M Paulmichl

Publications (104)313.07 Total impact

• Article: STAT6 links IL-4/IL-13 stimulation with pendrin expression in asthma and chronic obstructive pulmonary disease.

  C Nofziger, V Vezzoli, S Dossena, T Schönherr, J Studnicka, J Nofziger, S Vanoni, S Stephan, M E Silva, G Meyer, M Paulmichl
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  ABSTRACT: Signaling through the interleukin-4/interleukin-13 (IL-4/IL-13) receptor complex is a crucial mechanism in the development of bronchial asthma and chronic obstructive pulmonary disease (COPD). In bronchial epithelial cells, this signaling pathway leads to changes in the expression levels of several genes that are possibly involved in protection against and/or pathogenesis of these diseases. The expression of pendrin (SLC26A4), a candidate for the latter category, is upregulated by IL-4/IL-13 and leads to overproduction of mucus and increased viscosity of the airway surface liquid (ASL). Therefore, elucidating the transcriptional regulation of pendrin could aid in the development of new pharmacological leads for asthma and/or COPD therapy. Here we show that IL-4/IL-13 significantly increased human pendrin promoter activity in HEK-Blue cells but not in STAT6-deficient HEK293 Phoenix cells; that mutation of the STAT6 binding site (N(4) GAS motif) rendered the promoter insensitive to IL-4/IL-13; and that addition of the N(4) GAS motif to an IL-4/IL-13-unresponsive sequence of the human pendrin promoter conferred sensitivity to both ILs.
  Clinical Pharmacology &#38 Therapeutics 09/2011; 90(3):399-405. · 6.04 Impact Factor
• Source

  Available from: Andrea Binelli

  Article: S-CMC-Lys-dependent stimulation of electrogenic glutathione secretion by human respiratory epithelium.

  F Guizzardi, S Rodighiero, A Binelli, S Saino, E Bononi, S Dossena, M L Garavaglia, C Bazzini, G Bottà, M Conese, L Daffonchio, R Novellini, M Paulmichl, G Meyer
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  ABSTRACT: Glutathione (GSH) is one of the most important defense mechanisms against oxidative stress in the respiratory epithelial lining fluid. Considering that GSH secretion in respiratory cells has been postulated to be at least partially electrogenic, and that the mucoregulator S-carbocysteine lysine salt monohydrate (S-CMC-Lys) can cause an activation of epithelial Cl(-) conductance, the purpose of this study was to verify whether S-CMC-Lys is able to stimulate GSH secretion. Experiments have been performed by patch-clamp technique, by high-performance liquid chromatography (HPLC) assay, and by Western blot analysis on cultured lines of human respiratory cells (WI-26VA4 and CFT1-C2). In whole-cell configuration, after cell exposure to 100 microM S-CMC-Lys, a current due to an outward GSH flux was observed, which was inhibitable by 5-nitro-2-(3-phenylpropylamino)-benzoate and glibenclamide. This current was not observed in CFT1-C2 cells, where a functional cystic fibrosis transmembrane conductance regulator (CFTR) is lacking. Inside-out patch-clamp experiments (GSH on the cytoplasm side, Cl(-) on the extracellular side) showed the activity of a channel, which was able to conduct current in both directions: the single channel conductance was 2-4 pS, and the open probability (P(o)) was low and voltage-independent. After preincubation with 100 microM S-CMC-Lys, there was an increase in P(o), in the number of active channels present in each patch, and in the relative permeability to GSH vs Cl(-). Outwardly directed efflux of GSH could also be increased by protein kinase A, adenosine 5'-triphosphate, and cyclic adenosine monophosphate (cAMP) added to the cytoplasmic side (whole-cell configuration). The increased secretion of GSH observed in the presence of S-CMC-Lys or 8-bromoadenosine-3',5'-cyclic monophosphate was also confirmed by HPLC assay of GSH on a confluent monolayer of respiratory cells. Western blot analysis confirmed the presence of CFTR in WI-26VA4 cells. This study suggests that S-CMC-Lys is able to stimulate a channel-mediated GSH secretion by human respiratory cells: electrophysiological and pharmacological characteristics of this channel are similar to those of the CFTR channel.
  Journal of Molecular Medicine 02/2006; 84(1):97-107. · 4.67 Impact Factor
• Article: Jejunal creatine absorption: what is the role of the basolateral membrane?

  M N Orsenigo, A Faelli, S De Biasi, C Sironi, U Laforenza, M Paulmichl, M Tosco
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  ABSTRACT: The mechanism of the intestinal creatine absorption is not well understood. Previous studies have established the involvement of a CT1 carrier system in jejunal apical membrane. The current research was aimed at completing the picture of creatine absorption. To investigate the process supporting creatine exit from enterocyte, basolateral membrane vesicles isolated from rat jejunum were used. The presence of various symport and antiport mechanisms was searched and a NaCl-dependent electrogenic transport system for creatine was evidenced, which shares some functional and kinetic features with the apical CT1. However, Western blot and immunohistochemical experiments ruled out the presence of a CT1 transporter in the basolateral membrane. Further studies are required to identify the basolateral transport mechanism. However, in the in vivo conditions, the NaCl gradient is inwardly directed, therefore such a mechanism cannot energetically mediate the exit of creatine from the cell into the blood during the absorptive process, but rather it may drive creatine into the enterocyte. To shed more light on the creatine absorption process, a possible creatine movement through the paracellular pathway has been examined using the jejunal tract everted and incubated in vitro. A linear relationship between creatine transport and concentration was apparent both in the mucosa-to-serosa and serosa-to-mucosa directions and the difference between the two slopes suggests that paracellular creatine movement by solvent drag may account for transintestinal creatine absorption. As a matter of fact, when transepithelial water flux is reduced by means of a mucosal hypertonic solution, the opposite creatine fluxes tend to overlap. The findings of the present study suggest that paracellular creatine movement by solvent drag may account for transintestinal creatine absorption.
  Journal of Membrane Biology 11/2005; 207(3):183-95. · 1.81 Impact Factor
• Article: Ion transport across the gallbladder epithelium.

  G Meyer, F Guizzardi, S Rodighiero, R Manfredi, S Saino, C Sironi, M L Garavaglia, C Bazzini, G Bottà, P Portincasa, G Calamita, M Paulmichl
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  ABSTRACT: The function of the gallbladder is not only to store bile, but also to concentrate it during the interdigestive phase by means of salt-dependent water reabsorption. On the contrary, secretions of water and salt take place during the digestive phase. Dysregulation of ion absorption or secretion are common in many gallbladder diseases, such as colelithiasis. Transepithelial absorptions are determined by the Na+/K+ pump on the basolateral membrane, and by several apical membrane Na(+)-coupled transporters. Among these, some isoforms of Na+/H+ and Cl-/HCO3(-) exchangers have been studied. The presence of a Na(+)-Cl(-) simport has been molecularly and functionally characterized in some animal species. The ion transepithelial secretion is mainly dependent on an apical chloride transport attributable to a CFTR-like cAMP-activated channel with high permeability to HCO3(-). The apical membrane electrical potential is one of the factors influencing anion secretion and is maintained by the activity of cAMP-dependent K+ channels. The regulation of the activity of these channels is complex, because of their sensitivity to voltage, and to intracellular calcium and pH. The coordinated interplay underlying the regulation of transporters and channels needs to be clarified yet, as well as the interactions between transporters, channels and aquaporins.
  Current Drug Targets - Immune Endocrine & Metabolic Disorders 07/2005; 5(2):143-51.
• Article: Jejunal Creatine Absorption: What is the Role of the Basolateral Membrane?

  M.N. Orsenigo, A. Faelli, S. De Biasi, C. Sironi, U. Laforenza, M. Paulmichl, M. Tosco
  [show abstract] [hide abstract]
  ABSTRACT: The mechanism of the intestinal creatine absorption is not well understood. Previous studies have established the involvement of a CT1 carrier system in jejunal apical membrane. The current research was aimed at completing the picture of creatine absorption. To investigate the process supporting creatine exit from enterocyte, basolateral membrane vesicles isolated from rat jejunum were used. The presence of various symport and antiport mechanisms was searched and a NaCl-dependent electrogenic transport system for creatine was evidenced, which shares some functional and kinetic features with the apical CT1. However, Western blot and immunohistochemical experiments ruled out the presence of a CT1 transporter in the basolateral membrane. Further studies are required to identify the basolateral transport mechanism. However, in the in vivo conditions, the NaCl gradient is inwardly directed, therefore such a mechanism cannot energetically mediate the exit of creatine from the cell into the blood during the absorptive process, but rather it may drive creatine into the enterocyte. To shed more light on the creatine absorption process, a possible creatine movement through the paracellular pathway has been examined using the jejunal tract everted and incubated in vitro. A linear relationship between creatine transport and concentration was apparent both in the mucosa-to-serosa and serosa-to-mucosa directions and the difference between the two slopes suggests that paracellular creatine movement by solvent drag may account for transintestinal creatine absorption. As a matter of fact, when transepithelial water flux is reduced by means of a mucosal hypertonic solution, the opposite creatine fluxes tend to overlap. The findings of the present study suggest that paracellular creatine movement by solvent drag may account for transintestinal creatine absorption.
  Journal of Membrane Biology 01/2005; 207(3):183-195. · 1.81 Impact Factor
• Article: Further characterization of the nematode IClnN2 protein reconstituted in lipid bilayers.

  M Ritter, C Bertocchi, M Jakab, J Fürst, M Paulmichl
  Advances in experimental medicine and biology 02/2004; 559:245-51. · 1.09 Impact Factor
• Article: Probing of the ICln channel pore by cysteine mutagenesis and cadmium-block.

  M Jakab, M L Garavaglia, J Fürst, S Rodighiero, F Guizzardi, G Meyer, M Ritter, M Paulmichl
  Advances in experimental medicine and biology 02/2004; 559:99-108. · 1.09 Impact Factor
• Article: Self-interactions and protein-membrane interactions of ICln assessed by fluorescence resonance energy transfer (FRET)

  M. Ritter, A. Ravasio, J. Furst, M. Jakab, S. Chwatal, M. Paulmichl
  Biophysical Journal. 01/2004; 86(1):348A-348A.
• Article: Cell swelling fosters cytosol to membrane shift of ICln

  M. Ritter, A. Ravasio, S. Chwatal, M. Jakab, J. Furst, C. Burtscher, L. Garavaglia, M. Paulmichl
  Biophysical Journal. 01/2003; 84(2):84A-84A.
• Article: The regulatory volume decrease current in embryonic cells of C-elegans

  M. Jakab, M. Gschwentner, J. Furst, M. Ritter, M. Paulmichl
  Biophysical Journal. 01/2003; 84(2):84A-84A.
• Article: Molecular and functional aspects of anionic channels activated during regulatory volume decrease in mammalian cells.

  J Fürst, M Gschwentner, M Ritter, G Bottà, M Jakab, M Mayer, L Garavaglia, C Bazzini, S Rodighiero, G Meyer, S Eichmüller, E Wöll, M Paulmichl
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  ABSTRACT: The ability of cells to readjust their volume after swelling, a phenomenon known as regulatory volume decrease (RVD), is a fundamental biological achievement guaranteeing survival and function of cells under osmotic stress. This article reviews the mechanisms of RVD in mammalian cells with special emphasis on the activation of ion channels during RVD.
  Pflügers Archiv - European Journal of Physiology 06/2002; 444(1-2):1-25. · 4.46 Impact Factor
• Article: The role of ICln in exercise induced asthma

  S. Eichmueller, S. Hofer, A. Schmarda, E. Scandella, J. Fuerst, M. Jakab, C. Sironi, M. Ritter, M. Paulmichl
  Pflügers Archiv - European Journal of Physiology 01/2002; 443(Supplement 1):S224-S224. · 4.46 Impact Factor
• Article: Probing the cell swelling induced cytosol to membrane shift of the ICln ion channel protein by fluorescence resonance energy transfer (FRET)

  A. Ravasio, M. Ritter, S. Chwatal, M. Jakab, S. Eichmueller, C. Burtscher, J. Fuerst, M. Paulmichl
  Pflügers Archiv - European Journal of Physiology 01/2002; 443(Supplement 1):S224-S224. · 4.46 Impact Factor
• Article: The regulatory volume decrease anion current in embryonic cells of the nematode Caenorhabditis elegans

  M. Jakab, M. Gschwentner, J. Fuerst, J. Rudzki, J. G. Danzl, C. Burtscher, M. Ritter, M. Paulmichl
  Pflügers Archiv - European Journal of Physiology 01/2002; 443(Supplement 1):S224-S224. · 4.46 Impact Factor
• Article: Hypotonicity induced cytosol to membrane shift of the ICln ion channel and acceleration of regulatory volume decrease currents by repeated cell swelling

  C. Burtscher, M. Jakab, M. Gschwentner, A. Ravasio, A. Laich, S. Chwatal, J. Schirmer, S. Eichmueller, J. Fuerst, S. Dossena, M. Ritter, M. Paulmichl
  Pflügers Archiv - European Journal of Physiology 01/2002; 443(Supplement 1):S224-S224. · 4.46 Impact Factor
• Article: Evidence for H+/K+-ATPase expressed in human polymorphonuclear leucocytes and HL60 cells

  S. Chwatal, I. Muehlhahn, A. Doerge, M. Jakab, H. Rossmann, U. Seidler, J. Schirmer, J. Fuerst, M. Paulmichl, M. Ritter
  Pflügers Archiv - European Journal of Physiology 01/2002; 443(Supplement 1):S283-S284. · 4.46 Impact Factor
• Source

  Available from: Michael W. Hess

  Article: Fusion pore expansion is a slow, discontinuous, and Ca2+-dependent process regulating secretion from alveolar type II cells.

  T Haller, P Dietl, K Pfaller, M Frick, N Mair, M Paulmichl, M W Hess, J Furst, K Maly
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  ABSTRACT: In alveolar type II cells, the release of surfactant is considerably delayed after the formation of exocytotic fusion pores, suggesting that content dispersal may be limited by fusion pore diameter and subject to regulation at a postfusion level. To address this issue, we used confocal FRAP and N-(3-triethylammoniumpropyl)-4-(4-[dibutylamino]styryl) pyridinium dibromide (FM 1-43), a dye yielding intense localized fluorescence of surfactant when entering the vesicle lumen through the fusion pore (Haller, T., J. Ortmayr, F. Friedrich, H. Volkl, and P. Dietl. 1998. Proc. Natl. Acad. Sci. USA. 95:1579-1584). Thus, we have been able to monitor the dynamics of individual fusion pores up to hours in intact cells, and to calculate pore diameters using a diffusion model derived from Fick's law. After formation, fusion pores were arrested in a state impeding the release of vesicle contents, and expanded at irregular times thereafter. The expansion rate of initial pores and the probability of late expansions were increased by elevation of the cytoplasmic Ca2+ concentration. Consistently, content release correlated with the occurrence of Ca2+ oscillations in ATP-treated cells, and expanded fusion pores were detectable by EM. This study supports a new concept in exocytosis, implicating fusion pores in the regulation of content release for extended periods after initial formation.
  The Journal of Cell Biology 11/2001; 155(2):279-89. · 10.26 Impact Factor
• Article: The presence of NHE1 and NHE3 Na+-H+ exchangers and an apical cAMP-independent Cl- channel indicate that both absorptive and secretory functions are present in calf gall bladder epithelium.

  C Bazzini, G Bottà, G Meyer, M D Baroni, M Paulmichl
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  ABSTRACT: We investigated the transport systems that can sustain Na+ and Cl- movements across bovine gall bladder epithelium, focusing on the Na+-H+ exchanger (NHE) family and chloride conductive pathways. Experiments conducted using the fluorescent probe acridine orange (AO) with brush-border membrane vesicles (BBMV) or vesicles obtained from the total epithelium (EMV) demonstrated the presence of a Na+-H+ exchange in both preparations. The use of specific inhibitors indicated the presence of an apical NHE3 exchanger and a NHE1 isoform which should reside in the basolateral membrane. Using reverse transcriptase (RT) PCR, we identified cDNA fragments corresponding to the NHE1, NHE3, Cl--HCO3- (AE2a) transporters and to the CFTR channel. Using the patch-clamp technique, we investigated Cl- conductances on cultured epithelial cells. We found a 5 pS Cl- channel with a voltage-independent open probability, insensitive to stilbenes (SITS), Zn2+ and cAMP. The results suggest that absorption and secretion coexist in calf gall bladder epithelium. A Na+-H+-Cl--HCO3- double exchange may, at least partially, sustain the absorptive function, and a Cl- apical conductive pathway may be involved in secretion. The conductance we observed does not seem to be cAMP-regulated, unlike other mammalian gall bladders.
  Experimental Physiology 10/2001; 86(5):571-83. · 3.21 Impact Factor
• Article: Na(+)/H(+)exchangers: linking osmotic dysequilibrium to modified cell function.

  M Ritter, J Fuerst, E Wöll, S Chwatal, M Gschwentner, F Lang, P Deetjen, M Paulmichl
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  ABSTRACT: The Na(+)/H(+) exchangers (NHEs) are among the major ion transporters involved in cell volume regulation. NHE activation leads to a cellular influx of Na(+) ions and extrusion of H(+) ions, which are readily replenished from intracellular buffers. This will result in a net import of Na(+). In many systems NHE operates in parallel to Cl(-)/ HCO3(-) exchange, resulting in cellular uptake of NaCl. The influx of osmotically obliged water will consequently lead to cell swelling. This makes NHEs suitable to serve as powerful mechanisms for increasing cell volume (CV). The low volume threshold for NHE activation enables the cells to respond to very minute reductions of the CV. By the coupling to the export of H(+) ions cell volume regulatory NHE activation may lead to changes in intracellular pH. On the other hand NHEs are activated by a broad variety of ligands and by intracellular acidosis, which, in turn, may consequently lead to cell swelling. In addition, NHEs are linked to other intracellular proteins and structures, like e.g. the cytoskeleton, which themelves are involved in the regulation of numerous cellular processes. Therefore NHEs link CV regulation to a diversity of cellular functions, both in physiological and pathophysiological conditions. Six isoforms of the Na(+)/H(+) exchanger, termed NHE1--6, have been cloned so far. NHE 1--5 are located in the plasma membrane, whereas NHE6 is sorted to the mitochondrial membrane. NHE1 and NHE6 are the ubiquitously expressed isoforms. The expression of the isoforms NHE2 to NHE5 is restricted to specific tissues and the pattern of their expression, as well as their subcellular localization indicate that they fulfill specialized functions. Cell shrinkage induced activation has been shown for NHE1,2 and 4. In contrast, NHE3 is inhibited by cell shrinkage. In many cells several isoforms are present and assigned to specific membrane domains where they may serve a functional crosstalk between the different ion transporters.
  Cellular Physiology and Biochemistry 02/2001; 11(1):1-18. · 2.86 Impact Factor
• Article: Determination of protein-protein interactions of ICIn by the yeast two-hybrid system.

  A Schmarda, F Fresser, M Gschwentner, J Fürst, M Ritter, F Lang, G Baier, M Paulmichl
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  ABSTRACT: ICln is a ubiquitously expressed eukaryotic protein. Expression of the protein in Xenopus laevis oocytes, the knocking-down of the protein in fibroblasts, or the reconstitution of the protein in lipid bilayer led to the assumption that this protein is an ionic channel or a significant part thereof. However, other possible roles for ICln in potential regulatory mechanisms have been postulated, as diverse as regulator of cell morphology by interacting with the Skb1 protein and/or interaction with core spliceosomal proteins. Here we show that ICln is able to interact with SnRNP core proteins SmD1, SmD2, SmD3, SmX5 and SmB/B'.
  Cellular Physiology and Biochemistry 02/2001; 11(1):55-60. · 2.86 Impact Factor