First Evidence of Function for <i>Schistosoma japonicum</i><i>riok-1</i> and RIOK-1

• Main Authors: Mudassar N. Mughal, Qing Ye, Lu Zhao, Christoph G. Grevelding, Ying Li, Wenda Di, Xin He, Xuesong Li, Robin B. Gasser, Min Hu
• Format: Article
• Language: English
• Published: MDPI AG 2021-07-01
• Series: Pathogens
• Subjects: schistosomiasis; <i>Schistosoma japonicum</i>; right open reading frame protein kinase (<i>riok</i>) genes; <i>riok</i>-1; RIOK-1; double-stranded RNA interference (RNAi)
• Online Access: https://www.mdpi.com/2076-0817/10/7/862

Protein kinases are known as key molecules that regulate many biological processes in animals. The right open reading frame protein kinase (<i>riok</i>) genes are known to be essential regulators in model organisms such as the free-living nematode <i>Caenorhabditis elegans</i>. However, very little is known about their function in parasitic trematodes (flukes). In the present study, we characterized the <i>riok-1</i> gene (<i>Sj</i>-<i>riok-1</i>) and the inferred protein (<i>Sj</i>-RIOK-1) in the parasitic blood fluke, <i>Schistosoma japonicum</i>. We gained a first insight into function of this gene/protein through double-stranded RNA interference (RNAi) and chemical inhibition. RNAi significantly reduced <i>Sj</i>-<i>riok-1</i> transcription in both female and male worms compared with untreated control worms, and subtle morphological alterations were detected in the ovaries of female worms. Chemical knockdown of <i>Sj</i>-RIOK-1 with toyocamycin (a specific RIOK-1 inhibitor/probe) caused a substantial reduction in worm viability and a major accumulation of mature oocytes in the seminal receptacle (female worms), and of spermatozoa in the sperm vesicle (male worms). These phenotypic alterations indicate that the function of <i>Sj</i>-<i>riok-1</i> is linked to developmental and/or reproductive processes in <i>S. japonicum</i>.