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

Area of Science:

• Developmental biology
• Neuroscience
• Ophthalmology

Background:

• microRNAs (miRNAs) are key regulators of early retinal development.
• The role of miRNAs in late-phase retinogenesis remains largely unknown.

Purpose of the Study:

• To investigate the impact of miRNA depletion in late retinal progenitor/precursor cells (RPCs/PCs) on postnatal retinogenesis and retinal function.

Main Methods:

• Conditional Dicer knock-out in late RPCs/PCs of mice.
• Analyses included optical coherence tomography (OCT), electroretinography (ERG), histology, and transcriptional profiling.
• Luciferase assays were used to investigate gene regulation.

Main Results:

• miRNA depletion caused altered gene expression in late-born retinal cells by postnatal day 7 (P7).
• Observed defects included impaired rod function, reduced rod bipolar cells, and decreased Müller glia population in adult mice.
• A persistent enlarged progenitor/precursor population suggested delayed differentiation and incomplete maturation. Increased HuC/D+ amacrine cells were noted, potentially due to lack of *Elavl3* suppression.

Conclusions:

• Dicer/miRNAs in late RPCs/PCs are essential for the proper formation and maturation of their progeny.
• These miRNAs play a critical role in regulating cell state during late retinogenesis and maintaining retinal function.