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Fighting Fat With Fat
Researchers at the Ottawa Hospital Research Institute in Canada have discovered a trigger that turns muscle stem cells into brown fat, a form of good fat that could play an important role in the fight against obesity.
The new study — published in Cell Metabolism — showed that adult skeletal-muscle stem cells not only have the ability to produce muscle fibers, 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 to regulate temperature. In addition, more brown fat is associated with less obesity.
The study also identified how adult muscle stem cells become brown fat. The key is a small gene regulator called microRNA-133 (miR-133). When miR-133 is present, the stem cells turn into muscle fiber; when reduced, the stem cells become brown fat.
The researchers found that adult mice injected with an agent to reduce miR-133 — called an antisense oligonucleotide (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 4 months.
Using an ASO to treat disease by reducing the levels of specific microRNAs is a method that is already being investigated in human clinical trials. However, a potential treatment using miR-133 to combat obesity is still years away, the researchers say.
Source: Ottawa Hospital Research Institute; February 5, 2013.