Referenced in: none

Automatically associated channels: Kir2.3

Title: UCP1 in brite/beige adipose tissue mitochondria is functionally thermogenic.

Authors: Irina G Shabalina, Natasa Petrovic, Jasper M A de Jong, Anastasia V Kalinovich, Barbara Cannon, Jan Nedergaard

Journal, date & volume: Cell Rep, 2013 Dec 12 , 5, 1196-203

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/24290753

Abstract
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.