Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
Department of Animal Science, North Carolina State University, Raleigh, NC, USA.
Sci Rep. 2019 Jul 30;9(1):11042. doi: 10.1038/s41598-019-47495-9.
Porcine reproductive and respiratory syndrome virus (PRRSV) activates NF-κB during infection. We examined the ability of all 22 PRRSV genes for NF-κB regulation and determined the nucleocapsid (N) protein as the NF-κB activator. Protein inhibitor of activated STAT1 (signal transducer and activator of transcription 1) (PIAS1) was identified as a cellular protein binding to N. PIAS1 is known to bind to p65 (RelA) in the nucleus and blocks its DNA binding, thus functions as a repressor of NF-κB. Binding of N to PIAS1 released p65 for NF-κB activation. The N-terminal half of PIAS1 was mapped as the N-binding domain, and this region overlapped its p65-binding domain. For N, the region between 37 and 72 aa was identified as the binding domain to PIAS1, and this domain alone was able to activate NF-κB. A nuclear localization signal (NLS) knock-out mutant N did not activate NF-κB, and this is mostly likely due to the lack of its interaction with PIAS1 in the nucleus, demonstrating the positive correlation between the binding of N to PIAS1 and the NF-κB activation. Our study reveals a role of N in the nucleus for NF-κB activation and proinflammatory cytokine production during infection.
猪繁殖与呼吸综合征病毒（PRRSV）在感染过程中激活 NF-κB。我们研究了 PRRSV 所有 22 个基因对 NF-κB 的调控能力，并确定核衣壳（N）蛋白是 NF-κB 的激活剂。蛋白抑制剂激活 STAT1（信号转导和转录激活因子 1）（PIAS1）被鉴定为与 N 结合的细胞蛋白。PIAS1 已知与核内的 p65（RelA）结合，并阻止其 DNA 结合，因此作为 NF-κB 的抑制剂发挥作用。N 与 PIAS1 的结合释放了 p65，从而激活 NF-κB。PIAS1 的 N 端一半被映射为 N 结合域，该区域与 p65 结合域重叠。对于 N，确定 37 到 72 个氨基酸残基的区域是与 PIAS1 结合的区域，并且该区域本身能够激活 NF-κB。没有核定位信号（NLS）的 N 突变体不能激活 NF-κB，这主要是由于其在核内与 PIAS1 缺乏相互作用，表明 N 与 PIAS1 的结合与 NF-κB 的激活之间存在正相关。我们的研究揭示了 N 在感染过程中在细胞核中激活 NF-κB 和促炎细胞因子产生的作用。
