Expression And Functional Studies Of Two Novel Type III GnRH Receptors (2 And 3) In The Sea Lamprey, A Basal Vertebrate.
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1
University of New Hampshire, Center for Molecular and Comparative Endocrinology, United States
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2
University of Guelph, Animal and Poultry Science, Canada
Gonadotropin-releasing hormone (GnRH) is a central regulator of reproduction in vertebrates. Its function is mediated by a GnRH receptor (GnRHR), a class A GPCR. Previously, we identified a unique lamprey GnRH receptor (lGnRH-1) that shares several characteristics of both type-I and type-II/-III vertebrate GnRH receptors (Silver et al., 2005). We will report on our latest findings of the identification, expression and functional studies of two novel GnRH receptors (lGnRHR-2 and -3) in the sea lamprey. The inositol phosphate (IP) and cAMP responses of these two receptors transiently expressed in COS7 cells were examined upon stimulation with increasing doses of lamprey GnRH-I, -II or –III. Lamprey GnRH-II and –III, induced an IP response in lamprey GnRH Receptor-2 and -3. There was no IP response in either receptor when treated with lGnRH-I. Lamprey GnRH-II was a more potent activator of the lamprey GnRH receptor-3 than lGnRH-III. Stimulation of lGnRHR-2 and -3 with increasing doses of each of the three GnRH ligands did not elicit a cAMP response. Lamprey GnRHR-2 precursor transcript was detected in a wide variety of tissues including the pituitary in both male and female adult lampreys. Lamprey GnRHR-3 precursor transcript was not as widely expressed and primarily expressed in the brain and eye of male and female lampreys. In summary, out of three functional GnRH receptors described in the sea lamprey to date only two, lGnRHR-1 and -2, are present in the pituitary. From our phylogenetic analysis, we propose that lGnRHR-1 evolved from a common ancestor of all vertebrate GnRH receptors and lamprey GnRHR-2 and -3 occurred due to a local duplication within the lamprey lineage. These novel GnRH receptors share the structural features and amino acid motifs common to other known gnathostome type II/III-GnRH receptors. (Supported by NSF IOS-0849569, NH AES Hatch 332 and NIH Grant 5R21RR024477-02 to SAS and UNH SURF grant to CM).
Acknowledgements
Supported by NIH Grant 5R21RR024477-02, NSF IOS-0849569 and Hatch 332 to S.A. Sower. Travel support was provided by the Center for Molecular and Comparative Endocrinology and the UNH Marine Program.
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References
Keywords:
GnRH,
Lamprey,
receptor
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:
Poster
Topic:
Developmental endocrinology
Citation:
Hall
J,
Aquilina-Beck
A,
Joseph
N,
MacDonald
C,
Decatur
WA,
Kavanaugh
S,
Freamat
M and
Sower
SA
(2011). Expression And Functional Studies Of Two Novel Type III GnRH Receptors (2 And 3) In The Sea Lamprey, A Basal Vertebrate..
Front. Endocrinol.
Conference Abstract:
NASCE 2011: The inaugural meeting of the North American Society for Comparative Endocrinology.
doi: 10.3389/conf.fendo.2011.04.00138
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Received:
22 Jul 2011;
Published Online:
09 Aug 2011.
*
Correspondence:
Dr. Stacia A Sower, University of New Hampshire, Center for Molecular and Comparative Endocrinology, Durham, NH, 03824, United States, sasower@unh.edu