ABSTRACT
Insects rely on their innate immune system to eliminate pathogenic microbes. As a system component, cytokines transmit intercellular signals to control immune responses. Growth-blocking peptide (GBP) is a member of the stress-responsive peptide family of cytokines found in several orders of insects, including Drosophila. However, the physiological role of GBP in defence against pathogens is not thoroughly understood. In this study, we explored the functions of GBP in a lepidopteran pest, Ostrinia furnacalis. Injection of recombinant O. furnacalis GBP (OfGBP) precursor (proGBP) and chemically synthesised GBP significantly induced the transcription of antimicrobial peptides (AMPs) and other immunity-related genes including immune deficiency (IMD) and Dorsal. The level of OfGBP mRNA was upregulated after bacterial infection. Knockdown of OfGBP expression led to a decrease in IMD, Relish, MyD88 and Dorsal mRNA levels. OfGBP induced phenoloxidase activity and affected hemocyte behaviours in O. furnacalis larvae. In summary, GBP is a potent cytokine, effectively regulating AMP synthesis, melanization response and cellular immunity to eliminate invading pathogens.
Subject(s)
Insect Proteins , Larva , Moths , Animals , Moths/immunology , Moths/genetics , Moths/growth & development , Insect Proteins/metabolism , Insect Proteins/genetics , Larva/growth & development , Larva/immunology , Antimicrobial Peptides/pharmacology , Antimicrobial Peptides/genetics , Antimicrobial Peptides/metabolism , Hemocytes/metabolism , Immunity, InnateABSTRACT
JAK/STAT signaling pathway is involved in important biological processes, such as cell growth, differentiation, apoptosis and immune regulation, and is one of the most important signal transduction pathways mediated by cytokines. JAK/STAT is a relatively conserved signaling pathway in insects, which is the main immune pathway together with Toll signaling pathway and Imd signaling pathway to resist the invasion of pathogens. It plays a vital role in insect immunity, hormone regulation and other physiological regulation processes. In this review, we summarize the cytokine receptor superfamily, JAKs family, STATs family, JAK/STAT signaling pathway and its mechanism of negative feedback regulation. We analyze the important functions and the latest research progress of JAK/STAT signaling pathway in insect infected by parasites, viruses and fungi. Finally, we propose the remaining problems in the study of JAK/STAT signaling pathway, so as to provide direction and reference for further research in this field.
