RESUMO
The high incidence of whole-arm chromosome aneuploidy and translocations in tumors suggests instability of centromeres, unique loci built on repetitive sequences and essential for chromosome separation. The causes behind this fragility and the mechanisms preserving centromere integrity remain elusive. We show that replication stress, hallmark of pre-cancerous lesions, promotes centromeric breakage in mitosis, due to spindle forces and endonuclease activities. Mechanistically, we unveil unique dynamics of the centromeric replisome distinct from the rest of the genome. Locus-specific proteomics identifies specialized DNA replication and repair proteins at centromeres, highlighting them as difficult-to-replicate regions. The translesion synthesis pathway, along with other factors, acts to sustain centromere replication and integrity. Prolonged stress causes centromeric alterations like ruptures and translocations, as observed in ovarian cancer models experiencing replication stress. This study provides unprecedented insights into centromere replication and integrity, proposing mechanistic insights into the origins of centromere alterations leading to abnormal cancerous karyotypes.
Assuntos
Centrômero , Sequências Repetitivas de Ácido Nucleico , Humanos , Centrômero/genética , Mitose/genética , Instabilidade GenômicaRESUMO
Chromosome inheritance depends on centromeres, epigenetically specified regions of chromosomes. While conventional human centromeres are known to be built of long tandem DNA repeats, much of their architecture remains unknown. Using single-molecule techniques such as AFM, nanopores, and optical tweezers, we find that human centromeric DNA exhibits complex DNA folds such as local hairpins. Upon binding to a specific sequence within centromeric regions, the DNA-binding protein CENP-B compacts centromeres by forming pronounced DNA loops between the repeats, which favor inter-chromosomal centromere compaction and clustering. This DNA-loop-mediated organization of centromeric chromatin participates in maintaining centromere position and integrity upon microtubule pulling during mitosis. Our findings emphasize the importance of DNA topology in centromeric regulation and stability.
Assuntos
Centrômero , Proteínas Cromossômicas não Histona , Autoantígenos/genética , Autoantígenos/metabolismo , Centrômero/genética , Centrômero/metabolismo , Proteína Centromérica A/genética , Proteína Centromérica A/metabolismo , Cromatina , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , DNA/genética , HumanosRESUMO
Centromeres are key elements for chromosome segregation. Canonical centromeres are built over long-stretches of tandem repetitive arrays. Despite being quite abundant compared to other loci, centromere sequences overall still represent only 2 to 5% of the human genome, therefore studying their genetic and epigenetic features is a major challenge. Furthermore, sequencing of centromeric regions requires high coverage to fully analyze length and sequence variations, and this can be extremely costly. To bypass these issues, we have developed a technique, named CenRICH, to enrich for centromeric DNA from human cells based on selective restriction digestion and size fractionation. Combining restriction enzymes cutting at high frequency throughout the genome, except within most human centromeres, with size-selection of fragments >20 kb, resulted in over 25-fold enrichment in centromeric DNA. High-throughput sequencing revealed that up to 60% of the DNA in the enriched samples is made of centromeric repeats. We show that this method can be used in combination with long-read sequencing to investigate the DNA methylation status of certain centromeres and, with a specific enzyme combination, also of their surrounding regions (mainly HSATII). Finally, we show that CenRICH facilitates single-molecule analysis of replicating centromeric fibers by DNA combing. This approach has great potential for making sequencing of centromeric DNA more affordable and efficient and for single DNA molecule studies.
Assuntos
Centrômero , DNA , Centrômero/genética , Segregação de Cromossomos , DNA/genética , HumanosRESUMO
Centromeres are built on repetitive DNA sequences (CenDNA) and a specific chromatin enriched with the histone H3 variant CENP-A, the epigenetic mark that identifies centromere position. Here, we interrogate the importance of CenDNA in centromere specification by developing a system to rapidly remove and reactivate CENP-A (CENP-AOFF/ON ). Using this system, we define the temporal cascade of events necessary to maintain centromere position. We unveil that CENP-B bound to CenDNA provides memory for maintenance on human centromeres by promoting de novo CENP-A deposition. Indeed, lack of CENP-B favors neocentromere formation under selective pressure. Occasionally, CENP-B triggers centromere re-activation initiated by CENP-C, but not CENP-A, recruitment at both ectopic and native centromeres. This is then sufficient to initiate the CENP-A-based epigenetic loop. Finally, we identify a population of CENP-A-negative, CENP-B/C-positive resting CD4+ T cells capable to re-express and reassembles CENP-A upon cell cycle entry, demonstrating the physiological importance of the genetic memory.
Assuntos
Linfócitos T CD4-Positivos/metabolismo , Proteína Centromérica A/metabolismo , Proteína B de Centrômero/metabolismo , Centrômero/metabolismo , Proteínas Cromossômicas não Histona/metabolismo , Segregação de Cromossomos , Nucleossomos/genética , Linfócitos T CD4-Positivos/citologia , Sistemas CRISPR-Cas , Ciclo Celular , Linhagem Celular Tumoral , Centrômero/genética , Segregação de Cromossomos/genética , Biologia Computacional , Epigênese Genética , Marcação de Genes , Humanos , Hibridização in Situ Fluorescente , Nucleossomos/metabolismo , RNA Interferente PequenoRESUMO
Intrinsic genomic features of individual chromosomes can contribute to chromosome-specific aneuploidy. Centromeres are key elements for the maintenance of chromosome segregation fidelity via a specialized chromatin marked by CENP-A wrapped by repetitive DNA. These long stretches of repetitive DNA vary in length among human chromosomes. Using CENP-A genetic inactivation in human cells, we directly interrogate if differences in the centromere length reflect the heterogeneity of centromeric DNA-dependent features and whether this, in turn, affects the genesis of chromosome-specific aneuploidy. Using three distinct approaches, we show that mis-segregation rates vary among different chromosomes under conditions that compromise centromere function. Whole-genome sequencing and centromere mapping combined with cytogenetic analysis, small molecule inhibitors, and genetic manipulation revealed that inter-chromosomal heterogeneity of centromeric features, but not centromere length, influences chromosome segregation fidelity. We conclude that faithful chromosome segregation for most of human chromosomes is biased in favor of centromeres with high abundance of DNA-dependent centromeric components. These inter-chromosomal differences in centromere features can translate into non-random aneuploidy, a hallmark of cancer and genetic diseases.
Assuntos
Aneuploidia , Proteína Centromérica A/metabolismo , Centrômero/metabolismo , Cromatina/metabolismo , Cromossomos Humanos/genética , DNA/metabolismo , Células Cultivadas , Centrômero/genética , Proteína Centromérica A/genética , Cromatina/genética , Segregação de Cromossomos , DNA/genética , Feminino , Humanos , MasculinoRESUMO
Specialized topoisomerases solve the topological constraints arising when replication forks encounter transcription. We have investigated the contribution of Top2 in S phase transcription. Specifically in S phase, Top2 binds intergenic regions close to transcribed genes. The Top2-bound loci exhibit low nucleosome density and accumulate gammaH2A when Top2 is defective. These intergenic loci associate with the HMG protein Hmo1 throughout the cell cycle and are refractory to the histone variant Htz1. In top2 mutants, Hmo1 is deleterious and accumulates at pericentromeric regions in G2/M. Our data indicate that Top2 is dispensable for transcription and that Hmo1 and Top2 bind in the proximity of genes transcribed in S phase suppressing chromosome fragility at the M-G1 transition. We propose that an Hmo1-dependent epigenetic signature together with Top2 mediate an S phase architectural pathway to preserve genome integrity.
Assuntos
Replicação do DNA , DNA Topoisomerases Tipo II/metabolismo , Proteínas de Grupo de Alta Mobilidade/metabolismo , Fase S , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Transcrição Gênica , Fragilidade Cromossômica , Epigênese Genética , Genoma Fúngico , RNA Polimerase II/metabolismo , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/enzimologiaRESUMO
Chromosome segregation relies on centromeres, yet their repetitive DNA is often prone to aberrant rearrangements under pathological conditions. Factors that maintain centromere integrity to prevent centromere-associated chromosome translocations are unknown. Here, we demonstrate the importance of the centromere-specific histone H3 variant CENP-A in safeguarding DNA replication of alpha-satellite repeats to prevent structural aneuploidy. Rapid removal of CENP-A in S phase, but not other cell-cycle stages, caused accumulation of R loops with increased centromeric transcripts, and interfered with replication fork progression. Replication without CENP-A causes recombination at alpha-satellites in an R loop-dependent manner, unfinished replication, and anaphase bridges. In turn, chromosome breakage and translocations arise specifically at centromeric regions. Our findings provide insights into how specialized centromeric chromatin maintains the integrity of transcribed noncoding repetitive DNA during S phase.
Assuntos
Aneuploidia , Proteína Centromérica A/metabolismo , Centrômero/metabolismo , Cromatina/metabolismo , Cromossomos Humanos/metabolismo , Replicação do DNA , Linhagem Celular , Centrômero/genética , Proteína Centromérica A/genética , Cromatina/genética , Cromossomos Humanos/genética , Humanos , Fase SRESUMO
During mitosis, sister chromatids attach to microtubules which generate ~ 700 pN pulling force focused on the centromere. We report that chromatin-localized signals generated by Polo-like kinase 1 (Plk1) maintain the integrity of the kinetochore and centromere against this force. Without sufficient Plk1 activity, chromosomes become misaligned after normal condensation and congression. These chromosomes are silent to the mitotic checkpoint, and many lag and mis-segregate in anaphase. Their centromeres and kinetochores lack CENP-A, CENP-C, CENP-T, Hec1, Nuf2, and Knl1; however, CENP-B is retained. CENP-A loss occurs coincident with secondary misalignment and anaphase onset. This disruption occurs asymmetrically prior to anaphase and requires tension generated by microtubules. Mechanistically, centromeres highly recruit PICH DNA helicase and PICH depletion restores kinetochore disruption in pre-anaphase cells. Furthermore, anaphase defects are significantly reduced by tethering Plk1 to chromatin, including H2B, and INCENP, but not to CENP-A. Taken as a whole, this demonstrates that Plk1 signals are crucial for stabilizing centromeric architecture against tension.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Cinetocoros/metabolismo , Microtúbulos/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Fenômenos Biomecânicos , Linhagem Celular , Proteína Centromérica A/metabolismo , Cromossomos Humanos/metabolismo , Fragmentação do DNA , DNA Helicases/metabolismo , Humanos , Modelos Biológicos , Quinase 1 Polo-LikeRESUMO
The centromere is the nucleoproteic chromosomal structure necessary for accurate chromosome segregation during cell division. One of the earliest centromeric proteins to be discovered was CENP-B, the only one capable of recognizing a specific centromeric DNA binding motif. The phylogenetic history of this protein and of its DNA binding site shows independent events of function acquisition across different species and raises questions on the evolutionary dynamics of CENP-B, including what may be the selective advantage provided by its role at the centromere. Recent results have provided insight into potential functions of CENP-B in chromosome dynamics, however, its function is still object of debate. The recurrent appearance of CENP-B centromeric activity along phylogenesis, together with its dispensability, represent strictly intertwined facets of this controversy. This chapter focuses on the evolution, function and homeostasis of CENP-B and its importance in centromere biology.
Assuntos
Proteína B de Centrômero/genética , Centrômero/metabolismo , DNA/genética , Eucariotos/genética , Evolução Molecular , Animais , Sítios de Ligação , Divisão Celular , Centrômero/ultraestrutura , Proteína B de Centrômero/metabolismo , Segregação de Cromossomos , DNA/metabolismo , Eucariotos/classificação , Eucariotos/metabolismo , Células Eucarióticas/citologia , Células Eucarióticas/metabolismo , Expressão Gênica , Humanos , Motivos de Nucleotídeos , Filogenia , Ligação ProteicaRESUMO
The mitotic checkpoint acts to maintain chromosome content by generation of a diffusible anaphase inhibitor. Unattached kinetochores catalyze a conformational shift in Mad2, converting an inactive open form into a closed form that can capture Cdc20, the mitotic activator of the APC/C ubiquitin ligase. Mad2 binding is now shown to promote a functional switch in Cdc20, exposing a previously inaccessible site for binding to BubR1's conserved Mad3 homology domain. BubR1, but not Mad2, binding to APC/C(Cdc20) is demonstrated to inhibit ubiquitination of cyclin B. Closed Mad2 is further shown to catalytically amplify production of BubR1-Cdc20 without necessarily being part of the complex. Thus, the mitotic checkpoint is produced by a cascade of two catalytic steps: an initial step acting at unattached kinetochores to produce a diffusible Mad2-Cdc20 intermediate and a diffusible step in which that intermediate amplifies production of BubR1-Cdc20, the inhibitor of cyclin B ubiquitination, by APC/C(Cdc20).
Assuntos
Proteínas de Ligação ao Cálcio/fisiologia , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/fisiologia , Pontos de Checagem da Fase M do Ciclo Celular/fisiologia , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Repressoras/fisiologia , Sítios de Ligação , Proteínas de Ligação ao Cálcio/metabolismo , Proteínas Cdc20 , Células HeLa , Humanos , Cinetocoros/metabolismo , Proteínas Mad2 , Modelos Genéticos , Proteínas Repressoras/metabolismoRESUMO
Centrioles organize the centrosome, and accurate control of their number is critical for the maintenance of genomic integrity. Centriole duplication occurs once per cell cycle and is controlled by Polo-like kinase 4 (Plk4). We showed previously that Plk4 phosphorylates itself to promote its degradation by the proteasome. Here we demonstrate that this autoregulated instability controls the abundance of endogenous Plk4. Preventing Plk4 autoregulation causes centrosome amplification, stabilization of p53, and loss of cell proliferation; moreover, suppression of p53 allows growth of cells carrying amplified centrosomes. Plk4 autoregulation thus guards against genome instability by limiting centrosome duplication to once per cell cycle.
Assuntos
Ciclo Celular/fisiologia , Centrossomo/fisiologia , Proteínas Serina-Treonina Quinases/metabolismo , Divisão Celular/genética , Linhagem Celular , Proliferação de Células , Estabilidade Enzimática/fisiologia , Marcação de Genes , Homeostase/fisiologia , Humanos , Proteínas Serina-Treonina Quinases/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
Chromosome replication initiates at multiple replicons and terminates when forks converge. In E. coli, the Tus-TER complex mediates polar fork converging at the terminator region, and aberrant termination events challenge chromosome integrity and segregation. Since in eukaryotes, termination is less characterized, we used budding yeast to identify the factors assisting fork fusion at replicating chromosomes. Using genomic and mechanistic studies, we have identified and characterized 71 chromosomal termination regions (TERs). TERs contain fork pausing elements that influence fork progression and merging. The Rrm3 DNA helicase assists fork progression across TERs, counteracting the accumulation of X-shaped structures. The Top2 DNA topoisomerase associates at TERs in S phase, and G2/M facilitates fork fusion and prevents DNA breaks and genome rearrangements at TERs. We propose that in eukaryotes, replication fork barriers, Rrm3, and Top2 coordinate replication fork progression and fusion at TERs, thus counteracting abnormal genomic transitions.
Assuntos
Antígenos de Neoplasias/metabolismo , Cromossomos Fúngicos , Replicação do DNA , DNA Topoisomerases Tipo II/metabolismo , DNA Fúngico/biossíntese , Proteínas de Ligação a DNA/metabolismo , Loci Gênicos , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Regiões Terminadoras Genéticas , Antígenos de Neoplasias/genética , Divisão Celular , Fragilidade Cromossômica , Quebras de DNA , DNA Helicases/metabolismo , DNA Topoisomerases Tipo II/genética , DNA Fúngico/química , Proteínas de Ligação a DNA/genética , Fase G2 , Rearranjo Gênico , Mutação , Conformação de Ácido Nucleico , Fase S , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/crescimento & desenvolvimento , Proteínas de Saccharomyces cerevisiae/genéticaRESUMO
The mitotic checkpoint (also known as the spindle assembly checkpoint) prevents premature anaphase onset through generation of an inhibitor of the E3 ubiquitin ligase APC/C, whose ubiquitination of cyclin B and securin targets them for degradation. Combining in vitro reconstitution and cell-based assays, we now identify dual mechanisms through which Bub3 promotes mitotic checkpoint signaling. Bub3 enhances signaling at unattached kinetochores not only by facilitating binding of BubR1 but also by enhancing Cdc20 recruitment to kinetochores mediated by BubR1's internal Cdc20 binding site. Downstream of kinetochore-produced complexes, Bub3 promotes binding of BubR1's conserved, amino terminal Cdc20 binding domain to a site in Cdc20 that becomes exposed by initial Mad2 binding. This latter Bub3-stimulated event generates the final mitotic checkpoint complex of Bub3-BubR1-Cdc20 that selectively inhibits ubiquitination of securin and cyclin B by APC/C(Cdc20). Thus, Bub3 promotes two distinct BubR1-Cdc20 interactions, involving each of the two Cdc20 binding sites of BubR1 and acting at unattached kinetochores or cytoplasmically, respectively, to facilitate production of the mitotic checkpoint inhibitor.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Pontos de Checagem da Fase M do Ciclo Celular/fisiologia , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais/fisiologia , Ciclossomo-Complexo Promotor de Anáfase/metabolismo , Sítios de Ligação/genética , Proteínas Cdc20/metabolismo , Proteínas de Ciclo Celular/genética , Linhagem Celular Tumoral , Ciclina B1/metabolismo , Recuperação de Fluorescência Após Fotodegradação , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Células HeLa , Humanos , Cinetocoros/metabolismo , Pontos de Checagem da Fase M do Ciclo Celular/genética , Microscopia de Fluorescência , Mutação , Proteínas de Ligação a Poli-ADP-Ribose , Ligação Proteica , Proteínas Serina-Treonina Quinases/genética , Interferência de RNA , Transdução de Sinais/genética , Imagem com Lapso de Tempo , UbiquitinaçãoAssuntos
Centrômero/química , Cromossomos Artificiais/química , Clonagem Molecular/métodos , Engenharia Genética/métodos , Terapia Genética/métodos , Vetores Genéticos/química , Animais , Instabilidade Cromossômica , Técnicas de Transferência de Genes , Humanos , Mamíferos/genética , Plantas/genética , Saccharomyces cerevisiae/genéticaRESUMO
Inducible degradation is a powerful approach for identifying the function of a specific protein or protein complex. Recently, a plant auxin-inducible degron (AID) system has been shown to degrade AID-tagged target proteins in nonplant cells. Here, we demonstrate that an AID-tagged protein can functionally replace an endogenous protein depleted by RNAi, leading to an inducible null phenotype rapidly after auxin addition. The AID system is shown to be capable of controlling the stability of AID-tagged proteins that are in either nuclear or cytoplasmic compartments and even when incorporated into protein complexes. Induced degradation occurs rapidly after addition of auxin with protein half-life reduced to as little as 9 min and proceeding to completion with first-order kinetics. AID-mediated instability is demonstrated to be rapidly reversible. Induced degradation is shown to initiate and continue in all cell cycle phases, including mitosis, making this system especially useful for identifying the function(s) of proteins of interest during specific points in the mammalian cell cycle.
Assuntos
Regulação da Expressão Gênica/genética , Ácidos Indolacéticos/metabolismo , Pontos de Checagem da Fase M do Ciclo Celular/fisiologia , Biologia Molecular/métodos , Proteínas/metabolismo , Proteólise , Linhagem Celular Tumoral , Meia-Vida , Humanos , Cinética , Pontos de Checagem da Fase M do Ciclo Celular/genética , Interferência de RNA , Proteínas Ligases SKP Culina F-Box/metabolismoRESUMO
Chromothripsis describes the catastrophic fragmentation of individual chromosomes followed by its haphazard reassembly into a derivative chromosome harboring complex rearrangements. This process can be initiated by mitotic cell division errors when one or more chromosomes aberrantly mis-segregate into micronuclei and acquire extensive DNA damage. Approaches to induce the formation of micronuclei encapsulating random chromosomes have been used; however, the eventual reincorporation of the micronucleated chromosome into daughter cell nuclei poses a challenge in tracking the chromosome for multiple cell cycles. Here we outline an approach to genetically engineer stable human cell lines capable of efficient chromosome-specific micronuclei induction. This strategy, which targets the CENP-B-deficient Y chromosome centromere for inactivation, allows the stepwise process of chromothripsis to be experimentally recapitulated, including the mechanisms and timing of chromosome fragmentation. Lastly, we describe the integration of a selection marker onto the micronucleated Y chromosome that enables the diverse genomic rearrangement landscape arising from micronuclei formation to be interrogated.
Assuntos
Cromotripsia , Humanos , Centrômero/genética , Divisão Celular , Núcleo Celular , Linhagem CelularRESUMO
DNA methylation is an essential epigenetic chromatin modification, and its maintenance in mammals requires the protein UHRF1. It is yet unclear if UHRF1 functions solely by stimulating DNA methylation maintenance by DNMT1, or if it has important additional functions. Using degron alleles, we show that UHRF1 depletion causes a much greater loss of DNA methylation than DNMT1 depletion. This is not caused by passive demethylation as UHRF1-depleted cells proliferate more slowly than DNMT1-depleted cells. Instead, bioinformatics, proteomics and genetics experiments establish that UHRF1, besides activating DNMT1, interacts with DNMT3A and DNMT3B and promotes their activity. In addition, we show that UHRF1 antagonizes active DNA demethylation by TET2. Therefore, UHRF1 has non-canonical roles that contribute importantly to DNA methylation homeostasis; these findings have practical implications for epigenetics in health and disease.
Assuntos
Metilação de DNA , Neoplasias , Humanos , Proteínas Estimuladoras de Ligação a CCAAT/genética , Proteínas Estimuladoras de Ligação a CCAAT/metabolismo , Cromatina , DNA (Citosina-5-)-Metiltransferase 1/genética , DNA (Citosina-5-)-Metiltransferase 1/metabolismo , Neoplasias/genética , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismoRESUMO
DNA methylation (DNAme) is a key epigenetic mark that regulates critical biological processes maintaining overall genome stability. Given its pleiotropic function, studies of DNAme dynamics are crucial, but currently available tools to interfere with DNAme have limitations and major cytotoxic side effects. Here, we present cell models that allow inducible and reversible DNAme modulation through DNMT1 depletion. By dynamically assessing whole genome and locus-specific effects of induced passive demethylation through cell divisions, we reveal a cooperative activity between DNMT1 and DNMT3B, but not of DNMT3A, to maintain and control DNAme. We show that gradual loss of DNAme is accompanied by progressive and reversible changes in heterochromatin, compartmentalization, and peripheral localization. DNA methylation loss coincides with a gradual reduction of cell fitness due to G1 arrest, with minor levels of mitotic failure. Altogether, this system allows DNMTs and DNA methylation studies with fine temporal resolution, which may help to reveal the etiologic link between DNAme dysfunction and human disease.
Assuntos
DNA (Citosina-5-)-Metiltransferase 1 , Metilação de DNA , DNA Metiltransferase 3A , Epigenômica , Humanos , Divisão Celular , Heterocromatina/genética , DNA (Citosina-5-)-Metiltransferase 1/genética , DNA Metiltransferase 3A/genética , Linhagem CelularRESUMO
The centromere is the fundamental unit for insuring chromosome inheritance. This complex region has a distinct type of chromatin in which histone H3 is replaced by a structurally different homologue identified in humans as CENP-A. In metazoans, specific DNA sequences are neither required nor sufficient for centromere identity. Rather, an epigenetic mark comprised of CENP-A containing chromatin is thought to be the major determinant of centromere identity. In this view, CENP-A deposition and chromatin assembly are fundamental processes for the maintenance of centromeric identity across mitotic and meiotic divisions. Several lines of evidence support CENP-A deposition in metazoans occurring at only one time in the cell cycle. Such cell cycle-dependent loading of CENP-A is found in divergent species from human to fission yeast, albeit with differences in the cell cycle point at which CENP-A is assembled. Cell cycle dependent CENP-A deposition requires multiple assembly factors for its deposition and maintenance. This review discusses the regulation of new CENP-A deposition and its relevance to centromere identity and inheritance.
Assuntos
Autoantígenos/metabolismo , Centrômero/genética , Cromatina/genética , Proteínas Cromossômicas não Histona/metabolismo , Replicação do DNA/fisiologia , Multimerização Proteica/genética , Animais , Autoantígenos/fisiologia , Centrômero/metabolismo , Proteína Centromérica A , Cromatina/metabolismo , Proteínas Cromossômicas não Histona/fisiologia , Replicação do DNA/genética , Humanos , Modelos Biológicos , Multimerização Proteica/fisiologia , Transdução de Sinais/genética , Transdução de Sinais/fisiologia , Fatores de Tempo , Distribuição TecidualRESUMO
In a recent issue of Cell, Bosco et al. present an innovative methodology named KaryoCreate that allows the generation of chromosome-specific aneuploidy in human cells in order to investigate the ontogenesis and the multifaceted aspects of aneuploidy in physio-pathological contexts.