Chromatin landscape of D4Z4 interactome unveils a muscle atrophy signature in Facioscapulohumeral Dystrophy. Homo sapiens

Facioscapulohumeral Dystrophy (FSHD, MIM158900) is associated with reduction of D4Z4 macrosatellite array below 11 units on 4q35.2 1-3. The deletion alters chromatin structure in cis, leading to gene upregulation 4-10, including DUX4 transcription factor 11,12, responsible for FSHD transcriptional outcome 13-20. However a comprehensive model that accounts for FSHD inter individual variability is still lacking. Here we demonstrate that D4Z4 interactome and chromatin states are impaired in FSHD; in particular, lost interactions with an activatory chromatin switch sustain a muscle atrophy signature. Among these, we further characterize Atrogin1 (8q24), showing strengthened enhancer-promoter chromatin loops at the locus and a gene upregulation during FSHD myogenic differentiation that could be restored by wild type D4Z4 array. We propose that D4Z4 array plays a role in fine-tuning the chromatin landscape in muscle cells and that its structural alteration is key for the phenotypic expression of FSHD disease.Overall design: on the same cell lines from healthy individuals and FSHD patients (two biological replicates each), we generated:- ChIP-seq datasets for the following histone marks: H3K4me3, H3K27me3 and H3K36me3 in human primary myoblasts and myotubes day 4 from healthy individuals (CN) and FSHD patients (FSHD); H3K27ac and H3K4me1 in human primary myoblasts and myotubes day 4 from FSHD.- 4C-seq datasets specific for 4q/10q region from human primary myoblasts from CN and FSHD designed with viewpoint at a single sequence length polymorphism (SSLP) located in the proximal 4q and 10q D4Z4 arrays .- 4C-seq datasets for the promoter region of Atrogin1 as viewpoint in human primary myoblasts from CN and FSHD.