FRG1P is localised in the nucleolus, Cajal bodies, and speckles

Facioscapulohumeral muscular dystrophy (FSHD) is thought to be caused by a position effect mechanism in which contraction of the subtelomeric D4Z4 repeat on 4q35 results in the transcriptional deregulation of one or more 4qter genes. FRG1 is a suitable candidate gene because of its position close to the D4Z4 repeat, its high conservation, and its transcriptional deregulation in FSHD muscle. To obtain more insight into the function of FRG1 protein (FRG1P), its subcellular localisation was studied. FRG1P appears to be localised in the nucleolus, Cajal bodies, and speckles. These results are suggestive of a role for FRG1P in RNA processing. Interestingly, two other neuromuscular disorders, oculopharyngeal muscular dystrophy and spinal muscular atrophy, are also caused by defects in genes involved in RNA biogenesis.