Fighting fat with fat: Stem cell discovery identifies potential obesity treatment
February 5, 2013—Ottawa—Ottawa scientists have discovered a trigger that turns muscle stem cells into brown fat, a form of good fat that could play a critical role in the fight against obesity. The findings from Dr. Michael Rudnicki’s lab, based at the Ottawa Hospital Research Institute, were published today in the journal Cell Metabolism.
“This discovery significantly advances our ability to harness this good fat in the battle against bad fat and all the associated health risks that come with being overweight and obese,” says Dr. Rudnicki, a senior scientist at the Ottawa Hospital Research Institute. He is also a Canada Research Chair in Molecular Genetics and professor in the Faculty of Medicine at the University of Ottawa.
Globally, obesity is the fifth leading risk for death, with an estimated 2.8 million people dying every year from the effects of being overweight or obese, according to the World Health Organization. The Public Health Agency of Canada estimates that 25% of Canadian adults are obese.
In 2007, Dr. Rudnicki led a team that was the first to prove the existence of adult skeletal muscle stem cells. In the paper published today, Dr. Rudnicki now shows (again for the first time) that these adult muscle stem cells not only have the ability to produce muscle fibres, but also to become brown fat. Brown fat is an energy-burning tissue that is important to the body’s ability to keep warm and regulate temperature. In addition, more brown fat is associated with less obesity.
Dr. Rudnicki’s lab showed that adult mice injected with an agent to reduce miR-133, called an antisense oligonucleotide or ASO, produced more brown fat, were protected from obesity and had an improved ability to process glucose. In addition, the local injection into the hind leg muscle led to increased energy production throughout the body—an effect observed after four months.
In this picture taken with a thermographic camera after four months, the mouse treated with miR-133 ASO (on the right) is noticeably leaner. In addition, the injected hind leg (on the left in the image) is 0.8 C hotter than the control mouse.
“While we are very excited by this breakthrough, we acknowledge that it’s a first step,” says Dr. Rudnicki.
The full article, “MicroRNA-133 Controls Brown Adipose Determination in Skeletal Muscle Satellite Cells by Targeting Prdm16,” was published by Cell Metabolism online ahead of print on February 5, 2013.
Photo Credit: Rudnicki et al., Ottawa Hospital Research Institute, published in Cell Metabolism
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