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 For a chimpanzee, one good turn deserves another
27.06.2017 | Max-Planck-Institut für Mathematik in den Naturwissenschaften (MPIMIS)

nachricht New method to rapidly map the 'social networks' of proteins
27.06.2017 | Salk Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Extensive Funding for Research on Chromatin, Adrenal Gland, and Cancer Therapy

28.06.2017 | Awards Funding

Predicting eruptions using satellites and math

28.06.2017 | Earth Sciences

Extremely fine measurements of motion in orbiting supermassive black holes

28.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>