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Description

Interleukin-4 (UniProt: P05112, also known as IL-4, B-cell stimulatory factor 1, BSF-1, Binetrakin, Lymphocyte stimulatory factor 1, Pitrakinra) is encoded by the IL4 gene (Gene ID: 3565) in human. IL-4 is a cytokine that is secreted primarily by mast cells, Th2 cells, eosinophils, and basophils. IL-4 is synthesized with a signal peptide (1-24), which is subsequently cleaved off to produce the mature form. It participates in the activation of B cells and other cell types. It also serves as a co-stimulator of DNA-synthesis. It induces the expression of class II MHC molecules on resting B-cells. It enhances both secretion and cell surface expression of IgE and IgG1. It also reported to regulate the expression of the low affinity Fc receptor for IgE (CD23) on both lymphocytes and monocytes. IL-4 inhibits macrophage production of proinflammatory cytokines, including TNF-a, IL-1, and IL-6 via transcriptional repression. It also enhances production of molecules that counteract these cytokines, such as IL-1R antagonist and the decoy receptor IL-1RII. The effects of IL-4 signaling are mediated through binding to the IL-4 receptor a chain (IL-4R ) that dimerizes with g-chain upon ligand binding to produce type I signaling complex located mainly of hematopoietic cells. It can also dimerize with IL-13a receptor a (IL-13Ra1) to produce type-2 complex that is expressed also on non-hematopoietic cells. IL-4 is also shown to stimulate autophagy in dendritic cells by interfering with mTORC1 signaling through the induction of RUN and FYVE domain containing 4 (RUFY4). (Ref.: Gadani, SP., et al. (2012). J. Immunol. 189(9), 4213-4219, Otsuka, TY., et al. (1986). Proc. Natl. Acad. Sci. USA. 83(16), 5894-5898).