title: Tissue-specific mechanisms for CCN2/CTGF persistence in fibrotic gingiva: interactions between cAMP and MAPK signaling pathways, and prostaglandin E2-EP3 receptor mediated activation of the c-JUN N-terminal kinase.
abstract: Prostaglandin E(2) blocks transforming growth factor TGF beta1-induced CCN2/CTGF expression in lung and kidney fibroblasts. PGE(2) levels are high in gingival tissues yet CCN2/CTGF expression is elevated in fibrotic gingival overgrowth. Gingival fibroblast expression of CCN2/CTGF in the presence of PGE(2) led us to compare the regulation of CCN2/CTGF expression in fibroblasts cultured from different tissues. Data demonstrate that the TGFbeta1-induced expression of CCN2/CTGF in human lung and renal mesangial cells is inhibited by 10 nm PGE(2), whereas human gingival fibroblasts are resistant. Ten nm PGE(2) increases cAMP accumulation in lung but not gingival fibroblasts, which require 1 mum PGE(2) to elevate cAMP. Micromolar PGE(2) only slightly reduces the TGFbeta1-stimulated CCN2/CTGF levels in gingival cells. EP2 prostaglandin receptor activation with butaprost blocks the TGFbeta1-stimulated expression of CCN2/CTGF expression in lung, but not gingival, fibroblasts. In lung fibroblasts, inhibition of the TGFbeta1-stimulated CCN2/CTGF by PGE(2), butaprost, or forskolin is due to p38, ERK, and JNK MAP kinase inhibition that is cAMP-dependent. Inhibition of any two MAPKs completely blocks CCN2/CTGF expression stimulated by TGFbeta1. These data mimic the inhibitory effects of 10 nm PGE(2) and forskolin that were dependent on PKA activity. In gingival fibroblasts, the sole MAPK mediating the TGFbeta1-stimulated CCN2/CTGF expression is JNK. Whereas forskolin reduces TGFbeta1-stimulated expression of CCN2/CTGF by 35% and JNK activation in gingival fibroblasts, micromolar PGE(2)-stimulated JNK in gingival fibroblasts and opposes the inhibitory effects of cAMP on CCN2/CTGF expression. Stimulation of the EP3 receptor with sulprostone results in a robust increase in JNK activation in these cells. Taken together, data identify two mechanisms by which TGFbeta1-stimulated CCN2/CTGF levels in human gingival fibroblasts resist down-regulation by PGE(2): (i) cAMP cross-talk with MAPK pathways is limited in gingival fibroblasts; (ii) PGE(2) activation of the EP3 prostanoid receptor stimulates the activation of JNK.
authors.affiliation: Department of Periodontology and Oral Biology, Division of Oral Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts 02118, USA.
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Black
authors.forename: Amitha H
authors.initials: AH
authors.lastname: Palamakumbura
authors.forename: Maria
authors.initials: M
authors.lastname: Stan
authors.forename: Philip C
authors.initials: PC
authors.lastname: Trackman
mesh_terms: D000328:Adult; D000527:Alprostadil / Q000031:analogs & derivatives / Q000494:pharmacology; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D055513:Connective Tissue Growth Factor; D000242:Cyclic AMP / Q000378:metabolism*; D015232:Dinoprostone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D005355:Fibrosis; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D005881:Gingiva / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D017874:Immediate-Early Proteins / Q000096:biosynthesis*; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008168:Lung / Q000166:cytology / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000502:physiology; D050527:Mesangial Cells / Q000166:cytology / Q000378:metabolism; D009928:Organ Specificity / Q000502:physiology; D018078:Receptors, Prostaglandin E / Q000378:metabolism*; D058308:Receptors, Prostaglandin E, EP3 Subtype; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: C526317:CCN2 protein, human; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; C545647:PTGER3 protein, human; D018078:Receptors, Prostaglandin E; D058308:Receptors, Prostaglandin E, EP3 Subtype; D053773:Transforming Growth Factor beta1; D055513:Connective Tissue Growth Factor; D005576:Colforsin; D000242:Cyclic AMP; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D000527:Alprostadil; C048491:butaprost; D015232:Dinoprostone