Evolution of Dopamine Receptor Genes of the D sub(1) Class in Vertebrates

• Published in: Molecular biology and evolution 2013-04, Vol.30 (4), p.833-843
• Main Authors: Yamamoto, Kei, Mirabeau, Olivier, Bureau, Charlotte, Blin, Maryline, Michon-Coudouel, Sophie, Demarque, Michaeel, Vernier, Philippe
• Format: Article
• Language: English
• Subjects: Danio rerio; Freshwater
• ISSN: 0737-4038; 1537-1719
• DOI: 10.1093/molbev/mss268

The receptors of the dopamine neurotransmitter belong to two unrelated classes named D sub(1) and D sub(2). For the D sub(1) receptor class, only two subtypes are found in mammals, the D sub(1A) and D sub(1B,) receptors, whereas additional subtypes, named D sub(1C), D sub(1D), and D sub(1X), have been found in other vertebrate species. Here, we analyzed molecular phylogeny, gene synteny, and gene expression pattern of the D sub(1) receptor subtypes in a large range of vertebrate species, which leads us to propose a new view of the evolution of D sub(1) dopamine receptor genes. First, we show that D sub(1) sub(C) and D sub(1) sub(D) receptor sequences are encoded by orthologous genes. Second, the previously identified Cypriniform D sub(1) sub(X) sequence is a teleost-specific paralog of the D sub(1) sub(B) sequences found in all groups of jawed vertebrates. Third, zebrafish and several sauropsid species possess an additional D sub(1)-like gene, which is likely to form another orthology group of vertebrate ancestral genes, which we propose to name D sub(1) sub(E). Ancestral jawed vertebrates are thus likely to have possessed four classes of D sub(1) receptor genes-D sub(1) sub(A), D sub(1) sub(B(X)), D sub(1) sub(C(D)), and D sub(1) sub(E)-which arose from large-scale gene duplications. The D sub(1) sub(C) receptor gene would have been secondarily lost in the mammalian lineage, whereas the D sub(1) sub(E) receptor gene would have been lost independently in several lineages of modern vertebrates. The D sub(1) sub(A) receptors are well conserved throughout jawed vertebrates, whereas sauropsid D sub(1) sub(C) receptors have rapidly diverged, to the point that they were misidentified as D sub(1) sub(D). The functional significance of the D sub(1) sub(C) receptor loss is not known. It is possible that the function may have been substituted with D sub(1) sub(A) or D sub(1) sub(B) receptors in mammals, following the disappearance of D sub(1) sub(C) receptors in these species.