Obesity Week Keynote Highlights Fat Cell Browning

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Obesity Initiative at UGA

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Fat, exercise and a molecule with a peculiar name took center-stage in the Obesity Week 2013 keynote by Bruce Spiegelman in Atlanta last week. Recent experiments indicate that molecule, called “meteorin-like,” can cause calorie-storing fat to more closely resemble a type of fat that actually burns calories.

The two types of fat are known as “white fat” and “brown fat.”  White fat cells are used to store excess energy, while brown fat cells are used to burn energy for heat. Newborns and small mammals have high amounts of brown fat that help them survive cold temperatures. Recently, researchers have started investigating brown fat as a way to fight obesity. The meteorin-like molecule is a polypeptide, or protein component, that may play a role in the fight.

Muscles release meteorin-like during exercise. Spiegelman showed that injecting the polypeptide into the tail veins of mice causes white fat to become more like brown, heat generating fat.  As a result of the injections, mice use up a lot more energy than usual.

The polypeptide drives the production of two molecules – interleukin 4 (IL4) and interleukin 13 (IL13) – that give rise to white blood cells called M2 macrophages. Unlike “classical” macrophages, which Spiegelman described as “spitting out nasty things,” these cells release anti-inflammatory hormones called catecholamines. These catecholamines act on white fat cells and make them more closely resemble the energy-burning profile of brown fat cells.

The global increase in obesity and Type 2 diabetes underlines the need for multiple therapeutic approaches to these issues. However, it is unlikely that meteorin-like treatments will be available for humans soon. The molecule used in mice was unstable, and its effects were short lived.  But someday, Spiegelman hopes, some variation on the polypeptide with the awkward name will help treat obesity in humans.

Beyond the University of Georgia research projects mentioned in the previous post, the Obesity Week conference included presentations on a variety of topics – from possible causes to new treatments. The above post is a guest post by Hyacinth Empinado, a graduate student in UGA’s Health and Medical Journalism Program, who attended the conference.