Dmwd, the dystrophia myotonica WD repeat-containing protein, has a largely uncharacterized function. Its amino acid sequence is similar to that of WDR20, and they likely arose from a common ancestor during whole-genome duplication in the vertebrate lineage. Dmwd binds to USP12 and USP46 deubiquitinases, and along with WDR20, promotes USP12 enzymatic activity while differentially modulating its subcellular localization, potentially leading to distinct deubiquitinase complexes [1].

The Dmwd gene is located in the myotonic dystrophy (DM1) gene cluster on 19q, upstream of the DMPK gene. Its RNA and protein products are ubiquitously expressed, with higher abundance in testes and brain. In mouse brain, Dmwd protein levels gradually increase between postnatal days P7 and P21 while mRNA levels remain constant, and it is prominently expressed in neurons and synapse-dense brain areas [2]. In DM1 patients, the level of the DM-associated allele of Dmwd in the cytoplasm of DM cell lines is reduced by 20-50% compared to the wild-type allele [3]. Mice with additional Dmwd mutation, in addition to mutant Dmpk, Six5 and Mbnl1, recapitulate many major manifestations in congenital DM1, suggesting that Dmwd dosage reduction contributes to the complex symptoms of DM1 [4].

In conclusion, Dmwd is involved in regulating USP12-related deubiquitinase activity and subcellular localization. Its expression pattern in the brain and dosage-related effects in DM1 models suggest its importance in brain-related symptoms of DM1 and in understanding the complex pathophysiology of myotonic dystrophy.

References:

1. Olazabal-Herrero, Anne, Bilbao-Arribas, Martin, Carlevaris, Onintza, Berra, Edurne, Rodriguez, Jose Antonio. 2021. The dystrophia myotonica WD repeat-containing protein DMWD and WDR20 differentially regulate USP12 deubiquitinase. In The FEBS journal, 288, 5943-5963. doi:10.1111/febs.15875. https://pubmed.ncbi.nlm.nih.gov/33844468/

2. Westerlaken, Jolanda H A M, Van der Zee, Catharina E E M, Peters, Wilma, Wieringa, Bé. . The DMWD protein from the myotonic dystrophy (DM1) gene region is developmentally regulated and is present most prominently in synapse-dense brain areas. In Brain research, 971, 116-27. doi:. https://pubmed.ncbi.nlm.nih.gov/12691844/

3. Alwazzan, M, Newman, E, Hamshere, M G, Brook, J D. . Myotonic dystrophy is associated with a reduced level of RNA from the DMWD allele adjacent to the expanded repeat. In Human molecular genetics, 8, 1491-7. doi:. https://pubmed.ncbi.nlm.nih.gov/10400997/

4. Yin, Qi, Wang, Hongye, Li, Na, Hu, Ping, Li, Jinsong. 2019. Dosage effect of multiple genes accounts for multisystem disorder of myotonic dystrophy type 1. In Cell research, 30, 133-145. doi:10.1038/s41422-019-0264-2. https://pubmed.ncbi.nlm.nih.gov/31853004/