Protein hope for healthy vision

There is news this week of a protein that could help in the fight against blindness, and could even hold hope for people who have lost their sight.

That's according to Bo Chen and Constance Cepko from Harvard Medical School in the US who have been looking at a protein called histone deacetylase 4, or HDAC4 , in a study which appears in the journal Science this week.

HDAC4 is a protein that is expressed in the nervous system and floats around inside neurone cells. Chen and Cepko were able control the gene that produces HDAC4 in the eyes of laboratory mice and thereby determine how much of this protein is present. By injecting fluorescent dyes into the retinas of these mice they could watch what happened when more or less of the HDAC4 protein was produced.

What they found was that if the expression of HDAC4 was reduced it lead to the die-off of rod photoreceptors, the cells in animal eyes that play an important role in detecting low levels of light.

Reducing the amount of HDAC4 also led to the death of cells in the retina called bipolar inter-neurones, the cells that connect other neurones together and are an important stage in the visual pathway from the retina to the brain.

Then, when more of the protein was present, by over-expressing the gene, Chen and Cepko found that HDAC4 reduced the naturally occurring cell death of these bipolar inter-neurones and even slowed down the degeneration of the retinas in mice with diseased eyes.

The activity of HDAC4 relies at least partly on another protein called hypoxia-inducible factor 1 alpha and the researchers think there could be several different pathways that promote the survival of neurones that are essential for vision.