Our alarm clocks may spring forward on March 9, but our
biological clocks may take longer to adjust. That’s
because our internal clocks are so tightly wound to many
physiological and behavioral processes.
Researchers have learned that circadian rhythms—the
24-hour cycles that keep our bodies on time—are
involved in sleep, weight gain, mood disorders, and a
variety of diseases. Now, they’ve made remarkable
strides in identifying genes and neural pathways involved
in regulating our internal clocks. Building on this bed
of research could lead to new treatments for insomnia,
jet lag, depression, obesity, and other disorders.
Recent advances in circadian rhythms research follow.
The National Institute of General Medical Sciences, a
component of the National Institutes of Health, supported
these basic research studies and supports others on circadian
rhythms research.
Gaining Weight? Check Your Internal Time
Recent findings suggest that circadian rhythms are intricately
tied to weight gain. When Carla Green and her collaborators
at the University of Virginia fed high-fat diets to mice
with and without a protein involved in circadian rhythms,
they found that the mice lacking the protein gained only
a modest amount while the mice with the protein nearly
doubled their body weight. The findings suggest that circadian
rhythms regulate metabolic processes involved in diet-induced
weight gain.
Clock in a Box
Carl Johnson and colleagues at Vanderbilt University
have reconstituted a circadian clock in vitro using three
proteins. The synthetic clock follows a 24-hour rhythm,
and it maintains this cycle over a range of temperatures—a
defining, but poorly understood characteristic of circadian
rhythms. The advance offers an unprecedented opportunity
to study the mechanisms of internal clocks, the role of
temperature in regulating daily cycles, and even the evolution
of human circadian rhythms.
Single Change Starts the Clock
In a surprising finding, Paolo Sassone-Corsi of the University
of California-Irvine and colleagues found that a single
amino acid change in a protein triggers a chain of genetic
events involved in internal timekeeping. If the modification
is impaired, it could disrupt the cascade and serve as
the underpinning of circadian rhythms-related ailments.
The amino acid also could be a novel target for drug compounds
regulating body clocks.
