Doctor of Philosophy

dissertationThere are generally two types of photoreceptors in a vertebrate retina for image-forming vision, known as rods and cones. While large amounts of research have been focused on rods and rod visual pigments, less is known for cones and cone pigments. In this work, I studied the roles of cone opsins in retinal function (Chapter 2) and degeneration (Chapter 3). Briefly, by generating a mouse model lacking cone opsin, we found that the cone opsins were essential for cone outer segment formation, but not for cone survival. Cone opsins were necessary for intrinsic cone phototransduction, but not required for mediating extrinsic rod signals. I also provided evidence that cone opsins were important for trafficking of at least some other cone outer segment proteins. More detailed information was discussed in Chapter 2. In Chapter 3, I studied the role of M-opsin in the dorsal cone degeneration by using an LCA mouse model (Lrat -/- mice). I found that deletion of M-opsin can prevent dorsal cone from degeneration for at least 12 months. Deletion of M-opsin also relieved proteasome stress. The evidence supported the hypothesis that the M-opsin degradation associated proteasome stress probably underlies the dorsal cone degeneration in the absence of 11-cis retinal. The general retinal structure of rods was relatively normal compared to controls. Finally, I provided a summary and discussion in Chapter 4. Taken together, this dissertation research has expanded our knowledge of cone opsins