Interferon regulatory factors (IRFs) are key transcription factors that function in the immune system via the interferon (IFN) pathway. In the current study, we identified and characterized three IRFs (CsIRFL1, CsIRFL2, and CsIRFL3) from ascidian Ciona savignyi. Phylogenetic analysis showed that CsIRFL1 was clustered with two IRFs from Ciona robusta and shrimp IRF apart from the vertebrate IRFs, whereas CsIRFL2 and CsIRFL3 were grouped with an unnamed protein from Oikopleura dioica into a sub-branch highly identifying with the vertebrate IRF4, IRF8, and IRF9. Gene expression analysis revealed that CsIRFL1 and CsIRFL2 expressed in all the examined adult tissues (stomach, intestines, eggs, hemocytes, gonad, heart, and pharynx) and predominantly in hemocytes. However, the expression of CsIRFL3 was undetectable in the tested adult tissues. Furthermore, in situ hybridization showed that CsIRFL1 and CsIRFL2 mainly expressed in immunocytes within hemolymph, including phagocytes, macrophage-like cells, morula cells, and amoebocytes, suggesting CsIRFL1 and CsIRFL2 were involved in ascidian immune responses. We then performed LPS and poly(I:C) challenge assay and found that CsIRFL1 highly expressed in the cultured hemocytes following LPS infection for 24 h. After viral analogue poly(I:C) stimulation, the expression of CsIRFL2 was dramatically upregulated from 12 to 24 h. Meanwhile, two critical components of the IFN signaling pathways, STAT and TBK1, showed the increased expression as well after poly(I:C) induction, indicating that CsIRFL2 and IFN pathways genes were activated under the infection of viral analogue. Thus, our findings suggested that CsIRFL2 was a potential transcriptional regulatory factor that participated in regulating the ascidian anti-virus immune response.

干扰素调节因子（IRF）是通过干扰素（IFN）途径在免疫系统中起作用的关键转录因子。在当前的研究中，我们鉴定并鉴定了来自海鞘Ciona savignyi的三个IRF（CsIRFL1，CsIRFL2和CsIRFL3）。系统发育分析表明，CsIRFL1与来自脊椎动物IRF的两个来自Cionarobusta和虾IRF的IRF聚集在一起，而CsIRFL2和CsIRFL3与来自Oikopleura dioica的一个未命名蛋白分组到一个高度区分脊椎动物IRF4，IRF8和IRF9。基因表达分析显示CsIRFL1和CsIRFL2在所有检查的成人组织（胃，肠，卵，血细胞，性腺，心脏和咽）中表达，并且主要在血细胞中表达。但是，在测试的成人组织中无法检测到CsIRFL3的表达。此外，原位杂交表明CsIRFL1和CsIRFL2主要在血淋巴内的免疫细胞中表达，包括吞噬细胞，巨噬细胞样细胞，桑ula细胞和变形细胞，这表明CsIRFL1和CsIRFL2参与了海鞘免疫反应。然后，我们进行了LPS和poly（I：C）攻击检测，发现CsIRFL1LPS感染24 h后在培养的血细胞中高表达。病毒类似物poly（I：C）刺激后，CsIRFL2的表达从12到24 h显着上调。同时，在聚（I：C）诱导后，IFN信号通路的两个关键组成部分STAT和TBK1也显示出增加的表达，表明在病毒类似物的感染下，CsIRFL2和IFN通路基因被激活。因此，我们的发现表明CsIRFL2是参与调节海鞘抗病毒免疫应答的潜在转录调节因子。