Galactose-NlGr11 inhibits AMPK phosphorylation by activating the PI3K-AKT-PKF-ATP signaling cascade via insulin receptor and Gβγ

The interaction between 20-hydroxyecdysone and AMPK through PI3K activation in Chinese mitten crab, Eriocheir sinensis

In crustaceans, the steroid hormone 20-hydroxyecdysone (20E) initiates molting, and the molting process is also regulated by energy metabolism. AMPK is an energy sensor and plays a critical role in systemic energy balance. Here, the regulatory mechanism in the interaction between 20E and AMPK was investigated in Chinese mitten crab, Eriocheir sinensis. The results showed that the 20E concentration and the mRNA expression levels of 20E receptors in hepatopancreas were down-regulated post AMPK activator (AICAR) treatment, and were up-regulated after AMPK inhibitor (Compound C) injection in crabs. Besides, the molt-inhibiting hormone (MIH) gene expression in eyestalk showed the opposite patterns in response to the AICAR and Compound C treatment, respectively. Further investigation found that there was a significant reduction in 20E concentration post PI3K inhibitor (LY294002) treatment, and the phosphorylation level of PI3K was increased in hepatopancreas after AMPK inhibitor injection. On the other hand, the positive regulation of PI3K-mediated activation of AMPK was also observed, the phosphorylation levels of AMPKα, AMPKβ and PI3K in hepatopancreas were significantly increased post 20E injection. In addition, the phosphorylation levels of AMPKα and AMPKβ induced by 20E were decreased after the injection of PI3K inhibitor. Taken together, these results suggest that the regulatory cross-talk between 20E and AMPK is likely to act through PI3K pathway in E. sinensis, which appeared to be helpful for a better understanding in molting regulation.

Functional characterization of the InR/PI3K/AKT signaling pathway in female reproduction of the predatory bug Cyrtorhinus lividipennis (Hemiptera: Miridae)

The insulin signaling (IIS) pathway plays a key role in the regulation of various physiological functions in animals. However, the involvement of IIS pathway in the reproduction of natural enemy insects remains enigmatic. Here, 3 key genes (named ClInR, ClPI3K, and ClAKT) related to IIS pathway were cloned from Cyrtorhinus lividipennis (Reuter) (Hemiptera: Miridae), an important natural enemy in the rice ecosystem. These 3 proteins had the typical features of corresponding protein families and shared high similarity with their respective homologs from the Hemipteran species. The ClInR, ClPI3K, and ClAKT were highly expressed in the adult stage. Tissue distribution analysis revealed that ClInR, ClPI3K, and ClAKT were highly expressed in the midgut and ovary of adults. Silencing of ClInR, ClPI3K, and ClAKT caused 92.1%, 72.1%, and 57.8% reduction in the expression of ClVg, respectively. Depletion of these 3 genes impaired vitellogenin synthesis and ovary development. Moreover, the fecundity in the dsInR, dsPI3K, and dsAKT injected females were 53.9%, 50.8%, and 48.5% lower than the control treatment, respectively. These results indicated that ClInR, ClPI3K, and ClAKT are of great importance for the reproduction of C. lividipennis. Our results advance the knowledge about the molecular mechanism of reproduction regulation in natural enemy insects.

Impact of Preparative Isolation of C-Glycosylflavones Derived from Dianthus superbus on In Vitro Glucose Metabolism

Dianthus superbus L. has been extensively studied for its potential medicinal properties in traditional Chinese medicine and is often consumed as a tea by traditional folk. It has the potential to be exploited in the treatment of inflammation, immunological disorders, and diabetic nephropathy. Based on previous studies, this study continued the separation of another subfraction of Dianthus superbus and established reversed-phase/reversed-phase and reversed-phase/hydrophilic (RPLC) two-dimensional (2D) high-performance liquid chromatography (HPLC) modes, quickly separating two C-glycosylflavones, among which 2″-O-rhamnosyllutonarin was a new compound and isomer with 6‴-O-rhamnosyllutonarin. This is the first study to investigate the effects of 2″-O-rhamnosyllutonarin and 6‴-O-rhamnosyllutonarin on cellular glucose metabolism in vitro. First, molecular docking was used to examine the effects of 2″-O-rhamnosyllutonarin and 6″-O-rhamnosyllutonarin on AKT and AMPK; these two compounds exhibited relatively high activity. Following this, based on the HepG2 cell model of insulin resistance, it was proved that both of the 2″-O-rhamnosyllutonarin and 6‴-O-rhamnosyllutonarin demonstrated substantial efficacy in ameliorating insulin resistance and were found to be non-toxic. Simultaneously, it is expected that the methods developed in this study will provide a basis for future studies concerning the separation and pharmacological effects of C-glycosyl flavonoids.

Identification of a new gustatory receptor BminGR59b tuned to host wax in a specialist, Bactrocera minax (Diptera: Tephritidae)

Host location plays a pivotal role in the coevolution between insects and plants, particularly for specialist insect herbivores with a limited host range. However, how specialists precisely select the appropriate site for oviposition through gustatory system remains elusive. In this study, we investigated the effects of the gustatory system on the host plant selection of a devastating pest in Citrus spp., Bactrocera minax, by conducting behavioral assays. Through genomic and transcriptomic data analysis as well as RNAi technology, we identified a novel gustatory receptor, BminGR59b, highly expressed in the forelegs of female B. minax, which played a critical role in host plant selection before oviposition decision. Additionally, our results encompassing heterologous expression in Sf9 cells and oviposition behavior assay revealed that n-eicosane is the ligand for BminGR59b. Finally, employing the dual luciferase reporter system alongside yeast one-hybrid techniques and RNAi, we verified that the transcription factor BminCEBP regulated the up-regulation of BminGR59b in sexually matured adults. These findings offer new insights into the close-range host fruit recognition and selection for oviposition in a specialist tephritid fruit fly B. minax, which also sheds light on the transcriptional regulation mechanisms underlying the gustatory-mediated oviposition in specialist herbivores for the first time.

Ligand dose-dependent activation of signaling pathways through the gustatory receptor NlGr11 linked to feeding efficacy in Nilaparvata lugens

Insects often face both conditions with sufficient nutrients and conditions of undernutrition in the field. Through gustatory receptors, insects sense nutrients and regulate their physiological functions such as feeding and reproduction. However, it remains unclear whether signaling pathways activated by gustatory receptors depend on the concentration of nutrients and whether the difference in signaling pathways directly affects insects' physiological functions. Herein, we found that a sugar gustatory receptor, NlGr11, from the brown planthopper (BPH), Nilaparvata lugens, activated G protein-coupled signaling and ionotropic pathways when bound to high galactose concentration. BPHs subsequently demonstrated longer feeding times, feeding loads, and higher vitellogenin (NlVg) expression than BPHs exposed to high galactose concentrations, which only activated the ionotropic pathway. For the first time, our findings link plant nutrient conditions, signaling pathways activated by nutrients, and their gustatory receptors, and nutrient dose-dependent feeding efficacy and vitellogenin (Vg) expression in an insect. This will help us to better understand the molecular mechanism for insect feeding strategies on plants at different stages of nutritional conditions.

Comparison of the signaling pathways of wing dimorphism regulated by biotic and abiotic stress in the brown planthopper

Wing polymorphism is an evolutionary trait that is widely present in various insects and provides a model system for studying the evolutionary significance of insect dispersal. The brown planthopper (BPH, Nilaparvata lugens) can alter its wing morphs under biotic and abiotic stress. However, whether differential signaling pathways are induced by the 2 types of stress remain largely unknown. Here, we screened a number of candidate genes through weighted gene co-expression network analysis (WGCNA) and found that ornithine decarboxylase (NlODC), a key enzyme in the synthesis of polyamines, was associated with wing differentiation in BPH and mainly responded to abiotic stress stimuli. We analyzed the Kyoto Encyclopedia of Genes and Genomes enrichment pathways of differentially expressed genes under the 2 stresses by transcriptomic comparison, and found that biotic stress mainly influenced insulin-related signaling pathways while abiotic stress mainly influenced hormone-related pathways. Moreover, we found that insulin receptor 1 (NlInR1) may regulate wing differentiation of BPH by responding to both biotic and abiotic stress, but NlInR2 only responded to biotic stress. Similarly, the juvenile hormone epoxide hydrolase associated with juvenile hormone degradation and NlODC may regulate wing differentiation mainly through abiotic stress. A model based on the genes and stresses to modulate the wing dimorphism of BPH was proposed. These findings present a comprehensive molecular mechanism for wing polymorphism in BPH induced by biotic and abiotic stress.

Application of Silk-Fibroin-Based Hydrogels in Tissue Engineering

Silk fibroin (SF) is an excellent protein-based biomaterial produced by the degumming and purification of silk from cocoons of the Bombyx mori through alkali or enzymatic treatments. SF exhibits excellent biological properties, such as mechanical properties, biocompatibility, biodegradability, bioabsorbability, low immunogenicity, and tunability, making it a versatile material widely applied in biological fields, particularly in tissue engineering. In tissue engineering, SF is often fabricated into hydrogel form, with the advantages of added materials. SF hydrogels have mostly been studied for their use in tissue regeneration by enhancing cell activity at the tissue defect site or counteracting tissue-damage-related factors. This review focuses on SF hydrogels, firstly summarizing the fabrication and properties of SF and SF hydrogels and then detailing the regenerative effects of SF hydrogels as scaffolds in cartilage, bone, skin, cornea, teeth, and eardrum in recent years.

Oxalic Acid Inhibits Feeding Behavior of the Brown Planthopper via Binding to Gustatory Receptor Gr23a

Plants produce diverse secondary compounds as natural protection against microbial and insect attack. Most of these compounds, including bitters and acids, are sensed by insect gustatory receptors (Grs). Although some organic acids are attractive at low or moderate levels, most acidic compounds are potentially toxic to insects and repress food consumption at high concentrations. At present, the majority of the reported sour receptors function in appetitive behaviors rather than aversive taste responses. Here, using two different heterologous expression systems, the insect Sf9 cell line and the mammalian HEK293T cell line, we started from crude extracts of rice (Oryza sativa) and successfully identified oxalic acid (OA) as a ligand of NlGr23a, a Gr in the brown planthopper Nilaparvata lugens that feeds solely on rice. The antifeedant effect of OA on the brown planthopper was dose dependent, and NlGr23a mediated the repulsive responses to OA in both rice plants and artificial diets. To our knowledge, OA is the first identified ligand of Grs starting from plant crude extracts. These findings on rice-planthopper interactions will be of broad interest for pest control in agriculture and also for better understanding of how insects select host plants.

Therapeutic effects and mechanism of Atractylodis rhizoma in acute lung injury: Investigation based on an Integrated approach

Acute lung injury (ALI) is characterized by an excessive inflammatory response. Atractylodes lancea (Thunb.) DC. is a traditional chinese medicine with good anti-inflammatory activity that is commonly used clinically for the treatment of lung diseases in China; however, its mechanism of against ALI is unclear. We clarified the therapeutic effects of ethanol extract of Atractylodis rhizoma (EEAR) on lipopolysaccharide (LPS)-induced ALI by evaluation of hematoxylin-eosin (HE) stained sections, the lung wet/dry (W/D) ratio, and levels of inflammatory factors as indicators. We then characterized the chemical composition of EEAR by ultra-performance liquid chromatography and mass spectrometry (UPLC-MS) and screened the components and targets by network pharmacology to clarify the signaling pathways involved in the therapeutic effects of EEAR on ALI, and the results were validated by molecular docking simulation and Western blot (WB) analysis. Finally, we examined the metabolites in rat lung tissues by gas chromatography and mass spectrometry (GC-MS). The results showed that EEAR significantly reduced the W/D ratio, and tumor necrosis factor-α (TNF-α), interleukin-1 beta (IL-1β), interleukin-6 (IL-6) levels in the lungs of ALI model rats. Nineteen components of EEAR were identified and shown to act synergetically by regulating shared pathways such as the mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT) signaling pathways. Ferulic acid, 4-methylumbelliferone, acetylatractylodinol, atractylenolide I, and atractylenolide III were predicted to bind well to PI3K, AKT and MAPK1, respectively, with binding energies < -5 kcal/mol, although only atractylenolide II bound with high affinity to MAPK1. EEAR significantly inhibited the phosphorylation of PI3K, AKT, p38, and ERK1/2, thus reducing protein expression. EEAR significantly modulated the expression of metabolites such as D-Galactose, D-Glucose, serine and D-Mannose. These metabolites were mainly concentrated in the galactose and amino acid metabolism pathways. In conclusion, EEAR alleviates ALI by inhibiting activation of the PI3K-AKT and MAPK signaling pathways and regulating galactose metabolism, providing a new direction for the development of drugs to treat ALI.