Myo18a, a divergent member of the myosin family, is characterized by an amino-terminal PDZ domain. It participates in multiple intracellular transport processes, such as retrograde treadmilling of actin via a complex with LURAP1 and MRCK, transporting a protein complex from focal adhesions to the leading edge with PAK2, βPIX, and GIT1, and promoting vesicle budding for Golgi-to-plasma membrane trafficking in complex with GOLPH3. It may also be involved in the Smad4-MYO18A-PP1A complex regulating β-catenin phosphorylation in cholangiocarcinoma, and is associated with the Golgi apparatus in acute myeloid leukaemia (AML) prognosis [1,2,5].

Genetic deletion of Myo18a in mice is embryonic lethal and is associated with the disorganization of cardiac sarcomeres, suggesting its crucial role in maintaining myofibril structure and function in striated muscle cells. In macrophages, disruption of the longer splice isoform MYO18Aα renders macrophages hyper-inflammatory, likely due to epigenetic changes [3,4].

In summary, Myo18a is essential for multiple biological processes including intracellular transport, muscle development, and macrophage inflammatory regulation. Mouse models with Myo18a gene knockout have revealed its importance in cardiac sarcomere organization and in the context of certain cancers like cholangiocarcinoma and AML. The study of Myo18a provides insights into disease mechanisms and potential therapeutic targets.