Nucleolin and YB-1 are required for JNK-mediated interleukin-2 mRNA stabilization during T-cell activation

Regulated mRNA turnover is a highly important process, but its mechanism is poorly understood. Using interleukin-2 (IL-2) mRNA as a model, we describe d a role for the JNK-signaling pathway in stabilization of IL-2 mRNA during T-cell activation, acting via a JNK response element (JRE) in the 5' untra nslated region (UTR). We have now identified two major RNA-binding proteins , nucleolin and YB-1, that specifically bind to the JRE. Binding of both pr oteins is required for IL-2 mRNA stabilization induced by T-cell activation signals and for JNK-induced stabilization in a cell-free system that dupli cates essential features of regulated mRNA decay. Nucleolin and YB-1 are re quired for formation of an IL-2 mRNP complex that responds to specific mRNA stabilizing signals.