The CXC chemokine receptors of fish: Insights into CXCR evolution in the vertebrates

Identification and expression analysis of an atypical chemokine receptor-2 (ACKR2)/CC chemokine binding protein-2 (CCBP2) in rainbow trout (Oncorhynchus mykiss)

“…A DRY motif at the boundary of TM3 and ICL2 is well conserved in typical chemokine receptors and critical for ligand induced signalling activity [7,13]. Unlike ACKR2 molecules in higher vertebrates, this DRY motif has been previously described in Atlantic salmon ACKR2 [24] and, from the current study, reported in rainbow trout and coelacanth ACKR2 (Fig. 3).…”

“…Whilst humans have 48 chemokines, analysis of the genomes of several teleosts, including zebrafish, medaka, stickleback and tetraodon have shown they contain 89, 36, 24 and 20 chemokines, respectively [5]. The orthologues of most of the known 23 human chemokine receptors have also been identified in teleost fish [3e5, 18,23,24] together with a few chemokine receptors (eg CXCR3b/ssCXCR8 and drCCR12/ssCCR3) that are not present in humans [18,23e25]. In line with the fish specific (3R) wholegenome duplication (WGD) event, which occurred in ray finned fish species before the divergence of most teleost species [26], 3R fish often possess more than two genes for a single human counterpart, and in salmonids this can be even higher due to a 4R WGD event in this lineage [24].…”

“…The orthologues of most of the known 23 human chemokine receptors have also been identified in teleost fish [3e5, 18,23,24] together with a few chemokine receptors (eg CXCR3b/ssCXCR8 and drCCR12/ssCCR3) that are not present in humans [18,23e25]. In line with the fish specific (3R) wholegenome duplication (WGD) event, which occurred in ray finned fish species before the divergence of most teleost species [26], 3R fish often possess more than two genes for a single human counterpart, and in salmonids this can be even higher due to a 4R WGD event in this lineage [24]. So far, 40, 31, 24, 48 and 30 chemokine receptor genes have been identified in zebrafish, medaka, tetraodon, Atlantic salmon and pike, respectively [18,24].…”

“…In line with the fish specific (3R) wholegenome duplication (WGD) event, which occurred in ray finned fish species before the divergence of most teleost species [26], 3R fish often possess more than two genes for a single human counterpart, and in salmonids this can be even higher due to a 4R WGD event in this lineage [24]. So far, 40, 31, 24, 48 and 30 chemokine receptor genes have been identified in zebrafish, medaka, tetraodon, Atlantic salmon and pike, respectively [18,24].…”

“…The ACKR2 gene is present in birds and mammals, and recently has been identified in teleost fish (Atlantic salmon, zebrafish, pike) [24] and cartilaginous fish (elephant shark -accession. no.…”