Electrical channels in retina could play role in degenerative diseases

A new study has discovered cellular components in the epithelial tissue of the eye which were previously thought to be only present in electrically active tissues. According to the researchers, their findings could aid in identifying drug targets for retinal degenerative diseases.

The team, from Tampere University, Finland, found voltage-gated sodium (Nav) channels involved in the renewal of sensory cells in the adjacent neural tissue, the retina.

“The research project focused on the retinal pigment epithelium (RPE), a tissue that is critically important to the functioning of the retina. The project revealed proteins in the RPE whose function is essential for neural tissue, but whose prevalence or activity in epithelial tissue has not been previously reported,” said Academy of Finland Research Fellow Soile Nymark from Tampere University.

For vision to work properly, retinal sensory cells are constantly renewed which requires a strictly controlled and multistep phagocytosis process in the RPE. In this process, part of the retinal sensory cell is detached and enclosed within the adjacent epithelium. The tissue then metabolises these detached parts of the sensory cells in a controlled manner and thus maintains normal functioning of the retina.

The new discovery reveals how the ion channel proteins responsible for the electrical signalling of neurons influence the phagocytosis process. This is impaired in many retinal degenerative diseases, including age-related macular degeneration (AMD). The researchers say the mechanisms and causes of these diseases can be studied in the light of the new findings, creating opportunities for the development of treatments.

The researchers say they will now investigate the role of the newly discovered ion channels in the communication between epithelial cells.

The results were published in British BMC Biology.