DURHAM, N.C. -- Researchers from Harvard University and the Duke University
Comprehensive Cancer Center have discovered evidence for a new kind of "off-switch"
inside human cells that can deactivate one of the cell's most prevalent
biochemical mechanisms for responding to chemical stimuli such as hormones.
The scientists believe their basic discovery could eventually lead to new ways to "turn off" cancer cells, whose growth is out of control. The finding also may offer a fundamentally new route to regulating cell activity to treat heart disease, neurological disorders and other medical problems, say the researchers.
In a report in the Sept. 12 Nature, the researchers reported discovering a protein called RGS10 in human cells that seems to turn off, or desensitize, G proteins.
G proteins are important "signal transducer" molecules inside every cell in the body, including heart cells and brain cells. These protein switches transmit chemical signals from the cell surface into the cell's interior, triggering a vast array of cellular processes. G proteins are switched on by receptors on the cell's surface, which themselves are activated by hormones, neurotransmitters and other external chemical signals. Neurotransmitters are substances that trigger brain cells to fire in the process of propagating nerve impulses.
"This is the first example of a class of molecules that can turn off a G protein," said Patrick Casey, associate professor of molecular cancer biology at the Duke cancer center, and an author of the Nature paper. "Essentially all other routes to desensitization, all other ways to turn off this process in the past, have been drug molecules that acted on the cell-surface receptor." However, said Casey, such drugs may be rendered impotent because of the complex transformations that receptors undergo. Thus, he said, RGS10 may constitute a more direct and effective way to control the G-protein-activated cellular machinery
Contact: Sondra Casey