The 4q subtelomere harboring the FSHD locus is specifically anchored with peripheral heterochromatin unlike most human telomeres
Tam, Rose ; Smith, Kelly P. ; Lawrence, Jeanne B.
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UMass Chan Affiliations
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Keywords
Cell Line
Cell Nucleus
Chromosomes, Human, Pair 17
Chromosomes, Human, Pair 4
Fibroblasts
Heterochromatin
Heterozygote
Humans
Image Processing, Computer-Assisted
In Situ Hybridization
Interphase
Muscles
Muscular Dystrophy, Facioscapulohumeral
Mutation
Nuclear Proteins
Protein Structure, Tertiary
Proteins
Telomere
Cell Biology
Life Sciences
Medicine and Health Sciences
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Abstract
This paper investigates the nuclear localization of human telomeres and, specifically, the 4q35 subtelomere mutated in facioscapulohumeral dystrophy (FSHD). FSHD is a common muscular dystrophy that has been linked to contraction of D4Z4 tandem repeats, widely postulated to affect distant gene expression. Most human telomeres, such as 17q and 17p, avoid the nuclear periphery to reside within the internal, euchromatic compartment. In contrast, 4q35 localizes at the peripheral heterochromatin with 4p more internal, generating a reproducible chromosome orientation that we relate to gene expression profiles. Studies of hybrid and translocation cell lines indicate this localization is inherent to the distal tip of 4q. Investigation of heterozygous FSHD myoblasts demonstrated no significant displacement of the mutant allele from the nuclear periphery. However, consistent association of the pathogenic D4Z4 locus with the heterochromatic compartment supports a potential role in regulating the heterochromatic state and makes a telomere positioning effect more likely. Furthermore, D4Z4 repeats on other chromosomes also frequently organize with the heterochromatic compartment at the nuclear or nucleolar periphery, demonstrating a commonality among chromosomes harboring this subtelomere repeat family.
Source
J Cell Biol. 2004 Oct 25;167(2):269-79. Link to article on publisher's site