The Rhodopsin family of G protein coupled receptors (GPCRs) includes the phylogenetic α–group consisting of about 100 human members. The α–group is the only group of GPCRs that has many receptors for biogenic amines which are major drug targets. Several members of this group are orphan receptors and their functions are elusive. In this study we present a detailed phylogenetic and anatomical characterization of the Gpr153 receptor and also attempt to study its functional role. We identified the homologue of Gpr153 in the elephant shark genome and phylogenetic and synteny analyses revealed that Gpr162 and Gpr153 share a common ancestor that split most likely through a duplication event before the divergence of the tetrapods and the teleost lineage. A quantitative real–time PCR study reveals widespread expression of Gpr153 in the central nervous system and all the peripheral tissues investigated. Detailed in situ hybridization on mouse brain showed specifically high expression in the thalamus, cerebellum and the arcuate nucleus. The antisense oligodeoxynucleotide knockdown of Gpr153 caused a slight reduction in food intake and the elevated plus maze test showed significant reduction in the percentage of time spent in the centre square, which points towards a probable role in decision making. This report provides the first detailed characterization of the evolution, expression and primary functional properties of the Gpr153 gene.Database
Protein sequence data have been deposited to the DDJB database (http://www.ddbj.nig.ac.jp/) with accession numbers BR000916, BR000917 and BR000918 for elephant shark Gpr153_exon 1–3, Gpr153_exon 4 and Gpr153_exon 5 respectively.