Cellular and molecular characterisation of cone photoreceptor migration in normal and degenerate murine retinae
Spatiotemporal cues guiding neuronal migration are critical for the proper development of laminated neural structures, including the retina. Cone photoreceptors, a type of retinal neuron responsible for bright light photopic and colour vision, undergo a unique postmitotic, postnatal migration, yet the cellular and molecular mechanisms that initiate this migration process are still poorly understood. In this study, we explored the role of key phototransduction genes, Cnga3 and Pde6c, in postnatal cone migration by examining two mouse models of complete colour vision blindness, Cnga3-/- and Pde6ccpfl1, which have previously been shown to exhibit aberrant cone localization in adult animals. Retinal development was assessed at postnatal days 8, 12, and 16 using immunohistochemistry and confocal imaging. We found that cone migration and cone soma length were significantly affected in the disease models, indicating that these genes are essential for appropriate postnatal cone migration and final positioning. Furthermore, single-cell RNA sequencing from P12 wildtype and diseased cones identified significant changes to genes involved with the cytoskeleton and its regulation. Our findings strongly indicate a connection between the role of phototransduction genes with cytoskeletal function and cone migration in healthy and degenerating cones. Overall design: Fresh retinas were dissected out of the mouse eyes and dissociated with a papain digestion. Fluorescence-activated cell sorting (FACS) was performed to sort GFP+ cones into a 96-well plate for each mouse line. Sample preparation and sequencing was performed using an adapted approach of SMARTseq2 and MARS-seq.