Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Defective lymphatic vessels identified as a novel cause of adult-onset obesity

20.09.2005


Laboratory model missing one copy of Prox1 gene exhibits abnormal increase in fat accumulation around sites of lymph leakage from defective lymphatic vessels, according to St. Jude



Leaky lymphatic vessels are the leading cause of the adult onset obesity observed in a laboratory model developed by investigators at St. Jude Children’s Research Hospital. The findings suggest that the abnormal leakage of lymph fluid from the ruptured lymphatic vessels stimulates the accumulation of fat, particularly in regions of the body rich in lymphatics, the researchers said. The lymphatic vasculature (system of capillaries and vessels) that drains lymph is essential for the immune response in inflammation, and is the main route for the spreading of metastatic tumors to the lymph nodes.

The St. Jude investigators showed that removal of one of the two copies of the gene Prox1 disrupts normal development of the lymphatic vasculature, leading to leakage of lymph from ruptured lymphatic vessels, and subsequent obesity. Specifically, the researchers found that adipocytes (fat cells) near leaking lymphatic vessels under the skin and in the abdomen were significantly larger than normal, and therefore able to store more lipids (e.g., fatty acids and triglycerides, used as an energy source).


"This is the first such evidence in an in vivo model showing that defects in the integrity of the lymphatic vasculature could lead to adult obesity," said Guillermo Oliver, Ph.D., an associate member of the Genetics and Tumor Cell Biology Department at St. Jude. "And therefore, this is the first model available for studying obesity linked to faulty lymphatic vessels. It will be an important tool for studying this novel form of adult-onset obesity, as well as diseases of lymphatic vessels, and eventually, extending those findings to humans." Oliver is senior author of a report on this work that appears in the September 18 online issue of Nature Genetics.

The laboratory model (Prox1+/- ) lacked one of two copies of the Prox1 gene, which is required for proper development of the lymphatic system. Previously, Oliver’s laboratory reported that Prox1 activity is necessary for the normal development of cells making up the lymphatic vasculature; and that it is the subsequent budding and sprouting of those cells that give rise to the lymphatic system (Cell [98]:769-778; 1999).

Most Prox1+/- heterozygous (i.e., having only one copy of the gene) models die quickly in the postnatal period as a consequence of extensive lymphatic leakage that accumulates in the abdomen and thorax (chest). "However, those with a milder disruption of their lymphatic vasculature were able to survive and become obese with age," Oliver said.

"Interestingly, those that survived did not develop diabetes, as commonly seen in different types of obesity," he added. "This told us that the type of obesity we were seeing in this laboratory model was different from forms of obesity that are commonly associated with diabetes." The researchers also demonstrated that lymph removed from the abdominal cavity of the Prox1+/- models and added to cultured cells can promote adipocyte differentiation, most likely due to certain factors present in the collected lymph.

"Our findings might encourage physicians to consider that at least some of their obese patients might be suffering from a problem that can’t be solved by eating less and exercising more," Oliver said. Just as many vascular disorders arise because of blood vessel defects, other defects of the closely related lymphatic vessels in addition to edema could also occur in humans, he added.

Kelly Perry | EurekAlert!
Further information:
http://www.stjude.org

More articles from Life Sciences:

nachricht Link Discovered between Immune System, Brain Structure and Memory
26.04.2017 | Universität Basel

nachricht Researchers develop eco-friendly, 4-in-1 catalyst
25.04.2017 | Brown University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Link Discovered between Immune System, Brain Structure and Memory

26.04.2017 | Life Sciences

New survey hints at exotic origin for the Cold Spot

26.04.2017 | Physics and Astronomy

NASA examines newly formed Tropical Depression 3W in 3-D

26.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>