title: Cloning, ontogenesis, and localization of an atypical uncoupling protein 4 in Xenopus laevis.
abstract: Uncoupling protein 1 (UCP1) is the first UCP described. It belongs to the family of mitochondrial carrier proteins and is expressed mainly in brown adipose tissue. Recently, the family of the UCPs has rapidly been growing due to the successive cloning of UCP2, UCP3, UCP4, and UCP5, also called brain mitochondrial carrier protein 1. Phylogenetic studies suggest that UCP1/UCP2/UCP3 on one hand and UCP4/UCP5 on the other hand belong to separate subfamilies. In this study, we report the cloning from a frog Xenopus laevis (Xl) oocyte cDNA library of a novel UCP that was shown, by sequence homology, to belong to the family of ancestral UCP4. This cloning provides a milestone in the gap between Drosophila melanogaster or Caenorhabditis elegans on one hand and mammalian UCP4 on the other. Xl UCP4 is already expressed in the oocyte, being the first UCP described in germ cell lineage. During development, it segregates in the neural cord, and, in the adult, in situ hybridization shows its expression in the neurons and also in the choroid plexus of the brain. By RT-PCR analysis, it was found that Xl UCP4 is present in all the subdivisions of the brain and also that it differs from mammalian UCP4 by a very high relative level of expression in peripheral tissues such as the liver and kidney. The peripheral tissue distribution of Xl UCP4 reinforces the hypothesis that UCP4 might be the ancestral UCP from which other UCPs diverged from.
authors.affiliation: Department of Cell Physiology and Metabolism, University Medical Center 1, Geneva. Patrick.Keller@medecine.unige.ch
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Keller
authors.forename: Lorenz
authors.initials: L
authors.lastname: Lehr
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Giacobino
authors.forename: Yves
authors.initials: Y
authors.lastname: Charnay
authors.forename: Françoise
authors.initials: F
authors.lastname: Assimacopoulos-Jeannet
authors.forename: Natalia
authors.initials: N
authors.lastname: Giovannini
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D001921:Brain / Q000378:metabolism; D017173:Caenorhabditis elegans; D002352:Carrier Proteins / Q000737:chemistry; D019070:Cell Lineage; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D019143:Evolution, Molecular; D020224:Expressed Sequence Tags; D005786:Gene Expression Regulation; D018507:Gene Expression Regulation, Developmental; D015723:Gene Library; D005854:Germ Cells / Q000378:metabolism; D006801:Humans; D017403:In Situ Hybridization; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology*; D000071245:Mitochondrial Uncoupling Proteins; D008953:Models, Anatomic; D008954:Models, Biological; D008969:Molecular Sequence Data; D010802:Phylogeny; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D029867:Xenopus Proteins / Q000235:genetics* / Q000502:physiology*; D014982:Xenopus laevis / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D018076:DNA, Complementary; D026901:Membrane Transport Proteins; D000071245:Mitochondrial Uncoupling Proteins; D012333:RNA, Messenger; C510867:SLC25A27 protein, Xenopus; C117577:SLC25A27 protein, human; D029867:Xenopus Proteins