Binding of IL‐4 to the IL‐13Rα1/IL‐4Rα receptor complex leads to STAT3 phosphorylation but not to its nuclear translocation

Publisher Website
Google Scholar
Abstract
Interleukin-4 (IL-4) is a pleiotropic cytokine, which acts on both hematopoietic and non-hematopoietic cells, through different types of receptor complexes. In this study, we report that in human B cells, IL-4 caused rapid phosphorylation of Janus kinase (JAK) 1 and JAK3 tyrosine kinases. In keratinocytes, the hematopoietic-specific receptor common γc chain is not expressed and the IL-13 receptor α1 (IL-13Rα1) participates in IL-4 signal transduction. In keratinocytes, IL-4 induced JAK1 and JAK2 phosphorylation but, unlike in immune cells, IL-4 did not involve JAK3 activation for its signaling. In both cell types, IL-4 induced phosphorylation and DNA binding activation of the signal transducer and activator of transcription (STAT) 6 protein. Furthermore, IL-4 stimulation of keratinocytes also induced tyrosine phosphorylation of STAT3 which was found to bind to the phosphorylated IL-13Rα1. STAT3 however did not significantly translocate to the nucleus, nor did it bind with high affinity to target DNA sequences.