Novel anti-inflammatory role for glycogen synthase kinase-3β in the inhibition of tumor necrosis factor-α- and interleukin-1β-induced inflammatory gene expression

Abstract

Glycogen synthase kinase-3β (GSK-3β) is a serine/threonine kinase with a broad array of cellular targets, such as cytoskeletal proteins and transcription factors. Recent studies with GSK-3β-null mice showed impaired NFκB-mediated survival responses. Because NFκB serves a dual role as a key regulator of cytokine-induced inflammatory gene expression and apoptosis, we investigated whether modulation of GSK-3β expression affects cytokine-induced and NFκB-mediated inflammatory gene expression. We observed that tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) treatment of primary cultures of human microvascular cells reduced net endogenous active GSK-3β protein levels while inducing inflammatory cytokine (IL-6 and monocyte chemoattractant protein-1 (MCP-1)) expression. Interestingly, inhibition of GSK-3β by antisense oligonucleotides or pharmacological agent (10 mM lithium) potentiated TNF-induced expression of IL-6 and MCP-1 by 2-6-fold suggesting that inhibition of GSK-3β under inflammatory conditions (exposure to TNF-α and IL-1β) may contribute to enhanced cytokine expression. Overexpression of GSK-3β in endothelial cells, in contrast, significantly inhibited (by 70%, p < 0.01) both TNF-α and IL-1β-induced expression of IL-6, MCP-1, and vascular cell adhesion molecule-1. Using adenoviruses in lipopolysaccharide-stimulated mice, overexpression of GSK-3β significantly decreased TNF-α expression in lung and heart tissues (38 and 15%, respectively), further confirming the anti-inflammatory role of GSK-3β. Overexpression of GSK-3β did not affect the TNF-α-induced nuclear translocation of NFκB but reduced the nuclear half-life of TNF-α-induced NFκB considerably (by as much as 9 h) and enhanced phosphorylation (by as much as 33%). Interestingly, neither endothelial cell survival nor NFκB-mediated expression of anti-apoptotic genes was affected by GSK-3β overexpression. We conclude that GSK-3β selectively regulates NFκB-mediated inflammatory gene expression by controlling the flow of NFκB activity between transcription of inflammatory and survival genes. © 2006 by The American Society for Biochemistry and Molecular Biology, Inc.