Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Gene makes muscles in the obese store more fat

12.10.2005


The gene encoding an enzyme that hinders muscle from burning fat manufactures three times more enzyme in the muscle of obese people than lean people, researchers from Duke University Medical Center and Louisiana State University have found. This causes the obese muscle tissue to both store more fat and burn less fat, the researchers said.



"Obesity is a very complex disease, and this metabolic pathway does not fully explain obesity, but it is a likely contributor," said Deborah Muoio, Ph.D., senior study author and assistant professor of medicine at Duke’s Sarah W. Stedman Nutrition and Metabolism Center.

Excess fat storage in muscle tissue is a hallmark of obesity, and may contribute to problems such as diabetes and cardiovascular disease. The researchers discovered that skeletal muscle tissue and cells from obese people were programmed to store fat even when removed from the body and forced to grow in the laboratory. This finding suggests the gene is more active in obese people not only because of excess calorie intake, but also as a result of heritable changes in its regulation, Muoio said.


"The cells of obese people remembered their metabolic program, which could help explain, in part, why losing weight and maintaining weight loss is so difficult," Muoio said. "The good news is it’s possible to change your energy balance through exercise. Exercise can enhance muscle’s ability to burn fat," Muoio said. "This discovery also provides a potential drug target."

The results appear in the Oct. 12, 2005 issue of Cell Metabolism. The work was supported by National Institute of Diabetes & Digestive & Kidney Diseases, of the National Institutes of Health, the Pennington Biomedical Research Foundation and the American Diabetes Association.

Muoio suspects that the gene’s behavior is altered in obese people because of epigenetic control – alteration of gene activity states without variations in the DNA code. These changes can be triggered by environmental factors, such as nutrition or chemical exposure, and carried forward even after the stimulus is removed. The gene investigated in the study is present in obese and lean people, but was overexpressed, or more active, in obese muscle tissue and cells, which means the obese tissue produced larger quantities of enzyme.

In their study, the researchers analyzed stomach muscle tissue donated by non-diabetic obese and lean people who were having surgery. They examined muscle tissue and muscle satellite cells, which have the potential to develop into muscle. Both the tissue and cells from obese people were programmed to store excess fat in the form of fat droplets. The cells and tissue also burned less fat because they produced more of an enzyme that opposes fat oxidation. This excess fat storage may be linked to type 2 diabetes because skeletal muscle – muscle attached to bone – helps regulate sugar metabolism.

When the muscle satellite cells were encouraged to develop into mature muscle cells, they showed the same fat storage programming as muscle tissue. "This is a very important clue, because it indicates this program of fat storage is perpetuated as these cells divide. It’s not driven strictly by over-nutrition," Muoio said.

To identify the gene controlling this fat storage pathway, the research team relied on DNA microarrays, or "gene chips," to test the activity of thousands of genes at once. They also selected a few candidate genes (they chose culprits based on earlier research) to examine by a different method. In both cases, they arrived at the same gene, called steroyl-CoA desaturase 1 (SCD1), which was known to slow down fat burning and promotes fat storage.

"We found that obesity was associated with a threefold increase in SCD1 expression in obese muscle, as well as a threefold higher level of SCD1 enzyme, compared to lean muscle," Muoio said. The activity of other genes linked to fat metabolism and obesity were comparable between the two groups.

The researchers also investigated how muscle cells from lean individuals behaved when forced to overproduce the SCD1 enzyme. Using genetic engineering techniques, the team showed that cells from lean people mimicked the metabolism of obese cells, storing more fat droplets and burning less fat, when the amount of SCD1 was increased.

Becky Oskin | EurekAlert!
Further information:
http://www.duke.edu

More articles from Life Sciences:

nachricht Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory

nachricht How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>