The Knights Templar Eye Foundation has awarded two NEI scientists grants to research inherited retinal degenerations, diseases that can cause blindness in early childhood.
Robert Hufnagel, M.D., Ph.D., chief of the Medical Genetics and Ophthalmic Genomics Unit, and Oussama M’Hamdi, Ph.D., postdoctoral fellow in the Ophthalmic Molecular Genetics Section each received $65,000 toward their projects. The Knights Templar Eye Foundation, a charity sponsored by the Grand Encampment of Knights Templar, supports early career vision scientists who, like Hufnagel and M’Hamdi, study the biology of pediatric blinding conditions. Two other NEI scientists, Aman George, Ph.D. and Nathan Hotaling, Ph.D., have received grants from the Knights Templar Eye Foundation in recent years.
“Funding of young investigators is crucial to sustaining research,” said NEI Clinical Director Brian Brooks, M.D., Ph.D, who leads the Ophthalmic Genetics and Visual Function Branch, where the awardees work. “Generous funds today from the Knights Templar Eye Foundation is a downpayment on tomorrow’s cures for pediatric eye diseases.”
The health and maintenance of the retina, the light-sensitive tissue at the back of the eye, depends on coordination among its various cell layers. The light-sensing photoreceptors are nourished and supported by the adjacent retinal pigment epithelium (RPE) and choroid. Failure of one cell type can lead to retinal degeneration and subsequent blindness.
Robert Hufnagel, M.D., Ph.D. (left) and Oussama M'Hamdi, M.D. (right).
M’Hamdi, who works in the laboratory of J. Fielding Hejtmancik, M.D., Ph.D., has recently identified mutations in a novel retinal gene that cause an inherited form of retinal degeneration, called autosomal recessive retinitis pigmentosa (RP). The mutations in these families cause loss of vision in infancy or childhood and early onset blindness.
“There’s very little known about this gene,” said M’Hamdi. “We were the first to find this protein in the retina, but we still don’t know exactly what it’s doing.”
M’Hamdi believes that the mutated gene functions in the photoreceptor, providing support for the membranous disks containing rhodopsin in the outer segments. M’Hamdi is using cell culture systems as well as zebrafish and mice to study the gene’s role in photoreceptor function and survival.
Hufnagel is studying how the photoreceptors and RPE communicate. Mutations in the protein neuropathy target esterase (NTE) can lead to a syndrome known as Oliver-McFarlane syndrome, which causes retinal degeneration in childhood. NTE is important for maintaining cellular membranes. He proposes that NTE’s function might extend to the formation of membrane-enclosed vesicles, also called exosomes, that ferry proteins and metabolites between cells. Hufnagel believes that exosomes transport factors crucial for the health of photoreceptors from the RPE, and that impairment of this process may lead to vision loss in Oliver-McFarlane syndrome and other pediatric retinal degenerations. His Knights Templar grant will support Postdoctoral Fellow Takerra Johnson, Ph.D., who will investigate the formation and composition of exosomes in the retina.
“We’ve known for a long time that the retinal pigment epithelium maintains the function of the photoreceptors by recycling their outer segments and completing the visual transduction cycle,” said Hufnagel. “Less clear is how else the RPE, photoreceptors, and the choroid communicate and support each other to maintain function of the retina. That’s what we’re looking into.”
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