To switch the gene on and off, melanopsin is used, a protein found in the retina which forms a complex with vitamin A. When blue light hits this complex, a natural signaling cascade is initiated, resulting in the accumulation of calcium in the cell. This cascade is then coupled to another one, originally found in the immune system. The accumulation of calcium activates an enzyme that removes the phosphate group of the protein NFAT-P. This newly formed NFAT can enter the cell’s nucleus, where it binds to a synthetic switch to turn a specific gene on and off. Through careful control of the light intensity the amount of NFAT formed could be controlled. The light is administered either through ultra-thin fiber glass optic cables, or, if the cells are close enough to the skin, simply by placing the animals under blue light.
In the experiments, the researcher tested controlling the production of the hormone GLP-1, which directly controls insulin production. It turned out their approach worked. The regulation of the hormone through light improved the insulin production in diabetic mice and restored their blood-sugar balance.
It is not unimaginable that this could one day help treating diabetes in human patients. However, before that becomes reality, more research has to be done.
Ye, H.; Daoud-ElBaba, M.; Peng, R.-W. and Fussenegger, M. (2011). A Synthetic Optogenetic Transcription Device Enhances Blood-Glucose Homeostasis in Mice. Science. 332(6037), pp. 1565 – 1568. doi:10.1126/science.1203535.