Analysis of mir-9 Expression Pattern in Rat Retina during Postnatal Development.

Area of Science:

• Neuroscience
• Developmental Biology
• Ophthalmology

Background:

• MicroRNA-9 (miR-9) is known to play a role in retinal neurogenesis.
• Its specific expression patterns and functions during the postnatal developmental period remain largely uncharacterized.

Purpose of the Study:

• To investigate the temporal and spatial expression of miR-9 in the rat retina during the first three postnatal weeks.
• To identify potential targets of miR-9 and examine the expression of other microRNAs targeting the same proteins.

Main Methods:

• miRNA-small RNA sequencing and in situ hybridization were employed.
• Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used for expression measurements.
• In silico prediction was performed to identify miR-9 targets.
• Dual miRNA-in situ hybridization/immunocytochemistry was utilized to analyze co-expression patterns.

Main Results:

• miR-9 expression exhibited two distinct peaks within the first three postnatal weeks, specifically at postnatal Day 3 (P3) and P10.
• In silico analysis predicted OneCut2 and synaptotagmin-17 as targets of miR-9.
• Other microRNAs, mir-135 and mir-218, also predicted to target these proteins, showed inverse expression patterns.
• miR-9 was primarily localized in the inner retina, including ganglion, amacrine, and horizontal cells.
• Temporal and spatial expression alterations were observed for miR-9 and related microRNAs.

Conclusions:

• miR-9 regulation is significant during the early postnatal development of the rat retina.
• MicroRNAs may exert their functions on target genes in a stage-specific manner during retinal development.