Nociari Marcelo, Ocheretina Oksana, Murphy Mary, Falck-Pedersen Erik
Department of Medicine, Weill Medical College, Cornell University, New York, New York 10021, USA.
J Virol. 2009 May;83(9):4081-91. doi: 10.1128/JVI.02591-08. Epub 2009 Feb 11.
Pathogen recognition is a critical function of immune sentinel cells. Naïve macrophages or dendritic cells (DCs) undergo pathogen-directed activation and maturation, and as mature antigen-presenting cells (APCs), they contribute essential functions to both innate and adaptive immunity. Using recombinant adenovirus (rAdV) as a model for murine APC activation by DNA viruses, we demonstrate a critical role for stress kinase activation in cell intrinsic and extrinsic antiviral signaling cascades. We propose two viral triggers, viral capsid and viral DNA, are required for APC activation. Endosomal escape and presentation of cytosolic rAdV DNA induces phosphorylation of TANK-binding kinase 1 (TBK1) at serine 172 but does not induce IkappaB kinase epsilon activity as determined by in vitro kinase assays. However, induction of TBK1 alone is not sufficient for interferon regulatory factor 3 (IRF3) phosphorylation. We show that capsid-dependent activation of Jun N-terminal kinase (JNK) stress kinase is a necessary step, licensing TBK1 phosphorylation of IRF3 at Ser 396. A second later phase of JNK activity is required to coordinate phosphorylation of JNK-dependent transcription factors (c-Jun/ATF2) with activated IRF3 in the induction of primary IRF3-responsive transcripts. Finally, we demonstrate that maximal JNK/TBK1/IRF3 stimulation by rAdV depends on an intact type I interferon (IFN) signaling cascade. By requiring multiple viral triggers and type I IFN autocrine regulation, APCs have an inherent fail-safe mechanism against inappropriate activation and maturation.
病原体识别是免疫哨兵细胞的一项关键功能。未成熟的巨噬细胞或树突状细胞（DCs）会经历病原体导向的激活和成熟过程，作为成熟的抗原呈递细胞（APCs），它们对固有免疫和适应性免疫都发挥着重要作用。利用重组腺病毒（rAdV）作为DNA病毒激活小鼠APC的模型，我们证明了应激激酶激活在细胞内在和外在抗病毒信号级联反应中起着关键作用。我们提出，APC激活需要两种病毒触发因素，即病毒衣壳和病毒DNA。胞质内rAdV DNA的内体逃逸和呈递可诱导TANK结合激酶1（TBK1）丝氨酸172位点的磷酸化，但通过体外激酶分析确定其不会诱导IκB激酶ε的活性。然而，单独诱导TBK1不足以使干扰素调节因子3（IRF3）磷酸化。我们发现，衣壳依赖性激活Jun N末端激酶（JNK）应激激酶是一个必要步骤，可使TBK1在丝氨酸396位点对IRF3进行磷酸化。JNK活性的第二个后期阶段是必需的，以便在诱导初级IRF3反应性转录本时，将JNK依赖性转录因子（c-Jun/ATF2）的磷酸化与激活的IRF3进行协调。最后，我们证明rAdV对JNK/TBK1/IRF3的最大刺激依赖于完整的I型干扰素（IFN）信号级联反应。通过需要多种病毒触发因素和I型IFN自分泌调节，APCs具有一种内在的故障安全机制，可防止不适当的激活和成熟。
