The eye’s retina works like film in a camera. The retina’s rods sense dim light, while cone cells detect colors, contrasts and sharp images seen during daylight. A wide range of disorders can damage those rods and cones and lead to vision loss. But now, researchers at Washington University School of Medicine in St. Louis have identified a pathway involved in harming rods and cones and have found a way to halt that damage.
Targeting the pathway with therapies could save sight in patients with many types of retinal disorders, including those for which there are no treatments, such as retinitis pigmentosa and advanced dry age-related macular degeneration.
The findings, from studies in mice and in retinal cells, are published Sept. 27 in the journal Cell Reports.
“We believe we have uncovered a unifying pathway involved in inflicting severe damage to and even causing the death of rods and cones,” said Jonathan B. Lin, an MD/PhD student and co-first author with Shunsuke Kubota, MD, PhD, a former postdoctoral fellow at the School of Medicine. “These findings should help us develop treatments for retinal disorders, regardless of what’s causing them.”
Lin works in the laboratory of senior investigator Rajendra S. Apte, MD, PhD, the Paul A. Cibis Distinguished Professor of Ophthalmology and Visual Sciences. In a series of experiments first in mice and later in retinal cells, they identified a key molecule — NAD — in the cascade that leads to the death of the retina’s rods and cones.
Photoreceptor cells such as rods and cones are among the biggest users of energy in the body. The researchers identified problems in the cells’ mitochondria — the cells’ engines, where energy is produced — as a culprit in vision loss. The NAD molecule is well-known for its important role in energy production. Further, recent research has identified gene mutations along the NAD pathway as having a role in a disease that causes babies to go blind.
As Lin, Apte and colleagues studied several diseases of the retina, they found that defects in the same NAD pathway appeared to be involved in those disorders, too. When they then treated damaged photoreceptor cells in mice with a second molecule called NMN — a precursor molecule that boosts levels of NAD — the cells’ degeneration ceased and vision was restored. NMN is of particular interest to scientists who study problems related to aging.
The featured article was originally published at Washington University’s News Hub: Culprit identified as a major cause of vision loss