Myo18a, a divergent member of the myosin family, is characterized by an amino-terminal PDZ domain. It is involved in multiple intracellular transport processes, such as the retrograde treadmilling of actin in a complex with LURAP1 and MRCK, transporting the PAK2-βPIX-GIT1 protein complex from focal adhesions to the leading edge, and promoting vesicle budding for Golgi-to-plasma membrane trafficking in complex with GOLPH3 [1]. It has also been implicated in cancer and is essential in higher organisms.

Genetic deletion of Myo18a in mice is embryonic lethal and associated with the disorganization of cardiac sarcomeres, suggesting its crucial role in maintaining myofibril structure and function in striated muscle cells [2]. In macrophages, disruption of the longer splice isoform MYO18Aα renders macrophages hyper-inflammatory, likely due to epigenetic changes affecting transcriptional regulation of inflammatory pathways [3]. In acute myeloid leukaemia (AML) patients, higher serum levels of MYO18A are associated with a poor prognosis, indicating its potential as a diagnostic and prognostic biomarker [4].

In conclusion, Myo18a is essential for various biological processes, including intracellular transport, muscle structure maintenance, and macrophage inflammatory response regulation. Its dysregulation is associated with diseases like cancer and myopathies. Studies using gene knockout mouse models have significantly contributed to understanding its role in these biological processes and disease conditions.