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  • The EMBO Journal (2008) 27, 2766 - 2779
  • doi:10.1038/emboj.2008.201

Published online: 2 October 2008

An isogenetic myoblast expression screen identifies DUX4-mediated FSHD-associated molecular pathologies

Darko Bosnakovski1, Zhaohui Xu2, Eun Ji Gang2, Cristi L Galindo3, Mingju Liu2, Tugba Simsek2, Harold R Garner3, Siamak Agha-Mohammadi4, Alexandra Tassin5, Frédérique Coppée5, Alexandra Belayew5, Rita R Perlingeiro1 and Michael Kyba1

  1. Lillehei Heart Institute and Department of Pediatrics, University of Minnesota, MN, USA
  2. Department of Developmental Biology, UT Southwestern Medical Center, Dallas, TX, USA
  3. Center for Biomedical Invention, UT Southwestern Medical Center, Dallas, TX, USA
  4. Division of Plastic Surgery, University of Pittsburgh, Pittsburgh, PA, USA
  5. Laboratoire de Biologie Moleculaire, Universite de Mons-Hainaut Pentagone, Mons, Belgium

Correspondence to:

Michael Kyba, Lillehei Heart Institute and Department of Pediatrics, 4-126 Nils Hasselmo Hall, 312 Church Street SE, Minneapolis, MN 55455, USA. Tel.: +1 612 626 5869; Fax: +1 612 624 8118; E-mail: kyba@umn.edu

Received 5 December 2007; Accepted 10 September 2008

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.

  • Keywords:

    • cassette exchange,
    • DUX4,
    • facioscapulohumeral muscular dystrophy,
    • myoblast