Heterogeneous ribonucleoprotein D selectively regulates the expression of genes in the immune system

The immune response is critical for the elimination of pathogens. However, uncontrolled immune responses can lead to tissue damage and inflammatory diseases. The generation of an immune response requires the activation, differentiation and proliferation of various immune cells and the production of cytokines that are regulated directly or indirectly by multiple pathways, including posttranscriptional regulation by RNA-binding proteins (RBPs). Heterogeneous ribonucleoprotein D (hnRNPD), an RBP that is also known as AU-rich elements/poly(U)-binding/degradation factor 1 (AUF1), can regulate the expression of various target RNAs, including mRNAs, miRNAs, lncRNAs, by binding to their Au-rich elements (AREs) or U-/GU-rich sequences. The target RNAs of hnRNPD range from cytokines, inflammatory receptors and growth factors to G protein-coupled receptors; thus, hnRNPD influences various physiological processes, including the immune response. In addition, hnRNPD is strongly expressed in multiple lymphocytic tissues, suggesting that it may play an important role in the immune system. In this review, we discuss the roles of hnRNPD in the immune system and autoimmune diseases.