State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.
Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, United States.
Int J Parasitol. 2017 Dec;47(14):933-940. doi: 10.1016/j.ijpara.2017.06.005. Epub 2017 Aug 3.
Protein kinase RIOK-1 is a non-ribosomal factor essential for rRNA cleavage and ribosome small subunit maturation. It is encoded in all eukaryotic organisms. The RIOK-1 encoding gene of Caenorhabditis elegans (Ce-riok-1) is expressed in the neuronal and reproductive systems in larvae and adults of this free-living nematode, and it supports larval growth and development of the adult gonad. In spite of its recognised roles in model organisms such as C. elegans, little is known about the function of this molecule in parasitic nematodes. In a previous study, we characterised the structure, transcriptional profiles and in vivo transcriptional expression patterns of the Ss-riok-1 of human and canine parasitic nematode Strongyloides stercoralis. Here, we extend previous work to undertake functional studies, using transgenesis to assess the roles of Ss-RIOK-1 in the development of S. stercoralis. The results revealed that recombinant Ss-RIOK-1 with D282A mutation at its catalytic site lost its kinase phosphorylation activity in vitro. Both wild-type and mutant Ss-RIOK-1s were expressed in the cytoplasm of neurons and some hypodermal cells in the wild-type strain (UPD) of S. stercoralis. Larvae expressing the dominant negative mutant Ss-RIOK-1 that lost the catalytic activity had a decreased mobility and a severe defect in development to the infective L3 stage. Our findings demonstrated that Ss-RIOK-1 is essential for the development and survival of free-living larvae of S. stercoralis, and that catalytic activity is essential for its function in the parasitic nematode.
蛋白激酶 RIOK-1 是非核糖体因子，对于 rRNA 的切割和核糖体小亚基的成熟是必需的。它存在于所有真核生物中。秀丽隐杆线虫（Ce-riok-1）的 RIOK-1 编码基因在这种自由生活的线虫的幼虫和成虫的神经元和生殖系统中表达，它支持幼虫的生长和成虫性腺的发育。尽管它在模式生物如秀丽隐杆线虫中具有公认的作用，但对于这种分子在寄生线虫中的功能知之甚少。在之前的一项研究中，我们对人源和犬源寄生线虫旋毛虫的 Ss-riok-1 的结构、转录谱和体内转录表达模式进行了表征。在这里，我们扩展了之前的工作，进行功能研究，使用转基因来评估 Ss-RIOK-1 在旋毛虫发育中的作用。结果表明，其催化位点 D282A 突变的重组 Ss-RIOK-1 在体外失去了激酶磷酸化活性。野生型和突变型 Ss-RIOK-1 均在旋毛虫野生型菌株（UPD）的神经元和一些皮下细胞的细胞质中表达。表达失去催化活性的显性负突变 Ss-RIOK-1 的幼虫运动能力下降，并且严重缺陷发育至感染性 L3 期。我们的研究结果表明，Ss-RIOK-1 对于旋毛虫自由生活幼虫的发育和生存是必需的，并且其在寄生线虫中的功能需要催化活性。
