Analysis and characterization of the genes encoding the Dicer and Argonaute proteins of Schistosoma japonicum

Background: The Dicer and Argonaute( AGO) proteins within the small RNA regulatory pathways ( SRRPs) play an indispensable role in regulation of gene expression. In this study, we analyzed two genes, Dicer and Argonaute, from Schistosoma japonicum, along with their expression through a combination of bioinformatics and experimental approaches. Results: Our results indicate that one Dicer and four Argonaute genes exist in Schistosoma japonicum, termed SjDicer and SjAGO1, 2, 3, and 4, respectively. SjDicer encodes 2590 amino acid residues that contains 5 conserved domains, including one amino-terminal helicase domain, one PAZ ( Piwi-Argonaut-Zwille) domain, two RNAse III domains, and one dsRNA-binding domain. SjAGO1, 2, and 3 encode 1009, 945, and 904 amino acid residues, respectively, all of which contain PAZ and PIWI domains. In addition, we analyzed the expression profiles of SjDicer and SjAGO1 genes by qRT-PCR in eggs, miracidium, cercariae, schistosomula, and adult worms. Results showed consistent expression of both SjDicer and SjAGO1 in different stages; however, their expression levels were stage-dependent, with the highest being in the miracidium stage. Conclusions: This study provided the sequence of the Dicer and Ago genes of S. japonicum and their expression profiles which are essential for further investigation of functions of miRNA in Schistosoma japonicum.