Eleven oleanane triterpenoids (1-11) including two new ones (1 and 2) were isolated from the roots and stems of Caulophyllum robustum. Their structures were established by extensive spectroscopic analysis, comparison with literature, and NMR calculations. Compounds 1 and 2 represent the first examples of 23-hydroxy-28-nor-oleanane and 21-hydroxy-olean-3-one triterpenoids, respectively. All isolates were evaluated for their PTP1B and α-glucosidase inhibitory activities in vitro. Among them, the triterpene aglycones 1-5 showed almost equivalent PTP1B inhibitory activities to oleanolic acid and ursolic acid, while 1, 2, and the triterpene saponins 6-11 showed significant α-glucosidase inhibitory activities. Furthermore, compounds 1 and 3 were proved to regulate the expression of proteins implicated the PTP1B/IRS-1/pIRS-1 signalling pathway to improve insulin resistance.

BACKGROUND: The insulin/insulin-like signalling (IIS) pathway is common in mammals and invertebrates, and the IIS pathway is unknown in Fasciola gigantica. In the present study, the IIS pathway was reconstructed in F. gigantica. We defined the components involved in the IIS pathway and investigated the transcription profiles of these genes for all developmental stages of F. gigantica. In addition, the presence of these components in excretory and secretory products (ESPs) was predicted via signal peptide annotation.
RESULTS: The core components of the IIS pathway were detected in F. gigantica. Among these proteins, one ligand (FgILP) and one insulin-like molecule binding protein (FgIGFBP) were analysed. Interestingly, three receptors (FgIR-1/FgIR-2/FgIR-3) were detected, and a novel receptor, FgIR-3, was screened, suggesting novel functions. Fg14-3-3ζ, Fgirs, and Fgpp2a exhibited increased transcription in 42-day-old juveniles and 70-day-old juveniles, while Fgilp, Fgigfb, Fgsgk-1, Fgakt-1, Fgir-3, Fgpten, and Fgaap-1 exhibited increased transcription in metacercariae. FgILP, FgIGFBP, FgIR-2, FgIR-3, and two transcription factors (FgHSF-1 and FgSKN-1) were predicted to be present in FgESPs, indicating their exogenous roles.
CONCLUSIONS: This study helps to elucidate the signal transduction pathway of IIS in F. gigantica, which will aid in understanding the interaction between flukes and hosts, as well as in understanding fluke developmental regulation, and will also lay a foundation for further characterisation of the IIS pathways of trematodes.

A 60-d feeding trial was conducted to explore the potential regulatory effects of dietary Clostridium butyricum cultures (CBC) supplementation in high-carbohydrate diet (HCD) on carbohydrate utilisation, antioxidant capacity and intestinal microbiota of largemouth bass. Triplicate groups of largemouth bass (average weight 35·03 ± 0·04 g), with a destiny of twenty-eight individuals per tank, were fed low-carbohydrate diet and HCD supplemented with different concentration of CBC (0 %, 0·25 %, 0·50 % and 1·00 %). The results showed that dietary CBC inclusion alleviated the hepatic glycogen accumulation induced by HCD intake. Additionally, the expression of hepatic ampkα1 and insulin signaling pathway-related genes (ira, irb, irs, p13kr1 and akt1) increased linearly with dietary CBC inclusion, which might be associated with the activation of glycolysis-related genes (gk, pfkl and pk). Meanwhile, the expression of intestinal SCFA transport-related genes (ffar3 and mct1) was significantly increased with dietary CBC inclusion. In addition, the hepatic antioxidant capacity was improved with dietary CBC supplementation, as evidenced by linear decrease in malondialdehyde concentration and expression of keap1, and linear increase in antioxidant enzyme activities (total antioxidative capacity, total superoxide dismutase and catalase) and expression of antioxidant enzyme-related genes (nrf2, sod1, sod2 and cat). The analysis of bacterial 16S rRNA V3-4 region indicated that dietary CBC inclusion significantly reduced the enrichment of Firmicutes and potential pathogenic bacteria genus Mycoplasma but significantly elevated the relative abundance of Fusobacteria and Cetobacterium. In summary, dietary CBC inclusion improved carbohydrate utilization, antioxidant capacity and intestinal microbiota of largemouth bass fed HCD.

OBJECTIVE: What are the proteomic and phosphoproteomic differences between the endometrium of women with recurrent pregnancy loss (RPL) and the endometrium of healthy control women during the proliferative and secretory phases of the menstrual cycle?
METHODS: In total, 54 endometrial samples were collected during the proliferative and secretory phases from women with RPL (n = 28) and healthy controls (n = 26). Comprehensive proteomic and phosphoproteomic analyses were conducted using label-free liquid chromatography-tandem mass spectrometry (n = 44), and verified through Western blotting (n = 10). Three comparison groups were established: total RPL endometrium versus total control endometrium; RPL proliferative endometrium versus control proliferative endometrium; and RPL secretory endometrium versus control secretory endometrium.
RESULTS: Differentially expressed proteins and differentially phosphorylated proteins were identified in the three comparison groups. Combining pathway enrichment, network analysis and soft clustering analysis, the insulin/cyclic nucleotide signalling pathway and AMPK/mTOR signalling pathway were identified as the major contributors to the aberration of RPL endometrium. Western blotting verified altered expression of four proteins: cAMP-dependent protein kinase type I-β regulatory subunit, adenylate cyclase type 3, 5\'-AMP-activated protein kinase catalytic subunit α-2 and phosphatidate phosphatase LPIN2.
CONCLUSIONS: This exploratory study provides insights into the differentiated protein expression and phosphorylation profiles of the endometrium of women with RPL in both the proliferative and sectretory phases of the menstrual cycle. The results highlight potential proteins associated with the pathogenesis of RPL that may serve as potential indicators for RPL. The findings contribute to the identification of potential targets for RPL treatment as well as its pathogenesis.

BACKGROUND: Insulin signalling pathways play crucial roles in regulating growth and development in insects, but their effects on the growth and development of Arachnids, such as spiders, have rarely been studied. As a valuable pest natural enemy in agricultural fields, the molecular mechanisms of insulin signalling pathway-mediated growth and development of the wolf spider, Pardosa pseudoannulata, are of particular interest.
RESULTS: In this study, we identified and characterized six insulin signalling pathway genes - InR, InR2, IRS1, PI3K1, PI3K2, and PDK - in Pardosa pseudoannulata. Real-time quantitative polymerase chain reaction results were used to analyse the relative expression levels of the six genes in different developmental instars and tissues, and in response to starvation treatment. In addition, the function of the insulin receptor substrate (IRS1) gene was investigated using RNA interference technology, which found that IRS1 significantly influenced nutrient content, developmental duration, body weight, and gonad development.
CONCLUSIONS: This study revealed the roles of six key insulin signalling pathway genes in Pardosa pseudoannulata, and in particular the importance of the IRS1 gene in regulating growth and development in the spider. The results lay the foundation for further research on the internal regulation mechanisms of growth and development in Araneae species, and also provide a reference for the artificial breeding of spiders. © 2023 Society of Chemical Industry.

S-Adenosyl-l-methionine-dependent methyltransferases (SAMMTases) modulate important cellular and metabolic activities in both prokaryotes and eukaryotes. Here, we functionally characterized an SAMMTase gene (MTase15) in the migratory brown planthopper (BPH), Nilaparvata lugens, which is the most notorious rice pest in Asia. The cDNA sequence of MTase15 is 2764 nt in length with an open reading frame of 1218 nt encoding 405 amino acid residues. Quantitative real-time PCR analysis showed that MTase15 was readily detected from egg to adult stages and extensively distributed in various body parts of adult females and males, with slightly high levels in ovary and testis, respectively. In addition, MTase15 was transcriptionally regulated by the insulin signalling pathway in BPH. RNA-interference-mediated knockdown of MTase15 (dsMtase15) resulted in deficiencies in vitellogenin synthesis and oogenesis, and female infertility. Males with Mtase15 knockdown retained the capability of producing sperms with normal viability, but less sperm was transferred to wild-type (wt) females during copulation, and eggs laid by these wt females arrested embryogenesis. These findings not only assign a functional role to MTase15, but also provide a link between the insulin signalling pathway and epigenetic regulation in BPH reproduction.

Methamphetamine (METH), an amphetamine-like drug, is one of the most commonly used central nervous system psychostimulants worldwide. METH abuse frequently leads to cognitive decline and dementia-like changes, but the mechanisms remain poorly understood. In the present study, the mechanisms of METH-induced changes in Alzheimer\'s disease-like pathological protein in Neuro2A cells were explored. Our results indicated that METH exposure significantly increased the expression of the pathological protein hyperphosphorylated tau (p-tau). Further analysis revealed that METH exposure obviously disrupted insulin signalling, resulted in brain insulin resistance, which manifested as downregulation of the insulin receptor substrate-1, AKTser 473, and GSK3β activation. Notably, the linkage between p-tau expression and insulin signalling can be partially verified by treatment with the insulin-sensitizing drug rosiglitazone and GSK3β inhibitor TWS119 which specifically reversed METH-induced hyperphosphorylation of tau. Our results indicate that insulin signalling can be therapeutically exploited for attenuating METH-induced upregulation of p-tau.

OBJECTIVE: Even with great advances in modern medicine and therapeutic agent development, the search for effective antidiabetic drugs remains challenging. Coumarins are secondary metabolites found widely in nature plants and used mainly in anticoagulation and antithrombotic therapy. Over the past two decades, however, there has been an increasing body of literatures related to the effects of coumarins and their derivatives on diabetes and its complications. This review aimed to focus on research findings concerning the effects of coumarins against diabetes and its complications using in-vitro and in-vivo animal models, and also to discuss cellular and molecular mechanisms underlying these effects.
RESULTS: The search for new coumarins against diabetes and it complications, either isolated from traditional medicine or chemically synthesized, has been constantly expanding. The cellular and molecular mechanisms involved include protecting pancreatic beta cells from damage, improving abnormal insulin signalling, reducing oxidative stress/inflammation, activating AMP-activated protein kinase (AMPK), inhibiting α-glucosidases and ameliorating diabetic complications.
CONCLUSIONS: The effects and mechanisms of coumarins and their derivatives upon diabetes and its complications are discussed in current review. Further investigations remain to be carried out to develop a promising antidiabetic agent based on coumarin cores.

Recent studies have shown the therapeutic potential of curcumin in Alzheimer\'s disease (AD). In 2014, our lab found that curcumin reduced Aβ40, Aβ42 and Aβ-derived diffusible ligands in the mouse hippocampus, and improved learning and memory. However, the mechanisms underlying this biological effect are only partially known. There is considerable evidence in brain metabolism studies indicating that AD might be a brain-specific type of diabetes with progressive impairment of glucose utilisation and insulin signalling. We hypothesised that curcumin might target both the glucose metabolism and insulin signalling pathways. In this study, we monitored brain glucose metabolism in living APPswe/PS1dE9 double transgenic mice using a micro-positron emission tomography (PET) technique. The study showed an improvement in cerebral glucose uptake in AD mice. For a more in-depth study, we used immunohistochemical (IHC) staining and western blot techniques to examine key factors in both glucose metabolism and brain insulin signalling pathways. The results showed that curcumin ameliorated the defective insulin signalling pathway by upregulating insulin-like growth factor (IGF)-1R, IRS-2, PI3K, p-PI3K, Akt and p-Akt protein expression while downregulating IR and IRS-1. Our study found that curcumin improved spatial learning and memory, at least in part, by increasing glucose metabolism and ameliorating the impaired insulin signalling pathways in the brain.

OBJECTIVE: To screen a potential PTP1b inhibitor from the microbial origin-based compound library and to investigate the potential anti-diabetic effects of the inhibitor in vivo and determine its primary anti-diabetic mechanism in vitro and in silico.
METHODS: PTP1b inhibitory activity was measured using recombination protein as the enzyme and p-NPP as the substrate. The binding of the inhibitor to PTP1b was analysed by docking in silico and confirmed by ITC experiments. The intracellular signalling pathway was detected by Western blot analysis in HepG2 cells. The anti-diabetic effects were evaluated using a diabetic mice model in vivo.
RESULTS: Among 545 microbial origin-based pure compounds tested, trivaric acid, a tridepside, was selected as a PTP1B inhibitor exhibiting strong inhibitory activity with an IC50 of 173nM. Docking and ITC studies showed that trivaric acid was able to spontaneously bind to PTP1b and may inhibit PTP1b by blocking the catalytic domain of the phosphatase. Trivaric acid also enhanced the ability of insulin to stimulate the IR/IRS/Akt/GLUT2 pathway and increase the glucose consumption in HepG2 cells. In diabetic mice, trivaric acid that had been encapsulated into Eudrgit L100-5.5 showed significant anti-diabetic effects, improving insulin resistance, leptin resistance and lipid profile and weight control at doses of 5mg/kg and 50mg/kg.
CONCLUSIONS: Trivaric acid is a potential lead compound in the search for anti-diabetic agents targeting PTP1b.