Dicer is essential for proper maturation, composition, and function in the postnatal retina.

The impact of Dicer/miRNAs during postnatal retinogenesis is unknown. This study aimed to deplete Dicer in postnatal retinal progenitor/precursor cells (RPCs/PCs) and to evaluate the structure and function of the adult Dicer-cKO retina using optical coherence tomography (OCT), electroretinography (ERG), and histology. We found impaired rod function, a significantly reduced number of rod bipolar cells and their associated functions, a decreased Müller glia population, and an increased population of HuC/D + Pax6/+ amacrine cells in the adult Dicer-cKO retina. Transcriptional analyses conducted in one-week-old mice showed early alterations in mRNA and miRNA levels. Single-cell RNA sequencing and initial histological analysis in young mice revealed a delay in differentiation/incomplete maturation, as indicated by an enlarged progenitor/precursor population at young ages that persists into adulthood. This suggests that Dicer/miRNAs in late RPC/PCs are essential for the proper formation and maturation of late RPC progenies and may also play a role in regulating cell state.