Researchers at the University of Pennsylvania School of Medicine have identified proteins in the rod and cones of the eye that could lead to the discovery of the genetic causes of a host of inherited eye diseases.
The investigators hope to gain a clearer understanding of what goes wrong at the most basic level in these diseases that cause blindness and other disorders.
Specifically, they have identified and measured the types and amounts of proteins in the light-sensing parts of the eye's retina. These light-sensitive structures, called photoreceptor sensory cilia, enable the rod and cone cells of the retina to detect light. While the proteins of cilia in single-celled organisms have been studied, this is the first time that a comprehensive description of the proteins of a mammalian cilium - used for movement and sensing - has been determined.
"We want to understand how cilia work normally and how their function is disrupted in disease, because their dysfunction is such an important cause of disease," says senior author Eric A. Pierce, MD, PhD, Associate Professor of Ophthalmology at the F.M. Kirby Center for Molecular Ophthalmology at Penn. "One of the first steps to achieve this is to put together a complete parts list. Now that we have that, we can figure out how all 2000 proteins we've identified fit together correctly."
The study will appear in the August print issue of Molecular & Cellular Proteomics and has been pre-published online.
Cilia, specialized structures that extend from cells, have recently taken the spotlight in studying genetic diseases. They are commonly used by cells for movement or sensory purposes, and, in many cases with mammals, have been thought to be remnants of evolution without much purpose. But new research has shown that mutations in genes that encode the proteins of cilia are common causes of a host of genetic diseases, including inherited retinal diseases and polycystic kidney disease.
Cilia diseases can also affect multiple organ systems in such disorders as Bardet-Biedl Syndrome, which causes kidney disease, obesity, polydactyly, diabetes, and retinal degeneration; Senior-Loken Syndrome, which causes kidney disease and retinal degeneration; Joubert Syndrome, which causes neurological disease, kidney disease, and retinal degeneration; Usher Syndrome, which causes deafness and blindness; and Meckel Syndrome, which causes kidney disease and neural tube defects.