Cell-autonomous light sensitivity via Opsin3 regulates fuel utilization in brown adipocytes

PLoS Biol. 2020 Feb 10;18(2):e3000630. doi: 10.1371/journal.pbio.3000630. eCollection 2020 Feb.


Opsin3 (Opn3) is a transmembrane heptahelical G protein-coupled receptor (GPCR) with the potential to produce a nonvisual photoreceptive effect. Interestingly, anatomical profiling of GPCRs reveals that Opn3 mRNA is highly expressed in adipose tissue. The photosensitive functions of Opn3 in mammals are poorly understood, and whether Opn3 has a role in fat is entirely unknown. In this study, we found that Opn3-knockout (Opn3-KO) mice were prone to diet-induced obesity and insulin resistance. At the cellular level, Opn3-KO brown adipocytes cultured in darkness had decreased glucose uptake and lower nutrient-induced mitochondrial respiration than wild-type (WT) cells. Light exposure promoted mitochondrial activity and glucose uptake in WT adipocytes but not in Opn3-KO cells. Brown adipocytes carrying a defective mutation in Opn3's putative G protein-binding domain also exhibited a reduction in glucose uptake and mitochondrial respiration in darkness. Using RNA-sequencing, we identified several novel light-sensitive and Opn3-dependent molecular signatures in brown adipocytes. Importantly, direct exposure of brown adipose tissue (BAT) to light in living mice significantly enhanced thermogenic capacity of BAT, and this effect was diminished in Opn3-KO animals. These results uncover a previously unrecognized cell-autonomous, light-sensing mechanism in brown adipocytes via Opn3-GPCR signaling that can regulate fuel metabolism and mitochondrial respiration. Our work also provides a molecular basis for developing light-based treatments for obesity and its related metabolic disorders.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipocytes, Brown / metabolism*
  • Adipose Tissue, Brown / innervation
  • Animals
  • Diet, High-Fat / adverse effects
  • Energy Metabolism*
  • Gene Expression Regulation
  • Glucose / metabolism
  • Insulin Resistance
  • Light
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mitochondria / metabolism
  • Mutation
  • Obesity / genetics
  • Obesity / metabolism
  • Receptors, G-Protein-Coupled / genetics
  • Receptors, G-Protein-Coupled / metabolism
  • Rod Opsins / genetics
  • Rod Opsins / metabolism*
  • Signal Transduction
  • Thermogenesis


  • OPN3 protein, mouse
  • Receptors, G-Protein-Coupled
  • Rod Opsins
  • Glucose

Associated data

  • Dryad/10.5061/dryad.p5hqbzkkv