A fairly new method in genetic research, known as optogenetics (selected as Method of the Year in 2010 by Nature Methods, see video for a great explanation), uses light to control gene expression. Now, researchers form EHT Zürich have engineered human cells (implanted in mice) so that the expression of a gene that plays a role in diabetes can be controlled by light. Instead of creating a whole new genetic network, they combined existing signal pathways, one from the immune system, and one from the eye.

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.

Reference

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.