title: Three peroxisome proliferator-activated receptor isotypes from each of two species of marine fish.
abstract: The cloning and characterization of cDNAs and genes encoding three peroxisome proliferator-activated receptor (PPAR) isotypes from two species of marine fish, the plaice (Pleuronectes platessa) and the gilthead sea bream (Sparus aurata), are reported for the first time. Although differences in the genomic organization of the fish PPAR genes compared with their mammalian counterparts are evident, sequence alignments and phylogenetic comparisons show the fish genes to be homologs of mammalian PPARalpha, PPARbeta/delta, and PPARgamma. Like their mammalian homologs, fish PPARs bind to a variety of natural PPAR response elements (PPREs) present in the promoters of mammalian or piscine genes. In contrast, the mRNA expression pattern of PPARs in the two fish species differs from that observed in other vertebrates. Thus, PPARgamma is expressed more widely in fish tissues than in mammals, whereas PPARalpha and beta are expressed similarly in profile to mammals. Furthermore, nutritional status strongly influences the expression of all three PPAR isotypes in liver, whereas it has no effect on PPAR expression in intestinal and adipose tissues. Fish PPARalpha and beta exhibit an activation profile similar to that of the mammalian PPAR in response to a variety of activators/ligands, whereas PPARgamma is not activated by mammalian PPARgamma-specific ligands. Amino acid residues shown to be critical for ligand binding in mammalian PPARs are not conserved in fish PPARgamma and therefore, together with the distinct tissue expression profile of this receptor, suggest potential differences in the function of PPARgamma in fish compared with mammals.
authors.affiliation: Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, UK.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Leaver
authors.forename: Evridiki
authors.initials: E
authors.lastname: Boukouvala
authors.forename: Efthimia
authors.initials: E
authors.lastname: Antonopoulou
authors.forename: Amalia
authors.initials: A
authors.lastname: Diez
authors.forename: Laurence
authors.initials: L
authors.lastname: Favre-Krey
authors.forename: M Tariq
authors.initials: MT
authors.lastname: Ezaz
authors.forename: José M
authors.initials: JM
authors.lastname: Bautista
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Tocher
authors.forename: Grigorios
authors.initials: G
authors.lastname: Krey
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D005432:Flounder / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D047493:PPAR alpha / Q000235:genetics / Q000378:metabolism*; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism*; D048068:PPAR-beta / Q000235:genetics / Q000378:metabolism*; D047492:Peroxisome Proliferator-Activated Receptors / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D012333:RNA, Messenger / Q000378:metabolism; D020218:Response Elements / Q000502:physiology; D021541:Sea Bream / Q000235:genetics / Q000378:metabolism*; D014018:Tissue Distribution; D015533:Transcriptional Activation
chemical_list: D018076:DNA, Complementary; D047493:PPAR alpha; D047495:PPAR gamma; D048068:PPAR-beta; D047492:Peroxisome Proliferator-Activated Receptors; D012333:RNA, Messenger