Identification of dopamine receptors across the extant avian family tree and analysis with other clades uncovers a polyploid expansion among vertebrates.
Dopamine is an important central nervous system transmitter that functions through two classes of receptors (D1 and D2) to influence a diverse range of biological processes in vertebrates. With roles in regulating neural activity, behavior, and gene expression, there has been great interest in understanding the function and evolution dopamine and its receptors. In this study, we use a combination of sequence analyses, microsynteny analyses, and phylogenetic relationships to identify and characterize both the D1 (DRD1A, DRD1B, DRD1C, and DRD1E) and D2 (DRD2, DRD3, and DRD4) dopamine receptor gene families in 43 recently sequenced bird genomes representing the major ordinal lineages across the avian family tree. We show that the common ancestor of all birds possessed at least seven D1 and D2 receptors, followed by subsequent independent losses in some lineages of modern birds. Through comparisons with other vertebrate and invertebrate species we show that two of the D1 receptors, DRD1A and DRD1B, and two of the D2 receptors, DRD2 and DRD3, originated from a whole genome duplication event early in the vertebrate lineage, providing the first conclusive evidence of the origin of these highly conserved receptors. Our findings provide insight into the evolutionary development of an important modulatory component of the central nervous system in vertebrates, and will help further unravel the complex evolutionary and functional relationships among dopamine receptors.
Arizona Biological/Biomedical Sciences Program, University of Arizona Tucson, AZ, USA ; Genetics GIDP, University of Arizona Tucson, AZ, USA.
Asher
A
Haug-Baltzell
Department of Neurobiology, Duke University Medical Center Durham, NC, USA ; Howard Hughes Medical Institute Chevy Chase, MD, USA.
Erich D
ED
Jarvis
School of Animal and Comparative Biomedical Sciences, University of Arizona Tucson, AZ, USA ; BIO5 Institute, University of Arizona Tucson, AZ, USA.
Fiona M
FM
McCarthy
Genetics GIDP, University of Arizona Tucson, AZ, USA ; BIO5 Institute, University of Arizona Tucson, AZ, USA ; The School of Plant Sciences, University of Arizona Tucson, AZ, USA.
Eric
E
Lyons
comparative genomics; dopamine receptors; genome evolution; polyploidy; whole genome duplication