@article{SchmittEguWalteretal.2021,
  author    = {Schmitt, T. and Egu, D.T. and Walter, E. and Sigmund, A.M. and Eichkorn, R. and Yazdi, A. and Schmidt, E. and S{\´a}rdy, M. and Eming, R. and Goebeler, M. and Waschke, J.},
  title     = {Ca\(^{2+}\) signalling is critical for autoantibody-induced blistering of human epidermis in pemphigus},
  series = {British Journal of Dermatology},
  volume    = {185},
  journal   = {British Journal of Dermatology},
  number    = {3},
  doi       = {10.1111/bjd.20091},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-262810},
  pages     = {595 -- 604},
  year      = {2021},
  abstract  = {Background Pemphigus is a severe bullous autoimmune skin disease. Pemphigus foliaceus (PF) is characterized by antidesmoglein (Dsg) 1 IgG causing epidermal blistering; mucosal pemphigus vulgaris (mPV) by anti-Dsg3 IgG inducing erosions in the mucosa; and mucocutaneous pemphigus vulgaris (PV) by affecting both, with autoantibodies targeting Dsg1 and Dsg3. Objectives To characterize the Ca\(^{2+}\) flux pathway and delineate its importance in pemphigus pathogenesis and clinical phenotypes caused by different antibody profiles. Methods Immunoprecipitation, Ca\(^{2+}\) flux analysis, Western blotting, immunofluorescence staining, dissociation assays and a human skin ex vivo model were used. Results PV IgG and PF IgG, but neither Dsg3-specific monoclonal antibody (AK23) nor mPV IgG, caused Ca\(^{2+}\) influx in primary human keratinocytes. Phosphatidylinositol 4-kinase α interacts with Dsg1 but not with Dsg3. Its downstream target - phospholipase-C-γ1 (PLC) - was activated by PV IgG and PF IgG but not AK23 or mPV IgG. PLC releases inositol 1,4,5-trisphosphate (IP3) causing IP3 receptor (IP3R) activation and Ca2+ flux from the endoplasmic reticulum into the cytosol, which stimulates Ca2+ release-activated channels (CRAC)-mediated Ca\(^{2+}\) influx. Inhibitors against PLC, IP3R and CRAC effectively blocked PV IgG and PF IgG-induced Ca\(^{2+}\) influx; ameliorated alterations of Dsg1 and Dsg3 localization, and reorganization of keratin and actin filaments; and inhibited loss of cell adhesion in vitro. Finally, inhibiting PLC or IP3R was protective against PV IgG-induced blister formation and redistribution of Dsg1 and Dsg3 in human skin ex vivo. Conclusions Ca2+-mediated signalling is important for epidermal blistering and dependent on the autoantibody profile, which indicates different roles for signalling complexes organized by Dsg1 and Dsg3. Interfering with PLC and Ca\(^{2+}\) signalling may be a promising approach to treat epidermal manifestations of pemphigus.},
  language  = {en}
}
@article{NuhkatBroscheStoezleFeixetal.2021,
  author    = {Nuhkat, Maris and Brosch{\´e}, Mikael and Stoezle-Feix, Sonja and Dietrich, Petra and Hedrich, Rainer and Roelfsema, M. Rob G. and Kollist, Hannes},
  title     = {Rapid depolarization and cytosolic calcium increase go hand-in-hand in mesophyll cells' ozone response},
  series = {New Phytologist},
  volume    = {232},
  journal   = {New Phytologist},
  number    = {4},
  doi       = {10.1111/nph.17711},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-259646},
  pages     = {1692-1702},
  year      = {2021},
  abstract  = {Plant stress signalling involves bursts of reactive oxygen species (ROS), which can be mimicked by the application of acute pulses of ozone. Such ozone-pulses inhibit photosynthesis and trigger stomatal closure in a few minutes, but the signalling that underlies these responses remains largely unknown. We measured changes in Arabidopsis thaliana gas exchange after treatment with acute pulses of ozone and set up a system for simultaneous measurement of membrane potential and cytosolic calcium with the fluorescent reporter R-GECO1. We show that within 1 min, prior to stomatal closure, O\(_{3}\) triggered a drop in whole-plant CO\(_{2}\) uptake. Within this early phase, O\(_{3}\) pulses (200-1000 ppb) elicited simultaneous membrane depolarization and cytosolic calcium increase, whereas these pulses had no long-term effect on either stomatal conductance or photosynthesis. In contrast, pulses of 5000 ppb O\(_{3}\) induced cell death, systemic Ca\(^{2+}\) signals and an irreversible drop in stomatal conductance and photosynthetic capacity. We conclude that mesophyll cells respond to ozone in a few seconds by distinct pattern of plasma membrane depolarizations accompanied by an increase in the cytosolic calcium ion (Ca\(^{2+}\)) level. These responses became systemic only at very high ozone concentrations. Thus, plants have rapid mechanism to sense and discriminate the strength of ozone signals.},
  language  = {en}
}