Division of Signaling in Cancer and Immunology, Institute for Genetic Medicine, Hokkaido University, Sapporo, Hokkaido, 060-0815, Japan; Oral Biochemistry and Molecular Biology, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Hokkaido, 060-8586, Japan; Center for Medical Education, Graduate School of Medicine, Gunma University, Maebashi, Gunma, 371-8511, Japan.
Division of Signaling in Cancer and Immunology, Institute for Genetic Medicine, Hokkaido University, Sapporo, Hokkaido, 060-0815, Japan.
Biochem Biophys Res Commun. 2019 Apr 2;511(2):287-293. doi: 10.1016/j.bbrc.2019.02.029. Epub 2019 Feb 19.
Innate immunity is a system that recognizes primarily and excludes pathogenic microorganism. MAVS/IPS-1/Cardif/Visa functions as an adapter protein for RIG-I like receptors (RLRs) and plays a key role in the production of antiviral proteins, interferons (IFNs), for RNA viruses. However, the activation mechanism is not fully understood. Here, we show that BinCARD isoform2 (BinCARD2), carrying CARD domain structure like MAVS, functions in innate immune response. Knockdown of BinCARD2 reduced the RLR ligand-induced expression of IFN-β mRNA and activation of the IFNB promoter. The activation of the IFNB promoter by overexpression of MAVS or TBK1 was suppressed by silencing of BinCARD2, but no effect on IFNB promoter activation by overexpression of TRIF or constitutive activated IRF-3. Furthermore, we confirmed that BinCARD2 protein associated with MAVS but not TBK1 by immunoprecipitation and colocalized with MAVS. Accordingly, we investigated whether BinCARD2 was involved in MAVS activation and showed that siBinCARD2 did not affect RIG-I/MAVS binding but impaired the MAVS oligomerization. Moreover, we infected A549 cells with vesicular stomatitis virus (VSV) and found that induction of IFN-β and IL-6 mRNA after VSV infection was decreased by BinCARD2 knockdown. Thus, these data may suggest that BinCARD2 associates with MAVS to positively modulate the oligomerization in the RIG-I like receptors pathway and activates innate immune response.
固有免疫是一种主要识别并排除致病微生物的系统。MAVS/IPS-1/Cardif/Visa 作为 RIG-I 样受体 (RLRs) 的衔接蛋白，在 RNA 病毒的抗病毒蛋白干扰素 (IFNs) 的产生中发挥关键作用。然而，其激活机制尚未完全阐明。在这里，我们表明，具有 MAVS 样 CARD 结构域的 BinCARD 同种型 2 (BinCARD2) 可在先天免疫反应中发挥作用。BinCARD2 的敲低降低了 RLR 配体诱导的 IFN-β mRNA 的表达和 IFNB 启动子的激活。过表达 MAVS 或 TBK1 激活 IFNB 启动子时，BinCARD2 的沉默会受到抑制，但过表达 TRIF 或组成型激活的 IRF-3 对 IFNB 启动子的激活没有影响。此外，我们通过免疫沉淀证实了 BinCARD2 与 MAVS 而非 TBK1 相关联，并与 MAVS 共定位。因此，我们研究了 BinCARD2 是否参与 MAVS 激活，并表明 siBinCARD2 不影响 RIG-I/MAVS 结合，但会损害 MAVS 寡聚化。此外，我们用水疱性口炎病毒 (VSV) 感染 A549 细胞，发现 VSV 感染后 IFN-β 和 IL-6 mRNA 的诱导被 BinCARD2 敲低所降低。因此，这些数据表明 BinCARD2 与 MAVS 相关联，以正向调节 RIG-I 样受体途径中的寡聚化并激活先天免疫反应。
