DUX4-Induced Histone Variants H3.X and H3.Y Mark DUX4 Target Genes for Expression.

The DUX4 transcription factor is briefly expressed in the early cleavage-stage embryo, where it induces an early wave of zygotic gene transcription, whereas its mis-expression in skeletal muscle causes the muscular dystrophy facioscapulohumeral dystrophy (FSHD). Here, we show that DUX4 induces the expression of the histone variants H3.X and H3.Y. We have used a myoblast cell line with doxycycline-inducible DUX4 to show that these histone variants are incorporated throughout the body of DUX4-induced genes. Following a brief pulse of DUX4, these histones contribute to greater perdurance and to enhanced re-activation of DUX4 target gene expression. These findings provide a model for H3.X/Y as a chromatin mechanism that facilitates the expression of DUX4 target genes subsequent to a brief pulse of DUX4 expression.