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An isogenetic myoblast expression screen identifies DUX4‐mediated FSHD‐associated molecular pathologies
Author(s) -
Bosnakovski Darko,
Xu Zhaohui,
Ji Gang Eun,
Galindo Cristi L,
Liu Mingju,
Simsek Tugba,
Garner Harold R,
AghaMohammadi Siamak,
Tassin Alexandra,
Coppée Frédérique,
Belayew Alexandra,
Perlingeiro Rita R,
Kyba Michael
Publication year - 2008
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/emboj.2008.201
Subject(s) - biology , expression (computer science) , microbiology and biotechnology , computational biology , gene expression , genetics , gene , computer science , programming language
Facioscapulohumeral muscular dystrophy (FSHD) is caused by an unusual deletion with neomorphic activity. This deletion derepresses genes in cis ; however which candidate gene causes the FSHD phenotype, and through what mechanism, is unknown. We describe a novel genetic tool, inducible cassette exchange, enabling rapid generation of isogenetically modified cells with conditional and variable transgene expression. We compare the effects of expressing variable levels of each FSHD candidate gene on myoblasts. This screen identified only one gene with overt toxicity: DUX4 (double homeobox, chromosome 4), a protein with two homeodomains, each similar in sequence to Pax3 and Pax7. DUX4 expression recapitulates key features of the FSHD molecular phenotype, including repression of MyoD and its target genes, diminished myogenic differentiation, repression of glutathione redox pathway components, and sensitivity to oxidative stress. We further demonstrate competition between DUX4 and Pax3/Pax7: when either Pax3 or Pax7 is expressed at high levels, DUX4 is no longer toxic. We propose a hypothesis for FSHD in which DUX4 expression interferes with Pax7 in satellite cells, and inappropriately regulates Pax targets, including myogenic regulatory factors, during regeneration.