scholarly journals H3K9me3 maintenance on a human artificial chromosome is required for segregation but not centromere epigenetic memory

2020 ◽  
Vol 133 (14) ◽  
pp. jcs242610 ◽  
Author(s):  
Nuno M. C. Martins ◽  
Fernanda Cisneros-Soberanis ◽  
Elisa Pesenti ◽  
Natalia Y. Kochanova ◽  
Wei-Hao Shang ◽  
...  
Keyword(s):  
De Novo ◽  
Artificial Chromosome ◽  
Human Artificial Chromosome ◽  
Chimeric Proteins ◽  
Epigenetic Memory ◽  
Chromatin Signature ◽  
Protein Levels ◽  
Centromere Function ◽  
Histone 3

ABSTRACTMost eukaryotic centromeres are located within heterochromatic regions. Paradoxically, heterochromatin can also antagonize de novo centromere formation, and some centromeres lack it altogether. In order to investigate the importance of heterochromatin at centromeres, we used epigenetic engineering of a synthetic alphoidtetO human artificial chromosome (HAC), to which chimeric proteins can be targeted. By tethering the JMJD2D demethylase (also known as KDM4D), we removed heterochromatin mark H3K9me3 (histone 3 lysine 9 trimethylation) specifically from the HAC centromere. This caused no short-term defects, but long-term tethering reduced HAC centromere protein levels and triggered HAC mis-segregation. However, centromeric CENP-A was maintained at a reduced level. Furthermore, HAC centromere function was compatible with an alternative low-H3K9me3, high-H3K27me3 chromatin signature, as long as residual levels of H3K9me3 remained. When JMJD2D was released from the HAC, H3K9me3 levels recovered over several days back to initial levels along with CENP-A and CENP-C centromere levels, and mitotic segregation fidelity. Our results suggest that a minimal level of heterochromatin is required to stabilize mitotic centromere function but not for maintaining centromere epigenetic memory, and that a homeostatic pathway maintains heterochromatin at centromeres.This article has an associated First Person interview with the first authors of the paper.

De novo CpG methylation on an artificial chromosome-like vector maintained for a long-term in mammalian cells

2015 ◽  
Vol 38 (4) ◽  
pp. 731-740 ◽  
Author(s):  
Keisuke Nishioka ◽  
Tsunao Kishida ◽  
Shinji Masui ◽  
Osam Mazda
Keyword(s):  
Mammalian Cells ◽  
De Novo ◽  
Artificial Chromosome ◽  
Cpg Methylation

scholarly journals Epigenetic engineering shows that a human centromere resists silencing mediated by H3K27me3/K9me3

2016 ◽  
Vol 27 (1) ◽  
pp. 177-196 ◽  
Author(s):  
Nuno M. C. Martins ◽  
Jan H. Bergmann ◽  
Nobuaki Shono ◽  
Hiroshi Kimura ◽  
Vladimir Larionov ◽  
...  
Keyword(s):  
Artificial Chromosome ◽  
Pericentric Heterochromatin ◽  
Human Artificial Chromosome ◽  
Chromatin State ◽  
Centromere Function ◽  
Human Centromere ◽  
Pattern Characteristic ◽  
Active Transcription ◽  
Centromere Inactivation ◽  
Apparent Resistance

Centromeres are characterized by the centromere-specific H3 variant CENP-A, which is embedded in chromatin with a pattern characteristic of active transcription that is required for centromere identity. It is unclear how centromeres remain transcriptionally active despite being flanked by repressive pericentric heterochromatin. To further understand centrochromatin’s response to repressive signals, we nucleated a Polycomb-like chromatin state within the centromere of a human artificial chromosome (HAC) by tethering the methyltransferase EZH2. This led to deposition of the H3K27me3 mark and PRC1 repressor binding. Surprisingly, this state did not abolish HAC centromere function or transcription, and this apparent resistance was not observed on a noncentromeric locus, where transcription was silenced. Directly tethering the reader/repressor PRC1 bypassed this resistance, inactivating the centromere. We observed analogous responses when tethering the heterochromatin Editor Suv39h1-methyltransferase domain (centromere resistance) or reader HP1α (centromere inactivation), respectively. Our results reveal that the HAC centromere can resist repressive pathways driven by H3K9me3/H3K27me3 and may help to explain how centromeres are able to resist inactivation by flanking heterochromatin.

scholarly journals Human artificial chromosome (HAC) vector provides long-term therapeutic transgene expression in normal human primary fibroblasts

Gene Therapy ◽  
2005 ◽  
Vol 12 (10) ◽  
pp. 852-856 ◽  
Author(s):  
M Kakeda ◽  
M Hiratsuka ◽  
K Nagata ◽  
Y Kuroiwa ◽  
M Kakitani ◽  
...  
Keyword(s):  
Transgene Expression ◽  
Artificial Chromosome ◽  
Human Artificial Chromosome ◽  
Primary Fibroblasts ◽  
Normal Human

scholarly journals 391. De Novo Human Artificial Chromosome Formation Is Predetermined by Initial Chromatin Assembly and Transcriptional Patterns after Transfection

2006 ◽  
Vol 13 ◽  
pp. S149
Author(s):  
Hiroshi Nakashima ◽  
Megumi Nakano ◽  
Ryoko Ohnishi ◽  
Yasushi Hiraoka ◽  
Yasufumi Kaneda ◽  
...  
Keyword(s):  
De Novo ◽  
Artificial Chromosome ◽  
Chromatin Assembly ◽  
Human Artificial Chromosome ◽  
Chromosome Formation

Assay of centromere function using a human artificial chromosome

Chromosoma ◽  
1998 ◽  
Vol 107 (6-7) ◽  
pp. 406-416 ◽  
Author(s):  
Hiroshi Masumoto ◽  
Masashi Ikeno ◽  
Megumi Nakano ◽  
Tuneko Okazaki ◽  
Brenda Grimes ◽  
...  
Keyword(s):  
Artificial Chromosome ◽  
Human Artificial Chromosome ◽  
Centromere Function

scholarly journals CENP-B creates alternative epigenetic chromatin states permissive for CENP-A or heterochromatin assembly

2020 ◽  
Vol 133 (15) ◽  
pp. jcs243303 ◽  
Author(s):  
Koichiro Otake ◽  
Jun-ichirou Ohzeki ◽  
Nobuaki Shono ◽  
Kazuto Kugou ◽  
Koei Okazaki ◽  
...  
Keyword(s):  
De Novo ◽  
Artificial Chromosome ◽  
Human Artificial Chromosome ◽  
Open Chromatin ◽  
Histone Chaperones ◽  
Satellite Dnas ◽  
Chromatin States ◽  
Heterochromatin Formation ◽  
Acidic Domain ◽  
Alphoid Dna

ABSTRACTCENP-B binds to CENP-B boxes on centromeric satellite DNAs (known as alphoid DNA in humans). CENP-B maintains kinetochore function through interactions with CENP-A nucleosomes and CENP-C. CENP-B binding to transfected alphoid DNA can induce de novo CENP-A assembly, functional centromere and kinetochore formation, and subsequent human artificial chromosome (HAC) formation. Furthermore, CENP-B also facilitates H3K9 (histone H3 lysine 9) trimethylation on alphoid DNA, mediated by Suv39h1, at ectopic alphoid DNA integration sites. Excessive heterochromatin invasion into centromere chromatin suppresses CENP-A assembly. It is unclear how CENP-B controls such different chromatin states. Here, we show that the CENP-B acidic domain recruits histone chaperones and many chromatin modifiers, including the H3K36 methylase ASH1L, as well as the heterochromatin components Suv39h1 and HP1 (HP1α, β and γ, also known as CBX5, CBX1 and CBX3, respectively). ASH1L facilitates the formation of open chromatin competent for CENP-A assembly on alphoid DNA. These results indicate that CENP-B is a nexus for histone modifiers that alternatively promote or suppress CENP-A assembly by mutually exclusive mechanisms. Besides the DNA-binding domain, the CENP-B acidic domain also facilitates CENP-A assembly de novo on transfected alphoid DNA. CENP-B therefore balances CENP-A assembly and heterochromatin formation on satellite DNA.

Is 3 years adequate for tracking completely occluded coiled aneurysms?

2020 ◽  
Vol 133 (3) ◽  
pp. 758-764
Author(s):  
Eung Koo Yeon ◽  
Young Dae Cho ◽  
Dong Hyun Yoo ◽  
Su Hwan Lee ◽  
Hyun-Seung Kang ◽  
...  
Keyword(s):  
De Novo ◽  
Careful Monitoring ◽  
Surveillance Period ◽  
Radiological Data ◽  
De Novo Aneurysm ◽  
Low Probability ◽  
Almost All ◽  
Annual Risk

OBJECTIVEThe authors conducted a study to ascertain the long-term durability of coiled aneurysms completely occluded at 36 months’ follow-up given the potential for delayed recanalization.METHODSIn this retrospective review, the authors examined 299 patients with 339 aneurysms, all shown to be completely occluded at 36 months on follow-up images obtained between 2011 and 2013. Medical records and radiological data acquired during the extended monitoring period (mean 74.3 ± 22.5 months) were retrieved, and the authors analyzed the incidence of (including mean annual risk) and risk factors for delayed recanalization.RESULTSA total of 5 coiled aneurysms (1.5%) occluded completely at 36 months showed recanalization (0.46% per aneurysm-year) during the long-term surveillance period (1081.9 aneurysm-years), 2 surfacing within 60 months and 3 developing thereafter. Four showed minor recanalization, with only one instance of major recanalization. The latter involved the posterior communicating artery as an apparent de novo lesion, arising at the neck of a firmly coiled sac, and was unrelated to coil compaction or growth. Additional embolization was undertaken. In a multivariate analysis, a second embolization for a recurrent aneurysm (HR = 22.088, p = 0.003) independently correlated with delayed recanalization.CONCLUSIONSAlmost all coiled aneurysms (98.5%) showing complete occlusion at 36 months postembolization proved to be stable during extended observation. However, recurrent aneurysms were predisposed to delayed recanalization. Given the low probability yet seriousness of delayed recanalization and the possibility of de novo aneurysm formation, careful monitoring may be still considered in this setting but at less frequent intervals beyond 36 months.

scholarly journals A unique histone 3 lysine 14 chromatin signature underlies tissue-specific gene regulation

2021 ◽  
Author(s):  
Isabel Regadas ◽  
Olle Dahlberg ◽  
Roshan Vaid ◽  
Oanh Ho ◽  
Sergey Belikov ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Specific Gene ◽  
Chromatin Signature ◽  
Tissue Specific ◽  
Tissue Specific Gene ◽  
Histone 3
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