The DUX4 Homeodomains Mediate Inhibition of Myogenesis and Are Functionally Exchangeable with the Pax7 Homeodomain Darko Bosnakovski1,2, Erik A
© 2017. Published by The Company of Biologists Ltd | Journal of Cell Science (2017) 130, 3685-3697 doi:10.1242/jcs.205427 RESEARCH ARTICLE The DUX4 homeodomains mediate inhibition of myogenesis and are functionally exchangeable with the Pax7 homeodomain Darko Bosnakovski1,2, Erik A. Toso2, Lynn M. Hartweck2, Alessandro Magli3, Heather A. Lee2, Eliza R. Thompson2, Abhijit Dandapat2, Rita C. R. Perlingeiro3 and Michael Kyba2,* ABSTRACT downstream target genes, compared with controls (Celegato et al., Facioscapulohumeral muscular dystrophy (FSHD) is caused by 2006; Krom et al., 2012; Rahimov et al., 2012; Tassin et al., 2012; inappropriate expression of the double homeodomain protein DUX4. Tsumagari et al., 2011; Winokur et al., 2003a,b). In our previous work, DUX4 DUX4 has bimodal effects, inhibiting myogenic differentiation and we demonstrated that ,whenexpressedatlowlevelsinC2C12 blocking MyoD at low levels of expression, and killing myoblasts at myoblasts, recapitulates aspects of this FSHD myoblast phenotype, high levels. Pax3 and Pax7, which contain related homeodomains, namely that it sensitizes cells to oxidative stress and severely reduces MyoD antagonize the cell death phenotype of DUX4 in C2C12 cells, mRNA and protein levels (Bosnakovski et al., 2008b). High DUX4 suggesting some type of competitive interaction. Here, we show that levels of expression caused cell death (Bosnakovski et al., the effects of DUX4 on differentiation and MyoD expression require the 2008b). In addition to these effects, myoblasts expressing low levels of DUX4 homeodomains but do not require the C-terminal activation domain of had diminished differentiation potential, presumably caused DUX4. We tested the set of equally related homeodomain proteins by dysregulation of myogenic regulatory factors (MRFs), including (Pax6, Pitx2c, OTX1, Rax, Hesx1, MIXL1 and Tbx1) and found MyoD (Bosnakovski et al., 2008b).
[Show full text]