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Updated: May 26, 2026

Using an Automated Cell Counter to Simplify Gene Expression Studies: siRNA Knockdown of IL-4 Dependent Gene Expression in Namalwa Cells
Published on: April 14, 2010
IL-4 regulates chemokine CCL26 in keratinocytes through the Jak1, 2/Stat6 signal transduction pathway: Implication
Lei Bao1, Vivian Y Shi, Lawrence S Chan
1Department of Dermatology, University of Illinois, Chicago, IL, USA.
Abstract:
Atopic dermatitis (AD), a chronic, pruritic, inflammatory skin disease, is histopathologically characterized by epidermal hyperplasia and infiltration of T cells, mast cells, and eosinophils. Clinical study and basic research have established that IL-4 plays an important role in the pathogenesis of AD. In this report, using HaCat cells, we show that CCL26, a chemokine for eosinophils, is up-regulated by IL-4 at both the mRNA and protein levels. IL-4 also enhances CCL26 promoter activity. Serial 5' deletion of the promoter and mutagenesis study reveal that the proximal Stat site is the key response element for IL-4 regulation of CCL26. Although IL-4 increases phosphorylation of both Stat3 and Stat6, it only activates Stat6 as shown by dominant negative studies. In addition, we found that IL-4 induces Stat6 nuclear translocation and stimulates phosphorylation of Jak1 and Jak2 but not Tyk2. IL-4 up-regulation of CCL26 can be suppressed by Jak inhibitors in a dose-dependent manner. Taken together, results of this investigation reveal that IL-4 signals through the Jak1, 2/Stat6 pathway in keratinocytes to stimulate CCL26 expression and this may provide an explanation for the pathogenesis of AD.
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