Multiple regulatory domains of IRF-5 control activation, cellular localization, and induction of chemokines that mediate recruitment of T lymphocytes
Multiple regulatory domains of IRF-5 control activation, cellular localization, and induction of chemokines that mediate recruitment of T lymphocytes
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DOI：
10.1128/mcb.22.16.5721-5740.2002
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发表时间：
2002-08-01
影响因子：
5.3
通讯作者：
Pitha, PM
中科院分区：
文献类型：
--
作者：
Barnes, BJ;Kellum, MJ;Pitha, PM
干扰素调节因子(IRF)家族的转录因子是感染细胞早期炎症基因转录的关键介质。我们最近确定，除了IRF-3和IRF-7之外，IRF-5还是病毒介导的信号的直接转导者。与其他两个IP.F介导的激活不同，IRF-5介导的激活是病毒特异性的。我们发现，除了新城疫病毒(NDV)感染外，水泡性口炎病毒(VSV)和I型单纯疱疹病毒(HSV-1)感染还会激活IRF-5，导致IFNA基因亚型的诱导，这些亚型不同于新城疫病毒诱导的亚型。IRF-5介导的炎症基因的刺激不限于IFNA，因为在表达BJAB/IRF-5的细胞中，IRF-5以病毒特异性的方式刺激RANTES、巨噬细胞炎症蛋白1β、单核细胞趋化蛋白1、白细胞介素8和1-309基因的转录。通过瞬时转染法，我们在IRF-5多肽中确定了构成性激活(氨基酸[AA]410到489)和自身抑制(AA 490到539)结构域。我们鉴定了IRF-5的氨基和羧基末端的功能性核定位信号(NLS)，并表明这两种NLS都足以在感染细胞中进行核转位和滞留。此外，我们还证明了丝氨酸残基477和480在新城疫病毒感染的应答中起着关键作用。这些残基从丝氨酸突变为丙氨酸，极大地降低了磷酸化水平，并导致感染细胞中IRF-5反式激活的大量丧失。因此，本研究确定了在新城疫病毒感染细胞中控制IRF-5活性的调节磷酸化位点，并为进一步了解IRF-5的结构和功能提供了进一步的见解。它还表明，IRF-5免疫调节靶基因的范围包括细胞因子和趋化因子超家族成员。
Transcription factors of the interferon regulatory factor (IRF) family have been identified as critical mediators of early inflammatory gene transcription in infected cells. We recently determined that, besides IRF-3 and IRF-7, IRF-5 serves as a direct transducer of virus-mediated signaling. In contrast to that mediated by the other two IP.Fs, IRF-5-mediated activation is virus specific. We show that, in addition to Newcastle disease virus (NDV) infection, vesicular stomatitis virus (VSV) and herpes simplex virus type I (HSV-1) infection activates IRF-5, leading to the induction of IFNA gene subtypes that are distinct from subtypes induced by NDV. The IRF-5-mediated stimulation of inflammatory genes is not limited to IFNA since in BJAB/IRF-5-expressing cells IRF-5 stimulates transcription of RANTES, macrophage inflammatory protein 1beta, monocyte chemotactic protein 1, interleukin-8, and 1-309 genes in a virus-specific manner. By transient-transfection assay, we identified constitutive-activation (amino acids [aa] 410 to 489) and autoinhibitory (aa 490 to 539) domains in the IRF-5 polypeptide. We identified functional nuclear localization signals (NLS) in the amino and carboxyl termini of IRF-5 and showed that both of these NLS are sufficient for nuclear translocation and retention in infected cells. Furthermore, we demonstrated that serine residues 477 and 480 play critical roles in the response to NDV infection. Mutation of these residues from serine to alanine dramatically decreased phosphorylation and resulted in a substantial loss of IRF-5 transactivation in infected cells. Thus, this study defines the regulatory phosphorylation sites that control the activity of IRF-5 in NDV-infected cells and provides further insight into the structure and function of IRF-5. It also shows that the range of IRF-5 immunoregulatory target genes includes members of the cytokine and chemokine superfamilies.