Hemolin increases the immune response of a caterpillar to NPV infection.

Hemolin, a member of the immunoglobulin superfamily, plays a crucial role in the immune responses of insects against pathogens. However, the innate immune response of Hemolin to baculovirus infection varies among different insects, and the antiviral effects of Hemolin in Hyphantria cunea (HcHemolin) remain poorly understood. Our results showed that HcHemolin was expressed throughout all developmental stages, with higher expressions observed during pupal and adult stages of H. cunea. Additionally, HcHemolin was expressed in reproductive and digestive organs. The expression levels of the HcHemolin were induced significantly following H. cunea nucleopolyhedrovirus (HcNPV) infection. The susceptibility of H. cunea larvae to HcNPV decreased upon silencing of HcHemolin, resulting in a 40% reduction in median lifespan compared to the control group. The relative growth rate (RGR), the relative efficiency of consumption rate (RCR), the efficiency of the conversion of ingested food (ECI), and efficiency of the conversion of digested food (ECD) of silenced H. cunea larvae were significantly lower than those of the control group. Immune challenge assays showed that the median lifespan of treated H. cunea larvae was two-fold longer than the control group after HcNPV and HcHemolin protein co-injection. Therefore, we propose that HcHemolin plays a crucial role in regulating the growth, development, and food utilization of H. cunea, as well as in the antiviral immune response against HcNPV. These findings provide implications for the development of targeted nucleic acid pesticides and novel strategies for pollution-free biological control synergists for HcNPV.

Identification and characterization of key genes in insulin signaling pathway as molecular targets for controlling the fall webworm, Hyphantria cunea.

BACKGROUND: The insulin signaling pathway is closely related to metabolism, growth, reproductive capacity and lifespan of insects. However, the physiological function of the insulin signaling pathway is little known in Hyphantria cunea. RESULTS: Five insulin signaling pathway genes (HcInR, HcPI3K, HcAKT, HcFOXO and HcTOR) in H. cunea were identified and characterized in this study. The spatiotemporal expression profiles of the genes showed that HcInR, HcAKT, HcPI3K and HcTOR expressions were higher at the egg stage than those in other development stages, whereas HcFOXO was highly expressed in the adult stage; all of these genes were highly expressed in the larval digestive system, especially in the midgut and hindgut. After RNA interference (RNAi) of the five genes in 5th instar H. cunea larvae, weight gain and survival rate (except in the siHcAKT-injected group) were significantly decreased, and the developmental duration of larval and pupal stages were prolonged. In addition, knockdown of five genes in 7th instar larvae decreased the pupation rate, survival rate and oviposition capacity, and resulted in abnormal development during larval-pupal transition. CONCLUSION: Our findings indicate that the insulin signaling pathway plays essential roles in growth and development and the molting process in H. cunea, providing an important basis for developing new potentially molecular targets for RNAi-based pest control and understanding the mechanism of H. cunea outbreak. © 2022 Society of Chemical Industry.

Bursicon receptor gene HLGR2 as a potential RNA interference target for control of the fall webworm Hyphantria cunea.

BACKGROUND: Insect G protein-coupled receptors (GPCRs) have been identified as a new generation of attractive targets for RNA interference (RNAi)-based pest control. A functional study of the leucine-rich repeat-containing (LGR2) gene in Hyphantria cunea (HLGR2) was performed to examine whether it can be used in the molecular control of this notorious pest. RESULTS: The complementary DNA (cDNA) sequence and deduced amino acids of HLGR2 were obtained and analyzed in the present study. HLGR2 is a typical GPCR and shows high structural and sequence similarity with other insect LGR2 proteins. The spatiotemporal expression profiles of HLGR2 showed that HLGR2 was highly expressed at the egg stage and tissues of head and silk gland. After RNAi of HLGR2, distinct phenotypes were observed when HLGR2 expression was suppressed, indicating that HLGR2 is essential in pupation and eclosion. HLGR2 RNAi led to a low pupation rate (45.00%), body malformation, abnormal wing expansion, failed cuticle melanization (63.33%), and high mortality rate (48.33%). Furthermore, we identified eight genes that are regulated by HLGR2. The expression of these eight genes was induced by the HLGR2 signaling pathway and correlated well with cuticle sclerotization. Unlike LGR2 in other insect species, HLGR2 was found to play a crucial role in the control of H. cunea during ecdysis and postecdysial stages. CONCLUSION: HLGR2 is essential for the growth and development and wing expansion and maturation in H. cunea, suggesting HLGR2 is a promising candidate for application in RNAi-based control of this notorious agriculture-forest pest. © 2021 Society of Chemical Industry.

N-acetylcysteine stimulates protein synthesis in enterocytes independently of glutathione synthesis.

Dietary supplementation with N-acetylcysteine (NAC) has been reported to improve intestinal health and treat gastrointestinal diseases. However, the underlying mechanisms are not fully understood. According to previous reports, NAC was thought to exert its effect through glutathione synthesis. This study tested the hypothesis that NAC enhances enterocyte growth and protein synthesis independently of cellular glutathione synthesis. Intestinal porcine epithelial cells were cultured for 3 days in Dulbecco's modified Eagle medium containing 0 or 100 µM NAC. To determine a possible role for GSH (the reduced form of glutathione) in mediating the effect of NAC on cell growth and protein synthesis, additional experiments were conducted using culture medium containing 100 µM GSH, 100 µM GSH ethyl ester (GSHee), diethylmaleate (a GSH-depletion agent; 10 µM), or a GSH-synthesis inhibitor (buthionine sulfoximine, BSO; 20 µM). NAC increased cell proliferation, GSH concentration, and protein synthesis, while inhibiting proteolysis. GSHee enhanced cell proliferation and GSH concentration without affecting protein synthesis but inhibited proteolysis. Conversely, BSO or diethylmaleate reduced cell proliferation and GSH concentration without affecting protein synthesis, while promoting protein degradation. At the signaling level, NAC augmented the protein abundance of total mTOR, phosphorylated mTOR, and phosphorylated 70S6 kinase as well as mRNA levels for mTOR and p70S6 kinase in IPEC-1 cells. Collectively, these results indicate that NAC upregulates expression of mTOR signaling proteins to stimulate protein synthesis in enterocytes independently of GSH generation. Our findings provide a hitherto unrecognized biochemical mechanism for beneficial effects of NAC in intestinal cells.