LAUSR

Aims: Abundance of connexin 43 (Cx43), a transmembrane protein that forms hemichannels (HCs) and gap junctions (GJs), is dynamically regulated in human gingival fibroblasts (GFBLs) during wound healing. This may be important for fast and scarless gingival wound healing as Cx43 is involved in key cell functions important during this process. Our aim was to uncover the factors that regulate Cx43 expression and abundance in GFBLs. We hypothesized that cytokines and growth factors released during wound healing coordinately regulate Cx43 abundance in GFBLs. Results: TGF‐&bgr;1, ‐&bgr;2, ‐&bgr;3, PGE2 and IL‐1&bgr; significantly upregulated, while TNF‐&agr; and IFN‐&ggr; downregulated Cx43 in cultured GFBLs. TGF‐&bgr;1, ‐&bgr;2, ‐&bgr;3, IL‐1&bgr; and IFN‐&ggr; modulated Cx43 abundance at both mRNA and protein levels, while TNF‐&agr; and PGE2 regulated only Cx43 protein abundance, suggesting involvement of distinct transcriptional/post‐transcriptional and translational/post‐translational mechanisms, respectively. TGF‐&bgr;1‐induced upregulation of Cx43 was mediated by TGF&bgr;RI (ALK5) and SMAD2/3 signaling, and this was potently suppressed by PGE2, IL‐1&bgr;, TNF‐&agr; and IFN‐&ggr; that inhibited SMAD2/3 phosphorylation. Conclusion: Regulation of Cx43 abundance in GFBLs involves transcriptional/post‐transcriptional and translational/post‐translational mechanisms that are distinctly modulated by an interplay between TGF‐&bgr; isoforms and PGE2, IL‐1&bgr;, TNF‐&agr; and IFN‐&ggr;. HighlightsWound healing‐associated cytokines modulate connexin 43 abundance in human gingival fibroblasts.Interplay between these cytokines distinctly determines connexin 43 abundance via transcriptional/post‐transcriptional and translational/post‐translational mechanisms.TGF‐&bgr;‐induced upregulation of connexin 43 is mediated by SMAD2/3 pathway.TNF‐&agr;, IL‐1&bgr;, IFN‐&ggr; and PGE2 inhibit TGF‐&bgr;‐induced connexin 43 upregulation by suppressing SMAD2/3 phosphorylation.