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J Immunol. 2010 Dec 1;185(11):7037-46. doi: 10.4049/jimmunol.1000154. Epub 2010 Oct 27.

Galectin-3 exerts cytokine-like regulatory actions through the JAK-STAT pathway.

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1
Immune and Cell Therapy Branch, National Cancer Center, Goyang, Korea.

Abstract

Galectin-3, a β-galactoside-binding lectin, has been proposed to have multifaceted functions in various pathophysiological conditions. However, the characteristics of galectin-3 and its molecular mechanisms of action are still largely unknown. In this study, we show that galectin-3 exerts cytokine-like regulatory actions in rat and mouse brain-resident immune cells. Both the expression of galectin-3 and its secretion into the extracellular compartment were significantly enhanced in glia under IFN-γ-stimulated, inflamed conditions. After exposure to galectin-3, glial cells produced high levels of proinflammatory mediators and exhibited activated properties. Notably, within minutes after exposure to galectin-3, JAK2 and STAT1, STAT3, and STAT5 showed considerable enhancement of tyrosine phosphorylation; thereafter, downstream events of STAT signaling were also significantly enhanced. Treatment of the cells with pharmacological inhibitors of JAK2 reduced the galectin-3-stimulated increases of inflammatory mediators. Using IFN-γ receptor 1-deficient mice, we further found that IFN-γR 1 might be required for galectin-3-dependent activation of the JAK-STAT cascade. However, galectin-3 significantly induced phosphorylation of STATs in glial cells from IFN-γ-deficient mice, suggesting that IFN-γ does not mediate activation of STATs. Collectively, our findings suggest that galectin-3 acts as an endogenous danger signaling molecule under pathological conditions in the brain, providing a potential explanation for the molecular basis of galectin-3-associated pathological events.

PMID:
20980634
DOI:
10.4049/jimmunol.1000154
[Indexed for MEDLINE]
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