Imperial College London Centenary
 
About Imperial
About ImperialContacts/getting hereAlumniResearchCoursesAbout this site
Select your text size  for this site here: Small Text Normal Text Large Text Extra Large Text

Note: Some of the graphical elements of this site are only visible to browsers that support accepted web standards. The content of this site is, however, accessible to any browser or Internet device.

 

Researchers discover way to make cells in the eye sensitive to light


See also...
External Sites:
-University of Manchester
-Nature
(Imperial College is not responsible for the content of these external internet sites)

Under embargo for
18.00GMT/13.00EST
Wednesday 26 January 2005

Researchers have discovered a way to make light sensitive cells in the eye by switching on a single gene.

According to research published online today in Nature, the team from Imperial College London and the University of Manchester, have discovered that activating the melanopsin gene in the nerve cells causes them to become light responsive, or photoreceptive.

Using mouse cells, the researchers found that melanopsin could be used to make neurones light responsive. 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, the cells which signal to the brain, 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, and one of the papers authors, 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, and one of the papers authors, 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."

Professor Hankins and Dr Lucas were part of the team who previously discovered a new light detection system in the eye, totally independent of the rods and cones, which were thought to be the only systems providing sight. They measured light-induced pupillary constriction in genetically modified mice that lacked melanopsin. When the mice lacking melanopsin were exposed to low light, their pupillary response was the same as normal mice, but when they were exposed to bright light their pupil constriction was incomplete.

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. Retinitis pigmentosa is a form of hereditary blindness where the rods and cones are destroyed, but the rest of the eye and retina remains intact. By switching on the melanopsin it could be possible to restore the eyes ability to respond to light.

Although making cells in the eye responsive to light is not a cure for blindness, the team are collaborating with the Institute of Biomedical Engineering 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.

The research was supported by a Wellcome Trust Showcase Award and the BBSRC.

For further information please contact (media only):

Tony Stephenson
Imperial College London Press Office
Tel: +44 (0)20 7594 6712
Mobile: +44 (0)7753 739766
E-mail: at.stephenson@imperial.ac.uk

Notes to editors:

Addition of human melanopsin renders mammalian cells photoreceptive, Nature, 26 January 2005.

Consistently rated in the top three UK university institutions, Imperial College London is a world leading science-based university whose reputation for excellence in teaching and research attracts students (11,000) and staff (6,000) of the highest international quality.
Innovative research at the College explores the interface between science, medicine, engineering and management and delivers practical solutions that enhance the quality of life and the environment - underpinned by a dynamic enterprise culture.
Website: www.imperial.ac.uk

[up]