Researchers Discover How Liver Responds so Quickly to Food
Source: Salk Institute
Summary: Researchers have uncovered how the liver can have a speedy response to food; liver cells store up pre-RNA molecules involved in glucose and fat metabolism.
Minutes after you eat a meal, as nutrients rush into your bloodstream, your body makes massive shifts in how it breaks down and stores fats and sugars. Within half an hour, your liver has made a complete switch, going from burning fat for energy to storing as much glucose, or sugar, as possible. But the speed at which this happens has flummoxed scientists, it’s too short a time span for the liver’s cells to activate genes and produce the RNA blueprints needed to assemble new proteins to guide metabolism. Researchers from the Salk Institute have uncovered how the liver can have such a speedy response to food; liver cells store up pre-RNA molecules involved in glucose and fat metabolism. The study findings were published in the journal Cell Metabolism.
It was known that a RNA-binding protein called NONO was implicated in regulating daily (“circadian“) rhythms in the body. The research team wondered whether NONO had a specific role in the liver. They analyzed levels of NONO in response to feeding and fasting in mice. After the animals ate, speckled clumps of NONO suddenly appeared in their liver cells, newly attached to RNA molecules. Within half an hour, the levels of corresponding proteins those encoded by the NONO-bound RNA were increased. When mice lacked NONO, it took more than 3 hours for levels of the same proteins, involved in processing glucose, to increase. During that time lag, blood glucose levels shot up to unhealthy levels.
First author Giorgia Benegiamo said, “Understanding how glucose storage and fat burning are regulated at the molecular level will be important for the development of new therapies against obesity and diabetes.”
More Information: Giorgia Benegiamo et al, “The RNA-Binding Protein NONO Coordinates Hepatic Adaptation to Feeding”, Cell Metabolism (2018). DOI: 10.1016/j.cmet.2017.12.010