GSK-3 mediates differentiation and activation of proinflammatory dendritic cells

Universität Heidelberg, Heidelburg, Baden-Württemberg, Germany
Blood (Impact Factor: 10.45). 03/2007; 109(4):1584-92. DOI: 10.1182/blood-2006-06-028951
Source: PubMed


The key components of the intracellular molecular network required for the expression of a specific function of dendritic cells (DCs) are as yet undefined. Using an in vitro model of human monocyte-derived DC differentiation, this study investigates the role of glycogen synthase kinase 3 (GSK-3), a multifunctional enzyme critical for cellular differentiation, apoptosis, self-renewal, and motility, in this context. We demonstrate that GSK-3 (1) inhibits macrophage development during differentiation of DCs, (2) is constitutively active in immature DCs and suppresses spontaneous maturation, and (3) acquires a proinflammatory functional status mediating high levels of IL-12, IL-6, and TNF-alpha secretion, and partially inhibits IL-10 in the context of DC activation. In particular, GSK-3 enhances IL-12p35 mRNA expression and thus the production of the proinflammatory cytokine IL-12p70 by integrating the activities of other kinases priming GSK-3 targets and the inhibitory effects of Akt-1. GSK-3 may therefore act as a key integrator of activating and inhibitory pathways involved in proinflammatory DC differentiation and activation.

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Available from: Anthony Ho, Apr 30, 2015
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    • "Interestingly, the changes of the IFNβ and IL-10 showed similar trends in BMDMs and BMDCs. Since our previous studies have demonstrated that GSK3β negatively regulates IFNβ and IL-10[12,13], and GSK3β is also critical for the development and maturation of BMDCs[59], we postulate that the expression level of GSK3β could be responsible for the distinct effects of Syk on IFNβ production in BMDCs and BMDMs. Silencing of Syk in BMDMs, unlike in BMDCs, decreased phosphorylation of GSK3β upon LPS stimulation (Supplemental Fig. 1E), suggesting that altered levels of GSK3β in Syk-deficient macrophages, resulting from signaling possibly independent of PI3K, could be the reason for the distinct effects of Syk on the production of IFNβ in BMDMs. "
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    ABSTRACT: Background: While Syk has been shown to associate with TLR4, the immune consequences of Syk-TLR interactions and related molecular mechanisms are unclear. Methods: Gain- and loss-of-function approaches were utilized to determine the regulatory function of Syk and elucidate the related molecular mechanisms in TLR4-mediated inflammatory responses. Cytokine production was measured by ELISA and phosphorylation of signaling molecules determined by Western blotting. Results: Syk deficiency in murine dendritic cells resulted in the enhancement of LPS-induced IFNβ and IL-10 but suppression of pro-inflammatory cytokines (TNFα, IL-6). Deficiency of Syk enhanced activity of PI3K and elevated the phosphorylation of PI3K and Akt, which in turn, lead to the phospho-inactivation of the downstream, central gatekeeper of the innate response, GSK3β. Inhibition of PI3K or Akt abrogated the ability of Syk deficiency to enhance IFNβ and IL-10 in Syk deficient cells, confirmed by the overexpression of Akt (Myr-Akt) or constitutively active GSK3β (GSK3 S9A). Moreover, neither inhibition of PI3K-Akt signaling nor neutralization of de novo synthesized IFNβ could rescue TNFα and IL-6 production in LPS-stimulated Syk deficient cells. Syk deficiency resulted in decreased phosphorylation of IKKβ and the NF-κB p65 subunit, further suggesting a divergent influence of Syk of pro- and anti-inflammatory TLR responses. Conclusions: Syk negatively regulates TLR4-mediated production of IFNβ and IL-10 and promotes inflammatory responses in dendritic cells through divergent regulation of downstream PI3K-Akt and NF-κB signaling pathways. General significance: Syk may represent a novel target for manipulating the direction or intensity of the innate response, depending on clinical necessity.
    Full-text · Article · Dec 2015 · Biochimica et Biophysica Acta
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    • "In A and D, single and double asterisk represents P < 0.05 and P < 0.005, respectively. JOURNAL OF CELLULAR BIOCHEMISTRY GLYCOGEN SYNTHASE KINASE 3 INCREASES IL-1B INDUCED NO with other cell types [Martin et al., 2005; Rodionova et al., 2007; Rådinger et al., 2009] "
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    ABSTRACT: Excessive nitric oxide from the inducible nitric oxide synthase (iNOS) increases shock-induced hepatic injury, hepatic dysfunction, inflammation, and mortality in animal models. Cytokines increase the expression of iNOS in hepatocytes, but the signaling mechanisms involved are not completely understood. We have previously demonstrated that Akt mediates the inhibitory effect of cAMP and insulin on cytokine-induced hepatocyte iNOS expression. We hypothesized that glycogen synthase kinase 3 (GSK3), a target of Akt phosphorylation, would regulate hepatocyte iNOS expression. In cultured rat hepatocytes, GSK3 inhibitors decreased IL-1β mediated nitric oxide (NO) production and iNOS protein expression, while the phosphatidylinositol 3-kinase (PI3K)/Akt pathway inhibitor LY294002 increased the cytokine-mediated NO production and iNOS expression. Over-expression of the constitutively active form of GSK3β enhanced IL-1β-mediated iNOS expression. GSK3 catalyzes the phosphorylation of c-Jun at the c-terminal Thr239 that facilitates c-Jun degradation. Inhibition of GSK3 with SB216763 and lithium chloride significantly reduced, whereas blocking PI3K/Akt increased phosphorylation of c-Jun at Thr239. The levels of total-c-Jun and c-Jun phosphorylated at Ser63 inversely correlated with c-Jun phosphorylated at Thr239, GSK3 activation and iNOS expression. Over-expression of a dominant negative c-Jun not only caused an increase in iNOS promoter activity and iNOS protein expression but was also able to reverse the SB216763-mediated suppression of iNOS. These results demonstrate that GSK3, a downstream target of Akt, regulates IL-1β-stimulated iNOS expression in hepatocytes by directly phosphorylating c-Jun in an inhibitory manner. J. Cell. Biochem. © 2014 Wiley Periodicals, Inc.
    Full-text · Article · Jan 2015 · Journal of Cellular Biochemistry
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    • "The kinase is transiently phosphorylated upon lipopolysaccharide (LPS) stimulation [18], [19] but still contributes to the development of a proinflammatory phenotype of DCs [20]. Pharmacological inhibition of GSK3 has previously been shown to attenuate IL-12 [18]–[20], IL-6 and TNFα [20], [53] production and to enhance IL-10 production [18], [19]. Moreover, GSK3 inhibitors blunt the increase of IL12p70 secretion from monocyte-derived DCs following PI3 kinase inhibition with wortmannin [20]. "
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    Full-text · Article · Feb 2014 · PLoS ONE
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