title: Molecular basis of early epithelial response to streptococcal exotoxin: role of STIM1 and Orai1 proteins.
abstract: Streptolysin O (SLO) is a cholesterol-dependent cytolysin (CDC) from Streptococcus pyogenes. SLO induces diverse types of Ca(2+) signalling in host cells which play a key role in membrane repair and cell fate determination. The mechanisms behind SLO-induced Ca(2+) signalling remain poorly understood. Here, we show that in NCI-H441 cells, wild-type SLO as well as non-pore-forming mutant induces long-lasting intracellular Ca(2+) oscillations via IP(3) -mediated depletion of intracellular stores and activation of store-operated Ca(2+) (SOC) entry. SLO-induced activation of SOC entry was confirmed by Ca(2+) add-back experiments, pharmacologically and by overexpression as well as silencing of STIM1 and Orai1 expression. SLO also activated SOC entry in primary cultivated alveolar type II (ATII) cells but Ca(2+) oscillations were comparatively short-lived in nature. Comparison of STIM1 and Orai1 revealed a differential expression pattern in H441 and ATII cells. Overexpression of STIM1 and Orai1 proteins in ATII cells changed the short-lived oscillatory response into a long-lived one. Thus, we conclude that SLO-mediated Ca(2+) signalling involves Ca(2+) release from intracellular stores and STIM1/Orai1-dependent SOC entry. The phenotype of Ca(2+) signalling depends on STIM1 and Orai1 expression levels. Our findings suggest a new role for SOC entry-associated proteins in S. pyogenes-induced lung infection and pneumonia.
authors.affiliation: Institute of General Physiology, University of Ulm, Ulm, Germany.
authors.forename: Shariq M
authors.initials: SM
authors.lastname: Usmani
authors.forename: Jens
authors.initials: J
authors.lastname: von Einem
authors.forename: Manfred
authors.initials: M
authors.lastname: Frick
authors.forename: Pika
authors.initials: P
authors.lastname: Miklavc
authors.forename: Martina
authors.initials: M
authors.lastname: Mayenburg
authors.forename: Matthias
authors.initials: M
authors.lastname: Husmann
authors.forename: Paul
authors.initials: P
authors.lastname: Dietl
authors.forename: Oliver H
authors.initials: OH
authors.lastname: Wittekindt
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000494:pharmacology / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020013:Calcium Signaling; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004075:Diglycerides / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D054884:Host-Pathogen Interactions; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D008168:Lung / Q000473:pathology; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000071740:ORAI1 Protein; D061251:Primary Cell Culture; D021381:Protein Transport; D051381:Rats; D017207:Rats, Sprague-Dawley; D012141:Respiratory Tract Infections / Q000382:microbiology; D013290:Streptococcal Infections / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000502:physiology; D013301:Streptolysins / Q000494:pharmacology / Q000502:physiology*; D000071737:Stromal Interaction Molecule 1
chemical_list: D001426:Bacterial Proteins; D015220:Calcium Channels; D004075:Diglycerides; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D000071740:ORAI1 Protein; C510746:ORAI1 protein, human; C103530:STIM1 protein, human; D013301:Streptolysins; D000071737:Stromal Interaction Molecule 1; C025964:streptolysin O; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium