Comparative genomics provides evidence for close evolutionary relationships between the urotensin II and somatostatin gene families

doi:10.1073/pnas.0510700103

Comparative genomics provides evidence for close evolutionary relationships between the urotensin II and somatostatin gene families

*Institut National de la Santé et de la Recherche Médicale Unité 413, Laboratory of Cellular and Molecular Neuroendocrinology, European Institute for Peptide Research, University of Rouen, 76821 Mont-Saint-Aignan, France;
^†Center for Advanced Research in Environmental Genomics, Department of Biology, University of Ottawa, Ottawa, ON, Canada K1N 6N5;
^‡Laboratoire de Neurobiologie des Signaux Intercellulaires, Centre National de la Recherche Scientifique Unité Mixte Recherche 7101, Université Pierre et Marie Curie, 75252 Paris, France; and
^§Laboratoire de Génétique Cellulaire, Institut National de la Recherche Agronomique, 31326 Castanet-Tolosan, France

Communicated by Howard A. Bern, University of California, Berkeley, CA, December 16, 2005 (received for review August 20, 2005)

Abstract

Although urotensin II (UII) and somatostatin 1 (SS1) exhibit some structural similarities, their precursors do not show any appreciable sequence identity and, thus, it is widely accepted that the UII and SS1 genes do not derive from a common ancestral gene. The recent characterization of novel isoforms of these two peptides, namely urotensin II-related peptide (URP) and somatostatin 2 (SS2)/cortistatin (CST), provides new opportunity to revisit the phylogenetic relationships of UII and SS1 using a comparative genomics approach. In the present study, by radiation hybrid mapping and in silico sequence analysis, we have determined the chromosomal localization of the genes encoding UII- and somatostatin-related peptides in several vertebrate species, including human, chicken, and zebrafish. In most of the species investigated, the UII and URP genes are closely linked to the SS2/CST and SS1 genes, respectively. We also found that the UII-SS2/CST locus and the URP/SS1 locus are paralogous. Taken together, these data indicate that the UII and URP genes, on the one hand, and the SS1 and SS2/CST genes, on the other hand, arose through a segmental duplication of two ancestral genes that were already physically linked to each other. Our results also suggest that these two genes arose themselves through a tandem duplication of a single ancestral gene. It thus appears that the genes encoding UII- and somatostatin-related peptides belong to the same superfamily.

Footnotes

^¶To whom correspondence should be addressed. E-mail: hubert.vaudry{at}univ-rouen.fr
Author contributions: H.T., I.L., and H.V. designed research; H.T., L.J., C.P., A.L., and M.M. performed research; H.T., L.J., C.P., A.L., M.M., A.C., and M.E. contributed new reagents/analytic tools; H.T., L.J., I.L., and M.M. analyzed data; and H.T., I.L., and H.V. wrote the paper.
Conflict of interest statement: No conflicts declared.
Data deposition: The sequences reported in this paper have been deposited in the GenBank database [accession nos. NM_212848 (prepro-urotensin II-α, zebrafish); NM_205591 (prepro-urotensin II-β, zebrafish); NM_206990 (prepro-urotensin II, chicken); and NM_206989 (prepro-urotensin II-related peptide, chicken)].
↵ ∥ A measure of the frequency of chromosome breakage between DNA markers in radiation-reduced somatic cell hybrids. One centiRay is equivalent to a 1% probability that a chromosome break (double-stranded break for diploid hybrid panels) has occurred between two markers in a given hybrid cell line.
Abbreviations:

Abbreviations:

CST,

cortistatin;

RH,

radiation hybrid;

SS1,

somatostatin 1;

SS2,

somatostatin 2;

UII,

urotensin II;

URP,

urotensin II-related peptide.