Jiang Sen, Luo Jia, Zhang Youwen, Cao Qi, Wang Yuening, Xia Nengwen, Zheng Wanglong, Chen Nanhua, Meurens François, Wu Huiguang, Zhu Jianzhong
Comparative Medicine Research Institute, Yangzhou University, Yangzhou, China.
College of Veterinary Medicine, Yangzhou University, Yangzhou, China.
J Immunol. 2022 Jul 15;209(2):412-426. doi: 10.4049/jimmunol.2101212. Epub 2022 Jul 1.
The innate immune DNA sensing cyclic GMP-AMP synthase (cGAS)-stimulator of IFN genes (STING) signaling pathway plays a key role in host antiviral function. Although the cGAS-STING pathway has been extensively studied, the cGAS-STING signaling in livestock and poultry is not well understood, and whether the species specificity exists is still unknown. In this study, we found that porcine and chicken STING, but not cGAS, exhibit species differences in regulation of IFN; that is, porcine (p)STING mediates good induction of IFN in mammalian cells and low IFN induction in chicken DF-1 cells; on the contrary, chicken (ch)STING mediates IFN induction only in chicken cells but not in mammalian cells. Furthermore, it was found that the motifs pLxIS of pSTING and pLxVS of chSTING are responsible for the species disparity, with the IFN activity of pSTING and chSTING exchanged by swapping the two pLxI/VS motifs. The pLxI/VS motifs mediated the interactions of various STING with downstream IFN regulatory factors (IRFs), reflecting the species-specific pIRF3 and chIRF7. Next, the STING, IRFs, and STING-IRFs were reconstituted in porcine and chicken macrophages that were genetically knocked out for STING and/or IRFs by the CRISPR-Cas9 approach. The results showed that pSTING plus pIRF3 or chIRF7 are able to induce IFN; however, chSTING plus chIRF7 but not pIRF3 are able to induce IFN, suggesting that pIRF3 is specific and stringent, which underlies the inability of chSTING to induce IFN in mammalian cells. In summary, our findings reveal the differential species specificity in the cGAS-STING pathway and the underlying mechanisms, thus providing valuable insights on the cGAS-STING-IRF signaling axis for comparative immunology.
天然免疫DNA感应环磷酸鸟苷-腺苷合成酶（cGAS）-干扰素基因刺激因子（STING）信号通路在宿主抗病毒功能中起关键作用。尽管cGAS-STING通路已得到广泛研究，但畜禽中的cGAS-STING信号尚不明确，其是否存在物种特异性仍不清楚。在本研究中，我们发现猪和鸡的STING而非cGAS在干扰素调节方面存在物种差异；也就是说，猪（p）STING在哺乳动物细胞中能很好地诱导干扰素，但在鸡DF-1细胞中诱导干扰素的能力较低；相反，鸡（ch）STING仅在鸡细胞中介导干扰素诱导，而在哺乳动物细胞中则不能。此外，还发现pSTING的pLxIS基序和chSTING的pLxVS基序导致了这种物种差异，通过交换两个pLxI/VS基序，pSTING和chSTING的干扰素活性发生了互换。pLxI/VS基序介导了各种STING与下游干扰素调节因子（IRF）的相互作用，反映了物种特异性的pIRF3和chIRF7。接下来，通过CRISPR-Cas9方法在基因敲除了STING和/或IRF的猪和鸡巨噬细胞中重建了STING、IRF和STING-IRF。结果表明，pSTING加pIRF3或chIRF7能够诱导干扰素；然而，chSTING加chIRF7而非pIRF3能够诱导干扰素，这表明pIRF3具有特异性和严格性，这是chSTING在哺乳动物细胞中无法诱导干扰素的原因。总之，我们的研究结果揭示了cGAS-STING通路中不同的物种特异性及其潜在机制，从而为比较免疫学中的cGAS-STING-IRF信号轴提供了有价值的见解。
