IL-13 upregulates GPIIb expression in megakaryocytic cell lines via STAT6.

Interleukin 13 (IL-13) is a key cytokine involved in the regulation of inflammatory, immune responses, and cell differentiation. The present study was to investigate the effect of IL-13 on the expression of glycoprotein IIb (GPIIb), a megakaryocytic gene, in Dami cells (human megakaryoblastic leukemia cell line) and HEL cells (human erythroleukemic cell line, which has both erythroid and megakaryocytic markers). Furthermore, it addresses the mechanisms governing the regulation of GPIIb expression by IL-13. The molecular responses of Dami cells and HEL cells to IL-13 treatment were analyzed by RT-PCR, Western blot, chromatin immunoprecipitation (ChIP) and flow cytometry analysis. We show that IL-13Rα1 and IL-4Rα are expressed in Dami cells and HEL cells. The expression of GPIIb was significantly upregulated at the mRNA and protein levels by treatment with IL-13. Moreover, IL-13 induced phosphorylation of signal transducer and activator of transcription 6(STAT6). By using a STAT6-specific antibody and PCR primers designed to yield a product, which encompasses the STAT6 binding site of the GPIIb promoter, we have shown the binding of the IL-13-mediated activation of STAT6 to the promoter of GPIIb gene. These results broaden the involvement of IL-13 into megakaryocyte differentiation by STAT6 pathway.