scholarly journals Heat Stress Affects H3K9me3 Level at Human Alpha Satellite DNA Repeats

Genes ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 663
Author(s):  
Isidoro Feliciello ◽  
Antonio Sermek ◽  
Željka Pezer ◽  
Maja Matulić ◽  
Đurđica Ugarković
Keyword(s):  
Heat Stress ◽  
Satellite Dna ◽  
Constitutive Heterochromatin ◽  
Dna Repeats ◽  
Alpha Satellite ◽  
Satellite Dnas ◽  
Alpha Satellite Dna ◽  
Expression Of Genes ◽  
Insertion Sites ◽  
H3k9me3 Level

Satellite DNAs are tandemly repeated sequences preferentially assembled into large arrays within constitutive heterochromatin and their transcription is often activated by stress conditions, particularly by heat stress. Bioinformatic analyses of sequenced genomes however reveal single repeats or short arrays of satellite DNAs dispersed in the vicinity of genes within euchromatin. Here, we analyze transcription of a major human alpha satellite DNA upon heat stress and follow the dynamics of “silent” H3K9me3 and “active” H3K4me2/3 histone marks at dispersed euchromatic and tandemly arranged heterochromatic alpha repeats. The results show H3K9me3 enrichment at alpha repeats upon heat stress, which correlates with the dynamics of alpha satellite DNA transcription activation, while no change in H3K4me2/3 level is detected. Spreading of H3K9me3 up to 1–2 kb from the insertion sites of the euchromatic alpha repeats is detected, revealing the alpha repeats as modulators of local chromatin structure. In addition, expression of genes containing alpha repeats within introns as well as of genes closest to the intergenic alpha repeats is downregulated upon heat stress. Further studies are necessary to reveal the possible contribution of H3K9me3 enriched alpha repeats, in particular those located within introns, to the silencing of their associated genes.

CHARACTERIZATION OF HUMAN CHROMOSOMAL CONSTITUTIVE HETEROCHROMATIN

2020 ◽  
Vol 53 (02) ◽  
pp. 08-11
Author(s):  
Aytakin Hasanova
Keyword(s):  
Satellite Dna ◽  
Constitutive Heterochromatin ◽  
Chromosome Breakage ◽  
Centromeric Heterochromatin ◽  
Crossing Over ◽  
Alpha Satellite ◽  
Alpha Satellite Dna ◽  
Chromosome Regions ◽  
Chromosome Disjunction

Heterochromatin of centromeric chromosome regions contains late replicating, largely repetitive DNA. It is suggested that heterochromatin participates in chromosome pairing, crossing-over and in chromosome disjunction control (1,3). Centromeric heterochromatin, a variety of heterochromatin, is a tightly packed form of DNA.Centromeric heterochromatin is a constituent in the formation ofactive centromeres in most higher-order organisms; the domain exists on both mitotic and interphase chromosomes. (4,5,6,8) Centromeric heterochromatin is usually formed on alpha satellite DNA in humans; however, there have been cases where centric heterochromatin and centromeres have formed on originally euchromatin domains lacking alpha satellite DNA; this usually happens as a result of a chromosome breakage event and the formed centromere is called a neocentromere.

scholarly journals Evolutionary History of Alpha Satellite DNA Repeats Dispersed within Human Genome Euchromatin

2020 ◽  
Vol 12 (11) ◽  
pp. 2125-2138
Author(s):  
Isidoro Feliciello ◽  
Željka Pezer ◽  
Dušan Kordiš ◽  
Branka Bruvo Mađarić ◽  
Đurđica Ugarković
Keyword(s):  
Satellite Dna ◽  
Evolutionary History ◽  
Genomic Sequence ◽  
Sequence Divergence ◽  
Dna Repeats ◽  
Alpha Satellite ◽  
Alpha Satellite Dna ◽  
Satellite Repeats ◽  
Number Variation ◽  
History Of

Abstract Major human alpha satellite DNA repeats are preferentially assembled within (peri)centromeric regions but are also dispersed within euchromatin in the form of clustered or short single repeat arrays. To study the evolutionary history of single euchromatic human alpha satellite repeats (ARs), we analyzed their orthologous loci across the primate genomes. The continuous insertion of euchromatic ARs throughout the evolutionary history of primates starting with the ancestors of Simiformes (45–60 Ma) and continuing up to the ancestors of Homo is revealed. Once inserted, the euchromatic ARs were stably transmitted to the descendant species, some exhibiting copy number variation, whereas their sequence divergence followed the species phylogeny. Many euchromatic ARs have sequence characteristics of (peri)centromeric alpha repeats suggesting heterochromatin as a source of dispersed euchromatic ARs. The majority of euchromatic ARs are inserted in the vicinity of other repetitive elements such as L1, Alu, and ERV or are embedded within them. Irrespective of the insertion context, each AR insertion seems to be unique and once inserted, ARs do not seem to be subsequently spread to new genomic locations. In spite of association with (retro)transposable elements, there is no indication that such elements play a role in ARs proliferation. The presence of short duplications at most of ARs insertion sites suggests site-directed recombination between homologous motifs in ARs and in the target genomic sequence, probably mediated by extrachromosomal circular DNA, as a mechanism of spreading within euchromatin.

scholarly journals Distinct Regulation of the Expression of Satellite DNAs in the Beetle Tribolium castaneum

2020 ◽  
Vol 22 (1) ◽  
pp. 296
Author(s):  
Antonio Sermek ◽  
Isidoro Feliciello ◽  
Đurđica Ugarković
Keyword(s):  
Heat Stress ◽  
Tribolium Castaneum ◽  
Satellite Dna ◽  
Centromeric Heterochromatin ◽  
Satellite Dnas ◽  
Major Satellite ◽  
Satellite Repeats ◽  
Satellite Rnas ◽  
H3k9me3 Level ◽  
A Minor

In the flour beetle, Tribolium castaneum (peri)centromeric heterochromatin is mainly composed of a major satellite DNA TCAST1 interspersed with minor satellites. With the exception of heterochromatin, clustered satellite repeats are found dispersed within euchromatin. In order to uncover a possible satellite DNA function within the beetle genome, we analysed the expression of the major TCAST1 and a minor TCAST2 satellite during the development and upon heat stress. The results reveal that TCAST1 transcription was strongly induced at specific embryonic stages and upon heat stress, while TCAST2 transcription is stable during both processes. TCAST1 transcripts are processed preferentially into piRNAs during embryogenesis and into siRNAs during later development, contrary to TCAST2 transcripts, which are processed exclusively into piRNAs. In addition, increased TCAST1 expression upon heat stress is accompanied by the enrichment of the silent histone mark H3K9me3 on the major satellite, while the H3K9me3 level at TCAST2 remains unchanged. The transcription of the two satellites is proposed to be affected by the chromatin state: heterochromatin and euchromatin, which are assumed to be the prevalent sources of TCAST1 and TCAST2 transcripts, respectively. In addition, distinct regulation of the expression might be related to diverse roles that major and minor satellite RNAs play during the development and stress response.

On the mode of evolution of alpha satellite DNA in human populations

1991 ◽  
Vol 33 (1) ◽  
pp. 42-48 ◽  
Author(s):  
B. Marçais ◽  
J. P. Charlieu ◽  
B. Allain ◽  
E. Brun ◽  
M. Bellis ◽  
...  
Keyword(s):  
Satellite Dna ◽  
Human Populations ◽  
Alpha Satellite ◽  
Alpha Satellite Dna

scholarly journals Partial deletion of alpha satellite DNA associated with reduced amounts of the centromere protein CENP-B in a mitotically stable human chromosome rearrangement.

1990 ◽  
Vol 10 (12) ◽  
pp. 6374-6380 ◽  
Author(s):  
R Wevrick ◽  
W C Earnshaw ◽  
P N Howard-Peebles ◽  
H F Willard
Keyword(s):  
Human Chromosome ◽  
Satellite Dna ◽  
Centromeric Region ◽  
Chromosome Rearrangement ◽  
Specific Antigen ◽  
Chromosome 17 ◽  
Alpha Satellite ◽  
Protein Antigens ◽  
Alpha Satellite Dna ◽  
Human Chromosome 17

A familial, constitutionally rearranged human chromosome 17 is deleted for much of the DNA in its centromeric region but retains full mitotic centromere activity. Fluorescence in situ hybridization, pulsed-field gel electrophoresis, and Southern blot analysis of the residual centromeric region revealed a approximately 700-kb centromeric array of tandemly repeated alpha satellite DNA that was only approximately 20 to 30% as large as a normal array. This deletion was associated with a reduction in the amount of the centromere-specific antigen CENP-B detected by indirect immunofluorescence. The coincidence of the primary constriction, the small residual array of alpha satellite DNA, and the reduced amount of detectable CENP-B support the hypothesis that CENP-B is associated with alpha satellite DNA. Furthermore, the finding that both the deleted chromosome 17 and its derivative supernumerary fragment retained mitotic function and possess centromeric protein antigens suggests that human centromeres are structurally and functionally repetitive.

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