Metabolism Affected by Fat Cells that Sense Sunlight

Published January 2020 | Cell Reports

Scientists at Cincinnati Children’s who were studying how mice control their body temperature made a discovery that may shed new light on the often-unhealthy consequences of modern life.

A team led by Richard Lang, PhD, director of the Visual Systems Group, has shown that fat cells deep under the skin possess opsins that both sense and respond to a specific wavelength of visible sunlight.

Changing the exposure level of this 480-nanometer wavelength of blue light influences an internal fat-burning response that mice employ when exposed to chilly temperatures—about 40° F.

The team went on to show that this light response is controlled by the gene OPN3. When light exposure occurs, the OPN3 protein prompts white fat cells to release fatty acids into the bloodstream. In this mouse study, brown fat cells then oxidize the fatty acids to generate heat.

This data prompted the team to conclude that sunlight is required for normal energy metabolism. They also note that this blue wavelength of sunlight is found only in low amounts in typical indoor lighting.

“We are conducting further study to confirm that this light-OPN3 adipocyte pathway exists in humans. If so, there are potentially broad implications for human health,” Lang says. “Our modern lifestyle subjects us to unnatural lighting spectra, exposure to light at night, shift work, and jet lag, all of which result in metabolic disruption. Based on the current findings, it is possible that insufficient stimulation of the light-OPN3 adipocyte pathway is part of an explanation for the prevalence of metabolic deregulation in industrialized nations where unnatural lighting has become the norm.”