Secreted protein sends signal that fat is on the way

Dec 02, 2008

After you eat a burger and fries or other fat-filled meal, a protein produced by the liver may send a signal that fat is on the way, suggests a report in the December issue of the journal Cell Metabolism, a Cell Press publication.

Researchers have found in mice that the liver produces a protein called adropin, which rises in response to high-fat foods and falls after fasting. The protein seems to play a role in governing the activity of other metabolic genes, particularly those involved in the production of lipids from carbohydrates. Studies of the protein in obese animals suggest that it also plays a role in insulin response and in preventing the buildup of fat in the liver (a condition known as nonalcoholic fatty liver disease), the researchers said.

"What is remarkable is that it appears that this factor is specifically regulated by the fat content of the diet," making it one of the first such factors ever discovered, said Andrew Butler of Pennington Biomedical Research Center, part of the Louisiana State University System. (The findings follow another report in the November 26th issue of the journal Cell of a phospholipid produced by the gut that rises after a fatty meal, signaling the brain to eat less.)

The new results suggest that treatments designed to deliver adropin or otherwise boost its levels may hold promise in the war against obesity and associated metabolic disorders, including fatty liver disease and type 2 diabetes.

Indeed, Butler's team found that animals that become obese after eating a high-fat diet for a period of 3 months or due to a genetic mutation don't produce adropin normally. However, obese animals that are manipulated to produce excess adropin or that are given the protein show less fat in their livers and become more responsive to insulin. The mice also ultimately eat less and lose weight, but the other metabolic improvements do not depend on the animals' shrinking waistlines, Butler said.

"The good news is that when you provide a synthetic version of the peptide, it reverses some of the consequences of obesity," he said.

Butler noted, however, that there is still plenty left to learn. For instance, they would like to know whether mice that lack adropin become obese and show evidence of the metabolic syndrome, a cluster of diseases associated with obesity and insulin resistance. The protein is also produced in the brain, suggesting it may also affect behavior and metabolism in as-yet-undiscovered ways. The clinical promise of adropin will depend on whether the relationships between the protein, diet, and metabolism seen in mice will hold in human patients.

The researchers aren't yet certain exactly how adropin works its magic. Its benefits could involve effects within the liver and/or hormonal actions on other body tissues, they said. The answers to those questions will require further investigation.

"In summary," the researchers wrote, "adropin is a newly discovered secreted peptide that is involved in energy homeostasis and lipid metabolism … Adropin may form the basis for the development of new therapeutic targets for treating metabolic disorders associated with obesity."

Source: Cell Press

Explore further: Saved from Sandy: Shorebird efforts are declared a success

Related Stories

NSA winds down once-secret phone-records collection program

13 hours ago

The National Security Agency has begun winding down its collection and storage of American phone records after the Senate failed to agree on a path forward to change or extend the once-secret program ahead of its expiration ...

Recommended for you

11 new species come to light in Madagascar

3 hours ago

Madagascar is home to extraordinary biodiversity, but in the past few decades, the island's forests and associated biodiversity have been under greater attack than ever. Rapid deforestation is affecting the ...

Birds 'weigh' peanuts and choose heavier ones

May 23, 2015

Many animals feed on seeds, acorns or nuts. The common feature of these are that they have shells and there is no direct way to know what's inside. How do the animals know how much and what quality of food ...

Q&A: Why are antibiotics used in livestock?

May 22, 2015

Wal-Mart, the world's biggest retailer, is the latest company to ask its suppliers to curb the use of antibiotics in farm animals. Here's a rundown of what's driving the decision: ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.