A team from Imperial College London and the University of Manchester has discovered that activating the melanopsin gene in the nerve cells of mice causes them to become light responsive, or photoreceptive.

They found that as well as being sensitive to blue light, melanopsin uses light at different wavelengths to regenerate itself. In some forms of hereditary blindness photoreceptors are lost entirely, but the retinal ganglion cells remain intact. The researchers believe that by activating the melanopsin, these cells may gain the ability to sense and respond to light.

Professor Mark Hankins, from Imperial College London and Charing Cross Hospital, comments: "It is quite remarkable that the activation of a single gene can create a functional photoreceptor. It is an important proof of principle that melanopsin can make non-light sensitive cells receptive to light, and although not a cure, could have applications in treating some forms of blindness.”

Dr Rob Lucas from the University of Manchester adds: "The discovery that melanopsin is capable of making cells photosensitive has given us a unique opportunity to study the characteristics of this interesting protein. The textbook view of the eye is that it contains only two light sensing systems, the rods and cones. However, over the last few years it has become increasingly accepted that we have a third system, which uses melanopsin, that has lain undetected during decades of vigorous scientific investigation.”

The researchers believe that while not a cure for blindness, the findings could lead to therapies for treating some forms of blindness, such as retinitis pigmentosa.

Although making cells in the eye responsive to light is not a cure for blindness, the team are collaborating with engineers from Imperial to develop a functional retinal prosthesis which would allow the information from the light responsive cells to be used by the brain to process images.

MEDICA.de; Source: Imperial College London