Gonadotropin-Releasing Hormone inhibits Pituitary Adenylyl Cyclase-Activating Polypeptide coupling to 3', 5'-Cyclic Adenosine-5'-Monophosphate pathway in LbetaT2 gonadotrope cells through novel Protein Kinase C isoforms and phosphorylation of Pituitary Adenylyl Cyclase-Activating Polypeptide type I receptor. Export

@article{citeulike:3179778, abstract = {Gonadotrope cells are primarily regulated by GnRH but are also targets of the pituitary adenylyl cyclase-activating polypeptide (PACAP). Although it has been reported that reciprocal interactions between both neuropeptides contribute to regulation of gonadotrope function, the underlying mechanisms remain poorly understood. In this study, we reevaluated PACAP coupling to the cAMP pathway in LbetaT2 gonadotrope cells and analyzed GnRH effect on PACAP signaling. We established that PACAP38 markedly increases intracellular cAMP levels (EC50 of 4.7 +/- 1.3 nM) through the PAC1 receptor (PAC1-R), as evidenced by pharmacological and RT-PCR studies. Interestingly, although GnRH couples to cAMP pathway in LbetaT2 cells, the effects of both neuropeptides were not synergistical. Instead, the GnRH agonist triptorelin (GnRHa) rapidly and strongly inhibited (70\% inhibition as early as 5 min) PACAP38-induced cAMP production. Inhibition was calcium independent, mimicked by the phorbol ester PMA and blocked by the protein kinase C (PKC) inhibitor bisindoylmaleimide, indicating that GnRHa inhibitory action relies on PKC. Selective down-regulation of both conventional and novel PKC prevented GnRHa effect, whereas pharmacological inhibition of conventional PKC only was ineffective, strongly suggesting the involvement of novel PKC isoforms. GnRHa did not inhibit forskolin or cholera toxin-stimulated cAMP accumulation, suggesting that PAC1-R is the predominant target of GnRH. Accordingly, we demonstrated for the first time that GnRH increases PAC1-R phosphorylation through PKC, providing a potential molecular mechanism which may account for GnRH inhibitory effect.}, address = {Unit\'{e} Mixte de Recherche-Centre National de la Recherche Scientifique 7079 Physiologie \& Physiopathologie (S.L., G.G., V.S., R.C., J.C-T.), Universit\'{e} Pierre \& Marie Curie-Paris 6, Paris, France; Universit\'{e} Paris Diderot-Paris 7 (V.S., J.C.-T.), Paris, France; Molecular Neuropharmacology (N.S., A.B.), Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan.}, author = {Larivi\`{e}re, Sigol\`{e}ne and Garrel-Lazayres, Ghislaine and Simon, Violaine and Shintani, Norihito and Baba, Akemichi and Counis, Raymond and Cohen-Tannoudji, Jo\"{e}lle}, citeulike-article-id = {3179778}, citeulike-linkout-0 = {http://dx.doi.org/10.1210/en.2008-0504}, citeulike-linkout-1 = {http://view.ncbi.nlm.nih.gov/pubmed/18755795}, citeulike-linkout-2 = {http://www.hubmed.org/display.cgi?uids=18755795}, day = {28}, doi = {10.1210/en.2008-0504}, issn = {0013-7227}, journal = {Endocrinology}, keywords = {gnrh, pacap}, month = {August}, posted-at = {2008-09-01 19:59:55}, priority = {2}, title = {Gonadotropin-Releasing Hormone inhibits Pituitary Adenylyl Cyclase-Activating Polypeptide coupling to 3', 5'-Cyclic Adenosine-5'-Monophosphate pathway in L{beta}T2 gonadotrope cells through novel Protein Kinase C isoforms and phosphorylation of Pituitary Adenylyl Cyclase-Activating Polypeptide type I receptor.}, url = {http://dx.doi.org/10.1210/en.2008-0504}, year = {2008} }

TY - JOUR ID - citeulike:3179778 L3 - citeulike-article-id:3179778 N2 - Gonadotrope cells are primarily regulated by GnRH but are also targets of the pituitary adenylyl cyclase-activating polypeptide (PACAP). Although it has been reported that reciprocal interactions between both neuropeptides contribute to regulation of gonadotrope function, the underlying mechanisms remain poorly understood. In this study, we reevaluated PACAP coupling to the cAMP pathway in LbetaT2 gonadotrope cells and analyzed GnRH effect on PACAP signaling. We established that PACAP38 markedly increases intracellular cAMP levels (EC50 of 4.7 +/- 1.3 nM) through the PAC1 receptor (PAC1-R), as evidenced by pharmacological and RT-PCR studies. Interestingly, although GnRH couples to cAMP pathway in LbetaT2 cells, the effects of both neuropeptides were not synergistical. Instead, the GnRH agonist triptorelin (GnRHa) rapidly and strongly inhibited (70% inhibition as early as 5 min) PACAP38-induced cAMP production. Inhibition was calcium independent, mimicked by the phorbol ester PMA and blocked by the protein kinase C (PKC) inhibitor bisindoylmaleimide, indicating that GnRHa inhibitory action relies on PKC. Selective down-regulation of both conventional and novel PKC prevented GnRHa effect, whereas pharmacological inhibition of conventional PKC only was ineffective, strongly suggesting the involvement of novel PKC isoforms. GnRHa did not inhibit forskolin or cholera toxin-stimulated cAMP accumulation, suggesting that PAC1-R is the predominant target of GnRH. Accordingly, we demonstrated for the first time that GnRH increases PAC1-R phosphorylation through PKC, providing a potential molecular mechanism which may account for GnRH inhibitory effect. JF - Endocrinology SN - 0013-7227 AD - Unité Mixte de Recherche-Centre National de la Recherche Scientifique 7079 Physiologie & Physiopathologie (S.L., G.G., V.S., R.C., J.C-T.), Université Pierre & Marie Curie-Paris 6, Paris, France; Université Paris Diderot-Paris 7 (V.S., J.C.-T.), Paris, France; Molecular Neuropharmacology (N.S., A.B.), Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan. TI - Gonadotropin-Releasing Hormone inhibits Pituitary Adenylyl Cyclase-Activating Polypeptide coupling to 3', 5'-Cyclic Adenosine-5'-Monophosphate pathway in L{beta}T2 gonadotrope cells through novel Protein Kinase C isoforms and phosphorylation of Pituitary Adenylyl Cyclase-Activating Polypeptide type I receptor. KW - gnrh KW - pacap AU - Larivière, Sigolène AU - Garrel-Lazayres, Ghislaine AU - Simon, Violaine AU - Shintani, Norihito AU - Baba, Akemichi AU - Counis, Raymond AU - Cohen-Tannoudji, Joëlle PY - 2008/08/28/ UR - http://dx.doi.org/10.1210/en.2008-0504 ER -