COLLEGE STATION -- Researchers at Texas A&M University are shedding light on a rare form of early blindness, identifying the cells involved and paving the way for possible therapies to treat or even prevent what is currently an incurable disease.
The findings, funded by Fight for Sight and the National Institutes of Health, are published in the March 5-9 online Early Edition (EE) of the Proceedings of the National Academy of Sciences.
Since his post-doctoral days at Harvard University, Texas A&M biologist Dr. Brian Perkins has been studying protein transport within photoreceptorsthe rod and cone cells that allow organisms to detect their visual worldsin zebrafish, a vertebrate whose eye physiology is essentially identical to that of a human. Recently he became intrigued by a 30-year-old debate involving photoreceptor deathspecifically, whether it was a cause or an effectin choroideremia, an X chromosome-linked hereditary retinal degenerative disease that leads to blindness in an estimated one in every 100,000 people, beginning with severe loss of vision and night blindness as early as the pre-teen years and progressing to complete blindness by middle age.
Using a line of mutant zebrafish developed by Rockefeller Universitys Jim Hudspeth, Perkins and Texas A&M biology graduate student Bryan Krock zeroed in on a specific protein, the Rab escort protein-1 (REP1), which helps regulate intracellular traffic in the photoreceptors as well as a neighboring tissue called the retinal pigment epithelium (RPE). In collaboration with the University of Western Kentuckys Joseph Bilotta, they observed that mutations in REP1 disrupt cellular processes in the RPE, causing photoreceptor death as a secondary consequence. Their results suggest therapies that correct the RPE may successfully rescue photoreceptor loss in choroideremia and even reverse the disease.