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Unexpected multiplicity of QRFP receptors in early vertebrate evolution
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Pharmacology. (Pharmacology)
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Pharmacology. (Pharmacology)
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Pharmacology. (Pharmacology)
2014 (English)In: Frontiers in Neuroscience, ISSN 1662-4548, E-ISSN 1662-453X, Vol. 8, 337- p.Article in journal (Refereed) Published
Abstract [en]

The neuropeptide QRFP, also called 26RFa, and its G protein-coupled receptor GPR103 have been identified in all vertebrates investigated. In mammals, this peptide-receptor pair has been found to have several effects including stimulation of appetite. Recently, we reported that a QRFP peptide is present in amphioxus, Branchiostoma floridae, and we also identified a QRFP receptor (QRFPR) that mediates a functional response to sub-nanomolar concentrations of the amphioxus peptide as well as short and long human QRFP (Xu et al., submitted). Because the ancestral vertebrate underwent two tetraploidizations, it might be expected that duplicates of the QRFP gene and its receptor gene may exist. Indeed, we report here the identification of multiple vertebrate QRFPR genes. Three QRFPR genes are present in the coelacanth Latimeria chalumnae, representing an early diverging sarcopterygian lineage. Three QRFPR genes are present in the basal actinopterygian fish, the spotted gar. Phylogenetic and chromosomal analyses show that only two of these receptor genes are orthologous between the two species, thus demonstrating a total of four distinct vertebrate genes. Three of the QRFPR genes resulted from the early vertebrate tetraploidizations and were copied along with syntenic neuropeptide Y receptor genes. The fourth QRFPR gene may be an even older and distinct lineage. Because mammals and birds have only a single QRFPR gene, this means that three genes have been lost in these lineages, and at least one of these was lost independently in mammals and birds because it is still present in a turtle. In conclusion, these results show that the QRFP system gained considerable complexity in the early stages of vertebrate evolution and still maintains much of this in some lineages, and that it has been secondarily reduced in mammals.

Place, publisher, year, edition, pages
2014. Vol. 8, 337- p.
Keyword [en]
Neuropeptide, receptor, evolution
National Category
Natural Sciences
Research subject
Neuroscience; Evolutionary Genetics
URN: urn:nbn:se:uu:diva-240037DOI: 10.3389/fnins.2014.00337ISI: 000346532900001PubMedID: 25386115OAI: diva2:775795
Available from: 2015-01-05 Created: 2015-01-05 Last updated: 2015-02-02Bibliographically approved
In thesis
1. Evolutionary and Pharmacological Studies of NPY and QRFP Receptors
Open this publication in new window or tab >>Evolutionary and Pharmacological Studies of NPY and QRFP Receptors
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The neuropeptide Y (NPY) system consists of 3-4 peptides and 4-7 receptors in vertebrates. It has powerful effects on appetite regulation and is involved in many other biological processes including blood pressure regulation, bone formation and anxiety. This thesis describes studies of the evolution of the NPY system by comparison of several vertebrate species and structural studies of the human Y2 receptor, which reduces appetite, to identify amino acid residues involved in peptide-receptor interactions.

The NPY system was studied in zebrafish (Danio rerio), western clawed frog (Xenopus tropicalis), and sea lamprey (Petromyzon marinus). The receptors were cloned and functionally expressed and their pharmacological profiles were determined using the native peptides in either binding studies or a signal transduction assay. Some peptide-receptor preferences were observed, indicating functional specialization.

A receptor family closely related to the NPY receptors, called the QRFP receptors, was investigated. A QRFP receptor was cloned from amphioxus, Branchistoma floridae, showing that the receptor arose before the origin of the vertebrates. Evolutionary studies demonstrated that the ancestral vertebrate had as many as four QRFP receptors, only one of which remains in mammals today. This correlates with the NPY receptor family, located in the same chromosomal regions, which had seven members in the ancestral vertebrate but only 4-5 in living mammals. Some vertebrates have considerably more complex NPY and QRFP receptor systems than humans and other mammals.

Two studies investigated interactions of NPY-family peptides with the human Y2 receptor. Candidate residues, selected based on structural modeling and docking, were mutated to disrupt possible interactions with peptide ligands. The modified receptors were expressed in cultured cells and investigated by measuring binding and functional responses. Several receptor residues were found to influence peptide-receptor interactions, some of which are involved in maintaining receptor structure. In a pilot study, the kinetics of peptide-receptor interaction were found to be very slow, of the order several hours.

In conclusion, this thesis clarifies evolutionary relationships for the complex NPY and QRFP peptide-receptor systems and improves the structural models of the human NPY-family receptors, especially Y2. These results will hopefully facilitate drug design for targeting of NPY-family receptors.

Place, publisher, year, edition, pages
Uppsala, Sweden: Acta Universitatis Upsaliensis, 2014. 59 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1040
Neuropeptide Y, genome duplication, Evolution, vertebrate, Pharmacology, Modelling, Kinetics
National Category
Evolutionary Biology Pharmacology and Toxicology Cell and Molecular Biology Neurosciences Biochemistry and Molecular Biology Cell Biology Structural Biology
Research subject
Bioinformatics; Biology with specialization in Evolutionary Genetics; Biology with specialization in Evolutionary Functional Genomics; Pharmaceutical Pharmacology
urn:nbn:se:uu:diva-233461 (URN)978-91-554-9059-1 (ISBN)
Public defence
2014-11-21, C2, 305, Husargatan 3, BMC, Uppsala, 13:15 (English)
Available from: 2014-10-31 Created: 2014-10-06 Last updated: 2015-02-02

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