Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fat cells send message that aids insulin secretion

07.11.2007
The body's fat cells help the pancreas do its job of secreting insulin, according to research at Washington University School of Medicine in St. Louis. This previously unrecognized process ultimately could lead to new methods to improve glucose metabolism in type 2 diabetic or insulin-resistant people.

In a study using laboratory mice, published in the November 7, 2007 issue of Cell Metabolism, scientists at the School of Medicine report that fat cells release a protein that aids insulin secretion from pancreatic beta cells, which are the sole source of insulin. The protein is an enzyme that the pancreatic cells themselves produce in only minimal amounts. The enzyme works to enhance glucose-stimulated insulin secretion from pancreatic beta cells.

Insulin helps the body process blood sugar (glucose), and those with type 2 diabetes have a deficiency of insulin or a resistance to its effects. More than 7 million people in the U.S. are living with a diagnosis of type 2 diabetes and many more are undiagnosed.

The researchers assert that the enzyme secreted by fat cells, called Nampt, is an important component of the insulin-secretion pathway. "We think this secretion process allows fat cells to communicate with the pancreas and aid its function," says senior author Shin-ichiro Imai, M.D., Ph.D., assistant professor of medicine and of molecular biology and pharmacology. "I suspect this process could be critical for compensating pancreatic beta cell function in the face of increasing insulin resistance."

... more about:
»Diabetes »Insulin »NMN »pancreas »pancreatic »secretion

The association of type 2 diabetes and insulin resistance with obesity suggests there may be limits to the ability of the process to enhance pancreatic function, according to Imai. "It may be that in some obese individuals a threshold has been reached so that this mechanism no longer provides adequate compensation," he says. "But there may be ways to overcome this threshold."

Interestingly, in 2004 Nampt provoked excitement in the scientific community because it was reported to be a newly discovered fat-derived hormone that worked very much like insulin. That study named the enzyme visfatin. The scientists who made this assertion have since retracted their claim.

In the new study, the Washington University researchers contend that Nampt is not an insulin-like hormone. Instead, their investigation shows it's an enzyme that modulates pancreatic function.

"Our work marks a conceptual breakthrough," Imai says. "Nampt synthesizes a compound in the bloodstream, and when that compound reaches the pancreas it stimulates insulin secretion. This is a surprising mechanism by which a circulating metabolite modulates pancreatic function."

Imai says he believes it's possible that the compound produced by Nampt, called NMN for short, could be used to raise insulin secretion from pancreatic cells and thus help improve the way the body handles sugar. Imai and his group are collaborating with clinical researchers at the University to find out how much NMN is in the blood of normal and diabetic or obese patients. They also hope to initiate clinical trials to test NMN as a therapeutic agent in patients with type 2 diabetes or insulin resistance.

Nampt is actually a widespread enzyme and catalyzes such a fundamental process that most cells of the body have an internal form of it. But, studying mice, the researchers saw that Nampt could be secreted from cells — but only from fat cells. And because Nampt levels are low in pancreatic cells, the pancreas depends on the enzyme secreted from fat and its product, NMN, in the blood.

When pancreatic beta cells absorb enough NMN, it stimulates them to secrete insulin. In the bloodstreams of laboratory mice, NMN was measured at a concentration shown to be sufficient to enhance insulin secretion from pancreatic beta cells. No one had previously known that NMN circulated in the bloodstream.

Mice engineered to have just one instead of two copies of the Nampt gene had a mildly impaired ability to metabolize glucose and had a defect in insulin secretion. The researchers showed that NMN restored normal insulin secretion in these mice.

In conjunction with the Office of Technology Management at the University, Imai has patented the use of Nampt and NMN for the prevention and treatment of metabolic complications, such as type 2 diabetes.

Next, the researchers will try to identify the factors that cause secretion of Nampt from fat cells and the mechanisms by which NMN enhances insulin secretion in the pancreas.

Revollo JR, Körner A, Mills KF, Satoh A, Wang T, Garten A, Dasgupta B, Sasaki Y, Wolberger C, Townsend RR, Milbrandt J, Kiess W, Imai S. Nampt/PBEF/visfatin regulates insulin secretion in beta cells as a systemic NAD biosynthetic enzyme. Cell Metabolism. November 7, 2007.

Shin-ichiro Imai and Javier Revollo are the inventor and the co-inventor, respectively, of the intellectual properties regarding the uses of Nampt and NMN, one of which is licensed to Sirtris Pharmaceuticals Inc. Jeffrey Milbrandt and Cynthia Wolberger are members of the scientific advisory board of Sirtris Pharmaceuticals Inc.

This research was supported by funding from the Ellison Medical Foundation, the National Institute on Aging, the Washington University Clinical Nutrition Research Unit, Juvenile Diabetes Research Foundation, American Diabetes Association, the National Institute of Diabetes and Digestive and Kidney Diseases, the National Institutes of Health, the Muscular Dystrophy Association, the National Centers of Research Resources, the Deutsche Forschungsgemeinschaft, the Translational Centre for Regenerative Medicine and the German Diabetes Association.

Washington University School of Medicine's 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children's hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked fourth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is linked to BJC HealthCare.

Gwen Ericson | EurekAlert!
Further information:
http://www.wustl.edu

Further reports about: Diabetes Insulin NMN pancreas pancreatic secretion

More articles from Life Sciences:

nachricht Could this protein protect people against coronary artery disease?
17.11.2017 | University of North Carolina Health Care

nachricht Microbial resident enables beetles to feed on a leafy diet
17.11.2017 | Max-Planck-Institut für chemische Ökologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>