"What was incredibly surprising is that cryptochrome has a new function that nobody had predicted," said Eric Zhang, the first author of the study and a researcher in Kay's UCSD laboratory. "Until now, cryptochrome had been known as a protein inside the nucleus of mammalian cells that switches genes on and off in a rhythmic way. What we showed was that cryptochrome has a role outside the nucleus as well."
That additional function of cryptochrome in mammalian cells, the scientists discovered, is to regulate a process known as "gluconeogenesis," in which our bodies supply a constant stream of glucose to keep our brain and the rest of our organs and cells functioning. When we're awake and eating, sufficient glucose is supplied to our bloodstream. But when we're asleep or fasting, glucose needs to be synthesized from the glycogen stored in our liver to keep our glucose levels up.
"That is how our energy metabolism evolved to function in concert with our diurnal activity, or in the case of the mice, their nocturnal activity," said Kay. "This molecular mechanism involving cryptochrome presumably evolved to coordinate our energy metabolism with our daily activity and feeding levels. So could some instances of diabetes be the result of a faulty circadian clock? And if that's the case, can we find ways of fixing the clock to treat this disease? Such an approach would be a whole new way of thinking about how to develop new treatments for diabetes."
In their study, the scientists found evidence that suc
|Contact: Kim McDonald|
University of California -- San Diego