Ali M R, Lim J, Kim Y
Department of Bioresource Sciences, Andong National University, Andong, Korea; Department of Biological Sciences, Andong National University, Andong, Korea.
Insect Mol Biol. 2015 Feb;24(1):13-28. doi: 10.1111/imb.12132. Epub 2014 Sep 25.
The specialized wasp cells teratocytes (TCs) are derived from the embryonic serosal membrane of some parasitic hymenopteran insects. As a parasitic factor, TCs are multifunctional in host regulation, such as host nutritional deprivation, immunosuppression and developmental arrest; however, little is understood about their genetic constituents. The present study provides a comprehensive view of the genes expressed by TCs through a transcriptome analysis based on RNA sequencing technology. The assembled 34 686 contigs (>200 base pairs) were annotated into different functional categories, indicating a distinct distribution in gene transcripts compared with those of haemocytes and fat body. The TC transcriptome contained components of insulin signalling and biosyntheses of juvenile hormone and 20-hydroxyecdysone. TCs also expressed various groups of digestive enzymes, indicating that they have nutritional role for the growing parasitoid larvae in parasitism. Furthermore, through this transcriptome analysis two kinds of immunosuppressive serine protease inhibitors (serpins) and Rho GTPase-activating proteins (RhoGAPs) were annotated. To determine the biological functions of these factors, we devised ex vivo RNA interference (RNAi) by conducting knockdown of gene expression in in vitro-cultured TCs followed by injection of the treated TCs to test insects. Ex vivo RNAi revealed that some serpins and RhoGAPs expressed in TCs inhibited host cellular immunity. This study reports a transcriptome of the unique TC animal cell and its immunosuppressive genetic factors using ex vivo RNAi technology.
专门的黄蜂细胞——畸胎细胞（TCs）源自一些寄生膜翅目昆虫的胚胎浆膜。作为一种寄生因子，TCs在宿主调节方面具有多种功能，如使宿主营养匮乏、免疫抑制和发育停滞；然而，人们对其基因组成了解甚少。本研究通过基于RNA测序技术的转录组分析，全面展示了TCs表达的基因。组装得到的34686个重叠群（>200个碱基对）被注释到不同的功能类别中，这表明与血细胞和脂肪体相比，基因转录本存在明显的分布差异。TC转录组包含胰岛素信号传导以及保幼激素和20-羟基蜕皮酮生物合成的成分。TCs还表达了各类消化酶，这表明它们在寄生过程中对寄生幼虫的生长具有营养作用。此外，通过该转录组分析，注释了两种免疫抑制性丝氨酸蛋白酶抑制剂（丝氨酸蛋白酶抑制剂）和Rho GTP酶激活蛋白（RhoGAPs）。为了确定这些因子的生物学功能，我们设计了体外RNA干扰（RNAi），通过在体外培养的TCs中敲低基因表达，然后将处理过的TCs注射到受试昆虫体内来进行。体外RNAi显示，TCs中表达的一些丝氨酸蛋白酶抑制剂和RhoGAPs抑制了宿主的细胞免疫。本研究利用体外RNAi技术报道了独特的TC动物细胞的转录组及其免疫抑制遗传因子。
