title: PAC1hop, null and hip receptors mediate differential signaling through cyclic AMP and calcium leading to splice variant-specific gene induction in neural cells.
abstract: Pituitary adenylate cyclase-activating polypeptide (PACAP)-mediated activation of its G protein-coupled receptor PAC1 results in activation of the two G proteins Gs and Gq to alter second messenger generation and gene transcription in the nervous system, important for homeostatic responses to stress and injury. Heterologous expression of the three major splice variants of the rat PAC1 receptor, PAC1hop, null and hip, in neural NG108-15 cells conferred PACAP-mediated intracellular cAMP generation, while elevation of [Ca(2+)](i) occurred only in PAC1hop-, and to a lesser extent in PAC1null-expressing cells. Induction of vasoactive intestinal polypeptide (VIP) and stanniocalcin 1 (STC1), two genes potentially involved in PACAP's homeostatic responses, was examined as a function of the expressed PAC1 variant. VIP induction was greatest in PAC1hop-expressing cells, suggesting that a maximal transcriptional response requires combinatorial signaling through both cAMP and Ca(2+). STC1 induction was similar for all three receptor splice variants and was mimicked by the adenylate cyclase activator forskolin, indicating that cAMP elevation is sufficient to induce STC1. The degree of activation of two different second messenger pathways appears to determine the transcriptional response, suggesting that cellular responses to stressors are fine-tuned through differential receptor isoform expression. Signaling to the VIP gene proceeded through cAMP and protein kinase A (PKA) in these cells, independently of the MAP kinase ERK1/2. STC1 gene induction by PACAP was dependent on cAMP and ERK1/2, independently of PKA. Differential gene induction via different cAMP dependent signaling pathways potentially provides further targets for the design of treatments for stress-associated disorders.
authors.affiliation: Section on Molecular Neuroscience, Laboratory of Cellular and Molecular Regulation, National Institute of Mental Health, Bethesda, MD 20892, USA.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Holighaus
authors.forename: Tomris
authors.initials: T
authors.lastname: Mustafa
authors.forename: Lee E
authors.initials: LE
authors.lastname: Eiden
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D058953:Neural Stem Cells / Q000166:cytology / Q000378:metabolism*; D020033:Protein Isoforms; D012326:RNA Splicing; D051381:Rats; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I / Q000235:genetics* / Q000378:metabolism; D014660:Vasoactive Intestinal Peptide / Q000235:genetics / Q000378:metabolism
chemical_list: D006023:Glycoproteins; C105426:Hip chaperone; D018832:Molecular Chaperones; D020033:Protein Isoforms; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D014660:Vasoactive Intestinal Peptide; C051795:teleocalcin; D000242:Cyclic AMP; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D002118:Calcium