MYO7A

MYO7A is a human gene that encodes myosin VIIA, an unconventional actin-based motor protein in the myosin superfamily. It converts chemical energy from ATP hydrolysis into mechanical work to move cellular cargo along actin filaments. The protein has a typical motor domain at the N-terminus, a neck region, and a large C-terminal tail with cargo-binding motifs, enabling interactions with various adaptor proteins and organelles.

MYO7A is expressed in several tissues but is particularly abundant in the inner ear and retinal pigment epithelium. In the ear, it contributes to the development and maintenance of hair cell stereocilia and participates in the complex network that links mechanotransduction to proper cell structure. In the retina, it participates in intracellular transport and pigment granule movement, among other roles. It forms part of the Usher syndrome protein network, interacting with harmonin (USH1C) and SANS (USH1G) and with cadherin-23 and protocadherin-15 in hair bundles.

Mutations in MYO7A cause Usher syndrome type 1B, a syndromic form characterized by congenital sensorineural deafness, vestibular areflexia, and progressive retinal degeneration leading to blindness. The gene also underlies nonsyndromic autosomal recessive hearing loss in some cases. Inheritance is typically autosomal recessive, and many different mutations have been identified, spanning missense, nonsense, frameshift, and splice-site changes.

Research using animal models, such as shaker-1 mice, has illuminated MYO7A’s roles in sensory cells. Gene therapy and other targeted approaches are being explored in preclinical studies, offering potential avenues for treating MYO7A-related disorders in the future.