Cone dystrophy is a hereditary form of blindness which results in the death of photoreceptor cone cells, essential for most human vision capabilities. Earlier this year, British researchers reported that a group of patients who suffered from one form of this disease all carried a specific gene mutation. That gene happened to encode for one of the proteins that Alexander Dizhoor, PhD, assistant professor of ophthalmology, has been studying for the past several years. Within a few weeks, he and his colleagues replicated the gene mutation, produced the mutant protein and determined how such mutations changed the properties of that protein. Their findings were published in the July 10 issue of the Journal of Biological Chemistry.
Dr. Dizhoor and his colleagues have found that the mutant protein causes overproduction of a substance required for the signal transduction from photoreceptors in the brain. "In normal situations, when an eye is exposed to light, this protein plays the role of a switch that turns on the production of the substance in the cones. It also shuts it down in the dark, when cone cells are at rest," said Dr. Dizhoor. "The mutant protein, however, is like a broken switch that is always in the "on" position, so the cells may never rest--and that can burn them out."
Understanding this process may finally allow pharmacological agents to be developed to alter the activity of the mutant protein. Even further down the road, Dr. Dizhoor and his colleagues hope genetic therapies may be offered to replace the mutant gene.
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