Tnnt1-KO Mouse

Tnnt1, encoding slow skeletal muscle troponin T, is a crucial gene in the calcium regulation of actin thin filament function, essential for striated muscle contraction. It is one of three homologous genes in vertebrates, with TNNT2 for cardiac muscle TnT and TNNT3 for fast skeletal muscle TnT [1].

In genetic studies, loss-of-function mutations in TNNT1 have been linked to nemaline myopathies. For example, a Korean family with novel compound heterozygous mutations in TNNT1 showed progressive muscle weakness, and zebrafish loss-of-function models verified the impact on muscle integrity and locomotor activity [2]. French Canadians with a novel missense homozygous variant in TNNT1 developed slowly progressive limb-girdle weakness, and a zebrafish model confirmed the pathogenicity of this mutation [3]. In Amish nemaline myopathy, a lethal infantile-onset disease, a c.505G>T nonsense mutation in TNNT1 led to rapid proteolysis and clearance of the truncated protein from sarcoplasm, and similar phenotypes were observed in transgenic murine models [4].

In conclusion, TNNT1 is essential for striated muscle function. Studies using loss-of-function models, such as zebrafish and transgenic mice, have revealed its role in nemaline myopathies, providing insights into the disease mechanisms and potential molecular therapies for TNNT1-associated myopathies.