UCP1 in brite/beige adipose tissue mitochondria is functionally thermogenic

Cell Rep. 2013 Dec 12;5(5):1196-203. doi: 10.1016/j.celrep.2013.10.044. Epub 2013 Nov 27.


The phenomenon of white fat "browning," in which certain white adipose tissue depots significantly increase gene expression for the uncoupling protein UCP1 and thus supposedly acquire thermogenic, fat-burning properties, has attracted considerable attention. Because the mRNA increases are from very low initial levels, the metabolic relevance of the change is unclear: is the UCP1 protein thermogenically competent in these brite/beige-fat mitochondria? We found that, in mitochondria isolated from the inguinal "white" adipose depot of cold-acclimated mice, UCP1 protein levels almost reached those in brown-fat mitochondria. The UCP1 was thermogenically functional, in that these mitochondria exhibited UCP1-dependent thermogenesis with lipid or carbohydrate substrates with canonical guanosine diphosphate (GDP) sensitivity and loss of thermogenesis in UCP1 knockout (KO) mice. Obesogenic mouse strains had a lower thermogenic potential than obesity-resistant strains. The thermogenic density (UCP1-dependent oxygen consumption per g tissue) of inguinal white adipose tissue was maximally one-fifth of interscapular brown adipose tissue, and the total quantitative contribution of all inguinal mitochondria was maximally one-third of all interscapular brown-fat mitochondria, indicating that the classical brown adipose tissue depots would still predominate in thermogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue, Brown / metabolism*
  • Adipose Tissue, Brown / physiology
  • Adipose Tissue, White / metabolism*
  • Adipose Tissue, White / physiology
  • Animals
  • Carbohydrate Metabolism
  • Guanosine Diphosphate / metabolism
  • Ion Channels / genetics
  • Ion Channels / metabolism*
  • Lipid Metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mitochondria / metabolism*
  • Mitochondrial Proteins / genetics
  • Mitochondrial Proteins / metabolism*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Thermogenesis*
  • Uncoupling Protein 1


  • Ion Channels
  • Mitochondrial Proteins
  • RNA, Messenger
  • Ucp1 protein, mouse
  • Uncoupling Protein 1
  • Guanosine Diphosphate