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CENP-A

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https://www.readbyqxmd.com/read/28220502/variations-on-a-nucleosome-theme-the-structural-basis-of-centromere-function
#1
Olga Moreno-Moreno, Mònica Torras-Llort, Fernando Azorín
The centromere is a specialized chromosomal structure that dictates kinetochore assembly and, thus, is essential for accurate chromosome segregation. Centromere identity is determined epigenetically by the presence of a centromere-specific histone H3 variant, CENP-A, that replaces canonical H3 in centromeric chromatin. Here, we discuss recent work by Roulland et al. that identifies structural elements of the nucleosome as essential determinants of centromere function. In particular, CENP-A nucleosomes have flexible DNA ends due to the short αN helix of CENP-A...
February 21, 2017: BioEssays: News and Reviews in Molecular, Cellular and Developmental Biology
https://www.readbyqxmd.com/read/28186195/cenp-a-chromatin-disassembly-in-stressed-and-senescent-murine-cells
#2
Sabrine Hédouin, Giacomo Grillo, Ivana Ivkovic, Guillaume Velasco, Claire Francastel
Centromeres are chromosomal domains essential for genomic stability. We report here the remarkable transcriptional and epigenetic perturbations at murine centromeres in genotoxic stress conditions. A strong and selective transcriptional activation of centromeric repeats is detected within hours. This is followed by disorganization of centromeres with striking delocalization of nucleosomal CENP-A, the key determinant of centromere identity and function, in a mechanism requiring active transcription of centromeric repeats, the DNA Damage Response (DDR) effector ATM and chromatin remodelers/histone chaperones...
February 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28167779/integrity-of-the-human-centromere-dna-repeats-is-protected-by-cenp-a-cenp-c-and-cenp-t
#3
Simona Giunta, Hironori Funabiki
Centromeres are highly specialized chromatin domains that enable chromosome segregation and orchestrate faithful cell division. Human centromeres are composed of tandem arrays of α-satellite DNA, which spans up to several megabases. Little is known about the mechanisms that maintain integrity of the long arrays of α-satellite DNA repeats. Here, we monitored centromeric repeat stability in human cells using chromosome-orientation fluorescent in situ hybridization (CO-FISH). This assay detected aberrant centromeric CO-FISH patterns consistent with sister chromatid exchange at the frequency of 5% in primary tissue culture cells, whereas higher levels were seen in several cancer cell lines and during replicative senescence...
February 6, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28158539/defects-in-methylation-of-arginine-37-on-cenp-a-cse4-are-compensated-by-the-ubiquitin-ligase-complex-ubr2-mub1
#4
Anke Samel, Thi Kim Loan Nguyen, Ann E Ehrenhofer-Murray
No abstract text is available yet for this article.
February 2, 2017: FEMS Yeast Research
https://www.readbyqxmd.com/read/28137567/mass-spectrometry-based-methodology-for-identification-of-native-histone-variant-modifications-from-mammalian-tissues-and-solid-tumors
#5
A G Nuccio, M Bui, Y Dalal, A Nita-Lazar
Histone posttranslational modifications (PTMs) are key epigenetic marks involved in gene silencing or activation. Histone modifications impact chromatin organization and transcriptional processes through the changes in charge density between histones and DNA. They also serve as recognition and binding sites for specific binding proteins. Histone tails and globular cores contain many basic amino acid residues, which are subject to various dynamic modifications, making the modification repertoire extremely diverse...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28094382/the-supercoiling-state-of-dna-determines-the-handedness-of-both-h3-and-cenp-a-nucleosomes
#6
R Vlijm, S H Kim, P L De Zwart, Y Dalal, C Dekker
Nucleosomes form the unit structure of the genome in eukaryotes, thereby constituting a fundamental tenet of chromatin biology. In canonical nucleosomes, DNA wraps around the histone octamer in a left-handed toroidal ramp. Here, in single-molecule magnetic tweezers studies of chaperone-assisted nucleosome assembly, we show that the handedness of the DNA wrapping around the nucleosome core is intrinsically ambidextrous, and depends on the pre-assembly supercoiling state of the DNA, i.e., it is not uniquely determined by the octameric histone core...
January 17, 2017: Nanoscale
https://www.readbyqxmd.com/read/28073008/cenp-a-modifications-on-ser68-and-lys124-are-dispensable-for-establishment-maintenance-and-long-term-function-of-human-centromeres
#7
Daniele Fachinetti, Glennis A Logsdon, Amira Abdullah, Evan B Selzer, Don W Cleveland, Ben E Black
CENP-A is a histone H3 variant key to epigenetic specification of mammalian centromeres. Using transient overexpression of CENP-A mutants, two recent reports in Developmental Cell proposed essential centromere functions for post-translational modifications of human CENP-A. Phosphorylation at Ser68 was proposed to have an essential role in CENP-A deposition at centromeres. Blockage of ubiquitination at Lys124 was proposed to abrogate localization of CENP-A to the centromere. Following gene inactivation and replacement in human cells, we demonstrate that CENP-A mutants that cannot be phosphorylated at Ser68 or ubiquitinated at Lys124 assemble efficiently at centromeres during G1, mediate early events in centromere establishment at an ectopic chromosomal locus, and maintain centromere function indefinitely...
January 9, 2017: Developmental Cell
https://www.readbyqxmd.com/read/28069312/centromeres-drive-a-hard-bargain
#8
REVIEW
Leah F Rosin, Barbara G Mellone
Centromeres are essential chromosomal structures that mediate the accurate distribution of genetic material during meiotic and mitotic cell divisions. In most organisms, centromeres are epigenetically specified and propagated by nucleosomes containing the centromere-specific H3 variant, centromere protein A (CENP-A). Although centromeres perform a critical and conserved function, CENP-A and the underlying centromeric DNA are rapidly evolving. This paradox has been explained by the centromere drive hypothesis, which proposes that CENP-A is undergoing an evolutionary tug-of-war with selfish centromeric DNA...
January 7, 2017: Trends in Genetics: TIG
https://www.readbyqxmd.com/read/28059702/cdk-regulated-dimerization-of-m18bp1-on-a-mis18-hexamer-is-necessary-for-cenp-a-loading
#9
Dongqing Pan, Kerstin Klare, Arsen Petrovic, Annika Take, Kai Walstein, Priyanka Singh, Arnaud Rondelet, Alexander W Bird, Andrea Musacchio
Centromeres are unique chromosomal loci that promote the assembly of kinetochores, macromolecular complexes that bind spindle microtubules during mitosis. In most organisms, centromeres lack defined genetic features. Rather, they are specified epigenetically by a centromere-specific histone H3 variant, CENP-A. The Mis18 complex, comprising the Mis18α:Mis18β subcomplex and M18BP1, is crucial for CENP-A homeostasis. It recruits the CENP-A-specific chaperone HJURP to centromeres and primes it for CENP-A loading...
January 6, 2017: ELife
https://www.readbyqxmd.com/read/28017591/a-dual-inhibitory-mechanism-sufficient-to-maintain-cell-cycle-restricted-cenp-a-assembly
#10
Ana Stankovic, Lucie Y Guo, João F Mata, Dani L Bodor, Xing-Jun Cao, Aaron O Bailey, Jeffrey Shabanowitz, Donald F Hunt, Benjamin A Garcia, Ben E Black, Lars E T Jansen
Chromatin featuring the H3 variant CENP-A at the centromere is critical for its mitotic function and epigenetic maintenance. Assembly of centromeric chromatin is restricted to G1 phase through inhibitory action of Cdk1/2 kinases in other phases of the cell cycle. Here, we identify the two key targets sufficient to maintain cell-cycle control of CENP-A assembly. We uncovered a single phosphorylation site in the licensing factor M18BP1 and a cyclin A binding site in the CENP-A chaperone, HJURP, that mediated specific inhibitory phosphorylation...
January 19, 2017: Molecular Cell
https://www.readbyqxmd.com/read/27940888/constitutive-centromere-associated-network-controls-centromere-drift-in-vertebrate-cells
#11
Tetsuya Hori, Naoko Kagawa, Atsushi Toyoda, Asao Fujiyama, Sadahiko Misu, Norikazu Monma, Fumiaki Makino, Kazuho Ikeo, Tatsuo Fukagawa
Centromeres are specified by sequence-independent epigenetic mechanisms, and the centromere position may drift at each cell cycle, but once this position is specified, it may not be frequently moved. Currently, it is unclear whether the centromere position is stable. To address this question, we systematically analyzed the position of nonrepetitive centromeres in 21 independent clones isolated from a laboratory stock of chicken DT40 cells using chromatin immunoprecipitation combined with massive parallel sequencing analysis with anti-CENP-A antibody...
January 2, 2017: Journal of Cell Biology
https://www.readbyqxmd.com/read/27918550/selective-y-centromere-inactivation-triggers-chromosome-shattering-in-micronuclei-and-repair-by-non-homologous-end-joining
#12
Peter Ly, Levi S Teitz, Dong H Kim, Ofer Shoshani, Helen Skaletsky, Daniele Fachinetti, David C Page, Don W Cleveland
Chromosome missegregation into a micronucleus can cause complex and localized genomic rearrangements known as chromothripsis, but the underlying mechanisms remain unresolved. Here we developed an inducible Y centromere-selective inactivation strategy by exploiting a CENP-A/histone H3 chimaera to directly examine the fate of missegregated chromosomes in otherwise diploid human cells. Using this approach, we identified a temporal cascade of events that are initiated following centromere inactivation involving chromosome missegregation, fragmentation, and re-ligation that span three consecutive cell cycles...
January 2017: Nature Cell Biology
https://www.readbyqxmd.com/read/27911702/the-unconventional-kinetoplastid-kinetochore-from-discovery-toward-functional-understanding
#13
REVIEW
Bungo Akiyoshi
The kinetochore is the macromolecular protein complex that drives chromosome segregation in eukaryotes. Its most fundamental function is to connect centromeric DNA to dynamic spindle microtubules. Studies in popular model eukaryotes have shown that centromere protein (CENP)-A is critical for DNA-binding, whereas the Ndc80 complex is essential for microtubule-binding. Given their conservation in diverse eukaryotes, it was widely believed that all eukaryotes would utilize these components to make up a core of the kinetochore...
October 15, 2016: Biochemical Society Transactions
https://www.readbyqxmd.com/read/27893298/replication-checkpoint-suppression-and-structure-of-centromeric-dna
#14
Francesco Romeo, Lucia Falbo, Vincenzo Costanzo
Human centromeres contain large amounts of repetitive DNA sequences known as α satellite DNA, which can be difficult to replicate and whose functional role is unclear. Recently, we have characterized protein composition, structural organization and checkpoint response to stalled replication forks of centromeric chromatin reconstituted in Xenopus laevis egg extract. We showed that centromeric DNA has high affinity for SMC2-4 subunits of condensins and for CENP-A, it is enriched for DNA repair factors and suppresses the ATR checkpoint to ensure its efficient replication...
November 2016: Nucleus
https://www.readbyqxmd.com/read/27880912/cenp-a-is-dispensable-for-mitotic-centromere-function-after-initial-centromere-kinetochore-assembly
#15
Sebastian Hoffmann, Marie Dumont, Viviana Barra, Peter Ly, Yael Nechemia-Arbely, Moira A McMahon, Solène Hervé, Don W Cleveland, Daniele Fachinetti
Human centromeres are defined by chromatin containing the histone H3 variant CENP-A assembled onto repetitive alphoid DNA sequences. By inducing rapid, complete degradation of endogenous CENP-A, we now demonstrate that once the first steps of centromere assembly have been completed in G1/S, continued CENP-A binding is not required for maintaining kinetochore attachment to centromeres or for centromere function in the next mitosis. Degradation of CENP-A prior to kinetochore assembly is found to block deposition of CENP-C and CENP-N, but not CENP-T, thereby producing defective kinetochores and failure of chromosome segregation...
November 22, 2016: Cell Reports
https://www.readbyqxmd.com/read/27858158/structure-of-centromere-chromatin-from-nucleosome-to-chromosomal-architecture
#16
REVIEW
Thomas Schalch, Florian A Steiner
The centromere is essential for the segregation of chromosomes, as it serves as attachment site for microtubules to mediate chromosome segregation during mitosis and meiosis. In most organisms, the centromere is restricted to one chromosomal region that appears as primary constriction on the condensed chromosome and is partitioned into two chromatin domains: The centromere core is characterized by the centromere-specific histone H3 variant CENP-A (also called cenH3) and is required for specifying the centromere and for building the kinetochore complex during mitosis...
November 17, 2016: Chromosoma
https://www.readbyqxmd.com/read/27820823/cenp-a-and-h3-nucleosomes-display-a-similar-stability-to-force-mediated-disassembly
#17
Sung Hyun Kim, Rifka Vlijm, Jaco van der Torre, Yamini Dalal, Cees Dekker
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...
2016: PloS One
https://www.readbyqxmd.com/read/27811920/acetylation-of-histone-h4-lysine-5-and-12-is-required-for-cenp-a-deposition-into-centromeres
#18
Wei-Hao Shang, Tetsuya Hori, Frederick G Westhorpe, Kristina M Godek, Atsushi Toyoda, Sadahiko Misu, Norikazu Monma, Kazuho Ikeo, Christopher W Carroll, Yasunari Takami, Asao Fujiyama, Hiroshi Kimura, Aaron F Straight, Tatsuo Fukagawa
Centromeres are specified epigenetically through the deposition of the centromere-specific histone H3 variant CENP-A. However, how additional epigenetic features are involved in centromere specification is unknown. Here, we find that histone H4 Lys5 and Lys12 acetylation (H4K5ac and H4K12ac) primarily occur within the pre-nucleosomal CENP-A-H4-HJURP (CENP-A chaperone) complex, before centromere deposition. We show that H4K5ac and H4K12ac are mediated by the RbAp46/48-Hat1 complex and that RbAp48-deficient DT40 cells fail to recruit HJURP to centromeres and do not incorporate new CENP-A at centromeres...
November 4, 2016: Nature Communications
https://www.readbyqxmd.com/read/27807043/hjurp-interaction-with-the-condensin-ii-complex-during-g1-promotes-cenp-a-deposition
#19
Meghan C Barnhart-Dailey, Prasad Trivedi, P Todd Stukenberg, Daniel R Foltz
Centromeric chromatin is required for kinetochore assembly during mitosis and accurate chromosome segregation. A unique nucleosome containing the histone H3-specific variant CENP-A is the defining feature of centromeric chromatin. In humans, CENP-A nucleosome deposition occurs in early G1 just after mitotic exit at the time when the CENP-A deposition machinery localizes to centromeres. The mechanism by which CENP-A is deposited onto an existing, condensed chromatin template is not understood. Here we identify the selective association of the CENP-A chaperone HJURP with the condensin II complex and not condensin I...
January 1, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/27794026/histone-h4-facilitates-the-proteolysis-of-the-budding-yeast-cenp-acse4-centromeric-histone-variant
#20
Gary M R Deyter, Erica M Hildebrand, Adrienne D Barber, Sue Biggins
The incorporation of histone variants into nucleosomes can alter chromatin-based processes. CENP-A is the histone H3 variant found exclusively at centromeres that serves as an epigenetic mark for centromere identity and is required for kinetochore assembly. CENP-A mislocalization to ectopic sites appears to contribute to genomic instability, transcriptional misregulation, and tumorigenesis, so mechanisms exist to ensure its exclusive localization to centromeres. One conserved process is proteolysis, which is mediated by the Psh1 E3 ubiquitin ligase in Saccharomyces cerevisiae (budding yeast)...
January 2017: Genetics
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