Acta1-flox Mouse

ACTA1, encoding skeletal muscle alpha-actin, is one of six highly conserved actin proteins associated with human disease. It forms the core of the sarcomeric thin filament in adult skeletal muscle, crucial for muscle structure and function [1].

Mutations in ACTA1 are a significant cause of various muscle disorders. Over 50% of genetic defects in nemaline myopathies, a group of congenital myopathies causing muscle weakness, are related to mutations in ACTA1 and nebulin. ACTA1 mutations can lead to a wide range of clinical phenotypes, with the vast majority (74%) causing nemaline myopathy, and an increasing number associated with cardiomyopathy and novel phenotypes like distal myopathy. Challenges exist in identifying genotype-phenotype correlations for ACTA1 [1,2]. In an in vitro model of nemaline myopathy using iPSC-derived skeletal myocytes with an ACTA1 H40Y point mutation, mitochondrial dysfunction and oxidative stress were observed as disease phenotypes, though nemaline rods were absent [3]. A dilated cardiomyopathy-associated ACTA1 mutation R256H was shown to disrupt actin structure and function, causing cardiomyocyte hypocontractility [4].

In conclusion, ACTA1 is essential for the normal assembly and function of the sarcomeric thin filament in skeletal muscle. Studies on ACTA1-related mutations in various models, including in vitro cell models, have revealed its role in muscle-related diseases such as nemaline myopathy and cardiomyopathy. Understanding ACTA1's function and the impact of its mutations provides important insights into the pathogenesis of these muscle disorders.