This Article Full Text Full Text (PDF) All Versions of this Article: 149/3/1144    most recent Author Manuscript (PDF) Purchase Article View Shopping Cart 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 Google Scholar Google Scholar Articles by Casella, I. Articles by Costa, T. Search for Related Content PubMed PubMed Citation Articles by Casella, I. Articles by Costa, T.

Non-Gonadotropin-Releasing Hormone-Mediated Transcription and Secretion of Large Human Glycoprotein Hormone -Subunit in Human Embryonic Kidney-293 Cells

Department of Pharmacology (I.C., D.R., T.C.), Istituto Superiore di Sanità, 00161 Rome, Italy; Department of Clinical Biochemistry (H.L.), Medical University of Innsbruck, and Austrian Academy of Sciences (C.Z., P.B.), Institute for Biomedical Aging Research, A-6020 Innsbruck, Austria

Address all correspondence and requests for reprints to: Tommaso Costa, Dipartimento del Farmaco, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy. E-mail: tomcosta{at}iss.it; or Peter Berger, Ph.D., Institute for Biomedical Aging Research, Austrian Academy of Sciences, Rennweg 10, A-6020 Innsbruck, Austria. E-mail: peter.berger{at}oeaw.ac.at.

To identify genes that are most responsive to a sustained activation of a G_s protein-coupled receptor, HEK293 cells were stably transfected with the β₂-adrenergic receptor and stimulated with agonist isoproterenol (1 µM). A microarray study indicated that the gene with the highest stimulation index (500-fold) encoded the common -subunit of human glycoprotein hormones (GPH). Induction of GPH transcription in response to cAMP elevations resulted in a dramatic increase (600-fold) of protein secretion as shown by RT-PCR and a highly specific time-resolved immunofluorometric assay. Cloning and sequencing of the GPH cDNA and mass spectrometric analysis of HPLC-purified GPH derived from serum-free HEK293-β₂-adrenergic receptor-stimulated cells verified the nature of the molecule. Enzymatic deglycosylation with subsequent Western blots revealed that this was a large hyperglycosylated form of GPH that had not been associated with a β-subunit previously. This uncombined variant is known to be either cosecreted with GPHs from the pituitary, the placenta, and a variety of tumors or secreted without GPHs from APUD cells and rare tumors. Moreover, it is similar to GPH found at high concentrations in seminal plasma. As shown by a panel of endogenous or transfected G protein-coupled receptors in HEK293 cells, the expression of large GPH was controlled by G_s- and G_q- but not G_i-dependent receptors and mediated via cAMP and Ca⁺⁺ release. This suggests that Gq- or G_s-coupled receptors other than the classical GnRH receptor may play a role in the regulation of nonpituitary, nonplacental GPH secretion under physiological and pathological conditions.