TY - JOUR A1 - Stürmer, Karoline A1 - Baumann, Otto A1 - Walz, Bernd T1 - Actin-dependent light-induced translocation of mitochondria and ER cisternae in the photoreceptor cells of the locust schistocerca gregaria Y1 - 1995 ER - TY - JOUR A1 - Walz, Bernd A1 - Ukhanov, Kyrill A1 - Zimmermann, Bernhard T1 - Actions of neomycin on electrical light responses : Ca2+ release and intracellular Ca2+ changes in photoreceptors of the honeybee drone Y1 - 2000 SN - 0340-7594 ER - TY - JOUR A1 - Fechner, Lennart A1 - Baumann, Otto A1 - Walz, Bernd T1 - Activation of the cyclic AMP pathway promotes serotonin-induced Ca2+ oscillations in salivary glands of the blowfly Calliphora vicina JF - Cell calcium N2 - 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. KW - Calcium KW - Ca2+ KW - Calcium oscillations KW - cAMP KW - Signalling KW - Crosstalk KW - Salivary gland KW - Calliphora KW - Blowfly KW - Insect Y1 - 2013 U6 - https://doi.org/10.1016/j.ceca.2012.10.004 SN - 0143-4160 VL - 53 IS - 2 SP - 94 EP - 101 PB - Churchill Livingstone CY - Edinburgh ER - TY - JOUR A1 - Walz, Bernd T1 - Auch im Süßwasser - die Hydrozoe cordylophora caspia Y1 - 1997 ER - TY - JOUR A1 - Somlyo, A. V. A1 - Walz, Bernd T1 - Ca2+ in visual transduction and adaptation in vertebrates and invertebrates Y1 - 1995 ER - TY - JOUR A1 - Walz, Bernd A1 - Baumann, Otto A1 - Zimmermann, Bernhard A1 - Ciriacy-Wantrup, E.v. T1 - Caffeine- and ryanodine-sensitive Ca2+-induced Ca2+ release from the endo plasmatic reticulum in honeybee photoreceptors Y1 - 1995 ER - TY - JOUR A1 - Voss, Martin A1 - Fechner, Lennart A1 - Walz, Bernd A1 - Baumann, Otto T1 - Calcineurin activity augments cAMP/PKA-dependent activation of V-ATPase in blowfly salivary glands N2 - 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. Y1 - 2010 UR - http://ajpcell.physiology.org/ U6 - https://doi.org/10.1152/ajpcell.00328.2009 SN - 0363-6143 ER - TY - JOUR A1 - Dames, Petra A1 - Zimmermann, Bernhard A1 - Schmidt, Ruth A1 - Rein, Julia A1 - Voss, Martin A1 - Schewe, Bettina A1 - Walz, Bernd A1 - Baumann, Otto T1 - cAMP regulates plasma membrane vacuolar-type H+-ATPase assembly and activity in blowfly salivary glands N2 - Reversible assembly of the V0V1 holoenzyme from V-0 and V-1 subcomplexes is a widely used mechanism for regulation of vacuolar-type H+-ATPases (V-ATPases) in animal cells. in the blowfly (Calliphora vicina) salivary gland, V- ATPase is located in the apical membrane of the secretory cells and energizes the secretion of a KCl-rich saliva in response to the hormone serotonin. We have examined whether the CAMP pathway, known to be activated by serotonin, controls V-ATPase assembly and activity. Fluorescence measurements of pH changes at the luminal surface of isolated glands demonstrate that CAMP, Sp-adenosine-3',5'-cyclic monophosphorothioate, or forskolin, similar to serotonin, cause V-ATPase-dependent luminal acidification. In addition, V-ATPase-dependent ATP hydrolysis increases upon treatment with these agents. Immunofluorescence microscopy and pelleting assays have demonstrated further that V, components become translocated from the cytoplasm to the apical membrane and V-ATPase holoenzymes are assembled at the apical membrane during conditions that increase intracellular cAMP. Because these actions occur without a change in cytosolic Ca2+, our findings suggest that the cAMP pathway mediates the reversible assembly and activation of V-ATPase molecules at the apical membrane upon hormonal stimulus Y1 - 2006 UR - http://www.pnas.org/ U6 - https://doi.org/10.1073/pnas.0600011103 SN - 0027-8424 ER - TY - JOUR A1 - Heindorff, Kristoffer A1 - Blenau, Wolfgang A1 - Walz, Bernd A1 - Baumann, Otto T1 - Characterization of a Ca2+/calmodulin-dependent AC1 adenylyl cyclase in a non-neuronal tissue, the blowfly salivary gland JF - Cell calcium N2 - 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. KW - Adenylyl cyclase KW - Phosphodiesterase KW - Crosstalk KW - Ca2+ KW - cAMP KW - Intracellular signalling KW - Salivary gland KW - Calliphora vicina KW - Rutabaga Y1 - 2012 U6 - https://doi.org/10.1016/j.ceca.2012.04.016 SN - 0143-4160 VL - 52 IS - 2 SP - 103 EP - 112 PB - Churchill Livingstone CY - Edinburgh ER - TY - JOUR A1 - Baumann, Otto A1 - Arlt, Kathleen A1 - Römmling, Katja A1 - Goller, Helmut A1 - Walz, Bernd T1 - Characterization of an extremely motile cellular network in the rotifer Asplanchna : Structure, kinetics and the cytoskeleton Y1 - 2000 ER -