MicroRNA expression profile in mouse cone photoreceptors at P60 [miRNA-seq]. Mus musculus

The outer segments of cones serve as light detectors for daylight color vision, and their dysfunction leads to human blindness conditions. We show that the cone-specific disruption of DiGeorge Syndrome Critical Region Gene 8 (DGCR8) in adult mice led to the loss of miRNAs and the loss of outer segments, resulting in photoreceptors with significantly reduced light responses. Using next-generation sequencing of RNA from isolated wild type P60 cones, we determine the most highly expressed miRNAs as candidates for controlling outer segment maintenance. The expression pattern of miRNAs was highly uneven, with a single miRNA, miR-182, representing 64% of all miRNA expressed in cones. Re-expression of miR-182 and miR-183 (third most abundant miRNA) prevented outer segment loss. These miRNAs were also necessary and sufficient for the formation of inner segments, connecting cilia and short outer segments, as well as light responses in stem-cell-derived retinal cultures. Our results show that miR-182- and miR-183-regulated pathways are necessary for cone outer segment maintenance in vivo and functional outer segment formation in vitro. Overall design: microRNA profile in cone photoreceptors from P60 D4-cre/Ai9 tdTomato mice representing wild type control.