| Modification Notes |
Pre-mRNA splicing is a critical step in the post-transcriptional regulation of gene expression. Several protein complexes are involved in proper mRNA splicing and transport. The muscleblind proteins, MBNL1, MBNL2 and MBNL3, promote inclusion or exclusion of specific exons on different pre-mRNAs by antagonizing the activity of CUG-BP and ETR-3-like factors bound to distinct intronic sites. MBNL1 and MBNL2, associate with expanded CUG repeats in vitro and localize to the nuclear foci in both DM1 and DM2 (myotonic dystrophy types 1 and 2), suggesting that the nuclear accumulation of mutant RNA is pathogenic in DM1, therefore implicating muscleblind proteins MBNL1 and MBNL2 in the pathogenesis of both disorders. MBNL2, a 367 amino acid protein, participates in recruitment of Intergrin ?3 to focal adhesions in a RNA-dependent protein localization mechanism. |