Researchers Identify Potential Target for Combatting ‘Dry’ AMD
WASHINGTON — Researchers from the National Institutes of Health have discovered a potential new target for intervention in cases of dry age-related macular degeneration.
The study led by Kapil Bharti, Ph.D., and Ruchi Sharma, Ph.D., co-heads of the ocular stem cell and translational research section within NIH’s National Eye Institute, appears in the current issue of the journal Nature.
Working with colleagues at the NIH and Johns Hopkins University, the team discovered how a factor called AKT2 affects the function of organelles called lysosomes and results in the production of deposits in the retina called drusen.
Drusen are considered a hallmark sign of dry age-related macular degeneration, a condition that affects an estimated 19.8 million Americans aged 40 and older, according to the Centers for Disease Control and Prevention.
The condition is also considered one of the most common causes of vision loss in the United States
To better understand the research, consider lysosomes to be something like a cells’ garbage disposals, and they play a crucial role in maintaining the eye’s light-sensing retina.
Key cells that make up the retinal pigment epithelium provide oxygen and nutrients to the retina’s energetically active neurons. They also collect and process the retina’s waste products through lysosomes.
Failure in the cells’ ability to process these waste products leads to the formation of drusen.
People with dry AMD develop drusen in an area of the light-sensing retina called the macula that people use for sharp, central vision. As AMD progresses, drusen increase in number and volume.
Despite intensive research, drusen formation is still largely a mystery.
During studies on mice, the researchers manipulated AKT2 expression levels in retinal pigment epithelium.
When they overexpressed AKT2, lysosomes lost normal function and the mice developed dry AMD symptoms such as RPE degeneration.
The researchers saw similar features in retinal pigment epithelium cells from human donors with AMD and in retinal pigment epithelium cells generated from patient stem cells.
Cells from donors who possessed a gene variant called CFH Y402H, which increases AMD risk, had relatively greater expression of AKT2, showed functionally defective lysosomes, and formed drusen deposits.
The researchers believe their findings may form the basis for a possible future treatment for dry AMD, for which no therapy currently exists.
Dan can be reached at [email protected] and at https://twitter.com/DanMcCue
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