Bx42, the homologue of SNW1 in mammals, is involved in pre-mRNA splicing and transcriptional regulation. However, the presence and function of Bx42 have remained poorly understood in invertebrates until now. In the current study, a novel SNW domain-containing protein (MnBx42) from Macrobrachium nipponense was identified, and its potential role in the immune response was investigated. The full-length MnBx42 was 7467 bp with an open reading frame of 1653 bp, encoding 550 amino acids. Real-time PCR analysis suggested that MnBx42 was predominantly expressed in the intestine, gills and hepatopancreas, and immunofluorescence assays indicated that it was located in the nucleus. Its expression level was significantly decreased in M. nipponense post-challenge with white spot syndrome virus (WSSV) as well as Aeromonas hydrophila and Staphylococcus aureus, implying its participation in the innate immune response. The knockdown of MnBx42 in vivo notably increased the susceptibility of the prawns to bacterial infection, markedly increased the bacterial load in the gills, and significantly attenuated the phagocytic activity of haemocytes. Dual-luciferase reporter assays illustrated that MnBx42 could activate the NF-κB pathway. Consistent with this, when MnBx42 was silenced in vivo, the expression levels of antimicrobial peptides (AMPs), including ALF2, ALF3, ALF4, ALF5, Cru1 and Cru2, and NF-κB signalling genes, including dorsal, relish, TAK1, TAB1, Ikkβ, and Ikkε, were significantly reduced. Taken together, these findings may provide new insights about Bx42 in crustaceans and pave the way for a better understanding of the crustacean innate immune system.

Bx42 是哺乳动物中 SNW1 的同源物，参与前 mRNA 剪接和转录调控。然而，直到现在，对无脊椎动物中 Bx42 的存在和功能仍知之甚少。在当前的研究中，鉴定了一种来自日本沼虾的新型含有 SNW 结构域的蛋白质 ( Mn Bx42) ，并研究了其在免疫反应中的潜在作用。全长Mn Bx42 为 7467 bp，开放阅读框为 1653 bp，编码 550 个氨基酸。实时 PCR 分析表明Mn Bx42 主要在肠、鳃和肝胰腺中表达，免疫荧光分析表明它位于细胞核中。其表达水平显着降低M. nipponense感染白斑综合征病毒 (WSSV) 以及嗜水气单胞菌和金黄色葡萄球菌后，表明其参与了先天免疫反应。体内Mn Bx42的敲低显着增加了对虾对细菌感染的易感性，显着增加了鳃中的细菌负荷，并显着减弱了血细胞的吞噬活性。双荧光素酶报告基因检测表明Mn Bx42 可以激活 NF-κB 通路。与此一致，当Mn Bx42在体内沉默时, 抗菌肽 (AMP) 的表达水平，包括 ALF2、ALF3、ALF4、ALF5、Cru1 和 Cru2，以及 NF-κB 信号基因，包括背侧、津津有味、TAK1、TAB1、Ikkβ 和 Ikkε 的表达水平显着降低。综上所述，这些发现可能提供有关甲壳类动物 Bx42 的新见解，并为更好地了解甲壳类动物先天免疫系统铺平道路。