Department of Entomology, College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China.
State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, Shaanxi, China.
PLoS Pathog. 2020 Jun 25;16(6):e1008627. doi: 10.1371/journal.ppat.1008627. eCollection 2020 Jun.
Different from holometabolous insects, the hemipteran species such as pea aphid Acyrthosiphon pisum exhibit reduced immune responses with the absence of the genes coding for antimicrobial peptide (AMP), immune deficiency (IMD), peptidoglycan recognition proteins (PGRPs), and other immune-related molecules. Prior studies have proved that phenoloxidase (PO)-mediated melanization, hemocyte-mediated phagocytosis, and reactive oxygen species (ROS) participate in pea aphid defense against bacterial infection. Also, the conserved signaling, Jun N-terminal kinase (JNK) pathway, has been suggested to be involved in pea aphid immune defense. However, the precise role of the JNK signaling, its interplay with other immune responses and its regulation in pea aphid are largely unknown. In this study, using in vitro biochemical assays and in vivo bioassays, we demonstrated that the JNK pathway regulated hemolymph PO activity, hydrogen peroxide concentration and hemocyte phagocytosis in bacteria infected pea aphids, suggesting that the JNK pathway plays a central role in regulating immune responses in pea aphid. We further revealed the JNK pathway is regulated by microRNA-184 in response to bacterial infection. It is possible that in common the JNK pathway plays a key role in immune system of hemipteran insects and microRNA-184 regulates the JNK pathway in animals.
不同于全变态昆虫，半翅目物种，如豌豆蚜 Acyrthosiphon pisum，表现出免疫反应减弱，缺乏编码抗菌肽（AMP）、免疫缺陷（IMD）、肽聚糖识别蛋白（PGRPs）和其他免疫相关分子的基因。先前的研究已经证明，酚氧化酶（PO）介导的黑化、血细胞介导的吞噬作用和活性氧（ROS）参与了豌豆蚜抵御细菌感染的防御反应。此外，保守的信号转导 Jun N 端激酶（JNK）途径被认为参与了豌豆蚜的免疫防御。然而，JNK 信号的精确作用、它与其他免疫反应的相互作用及其在豌豆蚜中的调节作用在很大程度上尚不清楚。在这项研究中，我们使用体外生化测定和体内生物测定，证明了 JNK 途径调节了感染细菌的豌豆蚜的血淋巴 PO 活性、过氧化氢浓度和血细胞吞噬作用，表明 JNK 途径在调节豌豆蚜的免疫反应中起着核心作用。我们进一步揭示了 JNK 途径是通过 microRNA-184 来响应细菌感染进行调节的。可能在半翅目昆虫的免疫系统中，JNK 途径起着关键作用，而 microRNA-184 则在动物中调节 JNK 途径。
