vaccinated. Univariate analysis showed that a high education level and good subjective health status were protective factors for vaccination behavior, while suffering from chronic diseases was a risk factor. ROC analysis showed that subjective health status (AUC = 0.625, 95% CI: 0.594-0.656, P < 0.001) was the best predictor of vaccination behavior. Logistic regression analysis with subjective health status as a dependent variable indicated that older age, female sex, depression, neurasthenia, obsession, hypochondriasis and chronic disease were significant risk factors, while positive coping tendencies were a significant protective factor.
CONCLUSION
Our study found a simple and effective marker, subjective health status, that can predict vaccination behavior. This finding can guide future epidemic prevention work.
Topics: Adult; COVID-19; COVID-19 Vaccines; China; Cross-Sectional Studies; Diagnostic Self Evaluation; Female; Humans; Pandemics; Prometaphase; Vaccination
PubMed: 35287644
DOI: 10.1186/s12888-022-03830-5 -
Cell Cycle (Georgetown, Tex.) Sep 2019A single inner centromere protein (INCENP) found throughout eukaryotes modulates Aurora B kinase activity and chromosomal passenger complex (CPC) localization, which is...
A single inner centromere protein (INCENP) found throughout eukaryotes modulates Aurora B kinase activity and chromosomal passenger complex (CPC) localization, which is essential for timely mitotic progression. It has been proposed that INCENP might act as a rheostat to regulate Aurora B activity through mitosis, with successively higher activity threshold levels for chromosome alignment, the spindle checkpoint, anaphase spindle transfer and finally spindle elongation and cytokinesis. It remains mechanistically unclear how this would be achieved. Here, we reveal that the urochordate, , possesses two INCENP paralogs, which display distinct localizations and subfunctionalization in order to complete M-phase. INCENPa was localized on chromosome arms and centromeres by prometaphase, and modulated Aurora B activity to mediate H3S10/S28 phosphorylation, chromosome condensation, spindle assembly and transfer of the CPC to the central spindle. Polo-like kinase (Plk1) recruitment to CDK1 phosphorylated INCENPa was crucial for INCENPa-Aurora B enrichment on centromeres. The second paralog, INCENPb was enriched on centromeres from prometaphase, and relocated to the central spindle at anaphase onset. In the absence of INCENPa, meiotic spindles failed to form, and homologous chromosomes did not segregate. INCENPb was not required for early to mid M-phase events but became essential for the activity and localization of Aurora B on the central spindle and midbody during cytokinesis in order to allow abscission to occur. Together, our results demonstrate that INCENP paralog switching on centromeres modulates Aurora B kinase localization, thus chronologically regulating CPC functions during fast embryonic divisions in the urochordate . CCAN: constitutive centromere-associated network; CENPs: centromere proteins; cmRNA: capped messenger RNA; CPC: chromosomal passenger complex; INCENP: inner centromere protein; Plk1: polo-like kinase 1; PP1: protein phosphatase 1; PP2A: protein phosphatase 2A; SAC: spindle assembly checkpoint; SAH: single α-helix domain.
Topics: Aurora Kinase B; CDC2 Protein Kinase; Cell Cycle Proteins; Chromosomal Proteins, Non-Histone; Chromosome Segregation; Chromosomes; Cytokinesis; Humans; Kinetochores; Mitosis; Phosphorylation; Plankton; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Spindle Apparatus; Polo-Like Kinase 1
PubMed: 31306061
DOI: 10.1080/15384101.2019.1634954 -
Scientific Reports Apr 2018A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
Author Correction: Lateral attachment of kinetochores to microtubules is enriched in prometaphase rosette and facilitates chromosome alignment and bi-orientation establishment.
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.
PubMed: 29712957
DOI: 10.1038/s41598-018-25175-4 -
PloS One 2013Histone deacetylase inhibitors (HDACIs) have potent anti-cancer activity in a variety of cancer models. Understanding the molecular mechanisms involved in the...
Histone deacetylase inhibitors (HDACIs) have potent anti-cancer activity in a variety of cancer models. Understanding the molecular mechanisms involved in the therapeutic responsiveness of HDACI is needed before its clinical application. This study aimed to determine if a potent HDACI, LBH589 (Panobinostat), had differential therapeutic responsiveness towards LNCaP and PC-3 prostate cancer (PCa) cells. The former showed prometaphase arrest with subsequent apoptosis upon LBH589 treatment, while the latter was less sensitive and had late G2 arrest. The LBH589 treatment down-regulated HDAC6 and sustained ERK activation, and contributed to prometaphase arrest. Mechanistically, LBH589 inhibited HDAC6 activity, caused its dissociation from protein phosphatase PP1α, and increased 14-3-3ζ acetylation. Acetylated 14-3-3ζ released its mask effect on serine 259 of c-Raf and serine 216 of Cdc25C subsequent to de-phosphorylation by PP1α, which contributed to ERK activation. Enhanced ERK activity by LBH589 further down-regulated HDAC6 protein levels and sustained ERK activation by free-forward regulation. The sustained Cdc25C and ERK activation resulted in early M-phase (prometaphase) arrest and subsequent apoptosis in the most sensitive LNCaP cells but not in PC-3 cells. This study provides pre-clinical evidence that HDAC6 may serve as a sensitive therapeutic target in the treatment of prostate cancer with HDACI LBH589 for clinical translation. This study also posits a novel mechanism of HDAC6 participation in regulating the c-Raf-PP1-ERK signaling pathway and contributing to M phase cell-cycle transition.
Topics: 14-3-3 Proteins; Acetylation; Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Down-Regulation; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; G2 Phase Cell Cycle Checkpoints; Histone Deacetylase 6; Histone Deacetylase Inhibitors; Histone Deacetylases; Humans; Hydroxamic Acids; Indoles; M Phase Cell Cycle Checkpoints; Male; Panobinostat; Prostatic Neoplasms; Protein Phosphatase 1; Proto-Oncogene Proteins c-raf; Signal Transduction; cdc25 Phosphatases
PubMed: 24023871
DOI: 10.1371/journal.pone.0073401 -
PloS One 2017Mitotic prophase chromosome condensation plays an essential role in nuclear division being therefore regulated by highly conserved mechanisms. However, degrees of...
Mitotic prophase chromosome condensation plays an essential role in nuclear division being therefore regulated by highly conserved mechanisms. However, degrees of chromatin condensation in prophase-prometaphase cells may vary along the chromosomes resulting in specific condensation patterns. We examined different condensation patterns (CPs) of prophase and prometaphase chromosomes and investigated their relationship with genome size and distribution of histone H4 acetylated at lysine 5 (H4K5ac) in 17 plant species. Our results showed that most species with small genomes (2C < 5 pg) (Arachis pusilla, Bixa orellana, Costus spiralis, Eleutherine bulbosa, Indigofera campestris, Phaseolus lunatus, P. vulgaris, Poncirus trifoliata, and Solanum lycopersicum) displayed prophase chromosomes with late condensing terminal regions that were highly enriched in H4K5ac, and early condensing regions with apparently non-acetylated proximal chromatin. The species with large genomes (Allium cepa, Callisia repens, Araucaria angustifolia and Nothoscordum pulchellum) displayed uniformly condensed and acetylated prophase/prometaphase chromosomes. Three species with small genomes (Eleocharis geniculata, Rhynchospora pubera, and R. tenuis) displayed CP and H4K5ac labeling patterns similar to species with large genomes, whereas a forth species (Emilia sonchifolia) exhibited a gradual chromosome labeling, being more acetylated in the terminal regions and less acetylated in the proximal ones. The nucleolus organizer chromatin was the only chromosomal region that in prometaphase or metaphase could be hyperacetylated, hypoacetylated or non-acetylated, depending on the species. Our data indicate that the CP of a plant chromosome complement is influenced but not exclusively determined by nuclear and chromosomal DNA contents, whereas the CP of individual chromosomes is clearly correlated with H4K5ac distribution.
Topics: Acetylation; Chromatin Assembly and Disassembly; Chromosomes, Plant; Genome Size; Genome, Plant; Heterochromatin; Histones; Karyotyping; Plant Proteins; Plants; Prometaphase; Prophase; Protein Processing, Post-Translational; Species Specificity
PubMed: 28854212
DOI: 10.1371/journal.pone.0183341 -
Cells Jan 2023Conjugation with the small ubiquitin-like modifier (SUMO) modulates protein interactions and localisation. The kinase Aurora B, a key regulator of mitosis, was...
Conjugation with the small ubiquitin-like modifier (SUMO) modulates protein interactions and localisation. The kinase Aurora B, a key regulator of mitosis, was previously identified as a SUMOylation target in vitro and in assays with overexpressed components. However, where and when this modification genuinely occurs in human cells was not ascertained. Here, we have developed intramolecular Proximity Ligation Assays (PLA) to visualise SUMO-conjugated Aurora B in human cells in situ. We visualised Aurora B-SUMO products at centromeres in prometaphase and metaphase, which declined from anaphase onwards and became virtually undetectable at cytokinesis. In the mitotic window in which Aurora B/SUMO products are abundant, Aurora B co-localised and interacted with NUP358/RANBP2, a nucleoporin with SUMO ligase and SUMO-stabilising activity. Indeed, in addition to the requirement for the previously identified PIAS3 SUMO ligase, we found that NUP358/RANBP2 is also implicated in Aurora B-SUMO PLA product formation and centromere localisation. In summary, SUMOylation marks a distinctive window of Aurora B functions at centromeres in prometaphase and metaphase while being dispensable for functions exerted in cytokinesis, and RANBP2 contributes to this control, adding a novel layer to modulation of Aurora B functions during mitosis.
Topics: Humans; Centromere; Ligases; Mitosis; Molecular Chaperones; Nuclear Pore Complex Proteins; Protein Inhibitors of Activated STAT; Sumoylation
PubMed: 36766713
DOI: 10.3390/cells12030372 -
Molecular Biology of the Cell Nov 2018When untransformed human cells spend >1.5 h in prometaphase under standard culture conditions, all daughters arrest in G1 despite normal division of their mothers. We...
When untransformed human cells spend >1.5 h in prometaphase under standard culture conditions, all daughters arrest in G1 despite normal division of their mothers. We investigate what happens during prolonged prometaphase that leads to daughter cell arrest in the absence of DNA damage. We find that progressive loss of anti-apoptotic MCL-1 activity and oxidative stress act in concert to partially activate the apoptosis pathway, resulting in the delayed death of some daughters and senescence for the rest. At physiological oxygen levels, longer prometaphase durations are needed for all daughters to arrest. Partial activation of apoptosis during prolonged prometaphase leads to persistent caspase activity, which activates the kinase cascade mediating the post-mitotic activation of p38. This in turn activates p53, and the consequent expression of p21stops the cell cycle. This mechanism can prevent cells suffering intractable mitotic defects, which modestly prolong mitosis but allow its completion without DNA damage, from producing future cell generations that are susceptible to the evolution of a transformed phenotype.
Topics: Apoptosis; Caspase Inhibitors; Caspases; Cell Cycle Checkpoints; Cell Line; Cell Proliferation; Cellular Senescence; Enzyme Activation; Humans; Myeloid Cell Leukemia Sequence 1 Protein; Oxidative Stress; Oxygen; Prometaphase; Proto-Oncogene Proteins c-bcl-2; p38 Mitogen-Activated Protein Kinases
PubMed: 30133342
DOI: 10.1091/mbc.E18-01-0026 -
PLoS Genetics Aug 2011In many animal species the meiosis I spindle in oocytes is anastral and lacks centrosomes. Previous studies of Drosophila oocytes failed to detect the native form of the...
In many animal species the meiosis I spindle in oocytes is anastral and lacks centrosomes. Previous studies of Drosophila oocytes failed to detect the native form of the germline-specific γ-tubulin (γTub37C) in meiosis I spindles, and genetic studies have yielded conflicting data regarding the role of γTub37C in the formation of bipolar spindles at meiosis I. Our examination of living and fixed oocytes carrying either a null allele or strong missense mutation in the γtub37C gene demonstrates a role for γTub37C in the positioning of the oocyte nucleus during late prophase, as well as in the formation and maintenance of bipolar spindles in Drosophila oocytes. Prometaphase I spindles in γtub37C mutant oocytes showed wide, non-tapered spindle poles and disrupted positioning. Additionally, chromosomes failed to align properly on the spindle and showed morphological defects. The kinetochores failed to properly co-orient and often lacked proper attachments to the microtubule bundles, suggesting that γTub37C is required to stabilize kinetochore microtubule attachments in anastral spindles. Although spindle bipolarity was sometimes achieved by metaphase I in both γtub37C mutants, the resulting chromosome masses displayed highly disrupted chromosome alignment. Therefore, our data conclusively demonstrate a role for γTub37C in both the formation of the anastral meiosis I spindle and in the proper attachment of kinetochore microtubules. Finally, multispectral imaging demonstrates the presences of native γTub37C along the length of wild-type meiosis I spindles.
Topics: Animals; Cell Cycle Checkpoints; Chromosomes; Drosophila Proteins; Drosophila melanogaster; Female; Kinetochores; Male; Meiosis; Metaphase; Microtubules; Mutation, Missense; Oocytes; Prometaphase; Protein Binding; Spindle Apparatus; Tubulin
PubMed: 21852952
DOI: 10.1371/journal.pgen.1002209