title: Asymmetric bidirectional transcription from the FSHD-causing D4Z4 array modulates DUX4 production.
abstract: Facioscapulohumeral Disease (FSHD) is a dominantly inherited progressive myopathy associated with aberrant production of the transcription factor, Double Homeobox Protein 4 (DUX4). The expression of DUX4 depends on an open chromatin conformation of the D4Z4 macrosatellite array and a specific haplotype on chromosome 4. Even when these requirements are met, DUX4 transcripts and protein are only detectable in a subset of cells indicating that additional constraints govern DUX4 production. Since the direction of transcription, along with the production of non-coding antisense transcripts is an important regulatory feature of other macrosatellite repeats, we developed constructs that contain the non-coding region of a single D4Z4 unit flanked by genes that report transcriptional activity in the sense and antisense directions. We found that D4Z4 contains two promoters that initiate sense and antisense transcription within the array, and that antisense transcription predominates. Transcriptional start sites for the antisense transcripts, as well as D4Z4 regions that regulate the balance of sense and antisense transcripts were identified. We show that the choice of transcriptional direction is reversible but not mutually exclusive, since sense and antisense reporter activity was often present in the same cell and simultaneously upregulated during myotube formation. Similarly, levels of endogenous sense and antisense D4Z4 transcripts were upregulated in FSHD myotubes. These studies offer insight into the autonomous distribution of muscle weakness that is characteristic of FSHD.
authors.affiliation: University of Washington, Department of Pediatrics. Seattle, Washington, United States of America.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Block
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Petek
authors.forename: Divya
authors.initials: D
authors.lastname: Narayanan
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Amell
authors.forename: James M
authors.initials: JM
authors.lastname: Moore
authors.forename: Natalia A
authors.initials: NA
authors.lastname: Rabaia
authors.forename: Ashlee
authors.initials: A
authors.lastname: Tyler
authors.forename: Silvere M
authors.initials: SM
authors.lastname: van der Maarel
authors.forename: Rabi
authors.initials: R
authors.lastname: Tawil
authors.forename: Galina N
authors.initials: GN
authors.lastname: Filippova
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Miller
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002478:Cells, Cultured; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D053595:Embryonic Stem Cells / Q000378:metabolism; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D006239:Haplotypes; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D051379:Mice; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D005810:Multigene Family; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D020391:Muscular Dystrophy, Facioscapulohumeral / Q000235:genetics*; D016297:Mutagenesis, Site-Directed; D032448:Myoblasts, Skeletal / Q000378:metabolism; D011401:Promoter Regions, Genetic; D016372:RNA, Antisense / Q000235:genetics / Q000378:metabolism; D024363:Transcription Initiation Site; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; C121257:DUX4L1 protein, human; D018398:Homeodomain Proteins; D016372:RNA, Antisense; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins