Double-stranded RNA binding protein, Staufen, is required for the initiation of RNAi in coleopteran insects

RNA interference (RNAi) is being used to develop methods to control pests and disease vectors. RNAi is robust and systemic in coleopteran insects but is quite variable in other insects. The determinants of efficient RNAi in coleopterans, as well as its potential mechanisms of resistance, are not known. RNAi screen identified a double-stranded RNA binding protein (StaufenC) as a major player in RNAi. StaufenC is homologs have been identified in only coleopteran insects. Experiments in two coleopteran insects, Leptinotarsa decemlineata and Tribolium castaneum showed the requirement of StaufenC for RNAi especially for processing of dsRNA to siRNA. RNAi resistant cells selected by exposing Lepd-SL1 to the inhibitor of apoptosis 1 dsRNA for multiple generations showed lower levels of StaufenC expression when compared to its expression in susceptible cells. These studies showed that coleopteran specific StaufenC is required for RNAi and is a potential target for RNAi resistance. The data included in this paper will help to improve RNAi in non-coleopteran insects and manage RNAi resistance in coleopteran insects.

RNA干扰技术（RNAi）正被应用于开发控制害虫及疾病传播媒介的方法。RNAi在鞘翅目昆虫中表现出强大的系统性和稳定性，但在其他昆虫中则存在较大的变异性。鞘翅目昆虫中高效RNAi的决定因素及其潜在的抵抗机制尚不明确。RNAi筛选鉴定出一种双链RNA结合蛋白（StaufenC）为RNAi的主要作用者。仅在鞘翅目昆虫中发现了StaufenC的同源蛋白。在两种鞘翅目昆虫——黄粉甲（Leptinotarsa decemlineata）和拟谷盗（Tribolium castaneum）的实验中，证实了StaufenC对于RNAi的必要性，尤其是在双链RNA（dsRNA）向小干扰RNA（siRNA）的加工过程中。通过将Lepd-SL1暴露于凋亡1型双链RNA抑制剂多代，选育出的RNAi抵抗细胞相比易感细胞，StaufenC的表达水平显著降低。这些研究揭示了鞘翅目特异性的StaufenC对于RNAi至关重要，并且是RNAi抵抗的潜在靶点。本文所包含的数据将有助于提升非鞘翅目昆虫中的RNAi效果，并管理鞘翅目昆虫中的RNAi抵抗问题。