inter-FSHD-epigen

Despite the fact they constitute two thirds of the human genome, repetitive sequences are largely ignored. FSHD is an autosomal dominant disorder with a strong epigenetic component. Unlike the majority of genetic diseases, FSHD is not caused by mutation in a protein-coding gene. Instead, the disease is associated with a reduced copy number of the D4Z4 macrosatellite repeat mapping to 4q35. Despite years of intensive research, the molecular pathogenesis of FSHD remains largely unknown. We recently identified DBE-T, a chromatin-associated lncRNA produced preferentially in FSHD patients. DBE-T mediates a Polycomb to Trithorax epigenetic switch at the FSHD locus, driving chromatin remodeling and de-repression of 4q35 protein-coding genes in FSHD patients. In FSHD, up-regulation of multiple 4q35 candidate genes has been reported. Based on this, it has been suggested that FSHD could be considered a continuous gene disease in which the epigenetic alteration of multiple genes contributes to the final outcome. Since DBE-T behaves as a master regulator of the FSHD locus being required to activate all FSHD candidate genes, it is a very intriguing candidate to develop therapeutic approaches aimed at normalizing 4q35 gene expression in FSHD patients. Nevertheless, DBE-T mechanism of action is poorly understood. Here we propose to tackle these issues by addressing the following questions: – Is DBE-T responsible for the enhanced disease penetrance of FSHD in muscle? – How is DBE-T tethered to chromatin? – How does DBE-T activate FSHD candidate genes?