title: Counteracting effect of TRPC1-associated Ca2+ influx on TNF-α-induced COX-2-dependent prostaglandin E2 production in human colonic myofibroblasts.
abstract: TNF-α-NF-κB signaling plays a central role in inflammation, apoptosis, and neoplasia. One major consequence of this signaling in the gut is increased production of prostaglandin E(2) (PGE(2)) via cyclooxygenase-2 (COX-2) induction in myofibroblasts, which has been reported to be dependent on Ca(2+). In this study, we explored a potential role of canonical transient receptor potential (TRPC) proteins in this Ca(2+)-mediated signaling using a human colonic myofibroblast cell line CCD-18Co. In CCD-18Co cell, treatment with TNF-α greatly enhanced Ca(2+) influx induced by store depletion along with increased cell-surface expression of TRPC1 protein (but not of the other TRPC isoforms) and induction of a Gd(3+)-sensitive nonselective cationic conductance. Selective inhibition of TRPC1 expression by small interfering RNA (siRNA) or functionally effective TRPC1 antibody targeting the near-pore region of TRPC1 (T1E3) antagonized the enhancement of store-dependent Ca(2+) influx by TNF-α, whereas potentiated TNF-α induced PGE(2) production. Overexpression of TRPC1 in CCD-18Co produced opposite consequences. Inhibitors of NF-κB (curcumin, SN-50) attenuated TNF-α-induced enhancement of TRPC1 expression, store-dependent Ca(2+) influx, and COX-2-dependent PGE(2) production. In contrast, inhibition of calcineurin-nuclear factor of activated T-cell proteins (NFAT) signaling by FK506 or NFAT Activation Inhibitor III enhanced the PGE(2) production without affecting TRPC1 expression and the Ca(2+) influx. Finally, the suppression of store-dependent Ca(2+) influx by T1E3 antibody or siRNA knockdown significantly facilitated TNF-α-induced NF-κB nuclear translocation. In aggregate, these results strongly suggest that, in colonic myofibroblasts, NF-κB and NFAT serve as important positive and negative transcriptional regulators of TNF-α-induced COX-2-dependent PGE(2) production, respectively, at the downstream of TRPC1-associated Ca(2+) influx.
authors.affiliation: Department of Physiology, Fukuoka University School of Medicine, Japan.
authors.forename: Lin
authors.initials: L
authors.lastname: Hai
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kawarabayashi
authors.forename: Yuko
authors.initials: Y
authors.lastname: Imai
authors.forename: Akira
authors.initials: A
authors.lastname: Honda
authors.forename: Ryuji
authors.initials: R
authors.lastname: Inoue
mesh_terms: D002118:Calcium / Q000502:physiology*; D015220:Calcium Channels; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D003106:Colon / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000378:metabolism; D015232:Dinoprostone / Q000096:biosynthesis*; D006801:Humans; D058628:Myofibroblasts / Q000378:metabolism*; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D050778:NFATC Transcription Factors / Q000378:metabolism* / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism*; D034741:RNA, Small Interfering; D050052:TRPC Cation Channels / Q000378:metabolism* / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology / Q000502:physiology
chemical_list: D015220:Calcium Channels; D016328:NF-kappa B; D050778:NFATC Transcription Factors; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D050052:TRPC Cation Channels; D014409:Tumor Necrosis Factor-alpha; C096351:transient receptor potential cation channel, subfamily C, member 1; D051546:Cyclooxygenase 2; D015232:Dinoprostone; D002118:Calcium