Activation of 12-O-tetradecanoylphorbol-13-acetate response element- and dyad symmetry element-dependent transcription by interleukin-5 is mediated by Jun N-terminal kinase/stress-activated protein kinase kinases.

Interleukin-5 (IL-5) is one of the major regulators of eosinophilic granulocytes in vivo. IL-5 exerts its pleiotropic effects by binding to the IL-5 receptor, which is composed of an IL-5-specific alpha chain and a common betac chain shared with the receptors for IL-3 and granulocyte-macrophage colony-stimulating factor. Previous studies have shown that binding of IL-5 to its receptor triggers the activation of multiple signaling cascades, including the Ras/mitogen-activated protein kinase, the phosphatidyl -3'-kinase, and the Janus kinase/signal transducer and activator of transcription pathways. Here we describe that IL-5 activates the serine/threonine protein kinase Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) pathway. We show that IL-5 activates TPA response element (TRE)-dependent transcription in transfection experiments. TRE activation by IL-5 is mediated by a region of the betac (577-581) that is also responsible for activation of JNK/SAPK and for activation of dyad symmetry element (DSE)-dependent transcription. Dominant-negative SAPK or ERK kinase-1 was used to demonstrate that JNK/SAPK activation is necessary for induction of DSE- and TRE-dependent transcription by IL-5, whereas extracellular signal-regulated kinase 2 was not essential for TRE- and DSE-dependent transcription. By contrast, IL-5-induced activation of the tyrosine kinase Janus kinase 2 seems to be a prerequisite for TRE- and DSE-dependent transcription. Taken together, we show for the first time that IL-5 activates kinases of the JNK/SAPK family, and that this activation is linked to IL-5-induced TRE- and DSE-dependent transcription.