title: Ryanodine receptor-mediated rapid increase in intracellular calcium induced by 7,8-benzo(a)pyrene quinone in human and murine leukocytes.
abstract: Benzo(a)pyrene (BaP) is an environmentally prevalent polycyclic aromatic hydrocarbon (PAH) known to produce immunotoxicity in murine and human lymphocytes. Previous studies by our lab have shown that certain BaP metabolites increase intracellular Ca(2+) in human and murine lymphocytes. The mechanism by which these BaP metabolites increase Ca(2+) may involve src kinase activation and mitochondrial oxidative stress. We have implicated a new pathway of Ca(2+) elevation in lymphocytes produced by a novel BaP metabolite, BaP-7,8-dione (7,8-BPQ). This ortho quinone is produced from BaP-7,8-dihydrodiol by aldoketoreductase 1C1 (AKR1C) isoforms in human cells. We have previously shown that 7,8-BPQ increases Ca(2+) levels in an in vitro rabbit skeletal muscle sarcoplasmic reticulum (SR) vesicle model via interaction with ryanodine receptors (RyR). In the present study, we found that 7,8-BPQ produced a RyR-dependent rapid increase in intracellular Ca(2+) in the Daudi human B cell line. However, other BP-diones including 1,6-, 3,6-, and 6,12-BPQs failed to produce a rapid increase in Ca(2+). Instead they produced a late increase in intracellular Ca(2+), presumably via a redox-cycling-dependent loss of Ca(2+) buffering capacity by mitochondria. Functional RyR were detected in Daudi using a (3)H-ryanodine binding assay. The studies were extended to normal human peripheral blood and murine spleen cells, where it was found that 7,8-BPQ rapidly elevated intracellular Ca(2+) in B cells and T cells in both species. The Ca(2+)-elevating effect of 7,8-BPQ was prevented by pretreatment with a high concentration of ryanodine (500 muM). Collectively, these results demonstrate a novel mechanism of Ca(2+) elevation by an environmentally relevant metabolite of BaP in murine and human lymphocytes.
authors.affiliation: The University of New Mexico College of Pharmacy Toxicology Program, Albuquerque, 87131-0001, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Gao
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Voss
authors.forename: Isaac N
authors.initials: IN
authors.lastname: Pessah
authors.forename: Fredine T
authors.initials: FT
authors.lastname: Lauer
authors.forename: Trevor M
authors.initials: TM
authors.lastname: Penning
authors.forename: Scott W
authors.initials: SW
authors.lastname: Burchiel
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D001580:Benzopyrenes / Q000493:pharmacokinetics / Q000633:toxicity*; D001667:Binding, Competitive / Q000187:drug effects; D001711:Biotransformation; D002118:Calcium / Q000378:metabolism*; D002120:Calcium Channel Agonists / Q000494:pharmacology*; D002460:Cell Line; D005434:Flow Cytometry; D006801:Humans; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D012433:Ryanodine / Q000378:metabolism / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects* / Q000378:metabolism; D013154:Spleen / Q000166:cytology; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism
chemical_list: D001580:Benzopyrenes; D002120:Calcium Channel Agonists; D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine; C014357:benzo(a)pyrene-6,12-quinone; D002118:Calcium