title: The expression of UCP3 directly correlates to UCP1 abundance in brown adipose tissue.
abstract: UCP1 and UCP3 are members of the uncoupling protein (UCP) subfamily and are localized in the inner mitochondrial membrane. Whereas UCP1's central role in non-shivering thermogenesis is acknowledged, the function and even tissue expression pattern of UCP3 are still under dispute. Because UCP3 properties regarding transport of protons are qualitatively identical to those of UCP1, its expression in brown adipose tissue (BAT) alongside UCP1 requires justification. In this work, we tested whether any correlation exists between the expression of UCP1 and UCP3 in BAT by quantification of protein amounts in mouse tissues at physiological conditions, in cold-acclimated and UCP1 knockout mice. Quantification using recombinant UCP3 revealed that the UCP3 amount in BAT (0.51ng/(μg total tissue protein)) was nearly one order of magnitude higher than that in muscles and heart. Cold-acclimated mice showed an approximate three-fold increase in UCP3 abundance in BAT in comparison to mice in thermoneutral conditions. Surprisingly, we found a significant decrease of UCP3 in BAT of UCP1 knockout mice, whereas the protein amount in skeletal and heart muscles remained constant. UCP3 abundance decreased even more in cold-acclimated UCP1 knockout mice. Protein quantification in UCP3 knockout mice revealed no compensatory increase in UCP1 or UCP2 expression. Our results do not support the participation of UCP3 in thermogenesis in the absence of UCP1 in BAT, but clearly demonstrate the correlation in abundance between both proteins. The latter is important for understanding UCP3's function in BAT.
authors.affiliation: Institute of Physiology, Pathophysiology and Biophysics, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria.
authors.forename: Karolina E
authors.initials: KE
authors.lastname: Hilse
authors.affiliation: Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
authors.forename: Anastasia V
authors.initials: AV
authors.lastname: Kalinovich
authors.affiliation: Institute of Physiology, Pathophysiology and Biophysics, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria.
authors.forename: Anne
authors.initials: A
authors.lastname: Rupprecht
authors.affiliation: Institute of Physiology, Pathophysiology and Biophysics, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria.
authors.forename: Alina
authors.initials: A
authors.lastname: Smorodchenko
authors.affiliation: Institute of Physiology, Pathophysiology and Biophysics, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria.
authors.forename: Ute
authors.initials: U
authors.lastname: Zeitz
authors.affiliation: Institute of Pharmacology and Toxicology, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria.
authors.forename: Katrin
authors.initials: K
authors.lastname: Staniek
authors.affiliation: Institute of Physiology, Pathophysiology and Biophysics, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria.
authors.forename: Reinhold G
authors.initials: RG
authors.lastname: Erben
authors.affiliation: Institute of Physiology, Pathophysiology and Biophysics, Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria. Electronic address: elena.pohl@vetmeduni.ac.at.
authors.forename: Elena E
authors.initials: EE
authors.lastname: Pohl
mesh_terms: D002001:Adipose Tissue, Brown / Q000378:metabolism*; D000818:Animals; D007473:Ion Channels / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D024101:Mitochondrial Proteins / Q000502:physiology*; D022722:Thermogenesis; D000071256:Uncoupling Protein 1; D000071247:Uncoupling Protein 3
chemical_list: D007473:Ion Channels; D024101:Mitochondrial Proteins; C000604372:Ucp1 protein, mouse; C000604393:Ucp3 protein, mouse; D000071256:Uncoupling Protein 1; D000071247:Uncoupling Protein 3
keywords: Anti-UCP3 antibody; Cold-acclimated mice; Recombinant protein; Skeletal muscles; UCP3 knockout mice; Uncoupling protein 2