Motor Protein MYO1C is Critical for Photoreceptor Opsin Trafficking and Vision

Unconventional myosins linked to deafness are also proposed to play a role in retinal physiology. However, their direct role in photoreceptor structure and function remains unclear. Herein, we demonstrate that systemic loss of the unconventional myosin MYO1C in mice affected opsin trafficking and photoreceptor survival, leading to vision loss. Electroretinogram analysis of knockout (-KO) mice showed a progressive loss of rod and cone function. Immunohistochemistry and binding assays demonstrated MYO1C localization to photoreceptor inner and outer segments (OS) and identified a direct interaction of rhodopsin with the MYO1C cargo domain. In -KO retinas, rhodopsin mislocalized to rod inner segments and the cell bodies, while cone opsins in OS showed punctate staining. In aged mice, the histological and ultrastructural examination of -KO retinas showed a progressively degenerating photoreceptor OS phenotype. These results demonstrate that MYO1C is critical for opsin trafficking to the photoreceptor OS and normal visual function.