Figure 6.

Inhibition of myogenesis in zebrafish embryos by the c-terminal peptide sequence of DUX4. Zebrafish embryos were injected with mRNA encoding the full-length DUX4 (mkgDUX4, see Fig. 4A for nomenclature), the c-terminal fragment of DUX4 (mqgDUX4) or the c-terminal fragment with a stop codon to prevent protein translation (mqgDUX4-mqg*). Full-length DUX4 is highly toxic and broadly interferes with the development on the injected side. The mqgDUX4 injected side shows nearly normal development with normal expression of MyoD RNA, but has a very specific inhibition of muscle gene expression with decreased expression of myogenin (myog) and myosin light chain (mylz2). The stop-codon mutant of mqgDUX4 does not inhibit muscle gene expression, demonstrating that the mqg protein is required for inhibitory activity.