UC Davis researchers have been awarded a three-year, $1.8 million grant from the National Eye Institute to study the cellular changes that cause age-related macular degeneration (AMD), the leading cause of vision impairment among older Americans.
"This disease does not appear until between the ages of 55 and 60, and the prevalence grows dramatically with chronological age," said Larry Hjelmeland, UC Davis professor of ophthalmology with the UC Davis Eye Center and principal investigator on the grant. "We want to know the biochemical changes in retinal cells that occur with aging and increase the susceptibility for this disease."
AMD, which affects more than 1.75 million people in the U.S., is characterized by damage to the retina, the light-sensitive tissue that lines the inner surface of the eye. It results in loss of vision in the center of the visual field. Dry macular degeneration, the most common form of the disease, results in gradual vision loss and is usually less severe. The wet form of the disease is characterized by the growth of abnormal blood vessels, which leak fluid and blood into the macula and obscure vision.
Both forms of AMD can lead to vision loss that impedes mobility and independence. Many patients are unable to drive, read, recognize faces or perform tasks that require hand-eye coordination. Treatment options have improved in recent years, but there is no cure.
With the new funding, Hjelmeland and Zeljka Smit-McBride, co-principal investigator on the grant and an associate project scientist with the UC Davis Eye Center, will look at how the retinal pigment epithelium (RPE), a protective layer of cells just outside the retina, is affected by epigenetic factors -- changes that alter gene expression while leaving the original genome sequence intact. Preliminary research by the team showed that the expression in several genes important to RPE cells changes with age.
"Looking at aging as an epigenetic phenomenon clearly represents a big step forward for the study of AMD," said Hjelmeland, whose project is one of the first to be funded by the National Eye Institute to explore the link between epigenetics and eye disease.
Hjelmeland and Smit-McBride will test how aging in mice alters RPE gene expression via demethylation, a process by which methyl groups are removed from DNA, resulting in altered gene expression. A similar approach has been shown to play an important role in cancer by silencing tumor suppressor genes, and new treatments are under way that target this process. The UC Davis team hopes to make similar advances in epigenetics and vision science.
"This new research direction could lead to novel ways to prevent and manage AMD and perhaps a cure. We want to bring new and better options to those who are coping with this disease," said Hjelmeland.
The National Eye Institute, part of the National Institutes of Health, leads the federal government's research on the visual system and eye diseases. The institute supports basic and clinical science programs that result in the development of sight-saving treatments. For more information, visit www.nei.nih.gov.
The UC Davis Health System Eye Center is a leader in collaborative vision research that is leading to cures for blinding eye disease and in providing state-of-the-art, world-class eye care. For more information, visit http://www.ucdmc.ucdavis.edu/eyecenter/