MBNL2 Antibody #29733

Alternative splicing is a crucial biological process that promotes protein diversity and provides cells with an additional mechanism to regulate the expression of tissue-specific protein isoforms. Muscleblind-like proteins (MBNLs) are one such protein family responsible for tissue-specific alternative splicing regulation. MBNLs bind pre-mRNA through an evolutionarily conserved zinc finger domain, and act as either activators or repressors of splicing on specific pre-mRNA targets by promoting the inclusion or exclusion of exons (1). MBNLs are functionally antagonistic to CUG-BP and ETR-3-like factors (CELF proteins) that also control pre-mRNA splicing. The interplay between MBNL and CELF activity plays a key role in development, where predominant MBNL activity promotes adult differentiation, and predominant CELF activity promotes embryonic splicing patterns (1). Three MBNL homologs are expressed in humans (MBNL1, MBNL2, and MBNL3) that share similar structure and function, yet differ in their tissue- and developmental stage-specific expression patterns (2). MBNL1 is the predominant isoform in the majority of tissue, including muscle, and is therefore the most well characterized. MBNL2 is the predominant homolog in brain, and exhibits increased expression upon functional loss of MBNL1 in other tissue types, suggesting a compensatory role (3). MBNL3 appears to play a more specialized role, where it inhibits muscle differentiation in muscle precursor cells (4). Functional loss of MBNLs is observed in myotonic dystrophy (DM), where pathological repeats in the 3’-UTR of the myotonic dystrophy protein kinase (DMPK) gene or intron 1 of the cellular nucleic acid binding protein (CNBP) gene result in toxic RNA hairpins that sequester MBNLs in nuclear foci. This loss of available MBNLs causes an adult-to-fetal shift in alternative splicing patterns and ultimately results in respiratory and cardiac complications observed in DM patients (2,5).