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Open Access Highly Accessed Research article

The evolution of vertebrate somatostatin receptors and their gene regions involves extensive chromosomal rearrangements

Daniel Ocampo Daza1*, Görel Sundström12, Christina A Bergqvist1 and Dan Larhammar1

Author Affiliations

1 Department of Neuroscience, Science for Life Laboratory, Uppsala Universitet, Box 593, SE-75124, Uppsala, Sweden

2 Present address: Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala Universitet, Box 582, SE-75123, Uppsala, Sweden

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BMC Evolutionary Biology 2012, 12:231  doi:10.1186/1471-2148-12-231

Published: 29 November 2012

Abstract

Background

Somatostatin and its related neuroendocrine peptides have a wide variety of physiological functions that are mediated by five somatostatin receptors with gene names SSTR1-5 in mammals. To resolve their evolution in vertebrates we have investigated the SSTR genes and a large number of adjacent gene families by phylogeny and conserved synteny analyses in a broad range of vertebrate species.

Results

We find that the SSTRs form two families that belong to distinct paralogons. We observe not only chromosomal similarities reflecting the paralogy relationships between the SSTR-bearing chromosome regions, but also extensive rearrangements between these regions in teleost fish genomes, including fusions and translocations followed by reshuffling through intrachromosomal rearrangements. These events obscure the paralogy relationships but are still tractable thanks to the many genomes now available. We have identified a previously unrecognized SSTR subtype, SSTR6, previously misidentified as either SSTR1 or SSTR4.

Conclusions

Two ancestral SSTR-bearing chromosome regions were duplicated in the two basal vertebrate tetraploidizations (2R). One of these ancestral SSTR genes generated SSTR2, -3 and -5, the other gave rise to SSTR1, -4 and -6. Subsequently SSTR6 was lost in tetrapods and SSTR4 in teleosts. Our study shows that extensive chromosomal rearrangements have taken place between related chromosome regions in teleosts, but that these events can be resolved by investigating several distantly related species.

Keywords:
Somatostatin receptors; Whole genome duplications; Chromosome rearrangements