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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
Interleukin-4 induces expression of the integrin alpha v beta 3 via transactivation of the beta 3 gene
S Kitazawa1, F P Ross, K McHugh
1Department of Pathology, Washington University School of Medicine, St. Louis, Missouri 63110.
Abstract:
Osteoclastic bone resorption is dependent upon cell-matrix recognition. This process is mediated by the integrin alpha v beta 3 whose expression is enhanced, in avian osteoclast precursors, by bone-seeking steroids. The purpose of this study was to determine if bone-modulating cytokines impact on alpha v beta 3 expression by mouse marrow macrophages (BMMs), known to differentiate into osteoclasts. Of the cytokines tested. Interleukin-4 (IL-4) is most effective in increasing beta 3 mRNA levels by a mechanism involving transactivation of the beta 3 gene. Moreover, IL-4 augmented beta 3 mRNA is mirrored by plasma membrane appearance of alpha v beta 3. As IL-4 induces beta 3 and not alpha v mRNA, the beta 3 chain appears to regulate surface expression of the heterodimer. The functional significance of IL-4-induced alpha v beta 3 is underscored by the fact that, while attachment to fibronectin is unaltered, treatment of BMMs with the cytokine enhances alpha v beta 3-mediated binding to vitronectin 5-fold. Expression of this heterodimer by BMMs driven along a non-osteoclastic lineage suggests alpha v beta 3 may play a role in the inflammatory response of macrophages.
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