title: Adaptive evolution of the Retinoid X receptor in vertebrates.
abstract: Retinoid X receptors (RXR) are transcription factors with important roles in development, reproduction, homeostasis, and cell differentiation. Different types of vertebrate RXRs (α (RXRA), ß (RXRB) and γ (RXRG)) have arisen from multiple duplication events. The adaptive evolution mechanism that has preserved duplicate RXR paralogs, as well as their role in development and adaptation, is thus far unknown. In this work, we have investigated different aspects of vertebrate RXR evolution. Codon based tests of positive selection identified that RXR was under significant positive selection immediately after the whole genome duplications in vertebrates. Amino acid based rate shift analysis also revealed significant rate shifts immediately after the whole genome duplications and functional divergence between all the pairs of RXRs. However, the extant RXR genes are highly conserved, particularly the helix involved in dimerization and the DNA-binding domain, but positively selected sites can nevertheless be found in domains for RXR regulation.
authors.affiliation: CIMAR/CIIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Rua dos Bragas 177, 4050-123 Porto, Portugal.
authors.forename: Siby
authors.initials: S
authors.lastname: Philip
authors.forename: L Filipe C
authors.initials: LF
authors.lastname: Castro
authors.forename: Rute R
authors.initials: RR
authors.lastname: da Fonseca
authors.forename: Maria A
authors.initials: MA
authors.lastname: Reis-Henriques
authors.forename: Vítor
authors.initials: V
authors.lastname: Vasconcelos
authors.forename: Miguel M
authors.initials: MM
authors.lastname: Santos
authors.forename: Agostinho
authors.initials: A
authors.lastname: Antunes
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics; D000818:Animals; D019143:Evolution, Molecular; D005399:Fishes / Q000235:genetics*; D020440:Gene Duplication; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D016013:Likelihood Functions; D051379:Mice / Q000235:genetics; D008957:Models, Genetic; D008958:Models, Molecular; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D047488:Retinoid X Receptors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012641:Selection, Genetic; D026801:Synteny; D014714:Vertebrates
chemical_list: D047488:Retinoid X Receptors