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Centromere sliding on a mammalian chromosome.

Purgato S, Belloni E, Piras FM, Zoli M, Badiale C, Cerutti F, Mazzagatti A, Perini G, Della Valle G, Nergadze SG, Sullivan KF, Raimondi E, Rocchi M, Giulotto E - Chromosoma (2014)

Bottom Line: Examination of the ten instances of chromosome 11 in the five individuals revealed seven distinct 'positional alleles', each one extending for about 80-160 kb, were found across a region of about 500 kb.Our results demonstrate that CENP-A binding domains are autonomous relative to the underlying DNA sequence and are characterized by positional instability causing the sliding of centromere position.We propose that this dynamic behaviour may be common in mammalian centromeres and may determine the establishment of epigenetic alleles.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Farmacia e Biotecnologie (FABIT), Università di Bologna, Bologna, Italy.

ABSTRACT
The centromere directs the segregation of chromosomes during mitosis and meiosis. It is a distinct genetic locus whose identity is established through epigenetic mechanisms that depend on the deposition of centromere-specific centromere protein A (CENP-A) nucleosomes. This important chromatin domain has so far escaped comprehensive molecular analysis due to its typical association with highly repetitive satellite DNA. In previous work, we discovered that the centromere of horse chromosome 11 is completely devoid of satellite DNA; this peculiar feature makes it a unique model to dissect the molecular architecture of mammalian centromeres. Here, we exploited this native satellite-free centromere to determine the precise localization of its functional domains in five individuals: We hybridized DNA purified from chromatin immunoprecipitated with an anti CENP-A antibody to a high resolution array (ChIP-on-chip) of the region containing the primary constriction of horse chromosome 11. Strikingly, each individual exhibited a different arrangement of CENP-A binding domains. We then analysed the organization of each domain using a single nucleotide polymorphism (SNP)-based approach and single molecule analysis on chromatin fibres. Examination of the ten instances of chromosome 11 in the five individuals revealed seven distinct 'positional alleles', each one extending for about 80-160 kb, were found across a region of about 500 kb. Our results demonstrate that CENP-A binding domains are autonomous relative to the underlying DNA sequence and are characterized by positional instability causing the sliding of centromere position. We propose that this dynamic behaviour may be common in mammalian centromeres and may determine the establishment of epigenetic alleles.

No MeSH data available.


Related in: MedlinePlus

Real-time PCR analysis of the ChIP-on-chip samples. For each cell line (HSF-B, HSF-C, HSF-D, HSF-E and HSF-G), results are presented as the logarithm of the difference between the cycle threshold obtained with the CENP-A immunoprecipitated sample and the cycle threshold obtained with input sample, normalized for the control region (chr11:28,227,839-28,227,938). The x-axis shows the genomic position of each primer pair along chromosome 11
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Fig2: Real-time PCR analysis of the ChIP-on-chip samples. For each cell line (HSF-B, HSF-C, HSF-D, HSF-E and HSF-G), results are presented as the logarithm of the difference between the cycle threshold obtained with the CENP-A immunoprecipitated sample and the cycle threshold obtained with input sample, normalized for the control region (chr11:28,227,839-28,227,938). The x-axis shows the genomic position of each primer pair along chromosome 11

Mentions: At least seven functional epialleles were identified in the five horses and are sketched in panel b of Fig. 1; identification was obtained by combining the results of ChIP-on-chip (panel a), qPCR (Fig. 2), SNP analysis (Fig. 3) and fibre immuno-FISH (Fig. 4). Each epiallele occupies about 80–160 kb. These results demonstrate that the centromeric domain of horse chromosome 11 is characterized by great positional variation giving rise to ‘epigenetic polymorphism’. No functionally homozygous individuals were observed; therefore, in spite of our limited sample size, we can infer that this epigenetic locus is highly polymorphic.Fig. 2


Centromere sliding on a mammalian chromosome.

Purgato S, Belloni E, Piras FM, Zoli M, Badiale C, Cerutti F, Mazzagatti A, Perini G, Della Valle G, Nergadze SG, Sullivan KF, Raimondi E, Rocchi M, Giulotto E - Chromosoma (2014)

Real-time PCR analysis of the ChIP-on-chip samples. For each cell line (HSF-B, HSF-C, HSF-D, HSF-E and HSF-G), results are presented as the logarithm of the difference between the cycle threshold obtained with the CENP-A immunoprecipitated sample and the cycle threshold obtained with input sample, normalized for the control region (chr11:28,227,839-28,227,938). The x-axis shows the genomic position of each primer pair along chromosome 11
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4446527&req=5

Fig2: Real-time PCR analysis of the ChIP-on-chip samples. For each cell line (HSF-B, HSF-C, HSF-D, HSF-E and HSF-G), results are presented as the logarithm of the difference between the cycle threshold obtained with the CENP-A immunoprecipitated sample and the cycle threshold obtained with input sample, normalized for the control region (chr11:28,227,839-28,227,938). The x-axis shows the genomic position of each primer pair along chromosome 11
Mentions: At least seven functional epialleles were identified in the five horses and are sketched in panel b of Fig. 1; identification was obtained by combining the results of ChIP-on-chip (panel a), qPCR (Fig. 2), SNP analysis (Fig. 3) and fibre immuno-FISH (Fig. 4). Each epiallele occupies about 80–160 kb. These results demonstrate that the centromeric domain of horse chromosome 11 is characterized by great positional variation giving rise to ‘epigenetic polymorphism’. No functionally homozygous individuals were observed; therefore, in spite of our limited sample size, we can infer that this epigenetic locus is highly polymorphic.Fig. 2

Bottom Line: Examination of the ten instances of chromosome 11 in the five individuals revealed seven distinct 'positional alleles', each one extending for about 80-160 kb, were found across a region of about 500 kb.Our results demonstrate that CENP-A binding domains are autonomous relative to the underlying DNA sequence and are characterized by positional instability causing the sliding of centromere position.We propose that this dynamic behaviour may be common in mammalian centromeres and may determine the establishment of epigenetic alleles.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Farmacia e Biotecnologie (FABIT), Università di Bologna, Bologna, Italy.

ABSTRACT
The centromere directs the segregation of chromosomes during mitosis and meiosis. It is a distinct genetic locus whose identity is established through epigenetic mechanisms that depend on the deposition of centromere-specific centromere protein A (CENP-A) nucleosomes. This important chromatin domain has so far escaped comprehensive molecular analysis due to its typical association with highly repetitive satellite DNA. In previous work, we discovered that the centromere of horse chromosome 11 is completely devoid of satellite DNA; this peculiar feature makes it a unique model to dissect the molecular architecture of mammalian centromeres. Here, we exploited this native satellite-free centromere to determine the precise localization of its functional domains in five individuals: We hybridized DNA purified from chromatin immunoprecipitated with an anti CENP-A antibody to a high resolution array (ChIP-on-chip) of the region containing the primary constriction of horse chromosome 11. Strikingly, each individual exhibited a different arrangement of CENP-A binding domains. We then analysed the organization of each domain using a single nucleotide polymorphism (SNP)-based approach and single molecule analysis on chromatin fibres. Examination of the ten instances of chromosome 11 in the five individuals revealed seven distinct 'positional alleles', each one extending for about 80-160 kb, were found across a region of about 500 kb. Our results demonstrate that CENP-A binding domains are autonomous relative to the underlying DNA sequence and are characterized by positional instability causing the sliding of centromere position. We propose that this dynamic behaviour may be common in mammalian centromeres and may determine the establishment of epigenetic alleles.

No MeSH data available.


Related in: MedlinePlus