DUX4-induced transcripts from pericentric human satellite II repeats form double-stranded RNA [dsRIPseq]

The DUX4 transcription factor is normally expressed in the cleavage stage embryo and regulates genes involved in zygotic genome activation. Mis-expression of DUX4 in skeletal muscle, however, is toxic and causes facioscapulohumeral muscular dystrophy (FSHD). We recently showed DUX4-induced toxicity is due, in part, to the accumulation of double-stranded RNAs (dsRNAs) with concomitant activation of the PKR viral response pathway. Here, using dsRNA immunoprecipitation coupled with next-generation sequencing, we determined that DUX4-induced dsRNAs originate from intergenic regions enriched for Alu and LINE-1 elements, endogenous retroviruses, and pericentric human satellite II (HSATII) repeats. DUX4-induced HSATII dsRNAs are formed via temporally controlled bidirectional expression with predominant transcription of one strand preceding the other. Whereas DUX4 activation of dsRNAs derived from intergenic regions such as HSATII contributes to toxicity in FSHD, in the early embryo these dsRNAs might facilitate heterochromatin formation, as has been proposed for cleavage stage expression of mouse major satellites. Double-stranded RNA immunoprecipitations were conducted on MB135-DUX4i cells using K1 or J2 mouse monoclonal antibodies with three replicates per each -/+doxycycline condition which induces DUX4 expression. Mouse nonspecific IgG was used as comparator for analysis.