title: Staphylococcal leukotoxins trigger free intracellular Ca(2+) rise in neurones, signalling through acidic stores and activation of store-operated channels.
abstract: Headache, muscle aches and chest pain of mild to medium intensity are among the most common clinical symptoms in moderate Staphylococcus aureus infections, with severe infections usually associated with worsening pain symptoms. These nociceptive responses of the body raise the question of how bacterial infection impinges on the nervous system. Does S. aureus, or its released virulence factors, act directly on neurones? To address this issue, we evaluated the potential effects on neurones of certain bi-component leukotoxins, which are virulent factors released by the bacterium. The activity of four different leukotoxins was verified by measuring the release of glutamate from rat cerebellar granular neurones. The bi-component γ-haemolysin HlgC/HlgB was the most potent leukotoxin, initiating transient rises in intracellular Ca(2+) concentration in cerebellar neurones and in primary sensory neurones from dorsal root ganglia, as probed with the Fura-2 Ca(2+) indicator dye. Using pharmacological antagonists of receptors and Ca(2+) channels, the variations in intracellular Ca(2+) concentration were found independent of the activation of voltage-operated Ca(2+) channels or glutamate receptors. Drugs targeting Sarco-Endoplasmic Reticulum Ca(2+)-ATPase (SERCA) or H(+)-ATPase and antagonists of the store-operated Ca(2+) entry complex blunted, or significantly reduced, the leukotoxin-induced elevation in intracellular Ca(2+). Moreover, activation of the ADP-ribosyl cyclase CD38 was also required to initiate the release of Ca(2+) from acidic stores. These findings suggest that, prior to forming a pore at the plasma membrane, leukotoxin HlgC/HlgB triggers a multistep process which initiates the release of Ca(2+) from lysosomes, modifies the steady-state level of reticular Ca(2+) stores and finally activates the Store-Operated Calcium Entry complex.
authors.affiliation: INCI - UPR-CNRS 3212, Neurotransmission et sécrétion neuroendocrine, 5, rue Blaise Pascal, F- 67084 Strasbourg cedex, France. jover@inci-cnrs
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Jover
authors.forename: Mira Y
authors.initials: MY
authors.lastname: Tawk
authors.forename: Benoît-Joseph
authors.initials: BJ
authors.lastname: Laventie
authors.forename: Bernard
authors.initials: B
authors.lastname: Poulain
authors.forename: Gilles
authors.initials: G
authors.lastname: Prévost
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000494:pharmacology*; D001427:Bacterial Toxins / Q000494:pharmacology*; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000382:microbiology; D005724:Ganglia / Q000378:metabolism / Q000382:microbiology; D005727:Ganglia, Spinal / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D006460:Hemolysin Proteins / Q000494:pharmacology*; D006801:Humans; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology; D006180:Proton-Translocating ATPases / Q000378:metabolism; D051381:Rats; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013211:Staphylococcus aureus / Q000235:genetics / Q000472:pathogenicity*
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D006460:Hemolysin Proteins; C037956:gamma-hemolysin, Staphylococcus aureus; D002110:Caffeine; D018698:Glutamic Acid; D006180:Proton-Translocating ATPases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D002118:Calcium