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Published on: March 10, 2023
Age-dependent increase in miRNA-34a expression in the posterior pole of the mouse eye
Zeljka Smit-McBride1, Krisztina I Forward1, Anthony T Nguyen1
1UC Davis School of Medicine, Department of Ophthalmology, Vitreoretinal Research Lab, Davis, CA.
Purpose:
MicroRNA-34a (miR-34a) has been implicated in neurodegeneration. MiR-34a belongs to a signaling network involving p53 and Sirt-1. This network responds to DNA damage with further downstream signals that induce senescence or apoptosis. Our goal was to measure the expression level of miR-34a in the mouse retina and RPE as a function of age.
Methods:
The age-dependent change in miR-34a expression was quantified using a real-time PCR (RT-PCR) assay on microRNA isolates from eye tissue: the retina and RPE/choroid (4, 18, 24, and 32 months of age). Tissue localization of miR-34a was determined by in situ hybridization (ISH) for a series of time points. Expression of the miR-34a target gene Sirt1 was analyzed using RT-PCR and immunohistochemistry.
Results:
MiR-34a examined with real-time PCR showed a linear increase in expression with age when compared to that of 4-month-old mice. However, the level of expression between the 24 and 32-month-old animals showed mild downregulation. An age-related increase in miR-34a expression was confirmed in the mouse eye using in situ hybridization. An inverse relationship between the levels of expression of miR-34a and its target Sirt1 mRNA was found at 18 and 24 months of age.
Conclusions:
Our data showed that miR-34a expression increased in the retina and RPE with age. The level of DNA damage in mitochondria in the retina and RPE followed a similar time course. This suggests that miR-34a may play a role in the senescence and apoptosis of the retina and RPE cells in the aging eye.
Insights
MicroRNA-34a (miR-34a) expression increases with age in the mouse retina and RPE, potentially contributing to cellular senescence and apoptosis in the aging eye.
Area of Science:
- Ophthalmology
- Molecular Biology
- Aging Research
Background:
- MicroRNA-34a (miR-34a) is involved in neurodegeneration and linked to p53 and Sirt-1 signaling pathways.
- This network regulates cellular responses to DNA damage, including senescence and apoptosis.
Purpose of the Study:
- To quantify the age-dependent expression of miR-34a in the mouse retina and retinal pigment epithelium (RPE).
Main Methods:
- Real-time PCR (RT-PCR) was used to measure miR-34a expression in retinal and RPE/choroid tissues from mice aged 4 to 32 months.
- In situ hybridization (ISH) determined miR-34a tissue localization.
- RT-PCR and immunohistochemistry analyzed the expression of the miR-34a target gene, Sirt1.
Main Results:
- MiR-34a expression showed a linear increase with age in the mouse eye, with a slight downregulation between 24 and 32 months.
- An age-related increase in miR-34a was confirmed by ISH.
- An inverse relationship was observed between miR-34a and Sirt1 mRNA levels at 18 and 24 months.
Conclusions:
- MiR-34a expression rises in the retina and RPE with aging.
- Mitochondrial DNA damage in these tissues follows a similar age-dependent pattern.
- These findings suggest miR-34a may contribute to retinal and RPE cell senescence and apoptosis during eye aging.
