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Discovery of a sleep gene helps explain why we need rest

Sleep… we spend roughly one-third of our lives doing it, and while it may look like nothing, it’s a major part of a healthy lifestyle. The thing is, no one is really sure why sleep is necessary.

“Sleep must be serving some important function,” says Jason Gerstner, an assistant research professor at Washington State University’s College of Medicine, “But as scientists we still don’t understand what that is. One way to get closer to that is by understanding how it is regulated or what processes exist that are shared across species.”

In order to do this, Gerstner and his colleagues in Japan analyzed genes that change expression over the sleep-wake cycle. They discovered that expression of the gene FABP7 tended to change over the day in the brains of mice. Furthermore, they found that mice with a “knocked out” – or absent – FABP7 gene slept more fitfully compared to mice with a normal FABP7 gene.

The researchers thought these findings might mean that this gene is a requirement for normal sleep in all mammals. The next step was to observe the actions of this gene expression in humans.

Gerstner and his team looked at data from nearly 300 Japanese men who underwent a seven-day sleep study, which included analyzing their DNA. They found that 29 individuals had an abnormal variant of the gene responsible for the production of FABP7. These subjects – similar to the mice – tended to sleep more fitfully. In other words, while they would get the same amount of sleep as others, their sleep was not as good and included more waking events.

Delving further, the researchers made transgenic fruit flies by inserting mutated and normal human FABP7 genes into their astrocytes, which are cells that support neuronal activity and help control behavior. They then monitored the flies’ sleep using an infrared beam that detected motion.

As luck would have it, flies with mutated FABP7 genes slept more fitfully – aligning perfectly with the results from the mouse and human studies.

Gerstner believes these results suggest “there’s some underlying mechanism in astrocytes throughout all these species that regulates consolidated sleep.” Recent research has revealed that astrocytes – a form of glial cells – may have more of a role in the central nervous system than previously thought.

This particular research is especially exciting, Gerstner explains, “It’s the first time we’ve really gained insight into a particular cell’s and molecular pathway’s role in complex behavior across such diverse species.”

Given that fruit flies have been around for about 60 million years, it “suggests we have found an ancient mechanism that persisted over evolutionary time,” says Gerstner. “Evolution does not keep something around that long if it is not important.”

Moving forward, Gerstner and his colleagues will look to see how the functions of FABP7 proteins may shed light on current theories about why sleep is so important.

More information on this study can be found in the open-access journal Science Advances.

By Connor Ertz, Staff Writer

Source: Washington State University

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