Muscleblind-like protein 1-expanded RNA repeat complex (MBNL1-RNA complex)

The Muscleblind-like protein 1 (MBNL1)-expanded RNA repeat complex is a pathological ribonucleoprotein assembly central to the pathogenesis of Myotonic Dystrophy (DM) (Miller et al., 2000; Kanadia et al., 2003). In DM, expanded CUG or CCUG repeats in the 3' untranslated region of the DMPK or CNBP genes form stable hairpin structures that sequester MBNL1 within nuclear foci (UniProt Q9NR56). This sequestration leads to a functional loss of MBNL1, a critical regulator of alternative splicing, resulting in the mis-splicing of numerous downstream transcripts such as CLCN1 and INSR (NIH/GARD). Therapeutic strategies targeting this complex aim to either degrade the toxic expanded RNA or use small molecules to competitively inhibit the MBNL1-RNA interaction, thereby liberating the protein to restore normal cellular function (Warf et al., 2009). Restoring MBNL1 activity is expected to alleviate the multisystemic symptoms of DM, including myotonia, muscle wasting, and cardiac conduction defects. However, challenges include achieving high specificity for the expanded repeats over other RNA sequences and ensuring efficient delivery to affected tissues like skeletal and cardiac muscle.

Other names

MBNL1-CUG repeat complexMBNL1-CCUG repeat complexMBNL1-RNA fociMBNL1-CUGexp complex

Disruption of the MBNL1-RNA complex to release sequestered MBNL1 and restore normal alternative splicing patterns.