Dmd-Q995* Mouse

Duchenne muscular dystrophy (DMD) is a severe, progressive, and debilitating X-linked disorder characterized by muscle wasting. This condition precipitates difficulties with movement, eventually necessitating assisted ventilation, and often leads to premature death. The primary cause of DMD is mutations in the dystrophin muscular dystrophy (DMD) gene, which encodes the dystrophin protein. These mutations effectively eliminate the production of dystrophin protein in muscle tissues, instigating muscle atrophy and a myriad of complications ^[1]. The absence of dystrophin protein culminates in the disintegration of the dystrophin-associated protein complex (DAPC) within the muscle membrane. This disintegration disrupts the interaction between actin and the extracellular matrix, rendering muscles devoid of dystrophin more susceptible to damage. This susceptibility results in the progressive loss of muscle tissue and function, as well as the development of cardiomyopathy ^[2].

Dmd-Q995* mice carry a c.2983C>T (p.Q995) mutation in the Dmd gene, which results in the production of a premature termination codon (PTC). In eukaryotes, the nonsense-mediated mRNA decay (NMD) pathway degrades mRNAs containing PTCs to reduce errors in gene expression. These abnormal mRNAs may encode harmful gain-of-function or dominant-negative proteins that can damage normal human physiological mechanisms. In Dmd-Q995* mice, the mutation and the NMD pathway together result in the degradation of most Dmd transcripts. The remaining transcripts can only encode truncated dystrophin proteins that lack normal function, leading to the loss of dystrophin function ^[3-5]. This model, due to the lack of normal dystrophin expression, exhibits a series of muscle disease phenotypes similar to the clinical presentation of Duchenne muscular dystrophy (DMD), and can be used for research on DMD. Homozygous female mice and heterozygous males of this strain are viable and fertile.