Ye Wenwen, Li Chenghua, Zhu Si, Lv Zhimeng
State Key Laboratory of Agricultural Products Safety, Ningbo University, Ningbo, 315211, China.
State Key Laboratory of Agricultural Products Safety, Ningbo University, Ningbo, 315211, China.
Fish Shellfish Immunol. 2025 Jul;162:110340. doi: 10.1016/j.fsi.2025.110340. Epub 2025 Apr 14.
In vertebrates, the single immunoglobulin (Ig) interleukin-1 receptor-related molecule, SIGIRR, plays a role in controlling inflammatory responses. Its invertebrate homologous double Ig interleukin-1 receptor-related molecule, DIGIRR, is little known. We report here the cloning of a novel DIGIRR homologue in Apostichopus japonicus, named AjDIGIRR, using rapid amplification of cDNA ends (RACE). Gene structure analysis revealed that AjDIGIRR contains a conserved intracellular TIR domain that differs from SIGIRR and IL-1R by having a different number of extracellular Ig domains. Subcellular localization analysis showed that, unlike fish DIGIRR, which is cytoplasmic, AjDIGIRR was membrane-associated and had increased expression 24 h after infection. In vertebrates, two amino acid sites in the TIR domains of IL-1R family members, Ser and Arg-Tyr, are conserved and are required for receptor signaling. Sequence alignment revealed that the primary signaling site, S279, is conserved in DIGIRR, whereas the signal activation site, Arg-Tyr536, is mutated to Gln-Gly359 in AjDIGIRR. To investigate AjDIGIRR's role in inflammation regulation, an in vivo inflammation model was established using Vibrio splendidus. Following bacterial challenge, AjDIGIRR mRNA expression in coelomocytes peaked at 6 h (1.92-fold increase) and remained elevated (1.63-fold increase) for up to 48 h, consistent with the inflammatory response. AjDIGIRR knockdown (0.26-fold) significantly exacerbated inflammation, as shown by HE staining, whereas overexpression (7.85-fold) markedly alleviated the inflammatory response. Under inflammatory conditions, AjDIGIRR overexpression reduced IL-17 expression by 29 % compared to the V. splendidus-induced group. These findings suggest that AjDIGIRR is structurally and functionally more similar to mammalian SIGIRR than to fish DIGIRR. Acting as a key negative regulator, AjDIGIRR mitigates inflammation by downregulating IL-17 expression.
在脊椎动物中，单免疫球蛋白（Ig）白细胞介素-1受体相关分子SIGIRR在控制炎症反应中发挥作用。其无脊椎动物同源物双Ig白细胞介素-1受体相关分子DIGIRR却鲜为人知。我们在此报告，利用cDNA末端快速扩增（RACE）技术，在刺参中克隆出一种新型DIGIRR同源物，命名为AjDIGIRR。基因结构分析表明，AjDIGIRR含有一个保守的细胞内TIR结构域，该结构域与SIGIRR和白细胞介素-1受体不同，其细胞外Ig结构域数量不同。亚细胞定位分析显示，与鱼类中位于细胞质的DIGIRR不同，AjDIGIRR与膜相关，且在感染后24小时表达增加。在脊椎动物中，白细胞介素-1受体家族成员TIR结构域中的两个氨基酸位点，即丝氨酸和精氨酸-酪氨酸，是保守的，且是受体信号传导所必需的。序列比对显示，主要信号位点S279在DIGIRR中是保守的，而信号激活位点精氨酸-酪氨酸536在AjDIGIRR中突变为谷氨酰胺-甘氨酸359。为了研究AjDIGIRR在炎症调节中的作用，利用灿烂弧菌建立了体内炎症模型。在细菌攻击后，体腔细胞中AjDIGIRR mRNA表达在6小时达到峰值（增加1.92倍），并在长达48小时内保持升高（增加1.63倍），这与炎症反应一致。如苏木精-伊红染色所示，AjDIGIRR基因敲低（0.26倍）显著加剧了炎症，而过表达（7.85倍）则明显减轻了炎症反应。在炎症条件下，与灿烂弧菌诱导组相比，AjDIGIRR过表达使白细胞介素-17表达降低了29%。这些发现表明，AjDIGIRR在结构和功能上与哺乳动物SIGIRR的相似性高于与鱼类DIGIRR的相似性。作为关键的负调节因子，AjDIGIRR通过下调白细胞介素-17表达来减轻炎症。
