FRG1

This gene maps to a location 100 kb centromeric of the repeat units on chromosome 4q35 which are deleted in facioscapulohumeral muscular dystrophy (FSHD). It is evolutionarily conserved and has related sequences on multiple human chromosomes but DNA sequence analysis did not reveal any homology to known genes. In vivo studies demonstrate the encoded protein is localized to the nucleolus. [provided by RefSeq, Jul 2008]

FSHD Region Gene 1

Binds to mRNA in a sequence-independent manner. May play a role in regulation of pre-mRNA splicing or in the assembly of rRNA into ribosomal subunits. May be involved in mRNA transport. May be involved in epigenetic regulation of muscle differentiation through regulation of activity of the histone-lysine N-methyltransferase KMT5B.

mRNA splicing, via spliceosome Source: UniProtKB
muscle organ development Source: UniProtKB-KW
rRNA processing Source: UniProtKB-KW

Cytoplasm; Cajal body; Nucleolus; Z line. Localization changes during myogenesis from mainly cytoplasmic in undifferentiated myoblasts, to strongly nucleolar in early myotubes and back to cytoplasmic 5 days post-differentiation (PubMed:20970242). Localized at the Z-line in the sarcomere of matured myotubes 8 days post-differentiation (PubMed:20970242).

Facioscapulohumeral muscular dystrophy 1 (FSHD1):
The gene represented in this entry may be involved in disease pathogenesis. Overexpression of human FRG1 in mice leads to development of facioscapulohumeral muscular dystrophy (FSHD1)-like symptoms such as kyphosis, progressive muscle dystrophy and skeletal muscle atrophy (PubMed:16341202). It also causes aberrant pre-mRNA splicing of TNNT3 and MTMR1, affects the localization and activity of KMT5B, and leads to increased levels of EID3, resulting in inhibited muscle differentiation (PubMed:23720823). These results suggest that FSHD1 results from inappropriate overexpression of FRG1 which leads to abnormal alternative splicing of specific pre-mRNAs. A degenerative muscle disease characterized by slowly progressive weakness of the muscles of the face, upper-arm, and shoulder girdle. The onset of symptoms usually occurs in the first or second decade of life. Affected individuals usually present with impairment of upper extremity elevation. This tends to be followed by facial weakness, primarily involving the orbicularis oris and orbicularis oculi muscles.