Brown Fat Flexes its Muscle to Burn Energy – And Calories
Source: University of California – Berkeley
Summary: Researchers have discovered that the same kind of fat cells that help newborn babies regulate their body temperature could be a target for weight-loss drugs in adults.
Brown fat cells, which help mammals regulate their body temperature, work much like muscle cells. When the brain sends a signal to brown fat to start burning energy to generate heat, the cells stiffen, which triggers a biochemical pathway that ends with these cells burning calories for heat. A multidisciplinary research team of bioengineers and metabolic researchers from the University of California – Berkeley teased apart the steps of the pathway and identified a potential way for drugs to switch on brown fat cells. They have discovered that the same kind of fat cells that help newborn babies regulate their body temperature could be a target for weight-loss drugs in adults. This understanding of how brown fat is activated could unlock new ways to combat obesity. The study findings were published in the journal Cell Metabolism.
The research team stimulated brown fat and measured how much the cell flexed by measuring the increase in tension in the cell. They found that the cells became roughly twice as stiff when stimulated. Then the researchers disabled the muscle-like myosin in brown fat cells and found that the cells became significantly softer, with their stiffness reduced by about a factor of two. The study found that a protein called Uncoupling Factor-1 (UCP1’s) activity is directly tied to the increase in cell tension. The team then relieved the tension in activated brown fat cells and found that caused a 70% reduction in UCP1, so the cells generate less heat. The researchers then identified molecules in the cell that respond to increased tension to trigger the activation of UCP1. They found that cell stiffening really plays a big role in the function of brown adipocytes.
Prof. Andreas Stahl said, “Now that we better understand how brown fat cells work, we can think about ways to stimulate muscle-like myosin in brown fat to increase thermogenesis and burn calories”, “Drugs to stimulate muscle-like myosin in existing brown fat would probably create more active brown fat cells in adults.”
More Information: Kevin M. Tharp, “Actomyosin-Mediated Tension Orchestrates Uncoupled Respiration in Adipose Tissues”, Cell Metabolism (2018). DOI: 10.1016/j.cmet.2018.02.005