Identification of a functioning mitochondrial uncoupling protein 1 in thymus.
We present evidence that rat and mouse thymi contain mitochondrial uncoupling protein (UCP 1). Reverse transcriptase-PCR detected RNA transcripts for UCP 1 in whole thymus and in thymocytes. Furthermore, using antibodies to UCP 1 the protein was also detected in mitochondria isolated from whole thymus and thymocytes but not in thymus mitochondria from UCP 1 knock-out mice. Evidence for functional UCP 1 in thymus mitochondria was obtained by a comparative analysis with the kinetics of GDP binding in mitochondria from brown adipose tissue. Both tissues showed equivalent B(max) and K(D) values. In addition, a large component of the nonphosphorylating oxygen consumption by thymus mitochondria was inhibited by GDP and subsequently stimulated by addition of nanomolar concentrations of palmitate. UCP 1 was purified from thymus mitochondria by hydroxyapatite chromatography. The isolated protein was identified by peptide mass mapping and tandem mass spectrometry by using MALDI-TOF and LC-MS/MS, respectively. We conclude that the thymus contains a functioning UCP 1 that has the capacity to regulate metabolic flux and production of reactive oxygen-containing molecules in the thymus.
Carroll
Audrey M
AM
Department of Biochemistry, Trinity College Dublin, Dublin 2, Ireland.
Haines
Lee R
LR
Pearson
Terry W
TW
Fallon
Padraic G
PG
Walsh
Caitríona M
CM
Brennan
Clare M
CM
Breen
Eamon P
EP
Porter
Richard K
RK
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D005260:Female; D006153:Guanosine Diphosphate / Q000378:metabolism; D007473:Ion Channels; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013950:Thymus Gland / Q000378:metabolism*; D000071256:Uncoupling Protein 1
D000906:Antibodies; D002352:Carrier Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; C000604372:Ucp1 protein, mouse; C000604373:Ucp1 protein, rat; D000071256:Uncoupling Protein 1; D006153:Guanosine Diphosphate