Laboratory Animal Center, Xi'an Jiaotong University, Xi'an 710061, China.
Department of Laboratory Animal Science, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an 710061, China.
Viruses. 2022 May 8;14(5):1002. doi: 10.3390/v14051002.
Porcine reproductive and respiratory syndrome virus (PRRSV) induces secretion of high mobility group box 1 (HMGB1) to mediate inflammatory response that is involved in the pulmonary injury of infected pigs. Our previous study indicates that protein kinase C-delta (PKC-delta) is essential for HMGB1 secretion in PRRSV-infected cells. However, the underlying mechanism in HMGB1 secretion induced by PRRSV infection is still unclear. Here, we discovered that the phosphorylation level of HMGB1 in threonine residues increased in PRRSV-infected cells. A site-directed mutagenesis study showed that HMGB1 phosphorylation at threonine-51 was associated with HMGB1 secretion induced by PRRSV infection. Co-immunoprecipitation (co-IP) of HMGB1 failed to precipitate PKC-delta, but interestingly, mass spectrometry analysis of the HMGB1 co-IP product showed that PRRSV infection enhanced HMGB1 binding to ribosomal protein S3 (RPS3), which has various extra-ribosomal functions. The silencing of RPS3 by siRNA blocked HMGB1 secretion induced by PRRSV infection. Moreover, the phosphorylation of HMGB1 at threonine-51 was correlated with the interaction between HMGB1 and RPS3. In vivo, PRRSV infection also increased RPS3 levels and nuclear accumulation in pulmonary alveolar macrophages. These results demonstrate that PRRSV may induce HMGB1 phosphorylation at threonine-51 and increase its interaction with RPS3 to enhance HMGB1 secretion. This finding provides insights into the pathogenesis of PRRSV infection.
猪繁殖与呼吸综合征病毒 (PRRSV) 诱导高迁移率族蛋白 B1 (HMGB1) 的分泌，从而介导炎症反应，参与感染猪的肺损伤。我们之前的研究表明，蛋白激酶 C-δ (PKC-δ) 是 PRRSV 感染细胞中 HMGB1 分泌所必需的。然而，PRRSV 感染诱导 HMGB1 分泌的潜在机制仍不清楚。在这里，我们发现 PRRSV 感染细胞中 HMGB1 的丝氨酸残基磷酸化水平增加。定点突变研究表明，HMGB1 丝氨酸-51 的磷酸化与 PRRSV 感染诱导的 HMGB1 分泌有关。HMGB1 的共免疫沉淀（co-IP）未能沉淀 PKC-δ，但有趣的是，HMGB1 co-IP 产物的质谱分析表明，PRRSV 感染增强了 HMGB1 与核糖体蛋白 S3 (RPS3) 的结合，RPS3 具有各种核外核糖体功能。RPS3 的 siRNA 沉默阻断了 PRRSV 感染诱导的 HMGB1 分泌。此外，HMGB1 丝氨酸-51 的磷酸化与 HMGB1 与 RPS3 之间的相互作用有关。在体内，PRRSV 感染也增加了肺肺泡巨噬细胞中 RPS3 的水平和核积累。这些结果表明，PRRSV 可能诱导 HMGB1 丝氨酸-51 的磷酸化，并增加其与 RPS3 的相互作用，从而增强 HMGB1 的分泌。这一发现为 PRRSV 感染的发病机制提供了新的见解。
