Regulation of hepatic glucose metabolism in health and disease

Maternal exposure to E 551 during pregnancy leads to genome-wide DNA methylation changes and metabolic disorders in the livers of pregnant mice and their fetuses

The widespread use of nanoparticles in the food industry has raised concerns regarding their potential adverse effects on human health, particularly in vulnerable populations, including pregnant mothers and fetuses. However, studies evaluating the reproductive and developmental toxicity of food-grade nanomaterials are limited. This study investigated the potential risks of prenatal dietary exposure to food-grade silica nanoparticles (E 551) on maternal health and fetal growth using conventional toxicological and epigenetic methods. The results showed that prenatal exposure to a high-dose of E 551 induces fetal resorption. Moreover, E 551 significantly accumulates in maternal and fetal livers, triggering a hepatic inflammatory response. At the epigenetic level, global DNA methylation is markedly altered in the maternal and fetal livers. Genome-wide DNA methylation sequencing revealed affected mCG, mCHG, and mCHH methylation landscapes. Subsequent bioinformatic analysis of the differentially methylated genes suggests that E 551 poses a risk of inducing metabolic disorders in maternal and fetal livers. This is further evidenced by impaired glucose tolerance in pregnant mice and altered expression of key metabolism-related genes and proteins in maternal and fetal livers. Collectively, the results of this study highlighted the importance of epigenetics in characterizing the potential toxicity of maternal exposure to food-grade nanomaterials during pregnancy.

Hypoglycemic effects and associated mechanisms of resveratrol and related stilbenes in diet

Hyperglycemia has become a global health problem due to changes in diet and lifestyle. Most importantly, persistent hyperglycemia can eventually develop into type II diabetes. While the usage of current drugs is limited by their side effects, stilbenes derived from fruits and herbal/dietary plants are considered as important phytochemicals with potential hypoglycemic properties. Herein, the most common stilbenoids in consumed foods, i.e. resveratrol, pterostilbene, piceatannol, oxyresveratrol, and 2,3,5,4'-tetrahydroxystilbene-2-O-β-glucopyranoside (THSG), are reviewed in this paper. These stilbenes are found to regulate glucose homeostasis via (a) modulation of feeding behaviour and nutrition absorption; (b) restoration of insulin signalling by enhancing insulin production/insulin sensitivity; (c) improvement of gut permeability, gut microbial profile and resulting metabolomes; and (d) amelioration of circadian rhythm disruption. In this review, we have summarized the underlying mechanisms for the hypoglycemic effects of the five most common dietary stilbenoids listed above, providing a comprehensive framework for future study and applications.

Advances and challenges in measuring hepatic glucose uptake with FDG PET: implications for diabetes research

The liver plays a crucial role in the control of glucose homeostasis and is therefore of great interest in the investigation of the development of type 2 diabetes. Hepatic glucose uptake (HGU) can be measured through positron emission tomography (PET) imaging with the tracer [18F]-2-fluoro-2-deoxy-D-glucose (FDG). HGU is dependent on many variables (e.g. plasma glucose, insulin and glucagon concentrations), and the metabolic state for HGU assessment should be chosen with care and coherence with the study question. In addition, as HGU is influenced by many factors, protocols and measurement conditions need to be standardised for reproducible results. This review provides insights into the protocols that are available for the measurement of HGU by FDG PET and discusses the current state of knowledge of HGU and its impairment in type 2 diabetes. Overall, a scanning modality that allows for the measurement of detailed kinetic information and influx rates (dynamic imaging) may be preferable to static imaging. The combination of FDG PET and insulin stimulation is crucial to measure tissue-specific insulin sensitivity. While the hyperinsulinaemic-euglycaemic clamp allows for standardised measurements under controlled blood glucose levels, some research questions might require a more physiological approach, such as oral glucose loading, with both advantages and complexities relating to fluctuations in blood glucose and insulin levels. The available approaches to address HGU hold great potential but await more systematic exploitation to improve our understanding of the mechanisms underlying metabolic diseases. Current findings from the investigation of HGU by FDG PET highlight the complex interplay between insulin resistance, hepatic glucose metabolism, NEFA levels and intrahepatic lipid accumulation in type 2 diabetes and obesity. Further research is needed to fully understand the underlying mechanisms and potential therapeutic targets for improving HGU in these conditions.

Incidence of traffic light labelling on noncommunicable diseases: a roadmap for achieving sustainable development

The production and diversity of the supply of food products has grown exponentially in recent decades, along with the increase in cardiovascular diseases associated with poor diet. Among the factors, one of the most important is the lack of information for the consumer when purchasing. The present work evaluates the impact of implementing the traffic light labelling of foods in reducing deaths due to Noncommunicable Diseases (NCD). Econometric techniques of two-way effects panel data from 21 Ecuadorian provinces taken from official sources for the analysis period 2010-2019. For Ecuador, a favourable impact was found in the reduction of the NCD mortality rate, especially in the last three years; in 2017, it was reduced by 0.129%, in 2018 by 0.305%, and in 2019 by 0.289%. An implication of economic policy is the advertising regulation of products that may affect health, strengthening surveillance and sanctioning companies that fail to comply with the regulation.

The opposite role of lactate dehydrogenase a (LDHA) in cervical cancer under energy stress conditions

Due to insufficient and defective vascularization, the tumor microenvironment is often nutrient-depleted. LDHA has been demonstrated to play a tumor-promoting role by facilitating the glycolytic process. However, whether and how LDHA regulates cell survival in the nutrient-deficient tumor microenvironment is still unclear. Here, we sought to investigate the role and mechanism of LDHA in regulating cell survival and proliferation under energy stress conditions. Our results showed that the aerobic glycolysis levels, cell survival and proliferation of cervical cancer cells decreased significantly after inhibition of LDHA under normal culture condition while LDHA deficiency greatly inhibited glucose starvation-induced ferroptosis and promoted cell proliferation and tumor formation under energy stress conditions. Mechanistic studies suggested that glucose metabolism shifted from aerobic glycolysis to mitochondrial OXPHOS under energy stress conditions and LDHA knockdown increased accumulation of pyruvate in the cytosol, which entered the mitochondria and upregulated the level of oxaloacetate by phosphoenolpyruvate carboxylase (PC). Importantly, the increase in oxaloacetate production after absence of LDHA remarkably activated AMP-activated protein kinase (AMPK), which increased mitochondrial biogenesis and mitophagy, promoted mitochondrial homeostasis, thereby decreasing ROS level. Moreover, repression of lipogenesis by activation of AMPK led to elevated levels of reduced nicotinamide adenine dinucleotide phosphate (NADPH), which effectively resisted ROS-induced cell ferroptosis and enhanced cell survival under energy stress conditions. These results suggested that LDHA played an opposing role in survival and proliferation of cervical cancer cells under energy stress conditions, and inhibition of LDHA may not be a suitable treatment strategy for cervical cancer.

Renal tubule-specific Atgl deletion links kidney lipid metabolism to glucagon-like peptide 1 and insulin secretion independent of renal inflammation or lipotoxicity

OBJECTIVE

Lipotoxic injury from renal lipid accumulation in obesity and type 2 diabetes (T2D) is implicated in associated kidney damage. However, models examining effects of renal ectopic lipid accumulation independent of obesity or T2D are lacking. We generated renal tubule-specific adipose triglyceride lipase knockout (RT-SAKO) mice to determine if this targeted triacylglycerol (TAG) over-storage affects glycemic control and kidney health.

METHODS

Male and female RT-SAKO mice and their control littermates were tested for changes in glycemic control at 10-12 and 16-18 weeks of age. Markers of kidney health and blood lipid and hormone concentrations were analyzed. Kidney and blood lysophosphatidic acid (LPA) levels were measured, and a role for LPA in mediating impaired glycemic control was evaluated using the LPA receptor 1/3 inhibitor Ki-16425.

RESULTS

All groups remained insulin sensitive, but 16- to 18-week-old male RT-SAKO mice became glucose intolerant, without developing kidney inflammation or fibrosis. Rather, these mice displayed lower circulating insulin and glucagon-like peptide 1 (GLP-1) levels. Impaired first-phase glucose-stimulated insulin secretion was detected and restored by Exendin-4. Kidney and blood LPA levels were elevated in older male but not female RT-SAKO mice, associated with increased kidney diacylglycerol kinase epsilon. Inhibition of LPA-mediated signaling restored serum GLP-1 levels, first-phase insulin secretion, and glucose tolerance.

CONCLUSIONS

TAG over-storage alone is insufficient to cause renal tubule lipotoxicity. This work is the first to show that endogenously derived LPA modulates GLP-1 levels in vivo, demonstrating a new mechanism of kidney-gut-pancreas crosstalk to regulate insulin secretion and glucose homeostasis.

TOX3 deficiency mitigates hyperglycemia by suppressing hepatic gluconeogenesis through FoxO1

BACKGROUND

Excessive hepatic glucose production is a hallmark that contributes to hyperglycemia in type 2 diabetes (T2D). The regulatory network governing this process remains incompletely understood. Here, we demonstrate that TOX3, a high-mobility group family member, acts as a major transcriptional driver for hepatic glucose production.

METHODS

Tox3-overexpressed and knockout mice were constructed to explore its metabolic functions. Transcriptomic and chromatin-immunoprecipitation sequencing (ChIP-seq) were used to identify downstream targets of TOX3. Both FoxO1 silencing and inhibitor approaches were used to assess the contribution of FoxO1. TOX3 expression levels were examined in the livers of mice and human subjects. Finally, Tox3 was genetically manipulated in diet-induced obese mice to evaluate its therapeutic potential.

RESULTS

Hepatic Tox3 overexpression activates the gluconeogenic program, resulting in hyperglycemia and insulin resistance in mice. Hepatocyte-specific Tox3 knockout suppresses gluconeogenesis and improves insulin sensitivity. Mechanistically, integrated hepatic transcriptomic and ChIP-seq analyses identify FoxO1 as a direct target of TOX3. TOX3 stimulates FoxO1 transcription by directly binding to and activating its promoter, whereas FoxO1 silencing abrogates TOX3-induced dysglycemia in mice. In human subjects, hepatic TOX3 expression shows a significant positive correlation with blood glucose levels under normoglycemic conditions, yet is repressed by high glucose during T2D. Importantly, hepatic Tox3 deficiency markedly protects against and ameliorates the hyperglycemia and glucose intolerance in diet-induced diabetic mice.

CONCLUSIONS

Our findings establish TOX3 as a driver for excessive gluconeogenesis through activating hepatic FoxO1 transcription. TOX3 could serve as a promising target for preventing and treating hyperglycemia in T2D.

Influence of glutamine metabolism on diabetes Development:A scientometric review

Objective

"Metabolism affects function" is the consensus of researchers at present. It has potential clinical application value to study the effects of regulating glutamine (Gln) metabolism on diabetes physiology or pathology. Our research aimed to summarize the latest research progress, frontier hot topics and future development trends in this field from the perspective of scientometrics.

Methods

Relevant literatures and reviews were obtained from the Web of Science (WoS) between January 1, 2001 and May 31, 2022. An online analysis platform of bibliometrics, CiteSpace, and VOS viewer software were used to generate visual knowledge network graphs, including publication countries, institutions and authors partnership analysis, co-occurrence analysis, co-citation analysis, as well as citations and keywords burst detection to acquire research trends and hotspots.

Results

Our results showed that a total of 945 publications in the WoS database met the analysis requirements, with articles being the main type. The overall characteristics showed an increasing trend in the number of publications and citations. The United States was leading the way in this research and was a hub for aggregating collaborations across countries. Vanderbilt University delivered high-quality impact with the most published articles. DeBerardinis, RJ in this field was the most representative author and his main research contents were Gln metabolism and mitochondrial glutaminolysis. Significantly, there was a relative lack of collaboration between institutions and authors. In addition, "type 2 diabetes", "glutamine", "metabolism", "gene expression" and "metabolomics" were the keywords categories with high frequency in co-citation references and co-occurrence cluster keywords. Analysis of popular keywords burst detection showed that "branched chain", "oxidative phosphorylation", "kinase", "insulin sensitivity", "tca cycle", "magnetic resonance spectroscopy" and "flux analysis" were new research directions and emerging methods to explore the link between Gln metabolism and diabetes. Overall, exploring Gln metabolism showed a gradual upward trend in the field of diabetes.

Conclusion

This comprehensive scientometric study identified the general outlook for the field and provided valuable guidance for ongoing research. Strategies to regulate Gln metabolism hold promise as a novel target to treat diabetes, as well as integration and intersection of multidisciplinary provides cooperation strategies and technical guarantees for the development of this field.

TGF-β1 Signaling Impairs Metformin Action on Glycemic Control

Hyperglycemia is a hallmark of type 2 diabetes (T2D). Metformin, the first-line drug used to treat T2D, maintains blood glucose within a normal range by suppressing hepatic glucose production (HGP). However, resistance to metformin treatment is developed in most T2D patients over time. Transforming growth factor beta 1 (TGF-β1) levels are elevated both in the liver and serum of T2D humans and mice. Here, we found that TGF-β1 treatment impairs metformin action on suppressing HGP via inhibiting AMPK phosphorylation at Threonine 172 (T172). Hepatic TGF-β1 deficiency improves metformin action on glycemic control in high fat diet (HFD)-induced obese mice. In our hepatic insulin resistant mouse model (hepatic insulin receptor substrate 1 (IRS1) and IRS2 double knockout (DKO)), metformin action on glycemic control was impaired, which is largely improved by further deletion of hepatic TGF-β1 (TKObeta1) or hepatic Foxo1 (TKOfoxo1). Moreover, blockade of TGF-β1 signaling by chemical inhibitor of TGF-β1 type I receptor LY2157299 improves to metformin sensitivity in mice. Taken together, our current study suggests that hepatic TGF-β1 signaling impairs metformin action on glycemic control, and suppression of TGF-β1 signaling could serve as part of combination therapy with metformin for T2D treatment.

Adapting to stress: The effects of hibernation and hibernacula temperature on the hepatic transcriptome of Rhinolophus pusillus

Hibernation, a survival strategy in mammals for extreme climates, induces physiological phenomena such as ischemia-reperfusion and metabolic shifts that hold great potential for advancements in modern medicine. Despite this, the molecular mechanisms underpinning hibernation remain largely unclear. This study used RNA-seq and Iso-seq techniques to investigate the changes in liver transcriptome expression of Rhinolophus pusillus during hibernation and active periods, as well as under different microhabitat temperatures. We identified 11 457 differentially expressed genes during hibernation and active periods, of which 395 showed significant differential expression. Genes associated with fatty acid catabolism were significantly upregulated during hibernation, whereas genes related to carbohydrate metabolism and glycogen synthesis were downregulated. Conversely, immune-related genes displayed differential expression patterns: genes tied to innate immunity were significantly upregulated, while those linked to adaptive immunity and inflammatory response were downregulated. The analysis of transcriptomic data obtained from different microhabitat temperatures revealed that R. pusillus exhibited an upregulation of genes associated with lipid metabolism in lower microhabitat temperature. This upregulation facilitated an enhanced utilization rate of triglyceride, ultimately resulting in increased energy provision for the organism. Additionally, R. pusillus upregulated gluconeogenesis-related genes regardless of the microhabitat temperature, demonstrating the importance of maintaining blood glucose levels during hibernation. Our transcriptomic data reveal that these changes in liver gene expression optimize energy allocation during hibernation, suggesting that liver tissue adaptively responds to the inherent stress of its function during hibernation. This study sheds light on the role of differential gene expression in promoting more efficient energy allocation during hibernation. It contributes to our understanding of how liver tissue adapts to the stressors associated with this state.

Ceramide enhanced the hepatic glucagon response through regulation of CREB activity

BACKGROUND & AIMS

Hyperglycemia is associated with lipid disorders in patients with diabetes. Ceramides are metabolites involved in sphingolipid metabolism that accumulate during lipid disorders and exert deleterious effects on glucose and lipid metabolism. However, the effects of ceramide on glucagon-mediated hepatic gluconeogenesis remain largely unknown. This study was designed to investigate the impact of ceramides on gluconeogenesis in the context of the hepatic glucagon response, with the aim of finding new pharmacological interventions for hyperglycemia in diabetes.

METHODS

Liquid chromatography-mass spectrometry was used to quantify ceramide content in the serum of patients with diabetes. Primary hepatocytes were isolated from male C57BL/6J mice to study the effects of ceramide on hepatic glucose production. Immunofluorescence staining was performed to view cAMP-responsive element-binding protein (CREB)- regulated transcription co-activator 2 (CRTC2) nuclear translocation in hepatocytes. Serine palmitoyl-transferase, long chain base subunit 2 (Sptlc2) knockdown mice were generated using an adeno-associated virus containing shRNA, and hepatic glucose production was assessed glucagon tolerance and pyruvate tolerance tests in mice fed a normal chow diet and high-fat diet.

RESULTS

Increased ceramide levels were observed in the serum of patients newly diagnosed with type 2 diabetes. De novo ceramide synthesis was activated in mice with metabolic disorders. Ceramide enhanced hepatic glucose production in primary hepatocytes. In contrast, genetic silencing of Sptlc2 prevented this process. Mechanistically, ceramides de-phosphorylate CRTC2 (Ser 171) and facilitate its translocation into the nucleus for CREB activation, thereby augmenting the hepatic glucagon response. Hepatic Sptlc2 silencing blocked ceramide generation in the liver and thus restrained the hepatic glucagon response in mice fed a normal chow diet and high-fat diet.

CONCLUSIONS

These data indicate that ceramide serves as an intracellular messenger that augments hepatic glucose production by regulating CRTC2/CREB activity in the context of the hepatic glucagon response, suggesting that CRTC2 phosphorylation might be a potential node for pharmacological interventions to restrain the hyperglycemic response during fasting in diabetes.

d-Tetramethrin causes zebrafish hepatotoxicity by inducing oxidative stress and inhibiting cell proliferation

d-Tetramethrin is one of the main components of mosquito control products, and is widely used for the control of dengue fever and insecticide production. Due to its widespread use, d-tetramethrin is a ubiquitous environmental pollutant and poses potential risks to human health. However, the effects of d-tetramethrin on liver morphology and function are not clearly established. In this study, we used zebrafish as an animal model to analyze the acute and chronic effects of d-tetramethrin exposure on the liver. We exposed zebrafish larvae and adults to different concentrations of d-tetramethrin and examined the impact of d-tetramethrin on lipid and glycogen metabolism, cellular properties, oxidative stress, cell proliferation, and apoptosis in the liver. We also analyzed transcriptional changes in genes related to apoptosis, inflammation, and cell proliferation using qPCR. Zebrafish exposed to d-tetramethrin exhibited severe liver damage, as evidenced by the presence of vacuoles and nuclear distortion in liver cells. The liver area in zebrafish larvae of the treatment group was significantly smaller than that of the control group. Significant lipid accumulation and decreased glycogen levels were observed in the livers of both zebrafish larvae and adults exposed to d-tetramethrin. Furthermore, d-tetramethrin exposure induced apoptosis and inflammation in zebrafish embryos. Additionally, d-tetramethrin caused liver damage, metabolic dysfunction, and impaired liver function. These results suggest that d-tetramethrin induces liver toxicity in zebrafish, by inducing oxidative stress and inhibiting cell proliferation.

Tea seed saponin‑reduced extract ameliorates palmitic acid‑induced insulin resistance in HepG2 cells

Tea (Camellia sinensis) seed cake is a potential resource that contains a wealth of bioactive compounds. However, the high toxicity of tea saponins in tea seed cake restricts its applications. The present study aimed to i) develop a method of extracting bioactive compounds and reducing tea saponins during the process of tea seed cake extraction and ii) investigate the anti‑insulin resistance effect of tea seed saponin‑reduced extract (TSSRE) in a palmitic acid (PA)‑induced insulin resistance HepG2‑cell model. The concentration of tea saponins in TSSRE was ~10‑fold lower than that in tea seed crude extract (TSCE) after the saponin‑reduction process. In addition, TSSRE cytotoxicity was significantly lower than that of TSCE in HepG2 cells. TSSRE treatment improved glucose consumption as well as glucose transporter (GLUT) 2 and GLUT4 expression levels in PA‑stimulated HepG2 cells. Moreover, TSSRE enhanced the phosphorylation of the insulin receptor substrate 1/protein kinase B/forkhead box protein O1/glycogen synthase kinase 3β and inhibited the elevated expression of phosphoenolpyruvate carboxykinase in PA‑exposed HepG2 cells. The effect of TSSRE on the mediation of the insulin signaling pathway was attributed to the inhibition of PA‑induced mitogen‑activated protein kinase activation. The findings of the present study indicated that TSSRE ameliorates hepatic insulin resistance by ameliorating insulin signaling and inhibiting inflammation-related pathways.

Prenylated flavonoid fractions from Glycyrrhiza glabra alleviate insulin resistance in HepG2 cells by regulating the ERK/IRS-1 and PI3K/Akt signaling pathways

Insulin resistance (IR) is a key factor in the pathogenesis of disrupted glucose metabolism. Although the extract of Glycyrrhiza glabra has shown significant hypoglycemic activity, its bioactive components remain to be identified, and their mechanisms of action, especially on hepatocyte glucose metabolism, are yet to be explored. In the present study, the primary compounds from Glycyrrhiza glabra [named prenylated flavonoid fractions (PFFs)] have been identified and their chemical structures have been elucidated. The therapeutic effects of PFFs extracted from G. glabra on glucose metabolism disorders and IR in high insulin-induced insulin-resistant HepG2 (IR-HepG2) cells have been determined. Glabridin (GLD) was used as a control. The results indicated that, similar to GLD, PFFs increased glucose consumption, glucose uptake, and translocation of glucose transporter 4 to the plasma membrane in IR-HepG2 cells. In addition, they enhanced the activities of glycogen synthase, glucokinase, and pyruvate kinase, while reducing the activities of phosphoenolpyruvate carboxykinase and glucose-6-phosphatase. Furthermore, they activated the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) pathway and suppressed the extracellular signal-regulated kinase/insulin receptor substrate-1 (ERK/IRS-1) pathway. These findings suggest that, similar to GLD, PFFs can alleviate impaired glucose metabolism and alleviate IR in IR-HepG2 cells.Please check and confirm that the authors and their respective affiliations have been correctly identified and amend if necessary.The authors and their affiliations have been confirmed as correct.

In situ growth of self-supported CuO nanorods from Cu-MOFs for glucose sensing and elucidation of the sensing mechanism

Herein, we present a simple and mild method to in situ prepare CuO nanostructures for non-enzymatic glucose sensing. A Cu-metal organic framework (Cu-MOF) precursor was first directly grown on a pencil lead electrode with 3D graphene-like surfaces (EPLE) and then in situ transformed into CuO nanorods. The CuO nanorod-modified EPLE (CuO/EPLE) shows high sensitivity (1138.32 μA mM-1 cm-2), fast response time (1.5 s) and low detection limit (0.11 μM) for glucose oxidation. It has been found that NaOH promoted the generation of ˙OH groups and Cu(III) on the CuO surface, which then facilitated the electrochemical oxidation of glucose. Signals characteristic of hydroxyl and carbon-centered radical adducts were detected by EPR. Furthermore, the CuO/EPLE sensor also shows good accuracy in glucose determination in human serum samples.

Integrative analysis of pathogenic variants in glucose-6-phosphatase based on an AlphaFold2 model

Mediating the terminal reaction of gluconeogenesis and glycogenolysis, the integral membrane protein glucose-6-phosphate catalytic subunit 1 (G6PC1) regulates hepatic glucose production by catalyzing hydrolysis of glucose-6-phosphate (G6P) within the lumen of the endoplasmic reticulum. Consistent with its vital contribution to glucose homeostasis, inactivating mutations in G6PC1 causes glycogen storage disease (GSD) type 1a characterized by hepatomegaly and severe hypoglycemia. Despite its physiological importance, the structural basis of G6P binding to G6PC1 and the molecular disruptions induced by missense mutations within the active site that give rise to GSD type 1a are unknown. In this study, we determine the atomic interactions governing G6P binding as well as explore the perturbations imposed by disease-linked missense variants by subjecting an AlphaFold2 G6PC1 structural model to molecular dynamics simulations and in silico predictions of thermodynamic stability validated with robust in vitro and in situ biochemical assays. We identify a collection of side chains, including conserved residues from the signature phosphatidic acid phosphatase motif, that contribute to a hydrogen bonding and van der Waals network stabilizing G6P in the active site. The introduction of GSD type 1a mutations modified the thermodynamic landscape, altered side chain packing and substrate-binding interactions, and induced trapping of catalytic intermediates. Our results, which corroborate the high quality of the AF2 model as a guide for experimental design and to interpret outcomes, not only confirm the active-site structural organization but also identify previously unobserved mechanistic contributions of catalytic and noncatalytic side chains.

Physiological indices and liver gene expression related to glucose supply in Brandt's vole (Lasiopodomys brandtii) exhibit species- and oxygen concentration-specific responses to hypoxia

Brandt's vole (Lasiopodomys brandtii) is a species with hypoxia tolerance, and glucose serves as the primary energy substrate under hypoxia. However, the glucose supply in Brandt's voles under hypoxia has not been studied. This study aimed to investigate characteristics in physiological indices and liver gene expression associated with glucose supply in Brandt's voles under hypoxia. Serum glucose of Brandt's voles remained stable under 10% O2, increased under 7.5% O2, and decreased under 5% O2. Serum lactate increased under 10% O2, decreased under 7.5% O2, increased at 6 h and decreased at 12 h under 5% O2. Liver glycogen increased under 10% O2, remained constant under 7.5% O2, and reduced under 5% O2. Pepck and G6pase expression associated with gluconeogenesis decreased under 10% O2, while Pepck expression decreased and G6pase expression increased under 7.5% and 5% O2. Regarding genes related to glycogen metabolism, Gys expression decreased at all oxygen concentrations, Phk expression increased under 5% O2, and Gp expression increased under 7.5% and 5% O2. The alterations in glucose, lactate, liver glycogen, and gene expression related to glycogenolysis in Kunming mice (Mus musculus, control species) are similar to discovery of Brandt's voles under 7.5% O2, but gene expression involved in gluconeogenesis and glycogen synthesis increased. The findings suggest that Brandt's voles are more tolerant to hypoxia than Kunming mice, and their physiological indices and liver gene expression related to glucose supply exhibit species- and oxygen concentration-specific responses to hypoxia. This research offers novel insights for studying hypoxia tolerance of Brandt's voles.

Ketone bodies promote epididymal white adipose expansion to alleviate liver steatosis in response to a ketogenic diet

Liver can sense the nutrient status and send signals to other organs to regulate overall metabolic homoeostasis. Herein, we demonstrate that ketone bodies act as signals released from the liver that specifically determine the distribution of excess lipid in epididymal white adipose tissue (eWAT) when exposed to a ketogenic diet (KD). An acute KD can immediately result in excess lipid deposition in the liver. Subsequently, the liver sends the ketone body β-hydroxybutyrate (BHB) to regulate white adipose expansion, including adipogenesis and lipogenesis, to alleviate hepatic lipid accumulation. When ketone bodies are depleted by deleting 3-hydroxy-3-methylglutaryl-CoA synthase 2 gene in the liver, the enhanced lipid deposition in eWAT but not in inguinal white adipose tissue is preferentially blocked, while lipid accumulation in liver is not alleviated. Mechanistically, ketone body BHB can significantly decrease lysine acetylation of peroxisome proliferator-activated receptor gamma in eWAT, causing enhanced activity of peroxisome proliferator-activated receptor gamma, the key adipogenic transcription factor. These observations suggest that the liver senses metabolic stress first and sends a corresponding signal, that is, ketone body BHB, to specifically promote eWAT expansion to adapt to metabolic challenges.

Protein O-GlcNAcylation: The sweet hub in liver metabolic flexibility from a (patho)physiological perspective

O-GlcNAcylation is a dynamic, reversible and atypical O-glycosylation that regulates various cellular physiological processes via conformation, stabilisation, localisation, chaperone interaction or activity of target proteins. The O-GlcNAcylation cycle is precisely controlled by collaboration between O-GlcNAc transferase and O-GlcNAcase. Uridine-diphosphate-N-acetylglucosamine, the sole donor of O-GlcNAcylation produced by the hexosamine biosynthesis pathway, is controlled by the input of glucose, glutamine, acetyl coenzyme A and uridine triphosphate, making it a sensor of the fluctuation of molecules, making O-GlcNAcylation a pivotal nutrient sensor for the metabolism of carbohydrates, amino acids, lipids and nucleotides. O-GlcNAcylation, particularly prevalent in liver, is the core hub for controlling systemic glucose homeostasis due to its nutritional sensitivity and precise spatiotemporal regulation of insulin signal transduction. The pathology of various liver diseases has highlighted hepatic metabolic disorder and dysfunction, and abnormal O-GlcNAcylation also plays a specific pathological role in these processes. Therefore, this review describes the unique features of O-GlcNAcylation and its dynamic homeostasis maintenance. Additionally, it explains the underlying nutritional sensitivity of O-GlcNAcylation and discusses its mechanism of spatiotemporal modulation of insulin signal transduction and liver metabolic homeostasis during the fasting and feeding cycle. This review emphasises the pathophysiological implications of O-GlcNAcylation in nonalcoholic fatty liver disease, nonalcoholic steatohepatitis and hepatic fibrosis, and focuses on the adverse effects of hyper O-GlcNAcylation on liver cancer progression and metabolic reprogramming.

Study on the action mechanism of the Polygonum perfoliatum L. on non-alcoholic fatty liver disease, based on network pharmacology and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) holds that non-alcoholic fatty liver disease (NAFLD) belong to the category of "thoracic fullness". Polygonum perfoliatum L. (PPL), a Chinese medicinal herb with the effect of treating thoracic fullness, was recorded in the ancient Chinese medicine book "Supplements to Compendium of Materia Medica". It has been used since ancient times to treat NAFLD. However, the underlying mechanism and active components of PPL against NAFLD remains unclear.

AIM OF STUDY

To identify the main active components and the anti-NAFLD mechanism of PPL.

MATERIALS AND METHODS

Network pharmacology, UPLC/QE-HFX analysis, and molecular docking were employed to determine the main bioactive compounds and key targets of PPL for the NAFLD treatment. This effect was further validated with administration of PPL (200 mg/kg and 400 mg/kg) to NAFLD model mice for 5 weeks. Systemic signs of obesity, biochemical parameters, and histological changes were characterized. Immunohistochemistry, western blot, and PCR analysis were conducted to elucidate the mechanistic pathways through which PPL exerts its effects.

RESULTS

Network pharmacology revealed 77 crossover genes between the PPL and NAFLD. The kyoto encyclopedia of genes and genomes (KEGG) analysis show that PPL treat NAFLD mainly regulating glucose-lipid metabolism mediated by PI3K/AKT signal pathway. The Gene Ontology (GO) enrichment analysis show that PPL treat NAFLD mainly regulating inflammation mediated by cytokine-mediated signaling pathway. In accordance with the anticipated outcomes, administration of PPL in a dose-dependent manner effectively mitigated insulin resistance induced by a high-fat diet (HFD) by activating the PI3K/AKT signaling pathway. Histopathological evaluation corroborated the hepatoprotective effects of PPL against HFD-induced hepatic steatosis, as evidenced by the inhibition of de novo fatty acid synthesis and promotion of fatty acid β-oxidation (FAO). Further research showed that PPL blocked cytokine production by inhibiting the NF-κB pathway, thereby reducing immune cell infiltration. Furthermore, five flavonoids from PPL, including quercetin, baicalein, galangin, apigenin, and genistein were identified as key compounds based on ingredient-target-pathway network analysis. Molecular docking show that these active compounds have favorable binding interactions with AKT1, PIK3R1, and MAPK1, further confirming the impact of PPL on the PI3K/AKT pathway.

CONCLUSIONS

Through the combination of network pharmacology prediction and experimental validation, this work determined that therapeutic effect of PPL on NAFLD, and such protective effect is mediated by activating PI3K/AKT-mediated glucolipid metabolism pathway and hepatic NF-κB-mediated cytokine signaling pathway.

Dietary Tomato Pectin Attenuates Hepatic Insulin Resistance and Inflammation in High-Fat-Diet Mice by Regulating the PI3K/AKT Pathway

Chronic metabolic disease is a serious global health issue, which is accompanied by impaired insulin resistance. Tomato pectin (TP) is a naturally soluble complex hetero-polysaccharide with various biological functions. However, the impact of TP on hepatic insulin resistance in a high-fat diet (HFD) and its potential mechanism remains largely unknown. The results revealed that TP treatment significantly decreased the liver weight, hepatic fat accumulation and hepatic injury in HFD-fed mice. TP also improved fasting blood glucose levels and glucose tolerance in HFD-fed mice. The underlying mechanisms involved in the inflammation, oxidative stress and insulin signaling in the liver were also investigated by RT-qPCR and western blot, which indicated that TP ameliorated hepatic insulin resistance by regulating the PI3K/AKT/GSK-3β pathway, increasing the expression of GLUT4, decreasing the expression of PECK and G6P as well as restoring antioxidant activities and suppressing the inflammation statues in HFD-fed mice. Our data showed that dietary TP has profound effects on hepatic insulin resistance, inflammation and oxidative stress, demonstrating that TP might be a promising therapeutic agent against insulin resistance and related chronic metabolic disease.

Cardiorespiratory fitness mediates cortisol and lactate responses to winter and summer marches

Background

The influence of homeostatically regulated physiological processes, including cardiorespiratory fitness (VO2max), on the response to physical stressors such as acclimatisation and marching, remains understudied. We aimed to investigate the effects of summer and winter acclimatisation and marching on cortisol levels and blood lactate, to gain insight into the role of these physiological processes in the stress response.

Methods

Two groups of young Europeans, classified as poor (PCF; n=9) and good physical condition (GCF; n=21), based on a VO2MAX threshold of 40 mL O2/ kg/min, underwent 2-h March (6-7 km/h) in winter (5˚C) and summer (32˚C). Commercial tests, UniCel DxI Access Cortisol assay and EKF Biosen Clinic/GP assay were used for cortisol and lactate blood measurements (morning samples and those taken immediately after marches), respectively.

LONP1 ameliorates liver injury and improves gluconeogenesis dysfunction in acute-on-chronic liver failure

BACKGROUND

Acute-on-chronic liver failure (ACLF) is a severe liver disease with complex pathogenesis. Clinical hypoglycemia is common in patients with ACLF and often predicts a worse prognosis. Accumulating evidence suggests that glucose metabolic disturbance, especially gluconeogenesis dysfunction, plays a critical role in the disease progression of ACLF. Lon protease-1 (LONP1) is a novel mediator of energy and glucose metabolism. However, whether gluconeogenesis is a potential mechanism through which LONP1 modulates ACLF remains unknown.

METHODS

In this study, we collected liver tissues from ACLF patients, established an ACLF mouse model with carbon tetrachloride (CCl 4 ), lipopolysaccharide (LPS), and D-galactose (D-gal), and constructed an in vitro hypoxia and hyperammonemia-triggered hepatocyte injury model. LONP1 overexpression and knockdown adenovirus were used to assess the protective effect of LONP1 on liver injury and gluconeogenesis regulation. Liver histopathology, biochemical index, mitochondrial morphology, cell viability and apoptosis, and the expression and activity of key gluconeogenic enzymes were detected to explore the underlying protective mechanisms of LONP1 in ACLF.

RESULTS

We found that LONP1 and the expressions of gluconeogenic enzymes were downregulated in clinical ACLF liver tissues. Furthermore, LONP1 overexpression remarkably attenuated liver injury, which was characterized by improved liver histopathological lesions and decreased serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in ACLF mice. Moreover, mitochondrial morphology was improved upon overexpression of LONP1. Meanwhile, the expression and activity of the key gluconeogenic enzymes were restored by LONP1 overexpression. Similarly, the hepatoprotective effect was also observed in the hepatocyte injury model, as evidenced by improved cell viability, reduced cell apoptosis, and improved gluconeogenesis level and activity, while LONP1 knockdown worsened liver injury and gluconeogenesis disorders.

CONCLUSION

We demonstrated that gluconeogenesis dysfunction exists in ACLF, and LONP1 could ameliorate liver injury and improve gluconeogenic dysfunction, which would provide a promising therapeutic target for patients with ACLF.

Nourishing Yin traditional Chinese medicine: potential role in the prevention and treatment of type 2 diabetes

Type 2 diabetes mellitus (T2DM), a common and frequently occurring disease in contemporary society, has become a global health threat. However, current mainstream methods of prevention and treatment, mainly including oral hypoglycemic drugs and insulin injections, do not fundamentally block the progression of T2DM. Therefore, it is imperative to find new ways to prevent and treat diabetes. Traditional Chinese medicine is characterized by multiple components, pathways, and targets with mild and long-lasting effects. Pharmacological studies have shown that nourishing yin traditional Chinese medicine (NYTCM) can play a positive role in the treatment of T2DM by regulating pathways such as the phosphatidylinositol 3-kinase/serine-threonine kinase, mitogen-activated protein kinase, nuclear factor-kappa B, and other pathways to stimulate insulin secretion, protect and repair pancreatic β cells, alleviate insulin resistance, ameliorate disordered glucose and lipid metabolism, mitigate oxidative stress, inhibit inflammatory responses, and regulate the intestinal flora. The pharmacologic activity, mechanisms, safety, and toxicity of NYTCM in the treatment of T2DM are also reviewed in this manuscript.

Remodeling of Hepatic Glucose Metabolism in Response to Early Weaning in Piglets

This study aimed to investigate the dynamic changes in hepatic glucose metabolism in response to early weaning. A total of 60 piglets were randomly selected and weaned at 21 days old. Six piglets were slaughtered on the weaning day (d0) and at 1 (d1), 4 (d4), 7 (d7), and 14 (d14) days postweaning. The results illustrated that body weight significantly increased from d4 to d14 (p < 0.001). Serum glucose fell sharply after weaning and then remained at a low level from d1 to d14 (p < 0.001). Serum insulin decreased from d4 (p < 0.001), which caused hepatic glycogen to be broken down (p = 0.007). The glucose-6-phosphatase activity increased from d0 to d4 and then decreased from d4 to d14 (p = 0.039). The pyruvate carboxylase activity presented a significant sustained increase from d0 to d14 (p < 0.001). The succinate (p = 0.006) and oxaloacetate (p = 0.003) content on d4 was lower than that on d0. The succinate dehydrogenase activity (p = 0.008) and ATP (p = 0.016) production decreased significantly on d4 compared to that on d0. Taken together, these findings reveal the dynamic changes of metabolites and enzymes related to hepatic glycometabolism and the TCA (tricarboxylic acid) cycle in piglets after weaning. Our findings enrich weaning stress theory and might provide a reference for dietary intervention.

Long term integrated biomarker responses in freshwater African catfish Clarias gariepinus exposed to a new brand of herbicide fluazifop-p-butyl

The study investigated the sublethal effects of Fluazifop-p-butyl (FPB) on the haematological, biochemical and oxidative stress changes in Clarias gariepinus. Juvenile C. gariepinus were exposed to FPB concentrations of 1.80, 3.50, and 7.10 mg/l corresponding to 5, 10 and 20% of 96 h LC50 value of FPB respectively for 21 days and allowed to recover for 7 days. The blood, liver and gills were removed and analyzed. Fish exposed to different concentrations of FPB showed significant decline in the values the pack cell volume, hemoglobin and red blood cells but the white blood cell values increased. The neutrophil values increased while the lymphocyte declined but the monocytes, basophil and eosinophil values remain unchanged. The liver and gill aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase significantly increased compared to the control. There were mixed trends in the values of glucose but total protein was reduced in both tissues of the fish. There was significant decline in superoxide dismutase, catalase and glutathione peroxidase while malondialdehyde, total glutathione, and glutathione reductase increased in both liver and gill of the exposed fish. Following the 7-day withdrawal, most of the observed parameters returned to normal values. The present study revealed that FPB is toxic to C. gariepinus juveniles and prolonged exposure could result to major health risks to aquatic organisms, hence, they should be carefully used.

Control of lipolysis by a population of oxytocinergic sympathetic neurons

Oxytocin (OXT), a nine-amino-acid peptide produced in the hypothalamus and released by the posterior pituitary, has well-known actions in parturition, lactation and social behaviour1, and has become an intriguing therapeutic target for conditions such as autism and schizophrenia2. Exogenous OXT has also been shown to have effects on body weight, lipid levels and glucose homeostasis1,3, suggesting that it may also have therapeutic potential for metabolic disease1,4. It is unclear, however, whether endogenous OXT participates in metabolic homeostasis. Here we show that OXT is a critical regulator of adipose tissue lipolysis in both mice and humans. In addition, OXT serves to facilitate the ability of β-adrenergic agonists to fully promote lipolysis. Most surprisingly, the relevant source of OXT in these metabolic actions is a previously unidentified subpopulation of tyrosine hydroxylase-positive sympathetic neurons. Our data reveal that OXT from the peripheral nervous system is an endogenous regulator of adipose and systemic metabolism.

Emerging role of N6-methyladenosine in the homeostasis of glucose metabolism

N6-methyladenosine (m6A) is the most prevalent post-transcriptional internal RNA modification, which is involved in the regulation of diverse physiological processes. Dynamic and reversible m6A modification has been shown to regulate glucose metabolism, and dysregulation of m6A modification contributes to glucose metabolic disorders in multiple organs and tissues including the pancreas, liver, adipose tissue, skeletal muscle, kidney, blood vessels, and so forth. In this review, the role and molecular mechanism of m6A modification in the regulation of glucose metabolism were summarized, the potential therapeutic strategies that improve glucose metabolism by targeting m6A modifiers were outlined, and feasible directions of future research in this field were discussed as well, providing clues for translational research on combating metabolic diseases based on m6A modification in the future.

Kinin B1 receptor modulates glucose homeostasis and physical exercise capacity by altering adrenal catecholamine synthesis and secretion

Our group has shown in several papers that kinin B1 receptor (B1R) is involved in metabolic adaptations, mediating glucose homeostasis and interfering in leptin and insulin signaling. Since catecholamines are involved with metabolism management, we sought to evaluate B1R role in catecholamine synthesis/secretion. Using B1R global knockout mice, we observed increased basal epinephrine content, accompanied by decreased hepatic glycogen content and increased glucosuria. When these mice were challenged with maximal intensity exercise, they showed decreased epinephrine and norepinephrine response, accompanied by disturbed glycemic responses to effort and poor performance. This phenotype was related to alterations in adrenal catecholamine synthesis: increased basal epinephrine concentration and reduced norepinephrine content in response to exercise, as well decreased gene expression and protein content of tyrosine hydroxylase and decreased gene expression of dopamine beta hydroxylase and kinin B2 receptor. We conclude that the global absence of B1R impairs catecholamine synthesis, interfering with glucose metabolism at rest and during maximal exercise.

Body Fat Depletion: the Yin Paradigm for Treating Type 2 Diabetes

PURPOSE OF REVIEW

To highlight that body fat depletion (the Yin paradigm) with glucose-lowering treatments (the Yang paradigm) are associated with metabolic benefits for patients with type 2 diabetes mellitus (T2DM).

RECENT FINDINGS

The sodium-glucose cotransporter-2 inhibitor-mediated sodium/glucose deprivation can directly improve glycemic control and kidney outcome in patients with T2DM. The glucose deprivation might also promote systemic fatty acid β-oxidation to deplete ectopic/visceral fat and thereby contribute to the prevention of cardiovascular diseases. As with metabolic surgery, bioengineered incretin-based medications with potent anorexigenic and insulinotropic efficacy can significantly reduce blood glucose as well as body weight (especially in the ectopic/visceral fat depots). The latter effects could be a key contributor to their cardiovascular-renal protective effects. In addition to a healthy diet, the newer glucose-lowering medications, with body fat reduction effects, should be prioritized when treating patients with T2DM, especially for those with established cardiovascular/renal risks or diseases.

Adjudin improves beta cell maturation, hepatic glucose uptake and glucose homeostasis

AIMS/HYPOTHESIS

Recovering functional beta cell mass is a promising approach for future diabetes therapies. The aim of the present study is to investigate the effects of adjudin, a small molecule identified in a beta cell screen using zebrafish, on pancreatic beta cells and diabetes conditions in mice and human spheroids.

METHODS

In zebrafish, insulin expression was examined by bioluminescence and quantitative real-time PCR (qPCR), glucose levels were examined by direct measurements and distribution using a fluorescent glucose analogue, and calcium activity in beta cells was analysed by in vivo live imaging. Pancreatic islets of wild-type postnatal day 0 (P0) and 3-month-old (adult) mice, as well as adult db/db mice (i.e. BKS(D)-Leprdb/JOrlRj), were cultured in vitro and analysed by qPCR, glucose stimulated insulin secretion and whole mount staining. RNA-seq was performed for islets of P0 and db/db mice. For in vivo assessment, db/db mice were treated with adjudin and subjected to analysis of metabolic variables and islet cells. Glucose consumption was examined in primary human hepatocyte spheroids.

RESULTS

Adjudin treatment increased insulin expression and calcium response to glucose in beta cells and decreased glucose levels after beta cell ablation in zebrafish. Adjudin led to improved beta cell function, decreased beta cell proliferation and glucose responsive insulin secretion by decreasing basal insulin secretion in in vitro cultured newborn mouse islets. RNA-seq of P0 islets indicated that adjudin treatment resulted in increased glucose metabolism and mitochondrial function, as well as downstream signalling pathways involved in insulin secretion. In islets from db/db mice cultured in vitro, adjudin treatment strengthened beta cell identity and insulin secretion. RNA-seq of db/db islets indicated adjudin-upregulated genes associated with insulin secretion, membrane ion channel activity and exocytosis. Moreover, adjudin promoted glucose uptake in the liver of zebrafish in an insulin-independent manner, and similarly promoted glucose consumption in primary human hepatocyte spheroids with insulin resistance. In vivo studies using db/db mice revealed reduced nonfasting blood glucose, improved glucose tolerance and strengthened beta cell identity after adjudin treatment.

CONCLUSIONS/INTERPRETATION

Adjudin promoted functional maturation of immature islets, improved function of dysfunctional islets, stimulated glucose uptake in liver and improved glucose homeostasis in db/db mice. Thus, the multifunctional drug adjudin, previously studied in various contexts and conditions, also shows promise in the management of diabetic states.

DATA AVAILABILITY

Raw and processed RNA-seq data for this study have been deposited in the Gene Expression Omnibus under accession number GSE235398 ( https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE235398 ).

The role of anti-diabetic drugs in NAFLD. Have we found the Holy Grail? A narrative review

PURPOSE

Non-alcoholic fatty liver disease (NAFLD) has become a leading cause of liver disease, affecting 30% of the global population. NAFLD prevalence is particularly high in obese individuals and patients with type 2 diabetes mellitus (T2DM). NAFLD ranges from simple fat deposition in the liver to necroinflammation and fibrosis (non-alcoholic steatohepatitis (NASH)), NASH-cirrhosis, and/or hepatocellular carcinoma. Insulin resistance plays a key role in NAFLD pathogenesis, alongside dysregulation of adipocytes, mitochondrial dysfunction, genetic factors, and changes in gut microbiota. Since insulin resistance is also a major predisposing factor of T2DM, the administration of anti-diabetic drugs for the management of NAFLD seems reasonable.

METHODS

In this review we provide the NAFLD-associated mechanisms of action of some of the most widely used anti-diabetic drugs, namely metformin, pioglitazone, sodium-glucose transport protein-2 inhibitors (SGLT2i), glucagon-like peptide 1 receptor analogs (GLP1 RAs), and dipeptyl-peptidase-4 inhibitors (DPP4i) and present available data regarding their use in patients with NAFLD, with and without T2DM.

RESULTS

Both metformin and DPP4i have shown rather contradictory results, while pioglitazone seems to benefit patients with NASH and is thus the only drug approved for NASH with concomitant significant liver fibrosis by all major liver societies. On the other hand, SGLT2i and GLP1 RAs seem to be beneficiary in patients with NAFLD, showing both remarkable results, with SGLT2i proving to be more efficient in the only head-to-head study so far.

CONCLUSION

In patients with NAFLD and diabetes, pioglitazone, GLP1 RAs, and SGLT2i seem to be logical treatment options. Larger studies are needed before these drugs can be recommended for non-diabetic individuals.

Sympathetic circuits regulating hepatic glucose metabolism: where we stand

The prevalence of metabolic disorders, including type 2 diabetes mellitus, continues to increase worldwide. Although newer and more advanced therapies are available, current treatments are still inadequate and the search for solutions remains. The regulation of energy homeostasis, including glucose metabolism, involves an exchange of information between the nervous systems and peripheral organs and tissues; therefore, developing treatments to alter central and/or peripheral neural pathways could be an alternative solution to modulate whole body metabolism. Liver glucose production and storage are major mechanisms controlling glycemia, and the autonomic nervous system plays an important role in the regulation of hepatic functions. Autonomic nervous system imbalance contributes to excessive hepatic glucose production and thus to the development and progression of type 2 diabetes mellitus. At cellular levels, change in neuronal activity is one of the underlying mechanisms of autonomic imbalance; therefore, modulation of the excitability of neurons involved in autonomic outflow governance has the potential to improve glycemic status. Tissue-specific subsets of preautonomic neurons differentially control autonomic outflow; therefore, detailed information about neural circuits and properties of liver-related neurons is necessary for the development of strategies to regulate liver functions via the autonomic nerves. This review provides an overview of our current understanding of the hypothalamus-ventral brainstem-liver pathway involved in the sympathetic regulation of the liver, outlines strategies to identify organ-related neurons, and summarizes neuronal plasticity during diabetic conditions with a particular focus on liver-related neurons in the paraventricular nucleus.

6-Gingerol regulates triglyceride and cholesterol biosynthesis to improve hepatic steatosis in MAFLD by activating the AMPK-SREBPs signaling pathway

Excessive synthesis of triglycerides and cholesterol accelerates the progression of hepatic steatosis in metabolic-associated fatty liver disease (MAFLD). However, the precise mechanism by which 6-gingerol mitigates hepatic steatosis in MAFLD model mice has yet to be fully understood. The present study observed that 6-gingerol administration exhibited significant protective effects against obesity, insulin resistance, and hepatic steatosis in mice subjected to a high-fat diet (HFD), and mitigated lipid accumulation in HepG2 cells treated with palmitate (PA). Following the hepatic lipidomic analysis, we confirmed that the AMPK-SREBPs signaling pathway as the underlying molecular mechanism by which 6-gingerol inhibited triglyceride and cholesterol biosynthesis, both in vivo and in vitro, through Western blot and immunofluorescence assay. Additionally, the application of an AMPK agonist/inhibitor further validated that 6-gingerol promoted AMPK activation by increasing the phosphorylation level of AMPK in vitro. Notably, the inhibitory effect of 6-gingerol on cholesterol biosynthesis, rather than triglyceride biosynthesis, was significantly diminished after silencing SREBP2 using a lentiviral plasmid shRNA in HepG2 cells. Our study demonstrates that 6-gingerol mitigates hepatic triglyceride and cholesterol biosynthesis to alleviate hepatic steatosis by activating the AMPK-SREBPs signaling pathway, indicating that 6-gingerol may be a potential candidate in the therapy of MAFLD.

Effects of a Novel Glucokinase Activator, Dorzagliatin, on Glycemic Control and Glucose Fluctuation in Drug-Naïve Patients with Type 2 Diabetes Mellitus

Aim

The prevalence rate of type 2 diabetes mellitus (T2DM) has been increasing and a large proportion of patients still do not achieve adequate or sustainable glycemic control on the basis of previous hypoglycemic treatment. In this present study, we explored whether dorzagliatin, a novel glucokinase activator (GKA), could improve glycemic control and lessen glucose fluctuation in drug-naïve patients with T2DM.

Methods

A self-comparative observational study of 25 drug-naïve patients with T2DM (aged 18-75 years and HbA1c of 7.5%-11.0%) treated with dorzagliatin 75 mg twice daily for 52 weeks. Before and after dorzagliatin intervention, the serum levels of hemoglobin A1c (HbA1c), insulin, and C-peptide were measured repeatedly during fasting and after a mixed meal. The continuous glucose monitoring (CGM) device was also used to obtain 24-hour glucose profiles and assess the changes in glycemic variability parameters.

Results

After 52 weeks of treatment with dorzagliatin, a numerally greater reduction in HbA1c of 1.03% from the baseline was observed in patients with T2DM, accompanied by significant improvement in insulin resistance and insulin secretion. Moreover, the standard deviation of blood glucose (SDBG) and the mean amplitude of glycemic excursion (MAGE) derived from CGM data were significantly decreased after dorzagliatin therapy. The 24-h glucose variation profile showed that study patients had obviously lower mean glucose levels during the postprandial period from the baseline to week 52, an effect also demonstrated by the significant decrease in the incremental area under glucose concentration versus time curve for 2 h (iAUC0-2 h) after meals.

Conclusions

This study suggests that dorzagliatin therapy could effectively improve glycemic control and glucose fluctuation in drug-naïve patients with T2DM.

Aryl hydrocarbon receptor sulfenylation promotes glycogenolysis and rescues cancer chemoresistance

Elevation of reactive oxygen species (ROS) levels is a general consequence of tumor cells' response to treatment and may cause tumor cell death. Mechanisms by which tumor cells clear fatal ROS, thereby rescuing redox balance and entering a chemoresistant state, remain unclear. Here, we show that cysteine sulfenylation by ROS confers on aryl hydrocarbon receptor (AHR) the ability to dissociate from the heat shock protein 90 complex but to bind to the PPP1R3 family member PPP1R3C of the glycogen complex in drug-treated tumor cells, thus activating glycogen phosphorylase to initiate glycogenolysis and the subsequent pentose phosphate pathway, leading to NADPH production for ROS clearance and chemoresistance formation. We found that basic ROS levels were higher in chemoresistant cells than in chemosensitive cells, guaranteeing the rapid induction of AHR sulfenylation for the clearance of excess ROS. These findings reveal that AHR can act as an ROS sensor to mediate chemoresistance, thus providing a potential strategy to reverse chemoresistance in patients with cancer.

Dehulled Adlay (Coix lachryma-jobi L.) ameliorates hepatic gluconeogenesis and steatosis in streptozotocin/high-fat diet-induced diabetic rats

Adlay (Coix lachryma-jobi L.) is a traditional Chinese herbal medicine with various biological activities. We investigated the anti-diabetic effects of different parts of adlay seeds, including polished adlay (PA), adlay bran (AB) and dehulled adlay (DA) in a streptozotocin (STZ)/high fat diet (HFD) diabetic rat model (DM). DM rats supplemented with or without PA (43%), AB (3%), or DA (46%) diet for 8 weeks. The plasma glucose and insulin levels and the insulin resistance index (HOMA-IR) were increased in DM group; among the three adlay diets, DA has the best effects attenuating all of these alterations in DM rats. Both AB and DA alleviated diabetes-impaired glucose tolerance. The increased hepatic phosphoenolpyruvate carboxykinase protein expression in DM group was improved by all of the three adlay diets. The increased ratio of glucose-6-phosphatase to glucokinase in DM group was suppressed by DA supplementation, further suggesting DA diet is most effective among the three diets. Both AB and DA diets had beneficial effects against hepatic steatosis, with better effects observed in DA group. These results suggest that the DA diet, composed of both polished adlay and adlay bran, possesses the best potential to improve glucose homeostasis, at least in part, by alleviating hepatic glucose metabolism and steatosis.

Piperine Attenuates Bmal1-Mediated Glucose Metabolism Disorder in a Trpv1-Dependent Manner in HepG2 Cells

Piperine (PIP), a pungent alkaloid found in black pepper, has various pharmacological effects by activating the transient receptor potential vanilloid 1 (TRPV1) receptor. In this study, the regulating effect of PIP on glucose metabolism and the underlying mechanism were examined using an insulin-resistant cell model. Results showed that PIP alleviated glucosamine (GlcN)-induced glucose metabolism disorder (from 59.19 ± 1.90 to 88.36 ± 6.57%), restored cellular redox balance (from 148.43 ± 3.52 to 110.47 ± 3.52%), improved mitochondrial function (from 63.76 ± 4.87 to 85.98 ± 5.12%), and mitigated circadian disruption in HepG2 cells via the mediation of circadian clock gene Bmal1. After the knockdown of the Trpv1 gene, the modulating effect of PIP on Bmal1-mediated glucose metabolism was weakened, indicating that PIP alleviated Bmal1-involved insulin resistance and circadian misalignment in a Trpv1-dependent manner in HepG2 cells.

Rap1 in the Context of PCSK9, Atherosclerosis, and Diabetes

PURPOSE OF REVIEW

The focus of this article is to highlight the importance of the small GTPase, Ras-associated protein 1 (Rap1), in proprotein convertase subtilisin/kexin type 9 (PCSK9) regulation and atherosclerosis and type 2 diabetes etiology and discuss the potential therapeutic implications of targeting Rap1 in these disease areas.

REVIEW FINDINGS

Cardiometabolic disease characterized by obesity, glucose intolerance, dyslipidemia, and atherosclerotic cardiovascular disease remain an important cause of mortality. Evidence using mouse models of obesity and insulin resistance indicates that Rap1 deficiency increases proatherogenic PCSK9 and low-density lipoprotein cholesterol levels and predisposes these mice to develop obesity- and statin-induced hyperglycemia, which highlights Rap1's role in cardiometabolic dysfunction. Rap1 may also contribute to cardiovascular disease through its effects on vascular wall cells involved in the atherosclerosis progression. Rap1 activation, specifically in the liver, could be beneficial in the prevention of cardiometabolic perturbations, including type 2 diabetes, hypercholesterolemia, and atherosclerosis.

An integrative view on glucagon function and putative role in the progression of pancreatic neuroendocrine tumours (pNETs) and hepatocellular carcinomas (HCC)

Cancer metabolism research area evolved greatly, however, is still unknown the impact of systemic metabolism control and diet on cancer. It makes sense that systemic regulators of metabolism can act directly on cancer cells and activate signalling, prompting metabolic remodelling needed to sustain cancer cell survival, tumour growth and disease progression. In the present review, we describe the main glucagon functions in the control of glycaemia and of metabolic pathways overall. Furthermore, an integrative view on how glucagon and related signalling pathways can contribute for pancreatic neuroendocrine tumours (pNETs) and hepatocellular carcinomas (HCC) progression, since pancreas and liver are the major organs exposed to higher levels of glucagon, pancreas as a producer and liver as a scavenger. The main objective is to bring to discussion some glucagon-dependent mechanisms by presenting an integrative view on microenvironmental and systemic aspects in pNETs and HCC biology.

Toward Systems-Level Metabolic Analysis in Endocrine Disorders and Cancer

Metabolism is a dynamic network of biochemical reactions that support systemic homeostasis amidst changing nutritional, environmental, and physical activity factors. The circulatory system facilitates metabolite exchange among organs, while the endocrine system finely tunes metabolism through hormone release. Endocrine disorders like obesity, diabetes, and Cushing's syndrome disrupt this balance, contributing to systemic inflammation and global health burdens. They accompany metabolic changes on multiple levels from molecular interactions to individual organs to the whole body. Understanding how metabolic fluxes relate to endocrine disorders illuminates the underlying dysregulation. Cancer is increasingly considered a systemic disorder because it not only affects cells in localized tumors but also the whole body, especially in metastasis. In tumorigenesis, cancer-specific mutations and nutrient availability in the tumor microenvironment reprogram cellular metabolism to meet increased energy and biosynthesis needs. Cancer cachexia results in metabolic changes to other organs like muscle, adipose tissue, and liver. This review explores the interplay between the endocrine system and systems-level metabolism in health and disease. We highlight metabolic fluxes in conditions like obesity, diabetes, Cushing's syndrome, and cancers. Recent advances in metabolomics, fluxomics, and systems biology promise new insights into dynamic metabolism, offering potential biomarkers, therapeutic targets, and personalized medicine.

Hepatic palmitoyl-proteomes and acyl-protein thioesterase protein proximity networks link lipid modification and mitochondria

Acyl-protein thioesterases 1 and 2 (APT1 and APT2) reverse S-acylation, a potential regulator of systemic glucose metabolism in mammals. Palmitoylation proteomics in liver-specific knockout mice shows that APT1 predominates over APT2, primarily depalmitoylating mitochondrial proteins, including proteins linked to glutamine metabolism. miniTurbo-facilitated determination of the protein-protein proximity network of APT1 and APT2 in HepG2 cells reveals APT proximity networks encompassing mitochondrial proteins including the major translocases Tomm20 and Timm44. APT1 also interacts with Slc1a5 (ASCT2), the only glutamine transporter known to localize to mitochondria. High-fat-diet-fed male mice with dual (but not single) hepatic deletion of APT1 and APT2 have insulin resistance, fasting hyperglycemia, increased glutamine-driven gluconeogenesis, and decreased liver mass. These data suggest that APT1 and APT2 regulation of hepatic glucose metabolism and insulin signaling is functionally redundant. Identification of substrates and protein-protein proximity networks for APT1 and APT2 establishes a framework for defining mechanisms underlying metabolic disease.

Neuronal Glycogen Breakdown Mitigates Tauopathy via Pentose Phosphate Pathway-Mediated Oxidative Stress Reduction

Tauopathies encompass a range of neurodegenerative disorders, such as Alzheimer's disease (AD) and frontotemporal dementia (FTD). Unfortunately, current treatment approaches for tauopathies have yielded limited success, underscoring the pressing need for novel therapeutic strategies. We observed distinct signatures of impaired glycogen metabolism in the Drosophila brain of the tauopathy model and the brain of AD patients, indicating a link between tauopathies and glycogen metabolism. We demonstrate that the breakdown of neuronal glycogen by activating glycogen phosphorylase (GlyP) ameliorates the tauopathy phenotypes in flies and induced pluripotent stem cell (iPSC) derived neurons from FTD patients. We observed that glycogen breakdown redirects the glucose flux to the pentose phosphate pathway to alleviate oxidative stress. Our findings uncover a critical role for increased GlyP activity in mediating the neuroprotection benefit of dietary restriction (DR) through the cAMP-mediated protein kinase A (PKA) activation. Our studies identify impaired glycogen metabolism as a key hallmark for tauopathies and offer a promising therapeutic target in tauopathy treatment.

Stem cells therapy for diabetes: from past to future

Diabetes mellitus is a chronic disease of carbohydrate metabolism characterized by uncontrolled hyperglycemia due to the body's impaired ability to produce or respond to insulin. Oral or injectable exogenous insulin and its analogs cannot mimic endogenous insulin secreted by healthy individuals, and pancreatic and islet transplants face a severe shortage of sources and transplant complications, all of which limit the widespread use of traditional strategies in diabetes treatment. We are now in the era of stem cells and their potential in ameliorating human disease. At the same time, the rapid development of gene editing and cell-encapsulation technologies has added to the wings of stem cell therapy. However, there are still many unanswered questions before stem cell therapy can be applied clinically to patients with diabetes. In this review, we discuss the progress of strategies to obtain insulin-producing cells from different types of stem cells, the application of gene editing in stem cell therapy for diabetes, as well as summarize the current advanced cell encapsulation technologies in diabetes therapy and look forward to the future development of stem cell therapy in diabetes.

Hepatocyte TIPE2 is a fasting-induced Raf-1 inactivator that drives hepatic gluconeogenesis to maintain glucose homeostasis

BACKGROUND

The liver regulates metabolic balance during fasting-feeding cycle. Hepatic adaptation to fasting is precisely modulated on multiple levels. Tumor necrosis factor-α-induced protein 8-like 2 (TIPE2) is a negative regulator of immunity that reduces several liver pathologies, but its physiological roles in hepatic metabolism are largely unknown.

METHODS

TIPE2 expression was examined in mouse liver during fasting-feeding cycle. TIPE2-knockout mice, liver-specific TIPE2-knockout mice, liver-specific TIPE2-overexpressed mice were examined for fasting blood glucose and pyruvate tolerance test. Primary hepatocytes or liver tissues from these mice were evaluated for glucose production, lipid accumulation, gene expression and regulatory pathways. TIPE2 interaction with Raf-1 and TIPE2 transcription regulated by PPAR-α were examined using gene overexpression or knockdown, co-immunoprecipitation, western blot, luciferase reporter assay and DNA-protein binding assay.

RESULTS

TIPE2 expression was upregulated in fasted mouse liver and starved hepatocytes, which was positively correlated with gluconeogenic genes. Liver-specific TIPE2 deficiency impaired blood glucose homeostasis and gluconeogenic capacity in mice upon fasting, while liver-specific TIPE2 overexpression elevated fasting blood glucose and hepatic gluconeogenesis in mice. In primary hepatocytes upon starvation, TIPE2 interacted with Raf-1 to accelerate its ubiquitination and degradation, resulting in ERK deactivation and FOXO1 maintenance to sustain gluconeogenesis. During prolonged fasting, hepatic TIPE2 deficiency caused aberrant activation of ERK-mTORC1 axis that increased hepatic lipid accumulation via lipogenesis. In hepatocytes upon starvation, PPAR-α bound with TIPE2 promoter and triggered its transcriptional expression.

CONCLUSIONS

Hepatocyte TIPE2 is a PPAR-α-induced Raf-1 inactivator that sustains hepatic gluconeogenesis and prevents excessive hepatic lipid accumulation, playing beneficial roles in hepatocyte adaptation to fasting.

AMPD2 plays important roles in regulating hepatic glucose and lipid metabolism

Dysregulation of hepatic glucose and lipid metabolism can instigate the onset of various metabolic disorders including obesity, dyslipidemia, insulin resistance, type 2 diabetes, and fatty liver disease. Adenosine monophosphate (AMP) deaminase (AMPD), which converts AMP to inosine monophosphate, plays a key role in maintaining adenylate energy charge. AMPD2 is the major isoform present in the liver. However, the mechanistic link between AMPD2 and hepatic glucose and lipid metabolism remains elusive. In this study, we probed into the hepatic glucose and lipid metabolism in AMPD2-deficient (A2-/-) mice. These mice exhibited reduced body weight, fat accumulation, and blood glucose levels, coupled with enhanced insulin sensitivity while maintaining consistent calorie intake and spontaneous motor activity compared with wild type mice. Furthermore, A2-/- mice showed mitigated obesity and hyper-insulinemia induced by high-fat diet (HFD) but elevated levels of the serum triglyceride and cholesterol. The hepatic mRNA levels of several fatty acid and cholesterol metabolism-related genes were altered in A2-/- mice. RNA sequencing unveiled multiple alterations in lipid metabolic pathways due to AMPD2 deficiency. These mice were also more susceptible to fasting or HFD-induced hepatic lipid accumulation. The liver exhibited elevated AMP levels but unaltered AMP/ATP ratio. In addition, AMPD2 deficiency is not associated with the adenosine production. In summary, this study established a link between purine metabolism and hepatic glucose and lipid metabolism via AMPD2, providing novel insights into these metabolic pathways.

Autoimmune liver diseases and diabetes: A propensity score matched analysis and a proportional meta-analysis

BACKGROUND AND AIMS

Patients with some chronic liver diseases have increased risk of diabetes. Whether this is also the case for patients with autoimmune liver diseases is unknown. The study aimed to calculate risk and worldwide prevalence of diabetes in patients with autoimmune hepatitis (AIH), primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC).

METHODS

We performed a case-control study using data from the United Kingdom Biobank (UKB) and compared frequency of type 1 diabetes (T1D) and type 2 diabetes (T2D) in AIH and PBC with age-, sex-, BMI- and ethnicity-matched controls. Next, we performed a systematic review and proportional meta-analysis searching PubMed, Embase, Cochrane Library and Web of Science (inception to 1 May 2022 [AIH]; 20 August 2022 [PBC]; 11 November 2022 [PSC]). The pooled prevalence of diabetes was calculated using an inverse method random effects model.

RESULTS

Three hundred twenty-eight AIH patients and 345 PBC patients were identified in UKB and risk of T1D and T2D significantly increased compared with matched controls. Our systematic search identified 6914 records including the UKB study. Of these, 77 studies were eligible for inclusion comprising 36 467, 39 924 and 4877 individuals with AIH, PBC and PSC, respectively. The pooled prevalence of T1D was 3.8% (2.6%-5.7%), 1.7% (0.9%-3.1%), 3.1% (1.9%-4.8%) and of T2D 14.8% (11.1%-19.5%), 18.1% (14.6%-22.2%), 6.3% (2.8%-13.3%) in patients with AIH, PBC and PSC, respectively.

CONCLUSIONS

Patients with autoimmune liver diseases have increased risk of diabetes. Increased awareness of diabetes risk in patients with autoimmune liver diseases is warranted.

Chronic Glucocorticoid Exposure Induced an S1PR2-RORγ Axis to Enhance Hepatic Gluconeogenesis in Male Mice

It is well established that chronic glucocorticoid exposure causes hyperglycemia. While glucocorticoid receptor (GR) stimulates hepatic gluconeogenic gene transcription, additional mechanisms are activated by chronic glucocorticoid exposure to enhance gluconeogenesis. We found that chronic glucocorticoid treatment activated sphingosine-1-phosphate (S1P)-mediated signaling. Hepatic knockdown of hepatic S1P receptor 1 (S1PR1) had no effect on chronic glucocorticoid-induced glucose intolerance but elevated fasting plasma insulin levels. In contrast, hepatic S1PR3 knockdown exacerbated chronic glucocorticoid-induced glucose intolerance without affecting fasting plasma insulin levels. Finally, hepatic S1PR2 knockdown attenuated chronic glucocorticoid-induced glucose intolerance and reduced fasting plasma insulin levels. Here, we focused on dissecting the role of S1PR2 signaling in chronic glucocorticoid response on glucose homeostasis. We found that chronic glucocorticoid-induced hepatic gluconeogenesis, gluconeogenic gene expression, and GR recruitment to the glucocorticoid response elements (GREs) of gluconeogenic genes were all reduced in hepatic S1PR2 knockdown male mice. Hepatic S1PR2 knockdown also enhanced glucocorticoid suppression of RAR-related orphan receptor γ (RORγ) expression. Hepatic RORγ overexpression in hepatic S1PR2 knockdown mice restored glucocorticoid-induced glucose intolerance, gluconeogenic gene expression, and GR recruitment to their GREs. Conversely, RORγ antagonist and the reduction of hepatic RORγ expression attenuated such glucocorticoid effects. Thus, chronic glucocorticoid exposure induces an S1PR2-RORγ axis to cooperate with GR to enhance hepatic gluconeogenesis. Overall, this work provides novel mechanisms of and pharmaceutical targets against steroid-induced hyperglycemia.

ARTICLE HIGHLIGHTS

NAFLD: An Emerging Causal Factor for Cardiovascular Disease

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease worldwide that poses a significant threat to human health. Cardiovascular disease (CVD) is the leading cause of mortality in NAFLD patients. NAFLD and CVD share risk factors such as obesity, insulin resistance, and type 2 diabetes. However, whether NAFLD is a causal risk factor for CVD remains a matter of debate. This review summarizes the evidence from prospective clinical and Mendelian randomization studies that underscore the potential causal relationship between NAFLD and CVD. The mechanisms of NAFLD contributing to the development of CVD and the necessity of addressing CVD risk while managing NAFLD in clinical practice are also discussed.

A systematic review exploring the mechanisms by which citrus bioflavonoid supplementation benefits blood glucose levels and metabolic complications in type 2 diabetes mellitus

BACKGROUND

Citrus bioflavonoids are polyphenolic compounds that are derived from citrus fruits and vegetables. Although they are well known for their powerful antioxidant properties, their effects on glycemic control are not well understood. This review aims to highlight the potential benefits of using citrus bioflavonoids in patients with type 2 diabetes mellitus and its metabolic complications, as well as the medicinal effects of known subclasses of naturally occurring citrus bioflavonoids.

METHODS

In this systematic review, a survey of studies was conducted from January 2012 to February 2023 using various databases (PubMed, Medline, Google Scholar, and Scopus) to determine the effects of citrus bioflavonoid supplementation on reducing oxidative stress, improving lipid profiles, and glycemic index in patients with diabetes mellitus, as well as the proposed mechanisms of action.

RESULTS

The results of the survey indicate that citrus bioflavonoids may have a positive impact on reducing oxidative stress levels in patients with type 2 diabetes mellitus. In addition to reducing oxidative stress, citrus bioflavonoids may also have a positive impact on other markers of diabetes. For example, studies have shown that they can reduce non-enzymatic protein glycation, which is a process that occurs when glucose molecules bind to proteins in the body.

CONCLUSION

The reduction in oxidative stress that can be achieved using citrus bioflavonoids may help to maintain antioxidant levels in the body, thereby reducing the severity of diabetes and its complications. These findings suggest that citrus bioflavonoids may be a useful complementary therapy for patients with diabetes.