Progress Updates
MicroRNAs (miRNAs) are gene-expression controllers that play important roles in health and disease. However, their role in glaucoma remains unclear. This project uses mice with human-like glaucoma as a source of miRNAs from the retina and the optic nerve head, often the region first affected in glaucoma. Dr. Xu’s team is identifying those miRNA that change their activity at the start and during the progression of the disease. Ultimately, knowing their identities may translate into new drug targets for the prevention and treatment of glaucoma. Since receiving funding, the team has made progress, as follows:
They isolated total retinal RNA from glaucoma mice and their age-matched controls. The three stages of disease development on which they focused their studies were: four months, where the mice are pre-glaucoma with intraocular pressure (IOP) near or below the colony average; eight months, shortly after the onset of detectable glaucoma with elevated IOPs; and twelve months,, with further glaucoma development and elevated IOP. After further analysis, the team found that approximately 400 miRNAs are expressed in the retina of the glaucoma mouse and normal controls at all three ages (four, eight and twelve months old).
The team then compared these miRNA profiles and identified a series of miRNAs whose expression levels change in the glaucoma mice, but not in the normal controls. This is the first time that it has been reported that miRNAs are involved in the development of glaucoma. They also identified a series of miRNAs that are differentially expressed in the retina of different ages in both glaucoma and normal controls, suggesting that miRNAs are involved in normal retinal aging as well as glaucoma. They completed a further study that showed some of the differentially-expressed miRNAs may regulate other key proteins known to cause degeneration of retinal ganglion cells and play important roles in glaucoma.
The miRNAs identified by Dr. Xu’s team may serve as targets for new treatments. The team also established in this first year the methodology to isolate and identify miRNAs in optic nerve heads, which will help with future identification of additional miRNAs involved in early glaucoma.
