title: SORBS2 transcription is activated by telomere position effect-over long distance upon telomere shortening in muscle cells from patients with facioscapulohumeral dystrophy.
abstract: DNA is organized into complex three-dimensional chromatin structures, but how this spatial organization regulates gene expression remains a central question. These DNA/chromatin looping structures can range in size from 10-20 kb (enhancers/repressors) to many megabases during intra- and inter-chromosomal interactions. Recently, the influence of telomere length on chromatin organization prior to senescence has revealed the existence of long-distance chromatin loops that dictate the expression of genes located up to 10 Mb from the telomeres (Telomere Position Effect-Over Long Distances [TPE-OLD]). Here, we demonstrate the existence of a telomere loop at the 4q35 locus involving the sorbin and SH3 domain-containing protein 2 gene, SORBS2, a skeletal muscle protein using a modification of the chromosome conformation capture method. The loop reveals a cis-acting mechanism modifying SORBS2 transcription. The expression of this gene is altered by TPE-OLD in myoblasts from patients affected with the age-associated genetic disease, facioscapulohumeral muscular dystrophy (FSHD1A, MIM 158900). SORBS2 is expressed in FSHD myoblasts with short telomeres, while not detectable in FSHD myoblasts with long telomeres or in healthy myoblasts regardless of telomere length. This indicates that TPE-OLD may modify the regulation of the 4q35 locus in a pathogenic context. Upon differentiation, both FSHD and healthy myotubes express SORBS2, suggesting that SORBS2 is normally up-regulated by maturation/differentiation of skeletal muscle and is misregulated by TPE-OLD-dependent variegation in FSHD myoblasts. These findings provide additional insights for the complexity and age-related symptoms of FSHD.
authors.affiliation: Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas 75390, USA;
authors.forename: Jérôme D
authors.initials: JD
authors.lastname: Robin
authors.affiliation: Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas 75390, USA;
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Ludlow
authors.affiliation: Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas 75390, USA;
authors.forename: Kimberly
authors.initials: K
authors.lastname: Batten
authors.affiliation: Aix Marseille Universite, INSERM, GMGF, Marseille 13385 Cedex 05, France;
authors.forename: Marie-Cécile
authors.initials: MC
authors.lastname: Gaillard
authors.affiliation: Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas 75390, USA;
authors.forename: Guido
authors.initials: G
authors.lastname: Stadler
authors.affiliation: Aix Marseille Universite, INSERM, GMGF, Marseille 13385 Cedex 05, France;
authors.forename: Frédérique
authors.initials: F
authors.lastname: Magdinier
authors.affiliation: Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas 75390, USA;
authors.forename: Woodring E
authors.initials: WE
authors.lastname: Wright
authors.affiliation: Department of Cell Biology, UT Southwestern Medical Center, Dallas, Texas 75390, USA; Center for Excellence in Genomics Medicine Research, King Abdulaziz University, Jeddah 21589, Saudi Arabia.
authors.forename: Jerry W
authors.initials: JW
authors.lastname: Shay
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D001706:Biopsy; D002872:Chromosome Deletion; D002894:Chromosomes, Human, Pair 4; D019175:DNA Methylation; D004843:Epistasis, Genetic; D005786:Gene Expression Regulation; D056426:Genetic Loci; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D032342:Muscle Cells / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D020391:Muscular Dystrophy, Facioscapulohumeral / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D017570:MyoD Protein / Q000235:genetics / Q000378:metabolism; D032446:Myoblasts; D016601:RNA-Binding Proteins; D016615:Telomere / Q000235:genetics*; D059506:Telomere Shortening; D015533:Transcriptional Activation
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018398:Homeodomain Proteins; D017570:MyoD Protein; C057363:MyoD1 myogenic differentiation protein; D016601:RNA-Binding Proteins; C490755:SORBS2 protein, human