@misc{SchmidtBaumannWalz2008, author = {Schmidt, Ruth and Baumann, Otto and Walz, Bernd}, title = {cAMP potentiates InsP3-induced Ca2+ release from the endoplasmic reticulum in blowfly salivary glands}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe}, number = {842}, issn = {1866-8372}, doi = {10.25932/publishup-42977}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-429770}, pages = {13}, year = {2008}, abstract = {Background Serotonin induces fluid secretion from Calliphora salivary glands by the parallel activation of the InsP3/Ca2+ and cAMP signaling pathways. We investigated whether cAMP affects 5-HT-induced Ca2+ signaling and InsP3-induced Ca2+ release from the endoplasmic reticulum (ER). Results Increasing intracellular cAMP level by bath application of forskolin, IBMX or cAMP in the continuous presence of threshold 5-HT concentrations converted oscillatory [Ca2+]i changes into a sustained increase. Intraluminal Ca2+ measurements in the ER of ß-escin-permeabilized glands with mag-fura-2 revealed that cAMP augmented InsP3-induced Ca2+ release in a concentration-dependent manner. This indicated that cAMP sensitized the InsP3 receptor Ca2+ channel for InsP3. By using cAMP analogs that activated either protein kinase A (PKA) or Epac and the application of PKA-inhibitors, we found that cAMP-induced augmentation of InsP3-induced Ca2+ release was mediated by PKA not by Epac. Recordings of the transepithelial potential of the glands suggested that cAMP sensitized the InsP3/Ca2+ signaling pathway for 5-HT, because IBMX potentiated Ca2+-dependent Cl- transport activated by a threshold 5-HT concentration. Conclusion This report shows, for the first time for an insect system, that cAMP can potentiate InsP3-induced Ca2+ release from the ER in a PKA-dependent manner, and that this crosstalk between cAMP and InsP3/Ca2+ signaling pathways enhances transepithelial electrolyte transport.}, language = {en} } @misc{GraefSecklerHagemannetal.2012, author = {Gr{\"a}f, Ralph and Seckler, Robert and Hagemann, Alfred and D'Aprile, Iwan-Michelangelo and Schulte, Christoph and Zimmermann, Matthias and Blom, Hans and Horn-Conrad, Antje and Kampe, Heike and J{\"a}ger, Sophie and Haase, Jana and Eckardt, Barbara and Priebs-Tr{\"o}ger, Astrid and Walz, Bernd}, title = {Portal Wissen = Raum}, number = {01/2012}, organization = {Universit{\"a}t Potsdam, Referat f{\"u}r Presse- und {\"O}ffentlichkeitsarbeit}, issn = {2194-4237}, doi = {10.25932/publishup-44078}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-440785}, pages = {98}, year = {2012}, abstract = {Mit „Portal Wissen" laden wir Sie ein, die Forschung an der Universit{\"a}t Potsdam zu entdecken und in ihrer Vielfalt kennenzulernen. In der ersten Ausgabe dreht sich alles um „R{\"a}ume". R{\"a}ume, in denen geforscht wird, solche, die es zu erforschen gilt, andere, die durch Wissenschaft zug{\"a}nglich oder erschlossen werden, aber auch R{\"a}ume, die Wissenschaft braucht, um sich entfalten zu k{\"o}nnen. Forschung vermisst R{\"a}ume: „Wissenschaft wird von Menschen gemacht", schrieb der Physiker Werner Heisenberg. Umgekehrt l{\"a}sst sich sagen: Wissenschaft macht Menschen, widmet sich ihnen, beeinflusst sie. Dieser Beziehung ist „Portal Wissen" nachgegangen. Wir haben Wissenschaftler getroffen, sie gefragt, wie aus ihren Fragen Projekte entstehen, haben sie auf dem oft verschlungenen Weg zum Ziel begleitet. Ein besonderes Augenmerk dieses Heftes gilt den „Kulturellen Begegnungsr{\"a}umen", denen ein eigener Profilbereich der Forschung an der Universit{\"a}t Potsdam gewidmet ist. Forschung hat R{\"a}ume: Labore, Bibliotheken, Gew{\"a}chsh{\"a}user oder Archive - hier ist Wissenschaft zu Liebe Leserinnen und Leser, Hause. All diese Orte sind so einzigartig wie die Wissenschaftler, die in ihnen arbeiten, oder die Untersuchungen, die hier stattfinden. Erst die Vision davon, wie ein Problem zu l{\"o}sen ist, macht aus einfachen Zimmern „Laborr{\"a}ume". Wir haben ihre T{\"u}ren ge{\"o}ffnet, um zu zeigen, was - und wer - sich dahinter befindet. Forschung er{\"o}ffnet R{\"a}ume: Wenn Wissenschaft erfolgreich ist, bewegt sie uns, bringt uns voran. Auf dem Weg einer wissenschaftlichen Erkenntnis aus dem Labor in den Alltag stehen mitunter H{\"u}rden, die meist nicht auf den ersten Blick zu erkennen sind. Auf jeden Fall aber ist ihre Anwendung erster Ausgangspunkt von Wissenschaft, Antrieb und Motivation jedes Forschers. „Portal Wissen" zeigt, welche „Praxisr{\"a}ume" sich aus der {\"U}bersetzung von Forschungsresultaten ergeben. Dort, wo wir es unbedingt erwarten, und dort, wo vielleicht nicht. Forschung erschließt R{\"a}ume: Bei Expeditionen, Feldversuchen und Exkursionen wird nahezu jede Umgebung zum mobilen Labor. So er{\"o}ffnet Wissenschaft Zug{\"a}nge auch zu Orten, die auf vielfach andere Weise verschlossen oder unzug{\"a}nglich scheinen. Wir haben uns in Forscher- Reisetaschen gemogelt, um bei Entdeckungsreisen dabei zu sein, die weit weg - vor allem nach Afrika - f{\"u}hren. Zugleich haben wir beobachtet, wie „Entwicklungsr{\"a}ume" sich auch von Potsdam aus erschließen lassen oder zumindest ihre Vermessung in Potsdam beginnen kann. Forschung braucht R{\"a}ume: Wissenschaft hat zwei Geschlechter, endlich. Noch nie waren so viele Frauen in der Forschung t{\"a}tig wie derzeit. Ein Grund zum Ausruhen ist dies gleichwohl nicht. Deutschlandweit ist aktuell nur jede f{\"u}nfte Professur von einer Frau besetzt. „Portal Wissen" schaut, welche „Entwicklungsr{\"a}ume" Frauen sich in der Wissenschaft, aber auch dar{\"u}ber hinaus geschaffen haben. Und wo sie ihnen verwehrt werden. Wir w{\"u}nschen Ihnen eine anregende Lekt{\"u}re und dass auch Sie einen Raum finden, der Sie inspiriert. Prof. Dr. Robert Seckler Vizepr{\"a}sident f{\"u}r Forschung und wissenschaftlichen Nachwuchs}, language = {de} } @article{AstMuellerFlehretal.2011, author = {Ast, Sandra and M{\"u}ller, Holger and Flehr, Roman and Klamroth, Tillmann and Walz, Bernd and Holdt, Hans-J{\"u}rgen}, title = {High Na+ and K+-induced fluorescence enhancement of a pi-conjugated phenylaza-18-crown-6-triazol-substituted coumarin fluoroionophore}, series = {Chemical communications}, volume = {47}, journal = {Chemical communications}, number = {16}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1359-7345}, doi = {10.1039/c0cc04370b}, pages = {4685 -- 4687}, year = {2011}, abstract = {The new pi-conjugated 1,2,3-triazol-1,4-diyl fluoroionophore 1 generated via Cu(I) catalyzed [3 + 2] cycloaddition shows high fluorescence enhancement factors (FEF) in the presence of Na+ (FEF = 58) and K+ (FEF = 27) in MeCN and high selectivity towards K+ under simulated physiological conditions (160 mM K+ or Na+, respectively) with a FEF of 2.5 for K+.}, language = {en} } @article{ScheweBlenauWalz2012, author = {Schewe, Bettina and Blenau, Wolfgang and Walz, Bernd}, title = {Intracellular pH regulation in unstimulated Calliphora salivary glands is Na+ dependent and requires V-ATPase activity}, series = {The journal of experimental biology}, volume = {215}, journal = {The journal of experimental biology}, number = {8}, publisher = {Company of Biologists Limited}, address = {Cambridge}, issn = {0022-0949}, doi = {10.1242/jeb.063172}, pages = {1337 -- 1345}, year = {2012}, abstract = {Salivary gland cells of the blowfly Calliphora vicina have a vacuolar-type H+-ATPase (V-ATPase) that lies in their apical membrane and energizes the secretion of a KCl-rich primary saliva upon stimulation with serotonin (5-hydroxytryptamine). Whether and to what extent V-ATPase contributes to intracellular pH (pH(i)) regulation in unstimulated gland cells is unknown. We used the fluorescent dye BCECF to study intracellular pH(i) regulation microfluorometrically and show that: (1) under resting conditions, the application of Na+-free physiological saline induces an intracellular alkalinization attributable to the inhibition of the activity of a Na+-dependent glutamate transporter; (2) the maintenance of resting pHi is Na+, Cl-, concanamycin A and DIDS sensitive; (3) recovery from an intracellular acid load is Na+ sensitive and requires V-ATPase activity; (4) the Na+/H+ antiporter is not involved in pHi recovery after a NH4Cl prepulse; and (5) at least one Na+-dependent transporter and the V-ATPase maintain recovery from an intracellular acid load. Thus, under resting conditions, the V-ATPase and at least one Na+-dependent transporter maintain normal pH(i) values of pH.7.5. We have also detected the presence of a Na+-dependent glutamate transporter, which seems to act as an acid loader. Despite this not being a common pH(i)-regulating transporter, its activity affects steady-state pH(i) in C. vicina salivary gland cells.}, language = {en} } @misc{BaumannWalz2012, author = {Baumann, Otto and Walz, Bernd}, title = {The blowfly salivary gland - A model system for analyzing the regulation of plasma membrane V-ATPase}, series = {Journal of insect physiology}, volume = {58}, journal = {Journal of insect physiology}, number = {4}, publisher = {Elsevier}, address = {Oxford}, issn = {0022-1910}, doi = {10.1016/j.jinsphys.2011.11.015}, pages = {450 -- 458}, year = {2012}, abstract = {Vacuolar H+-ATPases (V-ATPases) are heteromultimeric proteins that use the energy of ATP hydrolysis for the electrogenic transport of protons across membranes. They are common to all eukaryotic cells and are located in the plasma membrane or in membranes of acid organelles. In many insect epithelia, V-ATPase molecules reside in large numbers in the apical plasma membrane and create an electrochemical proton gradient that is used for the acidification or alkalinization of the extracellular space, the secretion or reabsorption of ions and fluids, the import of nutrients, and diverse other cellular activities. Here, we summarize our results on the functions and regulation of V-ATPase in the tubular salivary gland of the blowfly Calliphora vicina. In this gland, V-ATPase activity energizes the secretion of a KCl-rich saliva in response to the neurohormone serotonin (5-HT). Because of particular morphological and physiological features, the blowfly salivary glands are a superior and exemplary system for the analysis of the intracellular signaling pathways and mechanisms that modulate V-ATPase activity and solute transport in an insect epithelium.}, language = {en} } @article{HeindorffBlenauWalzetal.2012, author = {Heindorff, Kristoffer and Blenau, Wolfgang and Walz, Bernd and Baumann, Otto}, title = {Characterization of a Ca2+/calmodulin-dependent AC1 adenylyl cyclase in a non-neuronal tissue, the blowfly salivary gland}, series = {Cell calcium}, volume = {52}, journal = {Cell calcium}, number = {2}, publisher = {Churchill Livingstone}, address = {Edinburgh}, issn = {0143-4160}, doi = {10.1016/j.ceca.2012.04.016}, pages = {103 -- 112}, year = {2012}, abstract = {Crosstalk between intracellular signalling pathways is a functionally important and widespread phenomenon in cell physiology across phyla. In the salivary gland of the blowfly, serotonin induces fluid secretion via parallel activation of both the InsP(3)/Ca2+ and the cAMP/PKA signalling pathways, which interact on multiple levels. We have determined the molecular identity of a link between both pathways that mediates a Ca2+-dependent rise of intracellular cAMP. Whereas hydrolysis of cAMP via phosphodiesterases is largely independent of Ca2+, cAMP synthesis by adenylyl cyclases (AC) is potentiated in a Ca2+/calmodulin (Ca2+/CaM)-dependent manner. The existence of a Ca2+/CaM-dependent AC is supported by physiological data and a molecular approach. We have cloned Cv rutabaga cDNA, encoding the first blowfly AC, and confirmed its expression in the salivary gland via reverse transcription followed by polymerase chain reaction. The putative gene product of Cv rutabaga is a Ca2+/CaM-dependent type I AC and shows highest homology to Rutabaga from Drosophila. Thus, a Ca2+/CaM-dependent AC serves as a link between the InsP(3)/Ca2+ and the cAMP/PKA signalling pathways in the salivary gland of the blowfly and might be important for the amplification and optimization of the secretory response.}, language = {en} } @article{RoeserJordanBalfanzetal.2012, author = {R{\"o}ser, Claudia and Jordan, Nadine and Balfanz, Sabine and Baumann, Arnd and Walz, Bernd and Baumann, Otto and Blenau, Wolfgang}, title = {Molecular and pharmacological characterization of serotonin 5-HT2 alpha and 5-HT7 receptors in the salivary glands of the blowfly calliphora vicina}, series = {PLoS one}, volume = {7}, journal = {PLoS one}, number = {11}, publisher = {PLoS}, address = {San Fransisco}, issn = {1932-6203}, doi = {10.1371/journal.pone.0049459}, pages = {13}, year = {2012}, abstract = {Secretion in blowfly (Calliphora vicina) salivary glands is stimulated by the biogenic amine serotonin (5-hydroxytryptamine, 5-HT), which activates both inositol 1,4,5-trisphosphate (InsP(3))/Ca2+ and cyclic adenosine 3',5'-monophosphate (cAMP) signalling pathways in the secretory cells. In order to characterize the signal-inducing 5-HT receptors, we cloned two cDNAs (Cv5-ht2 alpha, Cv5-ht7) that share high similarity with mammalian 5-HT2 and 5-HT7 receptor genes, respectively. RT-PCR demonstrated that both receptors are expressed in the salivary glands and brain. Stimulation of Cv5-ht2 alpha-transfected mammalian cells with 5-HT elevates cytosolic [Ca2+] in a dose-dependent manner (EC50 = 24 nM). In Cv5-ht7-transfected cells, 5-HT produces a dose-dependent increase in [cAMP](i) (EC50 = 4 nM). We studied the pharmacological profile for both receptors. Substances that appear to act as specific ligands of either Cv5-HT2 alpha or Cv5-HT7 in the heterologous expression system were also tested in intact blowfly salivary gland preparations. We observed that 5-methoxytryptamine (100 nM) activates only the Cv(5)-HT2 alpha receptor, 5-carboxamidotryptamine (300 nM) activates only the Cv5-HT7 receptor, and clozapine (1 mu M) antagonizes the effects of 5-HT via Cv5-HT7 in blowfly salivary glands, providing means for the selective activation of each of the two 5-HT receptor subtypes. This study represents the first comprehensive molecular and pharmacological characterization of two 5-HT receptors in the blowfly and permits the analysis of the physiological role of these receptors, even when co-expressed in cells, and of the modes of interaction between the Ca2+- and cAMP-signalling cascades. Citation: Roser C, Jordan N, Balfanz S, Baumann A, Walz B, et al. (2012) Molecular and Pharmacological Characterization of Serotonin 5-HT2a and 5-HT7 Receptors in the Salivary Glands of the Blowfly Calliphora vicina.}, language = {en} } @article{FechnerBaumannWalz2013, author = {Fechner, Lennart and Baumann, Otto and Walz, Bernd}, title = {Activation of the cyclic AMP pathway promotes serotonin-induced Ca2+ oscillations in salivary glands of the blowfly Calliphora vicina}, series = {Cell calcium}, volume = {53}, journal = {Cell calcium}, number = {2}, publisher = {Churchill Livingstone}, address = {Edinburgh}, issn = {0143-4160}, doi = {10.1016/j.ceca.2012.10.004}, pages = {94 -- 101}, year = {2013}, abstract = {Ca2+ and cAMP signalling pathways interact in a complex manner at multiple sites. This crosstalk fine-tunes the spatiotemporal patterns of Ca2+ and cAMP signals. In salivary glands of the blowfly Calliphora vicina fluid secretion is stimulated by serotonin (5-hydroxytryptamine, 5-HT) via activation of two different 5-HT receptors coupled to the InsP(3)/Ca2+ (Cv5-HT2 alpha) or the cAMP pathway (Cv5-HT7), respectively. We have shown recently in permeabilized gland cells that cAMP sensitizes InsP(3)-induced Ca2+ release to InsP(3). Here we study the effects of the CAMP signalling pathway on 5-HT-induced oscillations in transepithelial potential (TEP) and in intracellular [Ca2+]. We show: (1) Blocking the activation of the cAMP pathway by cinanserin suppresses the generation of TEP and Ca2+ oscillations, (2) application of 8-CPT-cAMP in the presence of cinanserin restores 5-HT-induced TEP and Ca2+ oscillations, (3) 8-CPT-cAMP sensitizes the InsP(3)/Ca2+ signalling pathway to 5-HT and the Cv5-HT2 alpha, receptor agonist 5-MeOT, (4) 8-CPT-cAMP induces Ca2+ oscillations in cells loaded with subthreshold concentrations of InsP(3), (5) inhibition of protein kinase A by H-89 abolishes 5-HT-induced TEP and Ca2+ spiking and mimics the effect of cinanserin. These results suggest that activation of the cyclic AMP pathway promotes the generation of 5-HT-induced Ca2+ oscillations in blowfly salivary glands.}, language = {en} } @article{VossSchmidtWalzetal.2009, author = {Voss, Martin and Schmidt, Ruth and Walz, Bernd and Baumann, Otto}, title = {Stimulus-induced translocation of the protein kinase A catalytic subunit to the apical membrane in blowfly salivary glands}, issn = {0302-766X}, doi = {10.1007/s00441-008-0673-x}, year = {2009}, abstract = {Secretion in blowfly (Calliphora vicina) salivary glands is regulated by the neurohormone serotonin (5-HT), which activates the InsP(3)/Ca2+ pathway and the cAMP/protein kinase A (PKA) pathway in the secretory cells. The latter signaling cascade induces the activation of a vacuolar H+-ATPase on the apical membrane. Here, we have determined the distribution of PKA by using antibodies against the PKA regulatory subunit-II (PKA-RII) and the PKA catalytic subunit (PKA-C) of Drosophila. PKA is present in high concentrations within the secretory cells. PKA-RII and PKA-C co-distribute in non-stimulated glands, being enriched in the basal portion of the secretory cells. Exposure to 8-CPT-cAMP or 5-HT induces the translocation of PKA-C to the apical membrane, whereas the PKA-RII distribution remains unchanged. The recruitment of PKA-C to the apical membrane corroborates our hypothesis that vacuolar H+-ATPase, which is enriched in this membrane domain, is a target protein for PKA.}, language = {en} } @article{VossFechnerWalzetal.2010, author = {Voss, Martin and Fechner, Lennart and Walz, Bernd and Baumann, Otto}, title = {Calcineurin activity augments cAMP/PKA-dependent activation of V-ATPase in blowfly salivary glands}, issn = {0363-6143}, doi = {10.1152/ajpcell.00328.2009}, year = {2010}, abstract = {We have examined the role of the Ca2+-dependent protein phosphatase 2B (calcineurin) in the regulation of the vacuolar H+-ATPase (V-ATPase) in blowfly salivary glands. In response to the neurohormone serotonin [5-hydroxytryptamine (5-HT)] and under the mediation of the cAMP/PKA signaling pathway, the secretory cells assemble and activate V-ATPase molecules at the apical membrane. We demonstrate that the inhibition of calcineurin activity by cyclosporin A, by FK- 506, or by prevention of the elevation of Ca2+ diminishes the 5-HT-induced assembly and activation of V-ATPase. The effect of calcineurin on V-ATPase is mediated by the cAMP/PKA signaling pathway, with calcineurin acting upstream of PKA, because 1) cyclosporin A does not influence the 8-(4-chlorophenylthio) adenosine-3',5'-cyclic monophosphate (8-CPT-cAMP)-induced activation of V-ATPase, and 2) the 5-HT-induced rise in cAMP is highly reduced in the presence of cyclosporin A. Moreover, a Ca2+ rise evoked by the sarco(endo) plasmic reticulum Ca2+-ATPase (SERCA) inhibitor cyclopiazonic acid leads to an increase in intracellular cAMP concentration and a calcineurin-mediated PKA- dependent activation of V-ATPase. We propose that calcineurin activity mediates cross talk between the inositol 1,4,5- trisphosphate/Ca2+ and the cAMP/PKA signaling pathways, thereby augmenting the 5-HT-induced rise in cAMP and thus the cAMP/PKA-mediated activation of V-ATPase.}, language = {en} }