Featured Research

from universities, journals, and other organizations

Enzyme boosts metabolism, prevents weight gain in mice

Date:
November 14, 2011
Source:
Brown University
Summary:
Male and female mice engineered to express the inflammatory enzyme IKKbeta in their fat tissue ate more but gained less weight. They burned sugar and fat more effectively than mice who were left unaltered. The research may shed light on how obesity and inflammation affect insulin resistance and sensitivity.

Reduced fat. Mice altered to express the IKKbeta enzyme (right column) in their fat had smaller globules of fat in their subcutaneous adipose tissue (top row) and in their liver (bottom row) than normal mice (left column).
Credit: Xu Lab/Brown University

Male and female mice engineered to express the inflammatory enzyme IKKbeta in their fat tissue ate more but gained less weight. They burned sugar and fat more effectively than mice who were left unaltered. The research may shed light on how obesity and inflammation affect insulin resistance and sensitivity.

In a new study, scientists report that they substantially curbed weight gain, improved metabolism, and improved the efficacy of insulin in mice by engineering them to express a specific human enzyme in their fat tissue. Although the obesity prevention came at the significant cost of widespread inflammation, the research offers new clues about the connections among obesity, insulin resistance and type 2 diabetes, and inflammation.

"Turning on this molecule has a very dramatic impact on lipid metabolism," said Haiyan Xu, assistant professor of medicine (research) in the Warren Alpert Medical School of Brown University and a researcher at Rhode Island Hospital's Hallett Center for Diabetes and Endocrinology. Xu is the corresponding author of a paper describing the research in the January 2012 issue of Endocrinology and released early online.

Obesity and inflammation are both promoters of insulin resistance, but obesity seems to be the worse one. "Lower body weight is always a beneficial thing for influencing insulin sensitivity."The relationship between fat, inflammation, and insulin performance is complex. The conventional wisdom is that obesity leads to inflammation which contributes to insulin resistance. In this study, the researchers changed the sequence of events for transgenically engineered mice by inducing inflammation via the enzyme IKKbeta in their fatty tissue before they were obese. The result for metabolism was much more positive than for control mice who were left unaltered but were fed the same diets.

For both male and female mice, the ones who were altered still put on weight but significantly more slowly. All the mice started at the same weight. After about 22 weeks on a high-fat diet, however, altered male mice weighed less than 38 grams while unaltered male mice weighed more than 45 grams. On a less extravagant diet named "chow" the difference was considerably lessened but was still statistically significant. Both trends held for females as well.

The altered mice experienced slower weight gain despite eating much more food. Their increased metabolism allowed them to dispatch the extra calories much more efficiently. After being injected with glucose, for example, altered mice maintained lower blood sugar levels than unaltered mice. The same was true after insulin injections, suggesting that insulin was more effective. In addition, the transgenic mice expended much more energy than their normal counterparts, suggesting that the sugar was indeed metabolized.

The mechanisms by which IKKbeta in fatty tissue increases metabolic performance are not completely clear, but the researchers measured increased expression of genes associated both with fatty acid oxidation and with making mitochondria, a cell part responsible for producing energy.

One possible lesson from the research seems to be that while obesity and inflammation are both promoters of insulin resistance, Xu said, obesity seems to be the worse one.

"Lower body weight is always a beneficial thing for influencing insulin sensitivity," she said. "Reduced adiposity wins over increased inflammation."

Another point is that IKKbeta's ability to aid metabolism may be specific to its activation in fat tissue. In previous studies, scientists had activated it in the liver with no weight-reduction benefits and in the brain's hypothalamus, leading to increased weight gain.

The paper's lead author is research fellow Ping Jiao also of the Hallett Center and Brown. Other authors were Bin Feng, Yaohui Nie, and Yujie Li of the Hallett Center; Jie Ma of Rhode Island Hospital and the Department of Medicine in the Alpert Medical School; and Erin Paul of Brown's Department of Molecular Biology, Cell Biology, and Biochemistry. Jiao and Ma are also affiliated with the Jilin University in China and Bin Feng is also affiliated with Huazhong Agricultural University in China.

Funding for the research came from the American Heart Association, which provided Xu with a scientist development grant, and Brown University, which awarded Jiao the George Bray fellowship.


Story Source:

The above story is based on materials provided by Brown University. Note: Materials may be edited for content and length.


Journal Reference:

  1. P. Jiao, B. Feng, J. Ma, Y. Nie, E. Paul, Y. Li, H. Xu. Constitutive Activation of IKK in Adipose Tissue Prevents Diet-Induced Obesity in Mice. Endocrinology, 2011; DOI: 10.1210/en.2011-1346

Cite This Page:

Brown University. "Enzyme boosts metabolism, prevents weight gain in mice." ScienceDaily. ScienceDaily, 14 November 2011. <www.sciencedaily.com/releases/2011/11/111114133740.htm>.
Brown University. (2011, November 14). Enzyme boosts metabolism, prevents weight gain in mice. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2011/11/111114133740.htm
Brown University. "Enzyme boosts metabolism, prevents weight gain in mice." ScienceDaily. www.sciencedaily.com/releases/2011/11/111114133740.htm (accessed July 25, 2014).

Share This




More Health & Medicine News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

New Painkiller Designed To Discourage Abuse: Will It Work?

New Painkiller Designed To Discourage Abuse: Will It Work?

Newsy (July 24, 2014) The FDA approved Targiniq ER on Wednesday, a painkiller designed to keep users from abusing it. Like any new medication, however, it has doubters. Video provided by Newsy
Powered by NewsLook.com
Doctor At Forefront Of Fighting Ebola Outbreak Gets Ebola

Doctor At Forefront Of Fighting Ebola Outbreak Gets Ebola

Newsy (July 24, 2014) Sheik Umar Khan has treated many of the people infected in the Ebola outbreak, and now he's become one of them. Video provided by Newsy
Powered by NewsLook.com
Condemned Man's US Execution Takes Nearly Two Hours

Condemned Man's US Execution Takes Nearly Two Hours

AFP (July 24, 2014) America's death penalty debate raged Thursday after it took nearly two hours for Arizona to execute a prisoner who lost a Supreme Court battle challenging the experimental lethal drug cocktail. Duration: 00:55 Video provided by AFP
Powered by NewsLook.com
Can Watching TV Make You Feel Like A Failure?

Can Watching TV Make You Feel Like A Failure?

Newsy (July 24, 2014) A study by German researchers claims watching TV while you're stressed out can make you feel guilty and like a failure. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins