When it’s dark, and we start to fall asleep, most of us think we’re tired because our bodies need rest. Yet circadian rhythms affect our bodies not just on a global scale, but at the level of individual organs, and even genes.
Now, scientists at the Salk Institute have determined the specific genetic switches that sync liver activity to the circadian cycle. Their finding gives further insight into the mechanisms behind health-threatening conditions such as high blood sugar and high cholesterol.
"We know that genes in the liver turn on and off at different times of day and they’re involved in metabolizing substances such as fat and cholesterol," says Satchidananda Panda, co-corresponding author on the paper and associate professor in Salk’s Regulatory Biology Laboratory. "To understand what turns those genes on or off, we had to find the switches."
To their surprise, they discovered that among those switches was chromatin, the protein complex that tightly packages DNA in the cell nucleus. While chromatin is well known for the role it plays in controlling genes, it was not previously suspected of being affected by circadian cycles.
Panda and his colleagues, including Joseph R. Eckercircadian cycles, holder of the Salk International Council Chair in Genetics, report their results December 5 in Cell Metabolism.
(via More than 3,000 epigenetic switches control daily liver cycles)