Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study identifies fat-secreted protein linked to insulin resistance

21.07.2005


Findings show new link between obesity and type 2 diabetes



A study led by researchers at Beth Israel Deaconess Medical Center (BIDMC) has shown that a protein found in fat cells is a newly discovered cause of insulin resistance, establishing a previously unidentified molecular link between obesity and type 2 diabetes and offering a potential new target for the development of drugs to treat diabetes. The findings appear in the July 21, 2005, issue of the journal Nature.

According to senior author Barbara B. Kahn, MD, Chief of the Division of Endocrinology, Diabetes, and Metabolism at BIDMC, these findings in both mice and humans represent the first evidence that elevated levels of retinol binding protein 4 (RBP4) play a key role in the development of insulin resistance, a primary risk factor for diabetes.


"Being resistant to insulin is one of the major causes of diabetes," says Kahn, who is also a Professor of Medicine at Harvard Medical School. "And even in the absence of diabetes, insulin resistance is a major risk factor for heart disease and early mortality."

Produced by the pancreas, the hormone insulin functions to help cells throughout the body take in glucose and convert the simple sugar to energy. In individuals who are resistant to insulin, the body’s muscle, fat and liver cells are unable to properly respond to the hormone, resulting in a build-up of glucose and insulin in the blood which, in turn, can lead to the development of diabetes and cardiovascular disease.

Earlier work in Kahn’s lab had focused on understanding the role of a glucose transporter protein called GLUT4 in the development of insulin resistance. Knowing that downregulation of GLUT4 expression in fat tissue is an almost universal feature of insulin-resistant states (including obesity, type 2 diabetes and the metabolic syndrome), previous members of Kahn’s lab developed two transgenic mouse models: One with fat-cell specific overexpression of GLUT4 and one with fat-cell specific reduction of GLUT4.

They found that the mice with overexpression of GLUT4 clearly demonstrated enhanced glucose tolerance and insulin sensitivity while, in contrast, the mice with reduced GLUT4 expression in fat tissue became insulin resistant and had an increased risk of developing diabetes.

"The results suggested that manipulating GLUT4 in adipose tissue affects whole body insulin sensitivity, very possibly through the secretion of proteins from fat cells," explains Kahn. "We therefore, measured the known fat-secreted molecules, including leptin, resistin and adiponectin, but found that in all cases, the levels were normal."

The study’s investigators, led by Qin Yang, MD, PhD, and Timothy Graham, MD, in Kahn’s lab, then conducted a global microarray analysis to identify a novel protein. "This led to our discovery of RBP4," says Kahn.

Further investigation found that both genetic and pharmacologic elevation of RBP4 can cause insulin resistance and that genetic and pharmacologic decrease of the protein in insulin-resistant states would ameliorate the condition. In humans with obesity or type 2 diabetes, the amount of excess RBP4 in the blood correlates with the severity of insulin resistance.

Until now, the sole function of RBP4 known to scientists was to deliver retinol (vitamin A) to tissues. With these new findings, it appears that this abundant transport (carrier) protein may have another function and that the metabolism of vitamin A or related compounds could possibly have some indirect impact on insulin action.

"There is a rapidly increasing epidemic of obesity and Type 2 diabetes in the Western world," says Kahn. "And, of particular concern, these conditions are becoming more common, not only in adults, but also in children and adolescents.

"It is, therefore, clear that more effective treatment strategies are needed to prevent and treat diabetes. RBP4 could prove to be a novel target for developing anti-diabetic therapies."

Bonnie Prescott | EurekAlert!
Further information:
http://www.bidmc.harvard.edu

More articles from Studies and Analyses:

nachricht Physics of bubbles could explain language patterns
25.07.2017 | University of Portsmouth

nachricht Obstructing the ‘inner eye’
07.07.2017 | Friedrich-Schiller-Universität Jena

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Physicists Design Ultrafocused Pulses

Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.

Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

Programming cells with computer-like logic

27.07.2017 | Life Sciences

Identified the component that allows a lethal bacteria to spread resistance to antibiotics

27.07.2017 | Life Sciences

Malaria Already Endemic in the Mediterranean by the Roman Period

27.07.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>