This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Cornea, A. Articles by Conn, P. M. Search for Related Content PubMed PubMed Citation Articles by Cornea, A. Articles by Conn, P. M.

Redistribution of G_q/11 in the Pituitary Gonadotrope in Response to a Gonadotropin-Releasing Hormone Agonist¹

Oregon Regional Primate Research Center (A.C., J.A.J., D.S., P.M.C.), Beaverton, Oregon 97006; and Department of Physiology and Pharmacology, Oregon Health Sciences University (D.S., P.M.C.), Portland, Oregon 97201

Address all correspondence and requests for reprints to: P. Michael Conn, Oregon Regional Primate Research Center, 505 Northwest 185th Avenue, Beaverton, Oregon 97006.

In the present study, we took advantage of high-resolution multilaser confocal microscopy to examine the distribution of the -subunit of the guanyl nucleotide binding protein subfamily G_q/11 (G_q/11). Dispersed cultures of pituitary cells were prepared from female weanling rats, fixed, permeabilized, and then stained with monoclonal antiserum (mouse) to the gonadotrope-specific form of secretogranin (SIIp), which was then tagged with Texas Red. Accordingly, the subpopulation of gonadotropes (15% of total cells) could be identified against a background of other pituitary cell types. G_q/11 was localized with antiserum made in rabbit, then tagged with fluorescein. Hoechst 33258 nuclear stain was also used in some experiments for topological reference. The data indicate localization of the G_q/11 in a cellular region near the plasma membrane and external to the border of the layer occupied by secretory granules. In the absence of activation, there were an average of six clusters of G_q/11 in a section 1 µm thick and through the center of the cell. This corresponds to an average of 60 clusters per cell, assuming a mean gonadotrope diameter of 10 µm. Following continuous treatment with 0.1 µg/ml Buserelin, a metabolically stable GnRH agonist, the average number of clusters increased to 200/cell after 40 min and remained approximately constant for 120 min. This increase was blocked by the protein synthesis inhibitor, cycloheximide. In response to Buserelin, there was an additional increase in the number of clusters inside the cell in the area occupied by the secretory granules and in the perinuclear area. Prolonged (24 h) treatment with Buserelin, sufficient to provoke the onset of desensitization, did not significantly change total numbers of G_q/11 clusters, although more were located in the peripheral compartment, an increase that occurred at the expense of the cytoplasmic compartment. Redistribution of the G_q/11 family may be functionally significant, because this moiety may be rate limiting at the site of regulation of signal transduction.

This article has been cited by other articles:

				D. Tran, N. Stelly, T. Tordjmann, T. Durroux, M. N. Dufour, A. Forchioni, R. Seyer, M. Claret, and G. Guillon Distribution of Signaling Molecules Involved in Vasopressin-induced Ca2+ Mobilization in Rat Hepatocyte Multiplets J. Histochem. Cytochem., May 1, 1999; 47(5): 601 - 616. [Abstract] [Full Text]

				N. Macrez, J.-L. Morel, and J. Mironneau Specific Galpha 11beta 3gamma 5 Protein Involvement in Endothelin Receptor-Induced Phosphatidylinositol Hydrolysis and Ca2+ Release in Rat Portal Vein Myocytes Mol. Pharmacol., April 1, 1999; 55(4): 684 - 692. [Abstract] [Full Text]

				J. J. Evans Modulation of Gonadotropin Levels by Peptides Acting at the Anterior Pituitary Gland Endocr. Rev., February 1, 1999; 20(1): 46 - 67. [Abstract] [Full Text]

				D. Stanislaus, S. Ponder, T. H. Ji, and P. M. Conn Gonadotropin-Releasing Hormone Receptor Couples to Multiple G Proteins in Rat Gonadotrophs and in GGH3 Cells: Evidence from Palmitoylation and Overexpression of G proteins Biol Reprod, July 1, 1998; 59(3): 579 - 586. [Abstract] [Full Text]

				D. Stanislaus, J. A. Janovick, T. Ji, T. M. Wilkie, S. Offermanns, and P. M. Conn Gonadotropin and Gonadal Steroid Release in Response to a Gonadotropin-Releasing Hormone Agonist in Gq{alpha} and G11{alpha} Knockout Mice Endocrinology, June 1, 1998; 139(6): 2710 - 2717. [Abstract] [Full Text] [PDF]

				X. Lin, J. A. Janovick, S. Brothers, M. Blömenrohr, J. Bogerd, and P. M. Conn Addition of Catfish Gonadotropin-Releasing Hormone (GnRH) Receptor Intracellular Carboxyl-Terminal Tail to Rat GnRH Receptor Alters Receptor Expression and Regulation Mol. Endocrinol., February 1, 1998; 12(2): 161 - 171. [Abstract] [Full Text]

				C. A. Chen and D. R. Manning Regulation of Galpha i Palmitoylation by Activation of the 5-Hydroxytryptamine-1A Receptor J. Biol. Chem., July 28, 2000; 275(31): 23516 - 23522. [Abstract] [Full Text] [PDF]