MBNL1
Function
Mediates pre-mRNA alternative splicing regulation. Acts either as activator or repressor of splicing on specific pre-mRNA targets. Inhibits cardiac troponin-T (TNNT2) pre-mRNA exon inclusion but induces insulin receptor (IR) pre-mRNA exon inclusion in muscle. Antagonizes the alternative splicing activity pattern of CELF proteins. Regulates the TNNT2 exon 5 skipping through competition with U2AF2. Inhibits the formation of the spliceosome A complex on intron 4 of TNNT2 pre-mRNA. Binds to the stem-loop structure within the polypyrimidine tract of TNNT2 intron 4 during spliceosome assembly. Binds to the 5'-YGCU(U/G)Y-3'consensus sequence. Binds to the IR RNA. Binds to expanded CUG repeat RNA, which folds into a hairpin structure containing GC base pairs and bulged, unpaired U residues. Together with RNA binding proteins RBPMS and RBFOX2, activates vascular smooth muscle cells alternative splicing events (PubMed:37548402). Regulates NCOR2 alternative splicing (By similarity).
Involvement in disease
Dystrophia myotonica 1
DM1
A muscular disorder characterized by myotonia, muscle wasting in the distal extremities, cataract, hypogonadism, defective endocrine functions, male baldness and cardiac arrhythmias.
None
The protein represented in this entry may be involved in disease pathogenesis. In muscle cells from patients, MBNL1 is sequestered by DMPK RNAs containing pathogenic CUG triplet repeat expansions. MBNL1 binding is proportional to repeat length consistent with the direct correlation between the length of repeat expansion and disease severity.
Corneal dystrophy, Fuchs endothelial, 3
FECD3
A late-onset form of Fuchs endothelial corneal dystrophy, a disease caused by loss of endothelium of the central cornea. It is characterized by focal wart-like guttata that arise from Descemet membrane and develop in the central cornea, epithelial blisters, reduced vision and pain. Descemet membrane is thickened by abnormal collagenous deposition.
None
The protein represented in this entry is involved in disease pathogenesis. In corneal endothelial cells from patients, MBNL1 is sequestered by TCF4 RNAs containing pathogenic CUG triplet repeat expansions. This results in missplicing of essential MBNL1-regulated mRNAs.
Sequence Similarities
Belongs to the muscleblind family.
Tissue Specificity
Highly expressed in cardiac, skeletal muscle and during myoblast differentiation. Weakly expressed in other tissues (at protein level). Expressed in heart, brain, placenta, lung, liver, skeletal muscle, kidney and pancreas.
Cellular localization
- Nucleus
- Cytoplasm
- Cytoplasmic granule
- Localized with DDX1, TIAL1 and YBX1 in stress granules upon stress (PubMed:18335541). Localized in the cytoplasm of multinucleated myotubes (PubMed:18335541). Colocalizes with nuclear foci of retained expanded-repeat transcripts in myotubes from patients affected by myotonic dystrophy (PubMed:10970838, PubMed:11590133, PubMed:11929853).
Alternative names
EXP, KIAA0428, MBNL, MBNL1, Muscleblind-like protein 1, Triplet-expansion RNA-binding protein