An AP‐1 site in the promoter of the human IL‐5Rα gene is necessary for promoter activity in eosinophilic HL60 cells

Interleukin-5 (IL-5) plays a crucial role in the proliferation, differentiation and activation of eosinophils. The IL-5 receptor is composed of an IL-5-specific α subunit, which is expressed by eosinophils and basophils, and a βc-subunit shared with the receptors for IL-3 and GM-CSF. We identified an AP-1 element which is important for IL-5Rα promoter activity in eosinophilic HL60 cells. The AP-1 site and the previously identified EOS1 site cooperate, since single mutation of either of the sites decreased promoter activity. We show that the AP-1 site of the IL-5Rα promoter binds multiple proteins, including cJun, CREB, and CREM.