Identification of genes that are regulated by TAK1 in human cutaneous T cell lymphoma HuT-102 cells

We previously reported that human T cell lymphotropic virus 1 (HTLV-1) Tax oncoprotein constitutively activates TAK1. Here, we established Tax-positive HuT-102 cells stably downregulated TAK1 expression by short-hairpin RNA (HuT-shTAK1 cells), and investigated the physiological function of TAK1. Microarray analysis demonstrated that several interferon (IFN)-inducible genes including chemokines such as CXCL10 and CCL5 were significantly downregulated in HuT-shTAK1 cells. In contrast, Tax-mediated constitutive activation of NF-kB was intact in HuT-shTAK1 cells. IRF3, a critical transcription factor in innate immunity to viral infection, was constitutively activated in a Tax-dependent manner. Activation of IRF3 and IRF3-dependent gene expression were dependent on TAK1 and TBK1. On the other hand, IRF4, another IRF family of transcription factor overexpressed in a Tax-independent manner, negatively regulated the TAK1-dependent IRF3 transcriptional activity. Together, HTLV-1 manipulates IFN signaling by regulating both positive and negative IRFs.

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Suzuki S, Zhou Y, Refaat A, Takasaki I, Koizumi K, Yamaoka S, Tabuchi Y, Saiki I, Sakurai H