A conserved RNAi molecule Ago2 involved in antiviral immunity of oyster Crassostrea gigas. (May 2023)

• Record Type: Journal Article
• Authors: Jin, Yuhao; Qiao, Xue; Lv, Xiaojing; Wang, Weilin; Wang, Sicong; Gao, Yuqian; Wang, Lingling; Song, Linsheng
• Is Part Of: Developmental and comparative immunology. Volume 142(2023)
• Publication Date: 2023-05
• Subjects: Crassostrea gigas -- RNAi -- Argonaute -- Antiviral immunity; Immunology -- Periodicals; Developmental immunology -- Periodicals; 616.079
• DOI: 10.1016/j.dci.2023.104668
• Languages: English
• ISSNs: 0145-305X

Abstract

Abstract: Argonaute (Ago) is the core component of RNA-induced silencing complex to play a crucial role in the antiviral immunity, which always cooperates with Dicer in RNA interference (RNAi) to silence the target genes. In the present study, an Ago homologue ( Cg Ago2) was identified in the Pacific oyster Crassostrea gigas . There were four classical functional domains in the predicted Cg Ago2 protein, including an N-terminal domain, a PAZ domain, a Mid domain, and a PIWI domain. The deduced amino acid sequence of Cg Ago2 shared 63.52%–84.27% identity with other Agos. Transcriptome analysis showed that Cg Ago2 was highly expressed in embryonic period and gradually decreased from blastula to gastrula. The transcripts of Cg Ago2 were detectable in all the examined tissues of adult oysters, with the highest expression in haemocytes (36.61-fold of that in adductor muscle, p < 0.001). The expression level of Cg Ago2 mRNA in haemocytes increased significantly at 12 h after poly (I:C) and dsRNA stimulation, which were 2.71-fold ( p < 0.05) and 58.00-fold ( p < 0.001) of that in the control group respectively. Immunocytochemistry assay revealed that Cg Ago2 proteins were mainly distributed in the cytoplasm and nucleus of haemocytes. The interaction between the recombinant Cg Ago2 protein (r Cg Ago2) and cleavage protein r Cg Dicer was observed in vitro by BLI and pull-down assays. These results indicated that Cg Ago2 participated in the antiviral immunity of oyster by functioning as a component of RNA-induced silencing complex in RNAi. Highlights: A conserved Ago molecule ( Cg Ago2) was identified from oyster C. gigas. The mRNA of Cg Ago2 was highly expressed in embryonic period and the haemocytes of adult oysters. The expression of Cg Ago2 in haemocytes increased after immune stimulation. The interaction between Cg Ago2 and Cg Dicer was observed by BLI and pull-down assays in vitro.