title: Quantification of uncoupling protein 2 reveals its main expression in immune cells and selective up-regulation during T-cell proliferation.
abstract: Uncoupling protein 2 (UCP2) is an inner mitochondrial membrane protein. Although the protein was discovered in 1997, its function and even its tissue distribution are still under debate. Here we present a quantitative analysis of mRNA and protein expression in various mice tissues, revealing that UCP2 is mainly expressed in organs and cells associated with the immune system. Although the UCP2 gene is present in the brain, as demonstrated using quantitative RT-PCR, the protein was not detectable in neurons under physiological conditions. Instead, we could detect UCP2 in microglia, which act in the immune defense of the central nervous system. In lymphocytes, activation led to a ten-fold increase of UCP2 protein expression simultaneously to the increase in levels of other mitochondrial proteins, whereas lymphocyte re-stimulation resulted in the selective increase of UCP2. The highest detected level of UCP2 expression in stimulated T-cells (0.54 ng/(µg total cellular protein)) was approximately 200 times lower than the level of UCP1 in brown adipose tissue from room temperature acclimated mice. Both the UCP2 expression pattern and the time course of up-regulation in stimulated T-cells imply UCP2's involvement in the immune response, probably by controlling the metabolism during cell proliferation.
authors.affiliation: Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria.
authors.forename: Anne
authors.initials: A
authors.lastname: Rupprecht
authors.forename: Anja U
authors.initials: AU
authors.lastname: Bräuer
authors.forename: Alina
authors.initials: A
authors.lastname: Smorodchenko
authors.forename: Justus
authors.initials: J
authors.lastname: Goyn
authors.forename: Karolina E
authors.initials: KE
authors.lastname: Hilse
authors.forename: Irina G
authors.initials: IG
authors.lastname: Shabalina
authors.forename: Carmen
authors.initials: C
authors.lastname: Infante-Duarte
authors.forename: Elena E
authors.initials: EE
authors.lastname: Pohl
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D005786:Gene Expression Regulation / Q000276:immunology*; D007473:Ion Channels / Q000096:biosynthesis / Q000276:immunology*; D008213:Lymphocyte Activation / Q000502:physiology*; D051379:Mice; D017628:Microglia / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000096:biosynthesis / Q000276:immunology*; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D000071246:Uncoupling Protein 2
chemical_list: D007473:Ion Channels; D024101:Mitochondrial Proteins; D009419:Nerve Tissue Proteins; C000604390:Ucp2 protein, mouse; D000071246:Uncoupling Protein 2