Interferon induction of gene expression through the Jak–Stat pathway

IFNα and IFNγ induce rapid activation of gene expression following binding to cell surface receptors on target cells. Gene transcription depends on latent transcription factors that become activated in response to IFN treatment. These proteins, termed Stats for signal transducers and activators of transcription, serve as intrinsic elements of the signaling pathway. In untreated cells, they are sequestered in the cytoplasm. Upon treatment of cells with IFN, they become tyrosine phophorylated by receptor-bound protein tyrosine kinases of the Jak family, assemble into multimeric complexes, and localize to the cell nucleus. Differential activation and combinatorial association of these transcription factors produce the biological responses characteristic of each IFN.