Christiane Otto

Publications of Christiane Otto

• Estradiol release kinetics determine tissue response in ovariectomized rats.

  Authors: Christiane Otto, Ingrid Kantner, Reinhard Nubbemeyer, Jenny Schkoldow, Iris Fuchs, Elisabeth Krahl, Richardus Vonk, Christiane Schüler, Karl-Heinrich Fritzemeier, Reinhold G Erben

  Endocrinology. 02/2012; 153(4):1725-33.

  Estrogen replacement is an effective therapy of postmenopausal symptoms such as hot flushes, bone loss, and vaginal dryness. Undesired estrogen effects are the stimulation of uterine and mammaryEstrogen replacement is an effective therapy of postmenopausal symptoms such as hot flushes, bone loss, and vaginal dryness. Undesired estrogen effects are the stimulation of uterine and mammary gland epithelial cell proliferation as well as hepatic estrogenicity. In this study, we examined the influence of different estradiol release kinetics on tissue responsivity in ovariectomized (OVX) rats. Pulsed release kinetics was achieved by ip or sc administration of estradiol dissolved in physiological saline containing 10% ethanol (EtOH/NaCl) whereas continuous release kinetics was achieved by sc injection of estradiol dissolved in benzylbenzoate/ricinus oil (1+4, vol/vol). Initial 3-d experiments in OVX rats showed that pulsed ip estradiol administration had profoundly reduced stimulatory effects on the uterus and the liver compared with continuous release kinetics. On the other hand, both administration forms prevented severe vaginal atrophy. Based on these results, we compared the effects of pulsed (sc in EtOH/NaCl) vs. continuous (sc in benzylbenzoate/ricinus oil) estradiol release kinetics on bone, uterus, mammary gland, and liver in a 4-month study in OVX rats. Ovariectomy-induced bone loss was prevented by both administration regimes. However, pulsed estradiol resulted in lower uterine weight, reduced induction of hepatic gene expression, and reduced mammary epithelial hyperplasia relative to continuous estradiol exposure. We conclude that organ responsivity is influenced by different hormone release kinetics, a fact that might be exploited to reduce undesired estradiol effects in postmenopausal women.

• Impaired left-ventricular cardiac function in male GPR30-deficient mice.

  Authors: Martina Delbeck, Stefan Golz, Richardus Vonk, Wiebke Janssen, Tim Hucho, Jörg Isensee, Stefan Schäfer, Christiane Otto

  Molecular medicine reports. 01/2011; 4(1):37-40.

  G-protein-coupled receptor 30 (GPR30) has been reported to act as a membrane-bound estrogen receptor that is involved in the mediation of non-genomic estradiol signalling. In this study, weG-protein-coupled receptor 30 (GPR30) has been reported to act as a membrane-bound estrogen receptor that is involved in the mediation of non-genomic estradiol signalling. In this study, we demonstrated that male, but not female, GPR30-deficient mice suffer from impaired left‑ventricular cardiac function. Left ventricles from male mutant mice were enlarged. There were no malformations in the valves or outflow tract of the heart. Both the contractility and relaxation capacity of the left ventricle were reduced, leading to increased left‑ventricular end-diastolic pressure in GPR30-deficient mice. In conclusion, our data support a role for GPR30 in the gender-specific aspects of heart failure.

• Comparative analysis of the uterine and mammary gland effects of progesterone and medroxyprogesterone acetate.

  Authors: Christiane Otto, Iris Fuchs, Richardus Vonk, Karl-Heinrich Fritzemeier

  Maturitas. 04/2010; 65(4):386-91.

  In combined hormone replacement therapy (HRT) progestins are used to inhibit estradiol-activated uterine epithelial cell proliferation. In comparison to estradiol-only therapy, combined HRT leads toIn combined hormone replacement therapy (HRT) progestins are used to inhibit estradiol-activated uterine epithelial cell proliferation. In comparison to estradiol-only therapy, combined HRT leads to enhanced proliferation of mammary epithelial cells. In a quantitative mouse model, we assessed the balance between uterine and undesired mammary gland effects for two progestins that are widely used in HRT, progesterone and medroxyprogesterone acetate. Mice were ovariectomized and after 14 days they were treated subcutaneously with either vehicle, estradiol (100 ng) or estradiol plus increasing doses of progesterone or medroxyprogesterone acetate for three weeks. Measures for progestogenic mammary gland activity were stimulation of side-branching and stimulation of epithelial cell proliferation. Progestogenic activity in the uterus was assessed by measuring inhibition of estradiol-activated uterine epithelial cell proliferation. ED(50) and ID(50) values for the distinct readouts were obtained and dissociation factors for uterine versus mammary gland activity were calculated. MPA demonstrated uterine activity and mitogenic activity in the mammary gland at the same doses. In contrast, progesterone showed uterine activity at doses lower than those leading to significant stimulation of epithelial cell proliferation in the mammary gland. Progestins do not behave the same. Use of the natural hormone progesterone, but not MPA, in combined hormone therapy might offer a safety window between uterine effects and undesired proliferative activity in the mammary gland.

• Effects of the cell type-specific ablation of the cAMP-responsive transcription factor in noradrenergic neurons on locus coeruleus firing and withdrawal behavior after chronic exposure to morphine.

  Authors: Rosanna Parlato, Hans Cruz, Christiane Otto, Patricia Murtra, Jan Rodriguez Parkitna, Miquel Martin, Simona A Bura, Yvonne Begus-Nahrmann, Oliver von Bohlen und Halbach, Rafael Maldonado, Günther Schütz, Christian Lüscher

  Journal of neurochemistry. 03/2010; 115(3):563-73.

  Repeated exposure to opiates leads to cellular and molecular changes and behavioral alterations reflecting a state of dependence. In noradrenergic neurons, cyclic AMP (cAMP)-dependent pathways areRepeated exposure to opiates leads to cellular and molecular changes and behavioral alterations reflecting a state of dependence. In noradrenergic neurons, cyclic AMP (cAMP)-dependent pathways are activated during opiate withdrawal, but their contribution to the activity of locus coeruleus noradrenergic neurons and behavioral manifestations remains controversial. Here, we test whether the cAMP-dependent transcription factors cAMP responsive element binding protein (CREB) and cAMP-responsive element modulator (CREM) in noradrenergic neurons control the cellular markers and the physical signs of morphine withdrawal in mice. Using the Cre/loxP system we ablated the Creb1 gene in noradrenergic neurons. To avoid adaptive effects because of compensatory up-regulation of CREM, we crossed the conditional Creb1 mutant mice with a Crem-/- line. We found that the enhanced expression of tyrosine hydroxylase normally observed during withdrawal was attenuated in CREB/CREM mutants. Moreover, the withdrawal-associated cellular hyperactivity and c-fos expression was blunted. In contrast, naloxone-precipitated withdrawal signs, such as jumping, paw tremor, tremor and mastication were preserved. We conclude by a specific genetic approach that the withdrawal-associated hyperexcitability of noradrenergic neurons depends on CREB/CREM activity in these neurons, but does not mediate several behavioral signs of morphine withdrawal.

• A dual estrogen receptor TR-FRET assay for simultaneous measurement of steroid site binding and coactivator recruitment.

  Authors: Tarek Hilal, Vera Puetter, Christiane Otto, Karsten Parczyk, Benjamin Bader

  Journal of biomolecular screening. 02/2010; 15(3):268-78.

  The human estrogen receptors (hER) are members of the nuclear hormone receptor (NHR) superfamily and represent important drug targets for the pharmaceutical industry. Initially, ligand binding assaysThe human estrogen receptors (hER) are members of the nuclear hormone receptor (NHR) superfamily and represent important drug targets for the pharmaceutical industry. Initially, ligand binding assays were used to identify novel ligands using receptors purified from native tissues. With the advent of molecular cloning techniques, cell-based transactivation assays have been the gold standard for many years of drug discovery. With the elucidation of the structural mechanisms underlying the activation of NHRs, cell-free assays with purified receptors have become important tools to directly assess different binding sites (e.g., the hormone binding site or the cofactor binding site). The available cell-free assays have so far facilitated the study of one binding site at a time. With the introduction of Terbium (Tb(3+))-based time-resolved fluorescence energy transfer (TR-FRET), it has become possible to measure 2 different interactions within 1 test tube in parallel. The authors have applied this technology to develop a dual readout system for the simultaneous monitoring of steroid hormone site binding and cofactor peptide recruitment. They took advantage of a commercially available fluorescent tracer as an indicator for classical steroid site binding and designed a novel peptide derived from the peroxisome proliferator-activated receptor gamma coactivator-1a (PGC1a) as an indicator for functional agonistic behavior of a test compound. The established assay is able to differentiate between agonists, antagonists, partial agonists, and compounds binding to the cofactor recruitment site. The IC(50) values obtained for a number of reference compounds in the multiplexed assay are in concordance with published data. The simple 1-step mix-and-measure protocol gives excellent quality and robustness and can be miniaturized to 5-microL volume.

• DNA binding by estrogen receptor-{alpha} is essential for the transcriptional response to estrogen in the liver and the uterus.

  Authors: Dörthe L Ahlbory-Dieker, Brenda D Stride, Gabriele Leder, Jenny Schkoldow, Susanne Trölenberg, Henrik Seidel, Christiane Otto, Anette Sommer, Malcolm G Parker, Günther Schütz, Tim M Wintermantel

  Molecular endocrinology (Baltimore, Md.). 08/2009;

  The majority of the biological effects of estrogens in the reproductive tract are mediated by estrogen receptor alpha, which regulates transcription by several mechanisms. As the tissue-specificThe majority of the biological effects of estrogens in the reproductive tract are mediated by estrogen receptor alpha, which regulates transcription by several mechanisms. As the tissue-specific effects of some ERalpha ligands may be caused by tissue-specific transcriptional mechanisms of ERalpha we aimed to identify the contribution of DNA recognition to these mechanisms in two clinically important target organs, namely uterus and liver. We used a genetic mouse model that dissects DNA binding-dependent versus independent transcriptional regulation elicited by ERalpha. The EAAE mutant harbors amino acid exchanges at four positions of the DNA binding domain of ERalpha. This construct was knocked in the ERalpha gene locus to produce ERalpha(EAAE/EAAE) mice devoid of a functional ERalpha DNA binding domain. The phenotype of the ERalpha(EAAE/EAAE) mice resembles the general loss-of-function phenotype of alphaERKO mutant mice with hypoplastic uteri, hemorrhagic ovaries, and impaired mammary gland development. In agreement with this phenotype, the expression pattern of the ERalpha(EAAE/EAAE) mutant mice in liver obtained by genome-wide gene expression profiling supports the observation of a near-complete loss of estrogen-dependent gene regulation in comparison to the wild-type. Further gene expression analyses to validate the results of the microarray data were performed by qRT-PCR. The analyses indicate that both gene activation and repression by estrogen-bound ERalpha relies on an intact DNA binding domain in vivo.

• Expression Pattern of Gpr30 in LacZ Reporter Mice.

  Authors: Jörg Isensee, Luca Meoli, Valeria Zazzu, Christoph Nabzdyk, Henning Witt, Dian Soewarto, Karin Effertz, Helmut Fuchs, Valérie Gailus-Durner, Dirk Busch, Thure Adler, Martin Hrabé de Angelis, Markus Irgang, Christiane Otto, Patricia Ruiz Noppinger

  Endocrinology. 01/2009;

  Multiple reports implicated the function of GPR30 with nongenomic effects of estrogen, suggesting that GPR30 might be a G-protein coupled estrogen receptor. However, the findings are controversialMultiple reports implicated the function of GPR30 with nongenomic effects of estrogen, suggesting that GPR30 might be a G-protein coupled estrogen receptor. However, the findings are controversial and the expression pattern of GPR30 on a cell type level as well as its function in vivo remains unclear. Therefore, the objective of this study was to identify cell types that express Gpr30 in vivo by analyzing a mutant mouse model that harbors a lacZ reporter (Gpr30-lacZ) in the Gpr30 locus leading to a partial deletion of the Gpr30 coding sequence. Using this strategy, we identified the following cell types expressing Gpr30: (I) an endothelial cell subpopulation in small arterial vessels of multiple tissues, (II) smooth muscle cells and pericytes in the brain, (III) gastric chief cells in the stomach, (IV) neuronal subpopulations in the cortex as well as in the polymorph layer of the dentate gyrus, and (V) cell populations in the intermediate and anterior lobe of the pituitary gland as well as (VI) in the medulla of the adrenal gland. In further experiments, we aimed to decipher the function of Gpr30 by analyzing the phenotype of Gpr30-lacZ mice. The body weight as well as fat mass was unchanged in Gpr30-lacZ mice, even if fed with a high fat diet. Flow cytometric analysis revealed lower frequencies of T cells in both sexes of Gpr30-lacZ mice. Within the T cell cluster, the amount of CD62L expressing cells was clearly reduced, suggesting an impaired production of T cells in the thymus of Gpr30-lacZ mice.

• Conditional inactivation of glucocorticoid receptor gene in dopamine-b-hydroxylase cells impairs chromaffin cell survival.

  Authors: Rosanna Parlato, Christiane Otto, Jan Tuckermann, Stefanie Stotz, Sylvia Kaden, Hermann-Josef Gröne, Klaus Unsicker, Günther Schütz

  Endocrinology. 12/2008;

  Glucocorticoid hormones (GCs) have been thought to determine the fate of chromaffin cells from sympathoadrenal progenitor cells. The analysis of mice carrying a germline deletion of theGlucocorticoid hormones (GCs) have been thought to determine the fate of chromaffin cells from sympathoadrenal progenitor cells. The analysis of mice carrying a germline deletion of the glucocorticoid receptor (GR) gene has challenged these previous results since the embryonic development of adrenal chromaffin cells is largely unaltered. In the present study, we have analyzed the role of GC-dependent signaling in postnatal development of adrenal chromaffin cells by conditional inactivation of the GR gene in cells expressing dopamine-beta-hydroxylase, an enzyme required for the synthesis of noradrenaline and adrenaline. These mutant mice are viable, allowing to study whether in absence of GC signaling further development of the adrenal medulla is affected. Our analysis shows that loss of GR leads not only to loss of phenylethanolamine-N-methyl-transferase (PNMT) expression and therefore to inhibition of adrenaline synthesis, but also to a dramatic reduction in the number of adrenal chromaffin cells. We provide evidence that increased apoptotic cell death is the main consequence of GR loss. These findings define the essential role of GCs for survival of chromaffin cells and underscore the specific requirement of GCs for adrenergic chromaffin cell differentiation and maintenance.

• GPR30 Does Not Mediate Estrogenic Responses in Reproductive Organs in Mice.

  Authors: Christiane Otto, Iris Fuchs, Gunther Kauselmann, Heidrun Kern, Branko Zevnik, Puk Andreasen, Gilda Schwarz, Helga Altmann, Mario Klewer, Michael Schoor, Richardus Vonk, Karl-Heinrich Fritzemeier

  Biology of reproduction. 10/2008;

  The G-protein-coupled receptor Gpr30 (Gper) was recently claimed to bind to estradiol and to activate cytoplasmic signal transduction pathways in response to estradiol. However, there are conflictingThe G-protein-coupled receptor Gpr30 (Gper) was recently claimed to bind to estradiol and to activate cytoplasmic signal transduction pathways in response to estradiol. However, there are conflicting data regarding the role of Gpr30 as an estrogen receptor: several laboratories were not able to demonstrate estradiol binding to GPR30 or estradiol-activated signal transduction in Gpr30 expressing cells. To clarify the potential role of Gpr30 as an estrogen receptor, we generated Gpr30-deficient mice. Although Gpr30 was expressed in all reproductive organs, histopathological analysis did not reveal any abnormalities in these organs in Gpr30-deficient mice. Mutant male and female mice were as fertile as their wildtype littermates indicating normal function of the hypothalamic-pituitary-gonadal axis. Moreover, we analyzed estrogenic responses in two major estradiol target organs, the uterus and the mammary gland. For that purpose, we examined different readout paradigms, such as morphological measures, cellular proliferation and target gene expression. Our data demonstrate that in vivo Gpr30 is dispensable for the mediation of estradiol effects in reproductive organs. These results are in clear contrast to the phenotype of mice lacking the classical estrogen receptor alpha (Esr1) or aromatase (Cyp19a1). We conclude that the perception of Gpr30 -- by homology related to peptide receptors -- as an estrogen receptor might be premature and has to be reconsidered.

• In vivo characterization of estrogen receptor modulators with reduced genomic versus nongenomic activity in vitro.

  Authors: Christiane Otto, Iris Fuchs, Helga Altmann, Mario Klewer, Gilda Schwarz, Rolf Bohlmann, Duy Nguyen, Ludwig Zorn, Richardus Vonk, Katja Prelle, Thua Osterman, Chira Malmström, Karl-Heinrich Fritzemeier

  The Journal of steroid biochemistry and molecular biology. 08/2008;

  Estrogen receptor (ER) ligands that are able to prevent postmenopausal bone loss, but have reduced activity in the uterus and the mammary gland might be of great value for hormone therapy. It is wellEstrogen receptor (ER) ligands that are able to prevent postmenopausal bone loss, but have reduced activity in the uterus and the mammary gland might be of great value for hormone therapy. It is well established that the classical ER can activate genomic as well as nongenomic signal transduction pathways. In this study, we analyse the in vivo behaviour of ER ligands that stimulate nongenomic ER effects to the same extent as estradiol, but show clearly reduced activation of genomic ER effects in vitro. Using different readout parameters such as morphological changes, cellular proliferation, and target gene induction, we are able to demonstrate that ER ligands with reduced genomic activity in vitro show a better dissociation of bone versus uterine and mammary gland effects than estradiol that stimulates genomic and nongenomic effects to the same extent. We conclude that pathway-selective ER ligands may represent an interesting option for hormone therapy.

• GPR30 localizes to the endoplasmic reticulum and is not activated by estradiol.

  Authors: Christiane Otto, Beate Rohde-Schulz, Gilda Schwarz, Iris Fuchs, Mario Klewer, Dominic Brittain, Gernot Langer, Benjamin Bader, Katja Prelle, Reinhard Nubbemeyer, Karl-Heinrich Fritzemeier

  Endocrinology. 07/2008;

  The classical estrogen receptor (ER) mediates genomic as well as rapid nongenomic estradiol responses. In case of genomic responses, the ER acts as a ligand-dependent transcription factor thatThe classical estrogen receptor (ER) mediates genomic as well as rapid nongenomic estradiol responses. In case of genomic responses, the ER acts as a ligand-dependent transcription factor that regulates gene expression in estrogen target tissues. In contrast, nongenomic effects are initiated at the plasma membrane and lead to rapid activation of cytoplasmatic signal transduction pathways. Recently, an orphan GPCR, GPR30, has been claimed to bind to and to signal in response to estradiol. GPR30 therefore might mediate some of the nongenomic estradiol effects. The present study was performed to clarify the controversy about the subcellular localization of GPR30 and to gain insight into the in vivo function of this receptor. In transiently transfected cells as well as cells endogenously expressing GPR30, we confirmed that the receptor localized to the endoplasmic reticulum. However, using radioactive estradiol, we only observed saturable, specific binding to the classical ER, but not to GPR30. Estradiol stimulation of cells expressing GPR30 had no impact on intracellular cAMP or calcium levels. To elucidate the physiological role of GPR30, we performed in vivo experiments with estradiol and G1, a compound that has been claimed to act as selective GPR30 agonist. In two classical estrogen target organs, the uterus and the mammary gland, G1 did not show any estrogenic effect. Taken together, we draw the conclusion that GPR30 is still an orphan receptor.

• Comparative analysis of the uterine and mammary gland effects of drospirenone and medroxyprogesterone acetate.

  Authors: Christiane Otto, Iris Fuchs, Helga Altmann, Mario Klewer, Alexander Walter, Katja Prelle, Richardus Vonk, Karl-Heinrich Fritzemeier

  Endocrinology. 05/2008;

  The role of progestins in combined hormone therapy is the inhibition of uterine epithelial cell proliferation. The Women's Health Initiative (WHI) study provided evidence for an increased risk ofThe role of progestins in combined hormone therapy is the inhibition of uterine epithelial cell proliferation. The Women's Health Initiative (WHI) study provided evidence for an increased risk of breast cancer in women treated with conjugated equine estrogens (CEE) plus the synthetic progestin medroxyprogesterone acetate (MPA), compared to CEE-only treatment. These findings continue to be discussed and it remains to be clarified whether the results obtained for MPA in the WHI study are directly applicable to other progestins employed in hormone therapy. In this study we compared in a mouse model the effects of the synthetic progestins, MPA and drospirenone, in two major target organs: the uterus and the mammary gland. As quantitative measures of progestin activity, we analyzed maintenance of pregnancy, ductal sidebranching in the mammary gland, proliferation of mammary and uterine epithelial cells, as well as target gene induction in both organs. The outcome of this study is that not all synthetic progestins exhibit the same effects. MPA demonstrated uterine activity and mitogenic activity in the mammary gland at the same doses. In contrast, drospirenone behaved similarly to the natural hormone, progesterone, and exhibited uterine activity at doses lower than those leading to considerable proliferative effects in the mammary gland. We hypothesize that the safety of combined hormone therapy in postmenopausal women may be associated with a dissociation between the uterine and mammary gland activities of the progestin component.

• Specific ablation of the transcription factor CREB in sympathetic neurons surprisingly protects against developmentally regulated apoptosis.

  Authors: Rosanna Parlato, Christiane Otto, Yvonne Begus, Stephanie Stotz, Günther Schütz

  Development (Cambridge, England). 06/2007; 134(9):1663-70.

  The cyclic-AMP response element-binding (CREB) protein family of transcription factors plays a crucial role in supporting the survival of neurons. However, a cell-autonomous role has not beenThe cyclic-AMP response element-binding (CREB) protein family of transcription factors plays a crucial role in supporting the survival of neurons. However, a cell-autonomous role has not been addressed in vivo. To investigate the cell-specific role of CREB, we used as a model developing sympathetic neurons, whose survival in vitro is dependent on CREB activity. We generated mice lacking CREB in noradrenergic (NA) and adrenergic neurons and compared them with the phenotype of the germline CREB mutant. Whereas the germline CREB mutant revealed increased apoptosis of NA neurons and misplacement of sympathetic precursors, the NA neuron-specific mutation unexpectedly led to reduced levels of caspase-3-dependent apoptosis in sympathetic ganglia during the period of naturally occurring neuronal death. A reduced level of p75 neurotrophin receptor expression in the absence of CREB was shown to be responsible. Thus, our analysis indicates that the activity of cell-autonomous pro-survival signalling is operative in developing sympathetic neurons in the absence of CREB.

• Pituitary adenylate cyclase-activating polypeptide stimulates renin secretion via activation of PAC1 receptors.

  Authors: Matthias Hautmann, Ulla G Friis, Michael Desch, Vladimir Todorov, Hayo Castrop, Florian Segerer, Christiane Otto, Günther Schütz, Frank Schweda

  Journal of the American Society of Nephrology : JASN. 05/2007; 18(4):1150-6.

  Besides of its functional role in the nervous system, the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) is involved in the regulation of cardiovascular function. Therefore,Besides of its functional role in the nervous system, the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) is involved in the regulation of cardiovascular function. Therefore, PACAP is a potent vasodilator in several vascular beds, including the renal vasculature. Because the kidney expresses both PACAP and PACAP-binding sites, it was speculated that PACAP might regulate cardiovascular function by direct vascular effects and indirectly by regulating renin release from the kidneys. PACAP (1-27) stimulated renin secretion from isolated perfused kidneys of rats 4.9-fold with a half-maximum concentration of 1.9 nmol/L. In addition, PACAP stimulated renin release and enhanced membrane capacitance of isolated juxtaglomerular cells, indicating a direct stimulation of exocytotic events. The effect of PACAP on renin release was mediated by the specific PACAP receptors (PAC1), because PACAP (1-27) applied in concentrations in the physiologic range (10 and 100 pmol/L) did not enhance renin release from isolated kidneys of PAC1 receptor knockout mice (PAC1-/-), whereas it stimulated renin release 1.38- and 2.5-fold in kidneys from wild-type mice. Moreover, plasma renin concentration was significantly lower in PAC1-/- compared with their wild-type littermates under control conditions as well as under a low- or high-salt diet and under treatment with the angiotensin-converting enzyme inhibitor ramipril, whereas no differences in plasma renin concentration between the genotypes were detectable after water deprivation. These data show that PACAP acting on PAC1 receptors potently stimulates renin release, serving as a tonic enhancer of the renin system in vivo.

• Target-dependent specification of the neurotransmitter phenotype: cholinergic differentiation of sympathetic neurons is mediated in vivo by gp 130 signaling.

  Authors: Matthias Stanke, Chi Vinh Duong, Manuela Pape, Markus Geissen, Guido Burbach, Thomas Deller, Hugues Gascan, Christiane Otto, Rosanna Parlato, Günther Schütz, Hermann Rohrer

  Development (Cambridge, England). 02/2006; 133(1):141-50.

  Sympathetic neurons are generated through a succession of differentiation steps that initially lead to noradrenergic neurons innervating different peripheral target tissues. Specific targets, likeSympathetic neurons are generated through a succession of differentiation steps that initially lead to noradrenergic neurons innervating different peripheral target tissues. Specific targets, like sweat glands in rodent footpads, induce a change from noradrenergic to cholinergic transmitter phenotype. Here, we show that cytokines acting through the gp 130 receptor are present in sweat glands. Selective elimination of the gp 130 receptor in sympathetic neurons prevents the acquisition of cholinergic and peptidergic features (VAChT, ChT1, VIP) without affecting other properties of sweat gland innervation. The vast majority of cholinergic neurons in the stellate ganglion, generated postnatally, are absent in gp 130-deficient mice. These results demonstrate an essential role of gp 130-signaling in the target-dependent specification of the cholinergic neurotransmitter phenotype.

• Identification of estrogen receptor ligands leading to activation of non-genomic signaling pathways while exhibiting only weak transcriptional activity.

  Authors: Silja Wessler, Christiane Otto, Nicola Wilck, Verena Stangl, Karl-Heinrich Fritzemeier

  The Journal of steroid biochemistry and molecular biology. 02/2006; 98(1):25-35.

  Estrogen receptors (ERs) stimulate genomic effects by acting as nuclear transcription factors as well as non-genomic effects by activating distinct cytoplasmic protein kinase cascades. Non-genomicEstrogen receptors (ERs) stimulate genomic effects by acting as nuclear transcription factors as well as non-genomic effects by activating distinct cytoplasmic protein kinase cascades. Non-genomic effects have been implicated in numerous cellular processes, such as proliferation, differentiation, apoptosis and vasorelaxation. To exploit non-genomic effects mediated by ERalpha for novel hormone replacement regimens, we screened a focused library of steroid receptor ligands to identify compounds exhibiting properties different from estradiol, i.e. substances that selectively stimulate non-genomic signal transduction pathways while exhibiting low genomic activities. Treatment of breast cancer cells and osteosarcoma cells with estradiol, estren, substance A and substance B led to non-genomic activation of Akt (protein kinase B) and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling cascades mediated by Src (Rous Sarcoma Virus, non-receptor tyrosine kinase) and phosphatidylinositol-3-kinase (PI3K) stimulation. Such compounds leading to prominent Akt/ERK activation but exhibiting only weak genomic properties were applied in vasorelaxation assays, modeling physiological non-genomic ER responses. As expected from PI3K and Src activation data, substances were as effective as estradiol in mediating vasorelaxation. We assume that these pathway-selective estrogen receptor ligands may serve as potent lead structures for novel hormone replacement strategies exhibiting lesser side effects than the existing treatment paradigms.

• Pulmonary hypertension and right heart failure in pituitary adenylate cyclase-activating polypeptide type I receptor-deficient mice.

  Authors: Christiane Otto, Lutz Hein, Marc Brede, Roland Jahns, Stefan Engelhardt, Hermann-Josef Gröne, Günther Schütz

  Circulation. 12/2004; 110(20):3245-51.

  BACKGROUND: Pituitary adenylate cyclase-activating polypeptide (PACAP), acting via 3 different G protein-coupled receptors, has been implicated in the regulation of several homeostatic systems in theBACKGROUND: Pituitary adenylate cyclase-activating polypeptide (PACAP), acting via 3 different G protein-coupled receptors, has been implicated in the regulation of several homeostatic systems in the body, including cardiopulmonary control. To define the physiologic role of the PACAP-preferring type I receptor, PAC1, in cardiopulmonary function, we developed a mutant mouse strain lacking functional PAC1 receptors. METHODS AND RESULTS: When PAC1-deficient mice were crossed onto a C57BL/6 background, almost all mutants died during the second postnatal week. Whereas mutant mice were indistinguishable from their wild-type littermates at birth, they showed progressive weakness and died from rapidly developing heart failure. Right ventricles of PAC1 mutants were massively dilated and showed cardiac myocyte hypertrophy, whereas left ventricular structure was unaltered. On direct cardiac catheterization, right ventricular pressure was elevated by 45% in PAC1-deficient mice, indicating increased pulmonary artery pressure, as no malformations were detected in the valves or outflow tract of the right ventricle. Consistent with elevated pulmonary pressure, lung capillary density was decreased by 30% and small pulmonary arteries of mutant mice had significant vascular smooth muscle cell hypertrophy compared with wild-type mice. CONCLUSIONS: Whereas PACAP induces vasodilation in isolated pulmonary vessels in wild-type mice, the absence of its specific receptor PAC1 causes pulmonary hypertension and right heart failure after birth. These in vivo findings demonstrate the crucial importance of PAC1-mediated signaling for the maintenance of normal pulmonary vascular tone during early postnatal life.

• Reduced expression of brain-derived neurotrophic factor in mice deficient for pituitary adenylate cyclase activating polypeptide type-I-receptor.

  Authors: Mathias Zink, Christiane Otto, Björn Zörner, Christiane Zacher, Günther Schütz, Fritz A Henn, Peter Gass

  Neuroscience letters. 05/2004; 360(1-2):106-8.

  In vitro pituitary adenylate cyclase activating polypeptide (PACAP) induces the expression of brain-derived neurotrophic factor (BDNF) via its specific receptor PAC1. Since BDNF has been implicatedIn vitro pituitary adenylate cyclase activating polypeptide (PACAP) induces the expression of brain-derived neurotrophic factor (BDNF) via its specific receptor PAC1. Since BDNF has been implicated in learning paradigms and mice lacking functional PAC1 have deficits in hippocampus-dependent associative learning, we investigated whether PAC1 mutants show alterations in hippocampal expression of BDNF and its receptor TrkB. Semi-quantitative in situ-hybridization using exon-specific BDNF-probes revealed significantly reduced expression of the exon-III and exon-V-specific transcripts within the hippocampal CA3 region in PAC1-deficient mice. A similar trend was observed for the exon-I-specific transcript. The expression of the exon-III-specific transcript was also reduced within the dentate gyrus, while Trk B-expression did not differ between genotypes. Our data demonstrate that even in vivo PAC1-mediated signaling seems to play a pivotal role for the transcriptional regulation of BDNF.

• Morphine withdrawal is modified in pituitary adenylate cyclase-activating polypeptide type I-receptor-deficient mice.

  Authors: Miquel Martin, Christiane Otto, Maria Teresa Santamarta, Maria Torrecilla, Joseba Pineda, Günther Schütz, Rafael Maldonado

  Brain research. Molecular brain research. 02/2003; 110(1):109-18.

  The pituitary adenylate cyclase-activating polypeptide type I-receptor (PAC1) is a G-protein-coupled receptor that is widely expressed in neurons of the central and peripheral nervous system. TheThe pituitary adenylate cyclase-activating polypeptide type I-receptor (PAC1) is a G-protein-coupled receptor that is widely expressed in neurons of the central and peripheral nervous system. The strong expression of PAC1 in the second sensory neuron as well as in brainstem regions such as the locus coeruleus prompted us to elucidate the potential in vivo role of PAC1-mediated signalling in pain perception and opioid addiction using a PAC1-deficient mouse line. We observed a selective involvement of PAC1 in the mediation of visceral pain. While there was no impairment in acute somatic pain perception, PAC1-mutants exhibited a dramatically decreased response in the abdominal writhing test. These data in concert with data from the literature implicate PAC1 in the mediation of visceral and chronic pain. In addition, we observed that PAC1 did not influence the motivational aspects of opioid addictive properties, since morphine-induced rewarding effects and sensitization to locomotor responses were completely maintained in PAC1-deficient mice. However, there was a dramatic increase in physical withdrawal signs after naloxone-precipitated morphine withdrawal in PAC1 mutants. At the cellular level, electrophysiological examinations in locus coeruleus neurons from morphine-dependent wild-type and PAC1-deficient mice did not reveal any differences in firing rates. These data therefore suggested that most likely disruption of PAC1-mediated signalling in afferents towards the locus coeruleus but not within the intrinsic locus coeruleus system led to the enhancement of somatic withdrawal signs.

• Disruption of CREB function in brain leads to neurodegeneration.

  Authors: Theo Mantamadiotis, Thomas Lemberger, Susanne C Bleckmann, Heidrun Kern, Oliver Kretz, Ana Martin-Villalba, François Tronche, Christoph Kellendonk, Daniel Gau, Josef Kapfhammer, Christiane Otto, Wolfgang Schmid, Günther Schütz

  Nature genetics. 06/2002; 31(1):47-54.

  Control of cellular survival and proliferation is dependent on extracellular signals and is a prerequisite for ordered tissue development and maintenance. Activation of the cAMP responsive elementControl of cellular survival and proliferation is dependent on extracellular signals and is a prerequisite for ordered tissue development and maintenance. Activation of the cAMP responsive element binding protein (CREB) by phosphorylation has been implicated in the survival of mammalian cells. To define its roles in the mouse central nervous system, we disrupted Creb1 in brain of developing and adult mice using the Cre/loxP system. Mice with a Crem(-/-) background and lacking Creb in the central nervous system during development show extensive apoptosis of postmitotic neurons. By contrast, mice in which both Creb1 and Crem are disrupted in the postnatal forebrain show progressive neurodegeneration in the hippocampus and in the dorsolateral striatum. The striatal phenotype is reminiscent of Huntington disease and is consistent with the postulated role of CREB-mediated signaling in polyglutamine-triggered diseases.

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