Requirements for Two Proximal NF- B Binding Sites and I B- in IL-17A-induced Human -Defensin 2 Expression by Conducting Airway Epithelium

Center for Comparative Respiratory Biology and Medicine, University of California-Davis, 451 Health Science Drive, Davis, CA 95616, USA.
Journal of Biological Chemistry (Impact Factor: 4.57). 06/2008; 283(22):15309-18. DOI: 10.1074/jbc.M708289200
Source: PubMed


Among a panel of 21 cytokines (IL-1α, -1β, -2–13, and -15–18; interferon-γ; granulocyte-macrophage colony-stimulating factor;
and tumor necrosis factor α), we have recently observed that IL-17A is the most potent inducer for human β-defensin 2 (hBD-2) in conducting airway epithelial cells (Kao, C. Y., Chen, Y., Thai, P., Wachi, S., Huang, F., Kim, C., Harper, R. W., and
Wu, R. (2004) J. Immunol. 173, 3482–3491). The molecular basis of this regulation is not known. In this study, we demonstrated a coordinated degradation
of inhibitory κB(IκB)-α followed by a nuclear translocation of p50 and p65 NF-κB subunits and their binding to NF-κB sites
of hBD-2 promoter region. With site-directed mutagenesis, we demonstrated the requirement of two proximal NF-κB binding sites (pκB1,
-205 to -186; pκB2, -596 to -572) but not the distal site (dκB, -2193 to -2182) in supporting IL-17A-induced hBD-2 promoter activity. These results are consistent with the data of the chromatin immunoprecipitation assay, which showed enhanced
p50 binding to these pκB sites but not the dκB site in cells after IL-17A treatment. We also found that the NF-κB binding
cofactor, IκB-ζ, was up-regulated by IL-17A, and the knockdown of IκB-ζ significantly diminished the IL-17A-induced hBD-2 expression. This is the first demonstration of the involvement of two proximal NF-κB sites and IκB-ζ in the regulation of
hBD-2 by IL-17A, two important genes responsible for host defense.

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    • "Indeed, IL-17A induces phosphorylation of p65 at Ser536; our lab and others have demonstrated p65 and p50 translocation into the nucleus following IL-17A stimulation [23, 104]. Mutation of NF-κB binding sites in the promoter region of the IL-17A target gene, human beta defensin 4 (DEFB4), severely attenuates promoter activation in response to IL-17A stimulation in airway epithelial cells [105]. NF-κB is also the major pathway responsible for IL-17 induced early response genes (<4 hours) [104]. "
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    ABSTRACT: The significance of Th17 cells and interleukin- (IL-)17A signaling in host defense and disease development has been demonstrated in various infection and autoimmune models. Numerous studies have indicated that Th17 cells and its signature cytokine IL-17A are critical to the airway's immune response against various bacteria and fungal infection. Cytokines such as IL-23, which are involved in Th17 differentiation, play a critical role in controlling Klebsiella pneumonia (K. pneumonia) infection. IL-17A acts on nonimmune cells in infected tissues to strengthen innate immunity by inducing the expression of antimicrobial proteins, cytokines, and chemokines. Mice deficient in IL-17 receptor (IL-17R) expression are susceptible to infection by various pathogens. In this review, we summarize the recent advances in unraveling the mechanism behind Th17 cell differentiation, IL-17A/IL-17R signaling, and also the importance of IL-17A in pulmonary infection.
    Full-text · Article · Jul 2013 · Clinical and Developmental Immunology
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    • "Cytokines such as IL-1 and IL-17 also play important roles in the regulation of HBD2 expression. Induction of HBD2 by IL-17A is mediated by PI3K pathway and MAPK pathway to activate NF-B in airway epithelial cells, whereas regulation of HBD2 by the activation of NF-B is not dependent on PI3K pathway in bronchial epithelial cell, (Huang et al., 2007; Jang et al., 2007; Kao et al., 2008), indicating that specific pathways involved in regulation of HBDs are cell type dependent. "

    Full-text · Chapter · Nov 2011
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    • "Accordingly, the genes Zc3h12a (p-value = 2.8E-7, ST q-value = 4.9E-5) and Nfkbiz (p-value = 3.6E-5, ST q-value = 2.2E-3) show the highest p-values for IL-17 dependent gene expression in the rANOVA. Nfkbiz is a well known IL-17 target gene [12,26], whereas Zc3h12a has not yet been described as IL-17 dependent gene, but as NF-κB regulated [27]. Interestingly, both genes also display properties of a transcription factor [28-30]. "
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    ABSTRACT: Cytokines such as TNF-alpha and IL-1 beta are known for their contribution to inflammatory processes in liver. In contrast, the cytokine IL-17 has not yet been assigned a role in liver diseases. IL-17 can cooperate with TNF-alpha to induce a synergistic response on several target genes in different cell lines, but no data exist for primary hepatocytes. To enhance our knowledge on the impact of IL-17 alone and combined with TNF-alpha in primary murine hepatocytes a comprehensive microarray study was designed. IL-1 beta was included as this cytokine is suggested to act in a similar manner as the combination of TNF-alpha and IL-17, especially with respect to its role in mRNA stabilization. The present microarray analysis demonstrates that primary murine hepatocytes responded to IL-17 stimulation by upregulation of chemokines and genes, which are functionally responsible to increase and sustain inflammation. Cxcl2, Nfkbiz and Zc3h12a were strongly induced, whereas the majority of the genes were only very moderately up-regulated. Promoter analysis revealed involvement of NF-kappaB in the activation of many genes. Combined stimulation of TNF-alpha/IL-17 resulted in enhanced induction of gene expression, but significantly synergistic effects could be applied only to a few genes, such as Nfkbiz, Cxcl2, Zc3h12 and Steap4. Comparison of the gene expression profile obtained after stimulation of TNF-alpha/IL-17 versus IL-1 beta proposed an "IL-1 beta-like effect" of the latter cytokine combination. Moreover, evidence was provided that modulation of mRNA stability may be a major mechanism by which IL-17 regulates gene expression in primary hepatocytes. This assumption was exemplarily proven for Nfkbiz mRNA for the first time in hepatocytes. Our studies also suggest that RNA stability can partially be correlated to the existence of AU rich elements, but further mechanisms like the RNase activity of the up-regulated Zc3h12a have to be considered. Our microarray analysis gives new insights in IL-17 induced gene expression in primary hepatocytes highlighting the crosstalk with the NF-kappaB signaling pathway. Gene expression profile suggests IL-17 alone and in concert with TNF-alpha a role in sustaining liver inflammatory processes. IL-17 might exceed this function by RNA stabilization.
    Full-text · Article · Apr 2010 · BMC Genomics
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