title: Telomere length regulates the epigenetic status of mammalian telomeres and subtelomeres.
abstract: Mammalian telomeres have epigenetic marks of constitutive heterochromatin. Here, we study the impact of telomere length on the maintenance of heterochromatin domains at telomeres. Telomerase-deficient Terc(-/-) mice with short telomeres show decreased trimethylation of histone 3 at Lys9 (H3K9) and histone 4 at Lys20 (H4K20) in telomeric and subtelomeric chromatin as well as decreased CBX3 binding accompanied by increased H3 and H4 acetylation at these regions. Subtelomeric DNA methylation is also decreased in conjunction with telomere shortening in Terc(-/-) mice. In contrast, telomere repeat factors 1 and 2 show normal binding to telomeres independent of telomere length. These results indicate that loss of telomeric repeats leads to a change in the architecture of telomeric and subtelomeric chromatin consisting of loss of heterochromatic features leading to a more 'open' chromatin state. These observations highlight the importance of telomere repeats in the establishment of constitutive heterochromatin at mammalian telomeres and subtelomeres and point to histone modifications as important in counting telomere repeats.
authors.affiliation: Telomeres and Telomerase Group, Molecular Oncology Program, Spanish National Cancer Centre (CNIO), 28029 Madrid, Spain.
authors.forename: Roberta
authors.initials: R
authors.lastname: Benetti
authors.forename: Marta
authors.initials: M
authors.lastname: García-Cao
authors.forename: María A
authors.initials: MA
authors.lastname: Blasco
mesh_terms: D000215:Acylation; D000818:Animals; D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D005347:Fibroblasts; D006570:Heterochromatin / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D051379:Mice; D018345:Mice, Knockout; D012150:Polymorphism, Restriction Fragment Length; D019098:Telomerase / Q000235:genetics / Q000502:physiology*; D016615:Telomere / Q000378:metabolism / Q000648:ultrastructure*; D034501:Telomere-Binding Proteins / Q000378:metabolism
chemical_list: C453799:Cbx3 protein, mouse; D002868:Chromosomal Proteins, Non-Histone; D006570:Heterochromatin; D006657:Histones; D034501:Telomere-Binding Proteins; D019098:Telomerase