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 Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View
22.06.2018 | University of Sussex

nachricht New cellular pathway helps explain how inflammation leads to artery disease
22.06.2018 | Cedars-Sinai Medical Center

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Graphene assembled film shows higher thermal conductivity than graphite film

22.06.2018 | Materials Sciences

Fast rising bedrock below West Antarctica reveals an extremely fluid Earth mantle

22.06.2018 | Earth Sciences

Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View

22.06.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>