ABSTRACT

Macroautophagy/autophagy is an important innate and adaptive immune response that can clear microbial pathogens through guiding their degradation. Virus infection in animals and plants is also known to induce autophagy. However, how virus infection induces autophagy is largely unknown. Here, we provide evidence that the early phase of rice black-streaked dwarf virus (RBSDV) infection in Laodelphax striatellus can also induce autophagy, leading to suppression of RBSDV invasion and accumulation. We have determined that the main capsid protein of RBSDV (P10) is the inducer of autophagy. RBSDV P10 can specifically interact with GAPDH (glyceraldehyde-3-phosphate dehydrogenase), both in vitro and in vivo. Silencing of GAPDH in L. striatellus could significantly reduce the activity of autophagy induced by RBSDV infection. Furthermore, our results also showed that both RBSDV infection and RBSDV P10 alone can promote phosphorylation of AMP-activated protein kinase (AMPK), resulting in GAPDH phosphorylation and relocation of GAPDH from the cytoplasm into the nucleus in midgut cells of L. striatellus or Sf9 insect cells. Once inside the nucleus, phosphorylated GAPDH can activate autophagy to suppress virus infection. Together, these data illuminate the mechanism by which RBSDV induces autophagy in L. striatellus, and indicate that the autophagy pathway in an insect vector participates in the anti-RBSDV innate immune response.

Abbreviations3-MA: 3-methyladenine; AMPK: AMP-activated protein kinase; ATG: autophagy-related; co-IP: co-immunoprecipitation; DAPI: 4ʹ,6-diamidino-2-phenylindole; dpf: days post-feeding; dsRNA: double-stranded RNA; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GST: glutathione-S-transferase; RBSDV: Rice black-streaked dwarf virus; TEM: transmission electron microscope.

摘要

巨自噬/自噬是一种重要的先天性和适应性免疫反应，可以通过引导微生物病原体降解来清除病原体。还已知动物和植物中的病毒感染会诱导自噬。然而，病毒感染如何诱导自噬在很大程度上是未知的。在这里，我们提供的证据表明，在灰飞虱中水稻黑条矮缩病毒 (RBSDV) 感染的早期阶段也可以诱导自噬，从而抑制 RBSDV 的侵袭和积累。我们已经确定 RBSDV 的主要衣壳蛋白 (P10) 是自噬的诱导剂。RBSDV P10 可以在体外和体内特异性地与 GAPDH（3-磷酸甘油醛脱氢酶）相互作用。GAPDH的沉默L. striatellus可显着降低 RBSDV 感染诱导的自噬活性。此外，我们的研究结果还表明 RBSDV 感染和 RBSDV P10 单独可以促进 AMP 活化蛋白激酶 (AMPK) 的磷酸化，导致 GAPDH 磷酸化和 GAPDH 从细胞质重新定位到L. striatellus或 Sf9中肠细胞的细胞核中昆虫细胞。一旦进入细胞核，磷酸化的 GAPDH 可以激活自噬以抑制病毒感染。总之，这些数据阐明了 RBSDV 在L. striatellus中诱导自噬的机制，并表明昆虫载体中的自噬途径参与了抗 RBSDV 先天免疫反应。

缩写3-MA：3-甲基腺嘌呤；AMPK：AMP激活的蛋白激酶；ATG：自噬相关；co-IP：免疫共沉淀；DAPI：4ʹ,6-二脒基-2-苯基吲哚；dpf：喂食后天数；dsRNA：双链 RNA；GAPDH：3-磷酸甘油醛脱氢酶；GST：谷胱甘肽-S-转移酶；RBSDV：水稻黑条矮缩病毒；TEM：透射电子显微镜。