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《Structure (London, England : 1993)》2020,28(1):44-53.e4
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《Cell cycle (Georgetown, Tex.)》2013,12(19):3369-3378
Centromeres are specialized chromatin domains where kinetochores assemble. Centromeres contain as a conserved feature nucleosomes that are composed of the canonical histones H2A, H2B and H4 and a centromere-specific histone H3 variant, known as CENP-A in humans and Cse4 in budding yeast. The incorporation of CENP-A homologs into centromeric chromatin is cell cycle regulated and is assisted by related assembly factors named Scm3 in yeast and HJURP in human cells. Here, we describe that the budding yeast Scm3 binds weakly to centromeres during interphase including S phase when Cse4 assembles into centromeres. In anaphase Scm3 then becomes 2.5-fold enriched at kinetochores where it is dynamic with a half recovery time t½ of 36 sec. In contrast, Cse4 is stably integrated into kinetochores. In addition, ten Scm3 molecules bind to a cluster of 16 kinetochores with 32 Cse4 molecules suggesting a 1:3 ratio at kinetochores between the two proteins. Analysis of conditional lethal scm3–1 mutant cells indicated that Scm3 participates in maintaining Cse4 at centromeres in anaphase. Thus, Scm3 interacts transiently with kinetochores in anaphase where it safeguards Cse4 even after its S phase incorporation into centromeres. 相似文献
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The human CENP-A centromeric nucleosome-associated complex 总被引:11,自引:0,他引:11
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Durand-Dubief M Ekwall K 《BioEssays : news and reviews in molecular, cellular and developmental biology》2008,30(6):526-529
The centromere is the region of the chromosome where the kinetochore forms. Kinetochores are the attachment sites for spindle microtubules that separate duplicated chromosomes in mitosis and meiosis. Kinetochore formation depends on a special chromatin structure containing the histone H3 variant CENP-A. The epigenetic mechanisms that maintain CENP-A chromatin throughout the cell cycle have been studied extensively but little is known about the mechanism that targets CENP-A to naked centromeric DNA templates. In a recent report published in Science, such de novo centromere assembly of CENP-A is shown to be dependent on heterochromatin and the RNA interference pathway. 相似文献
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Rafael Bernad 《Experimental cell research》2009,315(19):3233-582
Centromeres are the chromosomal loci that direct the formation of the kinetochores. These macromolecular assemblies mediate the interaction between chromosomes and spindle microtubules and thereby power chromosome movement during cell division. They are also the sites of extensive regulation of the chromosome segregation process. Except in the case of budding yeast, centromere identity does not rely on DNA sequence but on the presence of a special nucleosome that contains a histone H3 variant known as CenH3 or CENP-A (Centromere Protein A). It has been therefore proposed that CENP-A is the epigenetic mark of the centromere. Upon DNA replication the mark is diluted two-fold and must be replenished to maintain centromere identity. What distinguishes CENP-A nucleosomes from those containing histone H3, how CENP-A nucleosomes are incorporated specifically into centromeric chromatin, and how this incorporation is coordinated with other cell cycle events are key issues that have been the focus of intensive research over the last decade. Here we review some of the highlights of this research. 相似文献
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The composition and structure of centromeric nucleosomes, which contain the histone H3 variant CENP-A, is intensely debated. Two independent studies in this issue, in yeast and human cells, now suggest that CENP-A nucleosomes adopt different structures depending on the stage of the cell cycle. 相似文献
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Michael Mahler Liesbeth Maes Daniel Blockmans Rene Westhovens Xavier Bossuyt Gabriela Riemekasten Sandra Schneider Falk Hiepe Andreas Swart Irmgard Gürtler Karl Egerer Margrit Fooke Marvin J Fritzler 《Arthritis research & therapy》2010,12(3):1-14
Introduction
Anti-centromere antibodies (ACA) are useful biomarkers in the diagnosis of systemic sclerosis (SSc). ACA are found in 20 to 40% of SSc patients and, albeit with lower prevalence, in patients with other systemic autoimmune rheumatic diseases. Historically, ACA were detected by indirect immunofluorescence (IIF) on HEp-2 cells and confirmed by immunoassays using recombinant CENP-B. The objective of this study was to evaluate a novel CENP-A peptide ELISA.Methods
Sera collected from SSc patients (n = 334) and various other diseases (n = 619) and from healthy controls (n = 175) were tested for anti-CENP-A antibodies by the novel CENP-A enzyme linked immunosorbent assay (ELISA). Furthermore, ACA were determined in the disease cohorts by IIF (ImmunoConcepts, Sacramento, CA, USA), CENP-B ELISA (Dr. Fooke), EliA® CENP (Phadia, Freiburg, Germany) and line-immunoassay (LIA, Mikrogen, Neuried, Germany). Serological and clinical associations of anti-CENP-A with other autoantibodies were conducted in one participating centre. Inhibition experiments with either the CENP-A peptide or recombinant CENP-B were carried out to analyse the specificity of anti-CENP-A and -B antibodies.Results
The CENP-A ELISA results were in good agreement with other ACA detection methods. According to the kappa method, the qualitative agreements were: 0.73 (vs. IIF), 0.81 (vs. LIA), 0.86 (vs. CENP-B ELISA) and 0.97 (vs. EliA® CENP). The quantitative comparison between CENP-A and CENP-B ELISA using 265 samples revealed a correlation value of rho = 0.5 (by Spearman equation). The receiver operating characteristic analysis indicated that the discrimination between SSc patients (n = 131) and various controls (n = 134) was significantly better using the CENP-A as compared to CENP-B ELISA (P < 0.0001). Modified Rodnan skin score was significantly lower in the CENP-A negative group compared to the positive patients (P = 0.013). Inhibition experiments revealed no significant cross reactivity of anti-CENP-A and anti-CENP-B antibodies. Statistically relevant differences for gender ratio (P = 0.0103), specific joint involvement (Jaccoud) (P = 0.0006) and anti-phospholipid syndrome (P = 0.0157) between ACA positive SLE patients and the entire SLE cohort were observed.Conclusions
Anti-CENP-A antibodies as determined by peptide ELISA represent a sensitive, specific and independent marker for the detection of ACA and are useful biomarkers for the diagnosis of SSc. Our data suggest that anti-CENP-A antibodies are a more specific biomarker for SSc than antibodies to CENP-B. Furthers studies are required to verify these findings. 相似文献10.
Roshan L. Shrestha Austin Rossi Darawalee Wangsa Ann K. Hogan Kimberly S. Zaldana Evelyn Suva Yang Jo Chung Chelsea L. Sanders Simone Difilippantonio Tatiana S. Karpova Baktiar Karim Daniel R. Foltz Daniele Fachinetti Peter D. Aplan Thomas Ried Munira A. Basrai 《The Journal of cell biology》2021,220(4)
Chromosomal instability (CIN) is a hallmark of many cancers. Restricting the localization of centromeric histone H3 variant CENP-A to centromeres prevents CIN. CENP-A overexpression (OE) and mislocalization have been observed in cancers and correlate with poor prognosis; however, the molecular consequences of CENP-A OE on CIN and aneuploidy have not been defined. Here, we show that CENP-A OE leads to its mislocalization and CIN with lagging chromosomes and micronuclei in pseudodiploid DLD1 cells and xenograft mouse model. CIN is due to reduced localization of proteins to the kinetochore, resulting in defects in kinetochore integrity and unstable kinetochore–microtubule attachments. CENP-A OE contributes to reduced expression of cell adhesion genes and higher invasion of DLD1 cells. We show that CENP-A OE contributes to aneuploidy with karyotypic heterogeneity in human cells and xenograft mouse model. In summary, our results provide a molecular link between CENP-A OE and aneuploidy, and suggest that karyotypic heterogeneity may contribute to the aggressive phenotype of CENP-A–overexpressing cancers. 相似文献
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Bassett EA DeNizio J Barnhart-Dailey MC Panchenko T Sekulic N Rogers DJ Foltz DR Black BE 《Developmental cell》2012,22(4):749-762
Centromeres are defined by the presence of chromatin containing the histone H3 variant, CENP-A, whose assembly into nucleosomes requires the chromatin assembly factor HJURP. We find that whereas surface-exposed residues in the CENP-A targeting domain (CATD) are the primary sequence determinants for HJURP recognition, buried CATD residues that generate rigidity with H4 are also required for efficient incorporation into centromeres. HJURP contact points adjacent to the CATD on the CENP-A surface are not used for binding specificity but rather to transmit stability broadly throughout the histone fold domains of both CENP-A and H4. Furthermore, an intact CENP-A/CENP-A interface is a requirement for stable chromatin incorporation immediately upon HJURP-mediated assembly. These data offer insight into the mechanism by which HJURP discriminates CENP-A from bulk histone complexes and chaperones CENP-A/H4 for a substantial portion of the cell cycle prior to mediating chromatin assembly at the centromere. 相似文献
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The histone variant CENP-A and centromere specification 总被引:2,自引:0,他引:2
The centromere is the chromosomal locus that guides faithful inheritance. Centromeres are specified epigenetically, and the histone H3 variant CENP-A has emerged as the best candidate to carry the epigenetic centromere mark. Recent advances demonstrate the physical basis for this epigenetic mark whereby CENP-A confers conformational rigidity to the nucleosome it forms with other core histones. This nucleosome is recognized by a multisubunit complex of constitutive centromere proteins, termed the CENP-A(NAC). Evidence from two CENP-A relatives in diverse eukaryotes suggests that the histone complexes they form adopt highly unconventional arrangements on DNA. Centromere identity, itself, is propagated during mitotic exit and early G1, and it relies upon a cis-acting targeting domain within CENP-A and a proposed centromere 'priming' reaction. 相似文献
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《Journal of molecular biology》2021,433(6):166789
Centromeric loci of chromosomes are defined by nucleosomes containing the histone H3 variant CENP-A, which bind their DNA termini more permissively than their canonical counterpart, a feature that is critical for the mitotic fidelity. A recent cryo-EM study demonstrated that the DNA termini of CENP-A nucleosomes, reconstituted with the Widom 601 DNA sequence, are asymmetrically flexible, meaning one terminus is more clearly resolved than the other. However, an earlier work claimed that both ends could be resolved in the presence of two stabilizing single chain variable fragment (scFv) antibodies per nucleosome, and thus are likely permanently bound to the histone octamer. This suggests that the binding of scFv antibodies to the histone octamer surface would be associated with CENP-A nucleosome conformational changes, including stable binding of the DNA termini. Here, we present computational evidence that allows to explain at atomistic level the structural rearrangements of CENP-A nucleosomes resulting from the antibody binding. The antibodies, while they only bind the octamer façades, are capable of altering the dynamics of the nucleosomal core, and indirectly also the surrounding DNA. This effect has more drastic implications for the structure and the dynamics of the CENP-A nucleosome in comparison to its canonical counterpart. Furthermore, we find evidence that the antibodies bind the left and the right octamer façades at different affinities, another manifestation of the DNA sequence. We speculate that the cells could use induction of similar allosteric effects to control centromere function. 相似文献
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Centromere-specific nucleosomes are a central feature of the kinetochore complex during mitosis, in which microtubules exert pulling and pushing forces upon the centromere. CENP-A nucleosomes have been assumed to be structurally unique, thereby providing resilience under tension relative to their H3 canonical counterparts. Here, we directly test this hypothesis by subjecting CENP-A and H3 octameric nucleosomes, assembled on random or on centromeric DNA sequences, to varying amounts of applied force by using single-molecule magnetic tweezers. We monitor individual disassembly events of CENP-A and H3 nucleosomes. Regardless of the DNA sequence, the force-mediated disassembly experiments for CENP-A and H3 nucleosomes demonstrate similar rupture forces, life time residency and disassembly steps. From these experiments, we conclude that CENP-A does not, by itself, contribute unique structural features to the nucleosome that lead to a significant resistance against force-mediated disruption. The data present insights into the mechanistic basis for how CENP-A nucleosomes might contribute to the structural foundation of the centromere in vivo. 相似文献
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Michael McGregor Nirmala Hariharan Anya Joyo Robert L Margolis 《Cell cycle (Georgetown, Tex.)》2014,13(5):739-748
Centromere protein A (CENP-A) is a homolog of histone H3 that epigenetically marks the heterochromatin of chromosomes. CENP-A is a critical component of the cell cycle machinery that is necessary for proper assembly of the mitotic spindle. However, the role of CENP-A in the heart and cardiac progenitor cells (CPCs) has not been previously studied. This study shows that CENP-A is expressed in CPCs and declines with age. Silencing CENP-A results in a decreased CPC growth rate, reduced cell number in phase G2/M of the cell cycle, and increased senescence associated β-galactosidase activity. Lineage commitment is not affected by CENP-A silencing, suggesting that cell cycle arrest induced by loss of CENP-A is a consequence of senescence and not differentiation. CENP-A knockdown does not exacerbate cell death in undifferentiated CPCs, but increases apoptosis upon lineage commitment. Taken together, these results indicate that CPCs maintain relatively high levels of CENP-A early in life, which is necessary for sustaining proliferation, inhibiting senescence, and promoting survival following differentiation of CPCs. 相似文献
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Meghan C. Barnhart P. Henning J. L. Kuich Madison E. Stellfox Jared A. Ward Emily A. Bassett Ben E. Black Daniel R. Foltz 《The Journal of cell biology》2011,194(2):229-243
Centromeres of higher eukaryotes are epigenetically marked by the centromere-specific CENP-A nucleosome. New CENP-A recruitment requires the CENP-A histone chaperone HJURP. In this paper, we show that a LacI (Lac repressor) fusion of HJURP drove the stable recruitment of CENP-A to a LacO (Lac operon) array at a noncentromeric locus. Ectopically targeted CENP-A chromatin at the LacO array was sufficient to direct the assembly of a functional centromere as indicated by the recruitment of the constitutive centromere-associated network proteins, the microtubule-binding protein NDC80, and the formation of stable kinetochore–microtubule attachments. An amino-terminal fragment of HJURP was able to assemble CENP-A nucleosomes in vitro, demonstrating that HJURP is a chromatin assembly factor. Furthermore, HJURP recruitment to endogenous centromeres required the Mis18 complex. Together, these data suggest that the role of the Mis18 complex in CENP-A deposition is to recruit HJURP and that the CENP-A nucleosome assembly activity of HJURP is responsible for centromeric chromatin assembly to maintain the epigenetic mark. 相似文献