title: Corticotropin-releasing factor receptors induce calcium mobilization through cross-talk with Gq-coupled receptors.
abstract: The cross-talk between corticotropin-releasing factor (CRF) and muscarinic receptors was investigated by measuring evoked transient increases in cytosolic calcium concentration. HEK293 cells stably expressing human CRF type 1 (hCRF(1)) and type 2(a) (hCRF(2(a))) receptors were stimulated with the muscarinic receptor agonist carbachol and shortly after by a CRF agonist. Unexpectedly, this second response was enhanced when compared to stimulating naive cells either with carbachol or CRF agonist only. Priming with 100 microM carbachol increased the maximal CRF agonist response and shifted its concentration-response curve to the left to attain almost the same potency as for stimulating the production of the natural second messenger cyclic AMP. Yet, priming did not affect CRF agonist-stimulated cyclic AMP production itself. Carbachol priming was not restricted to recombinant CRF receptors only since endogenously expressed beta(2)-adrenoceptors also started to produce a robust calcium signal. Without priming no such signal was observed. Similar findings were made in the human retinoblastoma cell line Y79 for endogenously expressed CRF(1) receptors and the type 1 pituitary adenylate cyclase-activating polypeptide receptors but not for the CRF(2(a)) receptors. This differentiation between CRF(1) and CRF(2) receptors was further supported by use of selective agonists and antagonists. The results suggest that stimulating a Gq-coupled receptor shortly before stimulating a Gs-coupled receptor may result in a parallel signaling event on top of the classical cyclic AMP pathway.
authors.affiliation: Johnson & Johnson Research & Development, CNS Research, Turnhoutseweg 30, B-2340 Beerse, Belgium. gutknecht.eric@sfr.fr
authors.forename: Eric
authors.initials: E
authors.lastname: Gutknecht
authors.forename: Georges
authors.initials: G
authors.lastname: Vauquelin
authors.forename: Frank M
authors.initials: FM
authors.lastname: Dautzenberg
mesh_terms: D029845:Amphibian Proteins / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects; D002217:Carbachol / Q000494:pharmacology; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000096:biosynthesis; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D018721:Muscarinic Agonists / Q000494:pharmacology; D036361:Peptide Hormones / Q000494:pharmacology; D020239:Receptor Cross-Talk / Q000187:drug effects; D018019:Receptors, Corticotropin-Releasing Hormone / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000378:metabolism*; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I / Q000819:agonists; D000099052:CRF Receptor, Type 1
chemical_list: D029845:Amphibian Proteins; C101531:CRF receptor type 2; D018721:Muscarinic Agonists; D036361:Peptide Hormones; D018019:Receptors, Corticotropin-Releasing Hormone; D011976:Receptors, Muscarinic; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D000099052:CRF Receptor, Type 1; C025727:sauvagine; D002217:Carbachol; D000242:Cyclic AMP; D043802:GTP-Binding Protein alpha Subunits, Gq-G11