Identification and Characterization of the Gonadotropin-releasing Hormone Response Elements in the Mouse Gonadotropin-releasing Hormone Receptor Gene

The response of the pituitary gonadotrope to gonadotropin-releasing hormone (GnRH) correlates directly with the concentration of GnRH receptors (GnRHR) on the cell surface, which is mediated in part at the level of GnRHR gene expression. Several hormones have been implicated in this regulation, most...

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Bibliographic Details
Published in:The Journal of biological chemistry 1999-01, Vol.274 (2), p.867-880
Main Authors: Norwitz, Errol R., Cardona, Guemalli R., Jeong, Kyeong-Hoon, Chin, William W.
Format: Article
Language:English
Subjects:
Animals
Base Sequence
Blotting, Northern
Cell Line
Chlorocebus aethiops
DNA
Electrophoresis - methods
Gonadotropin-Releasing Hormone - metabolism
Humans
Mice
Promoter Regions, Genetic
Protein Kinase C - metabolism
Receptors, LHRH - genetics
Sequence Homology, Nucleic Acid
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Summary:The response of the pituitary gonadotrope to gonadotropin-releasing hormone (GnRH) correlates directly with the concentration of GnRH receptors (GnRHR) on the cell surface, which is mediated in part at the level of GnRHR gene expression. Several hormones have been implicated in this regulation, most notably GnRH itself. Despite these observations and the central role that GnRH is known to play in reproductive development and function, the molecular mechanism(s) by which GnRH regulates transcription of the GnRHR gene has not been well elucidated. Previous studies in this laboratory have identified and partially characterized the promoter region of the mouse GnRHR gene and demonstrated that the regulatory elements for tissue-specific expression as well as for GnRH regulation are present within the 1.2-kilobase 5′-flanking sequence. By using deletion and mutational analysis as well as functional transfection studies in the murine gonadotrope-derived αT3-1 cell line, we have localized GnRH responsiveness of the mouse GnRHR gene to two DNA sequences at −276/−269 (designated Sequence UnderlyingResponsiveness to GnRH-2 (SURG-2), which contains the consensus sequence for the activating protein-1-binding site) and −292/−285 (a novel element designated SURG-1), and demonstrated that this response is mediated via protein kinase C. By using the electrophoretic mobility shift assay, we further demonstrate that a member(s) of the Fos/Jun heterodimer superfamily is responsible in part for the DNA-protein complexes formed on SURG-2, using αT3-1 nuclear extracts. These data define a bipartite GnRH response element in the mouse GnRHR 5′-flanking sequence and suggest that the activating protein-1 complex plays a central role in conferring GnRH responsiveness to the murine GnRHR gene.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.274.2.867