In a study published in the journal Proceedings of the National Academy of Sciences, scientists used a modified form of vitamin A to initiate a reset mechanism and restart the proteins needed for human vision. The targeted protein was photosensitive rhodopsin, which belongs to a family of proteins located in cell membranes and transmitting an external signal to the internal cellular system. Discovery gives new opportunities for creating modified retina, which will improve vision.
The discovery deepens in the biochemistry of vision, in why the chemical configuration of the retina is important for the perception of human light. People see with the help of an extremely sensitive protein, rhodopsin, which is attached to retinal molecules to perceive light. Photons of light enter the eye and are absorbed by the retinal-rhodopsin complex, activating the cascade of descending signals, which constitute vision. It is especially important that the retina waits for light in one chemical configuration, and after absorption passes into another called full-trans-retinal. But this transformation is unidirectional, and in order to return the retina to the first configuration, many specialized proteins are needed. Inherited mutations in any of them can cause degenerative diseases of the retina. Researchers who want to cure such diseases must either straighten or circumvent the altered proteins.
The researchers discovered a self-renewing mechanism in cow rhodopsin, which is extremely similar to human. They used purified proteins in the laboratory to show how their modified retina binds to cow rhodopsin, successfully activates human proteins when light hits, and after the signal is transmitted with only thermal energy it slowly returns to an inactive form that can be re-activated by photons. The discovery suggests that retinal molecules with a specific chemical structure can stimulate rhodopsin, which is necessary for human vision, which means that mutated proteins can be bypassed and returned to people’s eyesight.