Publication Date:
2013-06-27
Description:
Syndecan-4, a cell-surface heparan sulfate proteoglycan, can participate in inflammation and wound healing as a host defense molecule. Tumour necrosis factor (TNF)-α, one of the most potent proinflammatory cytokines, is known to upregulate syndecan-4 expression, but the precise mechanisms are unclear. To elucidate these mechanisms in detail, we examined syndecan-4 upregulation by TNF-α in the endothelium-like EAhy926 cell. Of the two putative nuclear factor kappa-B (NF-B) binding sites in the syndecan-4 gene ( SDC4 ) promoter, deletion or mutation of one or both sites significantly diminished the effects of TNF-α. Electrophoretic mobility shift assays showed that p65 and c-Rel, but not p50, bound to these NF-B binding sites, whereas pull-down assays showed binding of all three NF-B components. Chromatin immunoprecipitation assays clearly showed that p65 and phosphorylated p65, but not p50 or c-Rel, bound to the SDC4 promoter. An NF-B inhibitor, p65 knockdown and a transcriptional elongation inhibitor completely blocked the effect of TNF-α on SDC4 promoter activity and significantly, but not completely, blocked that on SDC4 mRNA expression. These data suggest that NF-B p65 could be a key mediator of syndecan-4 upregulation by TNF-α through two binding sites in the SDC4 promoter, but other NF-B-p65 independent pathways might also be involved through transcriptional elongation.
Print ISSN:
0021-924X
Electronic ISSN:
1756-2651
Topics:
Biology
,
Chemistry and Pharmacology
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