ABSTRACT
Brain regions, such as the cortex and retina, are composed of layers of uniform thickness. The molecular mechanism that controls this uniformity is not well understood. Here we show that during mouse postnatal development the timed expression of Rncr4, a retina-specific long noncoding RNA, regulates the similarly timed processing of pri-miR-183/96/182, which is repressed at an earlier developmental stage by RNA helicase Ddx3x. Shifting the timing of mature miR-183/96/182 accumulation or interfering with Ddx3x expression leads to the disorganization of retinal architecture, with the photoreceptor layer being most affected. We identify Crb1, a component of the adhesion belt between glial and photoreceptor cells, as a link between Rncr4-regulated miRNA metabolism and uniform retina layering. Our results suggest that the precise timing of glia-neuron interaction controlled by noncoding RNAs and Ddx3x is important for the even distribution of cells across layers.
Subject(s)
Gene Expression Regulation, Developmental , MicroRNAs/genetics , Neuroglia/metabolism , Neurons/metabolism , RNA Helicases/metabolism , RNA, Long Noncoding/genetics , Retina/growth & development , Animals , Blotting, Northern , Blotting, Western , DEAD-box RNA Helicases , Gene Regulatory Networks , HEK293 Cells , Humans , Immunohistochemistry , Mice , MicroRNAs/metabolism , Microscopy, Confocal , Nerve Tissue Proteins/genetics , Nerve Tissue Proteins/metabolism , Photoreceptor Cells, Vertebrate/metabolism , RNA, Long Noncoding/metabolism , Real-Time Polymerase Chain Reaction , Retina/metabolismABSTRACT
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 DGCR8 in adult mice led to the loss of miRNAs and the loss of outer segments, resulting in photoreceptors with significantly reduced light responses. However, the number of cones remained unchanged. The loss of the outer segments occurred gradually over 1 month, and during this time the genetic signature of cones decreased. Reexpression of the sensory-cell-specific miR-182 and miR-183 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.
