COMPLEX EVOLUTION OF SOMATOSTATIN AND UROTENSIN II RECEPTORS: ELEVEN ANCESTRAL GNATHOSTOME GENES OF WHICH ONLY SIX REMAIN IN MAMMALS
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1
Uppsala University, Neuroscience, Sweden
Somatostatins, urotensin II and the urotensin II-related peptides (URPs) form a family of related short peptides. They are expressed in both endocrine cells and neurons and have numerous roles mediated by somatostatin and urotensin II receptors. Mammals have been reported to have five somatostatin receptor genes called SSTR1-5 and one gene for a urotensin II receptor (UTS2R) located close to the SSTR2 gene. We have investigated the evolution of these receptor genes by sequence comparisons for a broad range of species, followed by phylogenetic tree analyses using both Neighbor-Joining and Maximum Likelihood methods. We have also compared chromosomal positions and phylogenetic tree topologies for a large number of adjacent gene families to investigate conserved synteny. To our surprise, we discovered that the teleost fish somatostatin receptor gene that is annotated as either SSTR1-like or SSTR4 is in fact orthologous to neither of these in tetrapods. We therefore call this fish receptor SSTR6. Another surprise was that while mammals have only one UTS2R gene, the anole lizard has no less than five UTS2R genes and the western clawed frog and the investigated bird species have four genes. Reciprocal losses have occurred in the avian and amphibian lineages. We propose that the vertebrate ancestor had two SSTR genes; these were duplicated in the two basal vertebrate tetraploidizations (2R), followed by some losses. One of the ancestral genes generated SSTR2, 3 and 5. The other gave rise to SSTR1, 4 and 6, and subsequently SSTR6 was lost in tetrapods. A single ancestral UTS2R gene was quadrupled in 2R and one of these underwent a local duplication resulting in five genes. Thus, mammals have lost the SSTR6 gene and four of the five ancestral UTS2R genes. It will be interesting to investigate what roles the much more advanced urotensin II system has in non-mammalian vertebrates.
Acknowledgements
Supported by the Swedish Research Foundation and Carl Trygger’s Foundation
Keywords:
anole lizard,
Frog,
Gene Duplication,
Mammal,
receptor,
Somatostatin,
teleost fish,
urotensin II
Conference:
NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology, Ann Arbor, United States, 13 Jul - 16 Jul, 2011.
Presentation Type:
Invited Symposium
Topic:
Molecular evolution
Citation:
Larhammar
D,
Bergqvist
CA,
Sundström
G and
Ocampo Daza
D
(2011). COMPLEX EVOLUTION OF SOMATOSTATIN AND UROTENSIN II RECEPTORS: ELEVEN ANCESTRAL GNATHOSTOME GENES OF WHICH ONLY SIX REMAIN IN MAMMALS.
Front. Endocrinol.
Conference Abstract:
NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology.
doi: 10.3389/conf.fendo.2011.04.00100
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Received:
21 Jul 2011;
Published Online:
09 Aug 2011.
*
Correspondence:
Prof. Dan Larhammar, Uppsala University, Neuroscience, Uppsala, SE-75124, Sweden, dan.larhammar@uu.se