Control of type I interferon-induced cell death by Orai1-mediated calcium entry in T cells.
ABSTRACT Store-operated Ca(2+) entry (SOCE) is an essential process in T cell activation. SOCE is controlled by the Ca(2+) release-activated Ca(2+) (CRAC) channel encoded by the gene Orai1 that is expressed on the plasma membrane and activated by STIM1 when ER Ca(2+) stores are depleted. Our earlier work showed that a somatic T-cell line Jurkat mutant H123 bearing a defect in Ca(2+) signaling was susceptible to the apoptotic effects of type I interferons (IFN-α/β). The nature of the mutation and whether this mutation was linked to IFN-α/β apoptotic susceptibility was unknown. Here we show that H123 cells lacked Orai1 and exhibit reduced STIM1 protein. Reconstitution of both Orai1 and STIM1 in H123 cells rescued SOCE in response to thapsigargin and ionomycin and abrogated IFN-α/β-induced apoptosis. Reciprocally, overexpression of the dominant negative Orai1-E106A in either parental Jurkat cells or an unrelated human T cell line (CEM391) inhibited SOCE and led to sensitization to IFN-α/β-induced apoptosis. Furthermore, we showed that the Ca(2+) response pathway antagonized the IFN-α/β -induced transcriptional responses; in the absence of SOCE, this negative regulatory effect was lost. However, the inhibitory effect of Ca(2+) on type I IFN-induced gene transcription was diminished by pharmacological inhibition of NF-κB in cells with intact SOCE. Our findings reveal an unexpected and novel regulatory crosstalk mechanism between type I IFNs and store-operated Ca(2+) signaling pathways mediated at least in part by NF-κB activity with significant clinical implications to both viral and tumor immunology.
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ABSTRACT: Several reports have linked, among other aspects, the role of an opioid system in respiratory physiology with underlying mechanisms of panic attacks. The involvement of the opioid system in experimental panic is to be further probed. This study aimed to determine whether opioid blockade would increase panic-related symptomatology on provocation with 35% CO2 inhaled by healthy volunteers. Participants in a double-blind, randomised crossover design orally received either 50 mg of naltrexone or placebo. Most subjects undertook a double inhalation of 35% CO2 one hour after pre-medication, and a separate group did so after five hours. The reactivity to CO2 and the symptoms elicited by naltrexone alone were measured. Among other findings, naltrexone pre-medication alone elicited significant increments in panic-related symptoms. Responses to CO2 were not significantly different between conditions in either group. These preliminary findings suggest that exposure to opioid blockade alone can potentially elicit symptoms that resemble panic, however, without modifying the response to experimental panic provocation with 35% CO2.Journal of Psychopharmacology 11/2009; 23(8):975-8. · 3.04 Impact Factor