The cellular fate of glucose and its relevance in type 2 diabetes

Exogenous thyroxine increases cardiac GLUT4 translocation in insulin resistant OLETF rats

During insulin resistance, the heart undergoes a metabolic shift in which fatty acids (FA) account for roughly about 99% of the ATP production. This metabolic shift is indicative of impaired glucose metabolism. A shift in FA metabolism with impaired glucose tolerance can increase reactive oxygen species (ROS), lipotoxicity, and mitochondrial dysfunction, ultimately leading to cardiomyopathy. Thyroid hormones (TH) may improve the glucose intolerance by increasing glucose reabsorption and metabolism in peripheral tissues, but little is known on its effects on cardiac tissue during insulin resistance. In the present study, insulin resistant Otsuka Long Evans Tokushima Fatty (OLETF) rats were used to assess the effects of exogenous thyroxine (T4) on glucose metabolism in cardiac tissue. Rats were assigned to four groups: (1) lean, Long Evans Tokushima Otsuka (LETO; n=6), (2) LETO + T4 (8 μg/100 g BM/d × 5 wks; n = 7), (3) untreated OLETF (n = 6), and (4) OLETF + T4 (8 μg/100 g BM/d × 5 wks; n = 7). T4 increased GLUT4 gene expression by 85% in OLETF and increased GLUT4 protein translocation to the membrane by 294%. Additionally, T4 increased p-AS160 by 285%, phosphofructokinase-1 (PFK-1) mRNA, the rate limiting step in glycolysis, by 98% and hexokinase II by 64% in OLETF. T4 decreased both CPT2 mRNA and protein expression in OLETF. The results suggest that exogenous T4 has the potential to increase glucose uptake and metabolism while simultaneously reducing fatty acid transport in the heart of insulin resistant rats. Thus, L-thyroxine may have therapeutic value to help correct the impaired substrate metabolism associated with diabetic cardiomyopathy.

A nutrient responsive lipase mediates gut-brain communication to regulate insulin secretion in Drosophila

Pancreatic β cells secrete insulin in response to glucose elevation to maintain glucose homeostasis. A complex network of inter-organ communication operates to modulate insulin secretion and regulate glucose levels after a meal. Lipids obtained from diet or generated intracellularly are known to amplify glucose-stimulated insulin secretion, however, the underlying mechanisms are not completely understood. Here, we show that a Drosophila secretory lipase, Vaha (CG8093), is synthesized in the midgut and moves to the brain where it concentrates in the insulin-producing cells in a process requiring Lipid Transfer Particle, a lipoprotein originating in the fat body. In response to dietary fat, Vaha stimulates insulin-like peptide release (ILP), and Vaha deficiency results in reduced circulatory ILP and diabetic features including hyperglycemia and hyperlipidemia. Our findings suggest Vaha functions as a diacylglycerol lipase physiologically, by being a molecular link between dietary fat and lipid amplified insulin secretion in a gut-brain axis.

Clinical applications and mechanism insights of natural flavonoids against type 2 diabetes mellitus

Diabetes is a complex disease that affects a large percentage of the world's population, and it is associated with several risk factors. Self-management poses a significant challenge, but natural sources have shown great potential in providing effective glucose reducing solutions. Flavonoids, a class of bioactive substances found in different natural sources including medicinal plants, have emerged as promising candidates in this regard. Indeed, several flavonoids, including apigenin, arbutin, catechins, and cyanidin, have demonstrated remarkable anti-diabetic properties. The clinical effectiveness of these flavonoids is linked to their potential to decrease blood glucose concentration and increase insulin concentration. Thus, the regulation of certain metabolic pathways such as glycolysis and neoglycogenesis has also been demonstrated. In vitro and in vivo investigations revealed different mechanisms of action related to flavonoid compounds at subcellular, cellular, and molecular levels. The main actions reside in the activation of glycolytic signaling pathways and the inhibition of signaling that promotes glucose synthesis and storage. In this review, we highlight the clinical efficiency of natural flavonoids as well as the molecular mechanisms underlying this effectiveness.

Modulatory effects of rutin and vitamin A on hyperglycemia induced glycation, oxidative stress and inflammation in high-fat-fructose diet animal model

In the current study we investigated the impact of combination of rutin and vitamin A on glycated products, the glyoxalase system, oxidative markers, and inflammation in animals fed a high-fat high-fructose (HFFD) diet. Thirty rats were randomly divided into six groups (n = 5). The treatments, metformin (120 mg/kg), rutin (100 mg/kg), vitamin A (43 IU/kg), and a combination of rutin (100 mg/kg) and vitamin A (43 IU/kg) were given to relevant groups of rats along with high-fructose high-fat diet for 42 days. HbA1c, D-lactate, Glyoxylase-1, Hexokinase 2, malondialdehyde (MDA), glutathione peroxidase (GPx), catalase (CAT), nuclear transcription factor-B (NF-κB), interleukin-6 (IL-6), interleukin-8 (IL-8) and histological examinations were performed after 42 days. The docking simulations were conducted using Auto Dock package. The combined effects of rutin and vitamin A in treated rats significantly (p < 0.001) reduced HbA1c, hexokinase 2, and D-lactate levels while preventing cellular damage. The combination dramatically (p < 0.001) decreased MDA, CAT, and GPx in treated rats and decreased the expression of inflammatory cytokines such as IL-6 andIL-8, as well as the transcription factor NF-κB. The molecular docking investigations revealed that rutin had a strong affinity for several important biomolecules, including as NF-κB, Catalase, MDA, IL-6, hexokinase 2, and GPx. The results propose beneficial impact of rutin and vitamin A as a convincing treatment strategy to treat AGE-related disorders, such as diabetes, autism, alzheimer's, atherosclerosis.

Novel 4th-generation phytase improves broiler growth performance and reduces woody breast severity through modulation of muscle glucose uptake and metabolism

The objective of the present study was to determine the effect of a novel (4th generation) phytase supplementation as well as its mode of action on growth, meat quality, and incidence of muscle myopathies. One-day old male broilers (n = 720) were weighed and randomly allocated to 30 floor pens (24 birds/pen) with 10 replicate pens per treatment. Three diets were fed from hatch to 56- days-old: a 3-phase corn-soy based diet as a positive control (PC); a negative control (NC) formulated to be isocaloric and isonitrogenous to the PC and with a reduction in Ca and available P, respectively; and the NC supplemented with 2,000 phytase units per kg of diet (NC + P). At the conclusion of the experiment, birds fed with NC + P diet were significantly heavier and had 2.1- and 4.2-points better feed conversion ratio (FCR) compared to birds offered NC and PC diets, respectively. Processing data showed that phytase supplementation increased live weight, hot carcass without giblets, wings, tender, and skin-on drum and thigh compared to both NC and PC diets. Macroscopic scoring showed that birds fed the NC + P diet had lower woody breast (WB) severity compared to those fed the PC and NC diets, however there was no effect on white striping (WS) incidence and meat quality parameters (pH, drip loss, meat color). To delineate its mode of action, iSTAT showed that blood glucose concentrations were significantly lower in birds fed NC + P diet compared to those offered PC and NC diets, suggesting a better glucose uptake. In support, molecular analyses demonstrated that the breast muscle expression (mRNA and protein) of glucose transporter 1 (GLUT1) and glucokinase (GK) was significantly upregulated in birds fed NC + P diet compared to those fed the NC and PC diets. The expression of mitochondrial ATP synthase F0 subunit 8 (MT-ATP8) was significantly upregulated in NC + P compared to other groups, indicating intracellular ATP abundance for anabolic pathways. This was confirmed by the reduced level of phosphorylated-AMP-activated protein kinase (AMPKα1/2) at Thr172 site, upregulation of glycogen synthase (GYS1) gene and activation of mechanistic target of rapamycin and ribosomal protein S6 kinase (mTOR-P70S6K) pathway. In conclusion, this is the first report showing that in-feed supplementation of the novel phytase improves growth performance and reduces WB severity in broilers potentially through enhancement of glucose uptake, glycolysis, and intracellular ATP production, which used for muscle glycogenesis and protein synthesis.

Insulin signaling and pharmacology in humans and in corals

Once thought to be a unique capability of the Langerhans islets in the pancreas of mammals, insulin (INS) signaling is now recognized as an evolutionarily ancient function going back to prokaryotes. INS is ubiquitously present not only in humans but also in unicellular eukaryotes, fungi, worms, and Drosophila. Remote homologue identification also supports the presence of INS and INS receptor in corals where the availability of glucose is largely dependent on the photosynthetic activity of the symbiotic algae. The cnidarian animal host of corals operates together with a 20,000-sized microbiome, in direct analogy to the human gut microbiome. In humans, aberrant INS signaling is the hallmark of metabolic disease, and is thought to play a major role in aging, and age-related diseases, such as Alzheimer's disease. We here would like to argue that a broader view of INS beyond its human homeostasis function may help us understand other organisms, and in turn, studying those non-model organisms may enable a novel view of the human INS signaling system. To this end, we here review INS signaling from a new angle, by drawing analogies between humans and corals at the molecular level.

Label-free quantitative proteomics reveals the potential mechanisms of insoluble dietary fiber from okara in improving hepatic lipid metabolism of high-fat diet-induced mice

The high purity insoluble dietary fiber (IDF) from okara is a natural component with a potentially positive effect on a high-fat diet (HFD)-induced hepatic metabolic disorders, although its regulatory mechanism remains unclear. This study aims to elucidate the potential pathways and key proteins of IDF for the amelioration of hepatic lipid metabolism in mice fed with HFD. Here, we used label-free quantitative proteomics technology to quantity and identify differentially expressed proteins in the liver that are associated with IDF treatment. The differentially expressed proteins were assessed by GO annotation and KEGG pathways. Western blot and qRT-PCR analyses were conducted to validate the potential targets regulated by IDF. In total, 73 differentially expressed proteins were identified, of which 27 were up-regulated (FC > 1.5) and 46 were down-regulated (FC < 0.667). GO analysis suggested that differentially expressed proteins were mainly located in the cell and organelles, regulated biological processes, and were associated with enzyme activity and molecular binding. The KEGG pathway enrichment analysis further demonstrated glycolysis/gluconeogenesis, pyruvate metabolism, TCA cycle, arginine biosynthesis, alanine, aspartate and glutamate metabolism, and retinol metabolism were affected. The combination of proteomics, Western blot, and qRT-PCR suggested that ACS, ACLY, GOT1, GLS2, NAGS, CYP4A10, CYP3A25, and CYP2A5 in these pathways might be key proteins for IDF intervention. Taken together, our findings elucidate new mechanisms involved in how IDF affects hepatic metabolism, provide important information for the functional food industries, and improve the added value of okara. SIGNIFICANCE: Okara is evidenced as a high-quality by-product with several nutritional components, especially dietary fiber (50-60%) labeled as "The Seventh Nutrient". Previous studies have shown that IDF has a positive potential effect on a high-fat diet (HFD)-induced hepatic metabolic disorders, but its molecular mechanism remains unclear. To elucidate the therapeutic mechanism of IDF at the protein level, a label-free quantitative proteomic analysis was used to identify the dynamic changes of the liver proteome between HIDF and HFD groups in this study. These results provide a new perspective for exploring the therapeutic mechanism of IDF at the protein level and enlightenment for promoting the comprehensive utilization of okara.

Fortification of Fermented Camel Milk with Salvia officinalis L. or Mentha piperita Leaves Powder and Its Biological Effects on Diabetic Rats

The incorporation of fermented camel milk with natural additives possesses numerous benefits for the treatment of various pathological and metabolic conditions. The present study investigated the impact of fortification of fermented camel milk with sage or mint leaves powder (1 and 1.5%, respectively) on glucose and insulin levels, lipid profile, and liver and kidney functions in alloxan-induced diabetic rats. The gross chemical composition of sage and peppermint leaves powder was studied. The chemical composition of sage and mint extracts was performed using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-MS) of sage and mint extracts. Furthermore, a total of forty-two adult normal male albino rats were included in this study, whereas one group was kept as the healthy control group (n = 6 rats) and diabetes was induced in the remaining animals (n = 36 rats) using alloxan injection (150 mg/kg of body weight). Among diabetic rats groups, a control group (n = 6 rats) was kept as the diabetic control group whereas the other 5 groups (6 rats per group) of diabetic rats were fed fermented camel milk (FCM) or fermented camel milk fortified with 1 and 1.5% of sage or mint leaves powder. Interestingly, the oral administration of fermented camel milk fortified with sage or mint leaves powder, at both concentrations, caused a significant decrease in blood glucose level and lipid profile, and an increase in insulin level compared to the diabetic control and FCM groups. Among others, the best results were observed in the group of animals that received fermented camel milk fortified with 1.5% sage powder. In addition, the results revealed that the fermented camel milk fortified with sage or mint leaves powder improved the liver and kidney functions of diabetic rats. Our study concluded that the use of sage and mint leaves powder (at a ratio of 1.5%) with fermented camel milk produces functional food products with anti-diabetic activity.

Nutrient sensors and their crosstalk

The macronutrients glucose, lipids, and amino acids are the major components that maintain life. The ability of cells to sense and respond to fluctuations in these nutrients is a crucial feature for survival. Nutrient-sensing pathways are thus developed to govern cellular energy and metabolic homeostasis and regulate diverse biological processes. Accordingly, perturbations in these sensing pathways are associated with a wide variety of pathologies, especially metabolic diseases. Molecular sensors are the core within these sensing pathways and have a certain degree of specificity and affinity to sense the intracellular fluctuation of each nutrient either by directly binding to that nutrient or indirectly binding to its surrogate molecules. Once the changes in nutrient levels are detected, sensors trigger signaling cascades to fine-tune cellular processes for energy and metabolic homeostasis, for example, by controlling uptake, de novo synthesis or catabolism of that nutrient. In this review, we summarize the major discoveries on nutrient-sensing pathways and explain how those sensors associated with each pathway respond to intracellular nutrient availability and how these mechanisms control metabolic processes. Later, we further discuss the crosstalk between these sensing pathways for each nutrient, which are intertwined to regulate overall intracellular nutrient/metabolic homeostasis.

Oxidative phosphorylation in bone cells

The role of energy metabolism in bone cells is an active field of investigation. Bone cells are metabolically very active and require high levels of energy in the form of adenosine triphosphate (ATP) to support their function. ATP is generated in the cytosol via glycolysis coupled with lactic acid fermentation and in the mitochondria via oxidative phosphorylation (OXPHOS). OXPHOS is the final convergent metabolic pathway for all oxidative steps of dietary nutrients catabolism. The formation of ATP is driven by an electrochemical gradient that forms across the mitochondrial inner membrane through to the activity of the electron transport chain (ETC) complexes and requires the presence of oxygen as the final electron acceptor. The current literature supports a model in which glycolysis is the main source of energy in undifferentiated mesenchymal progenitors and terminally differentiated osteoblasts, whereas OXPHOS appears relevant in an intermediate stage of differentiation of those cells. Conversely, osteoclasts progressively increase OXPHOS during differentiation until they become multinucleated and mitochondrial-rich terminal differentiated cells. Despite the abundance of mitochondria, mature osteoclasts are considered ATP-depleted, and the availability of ATP is a critical factor that regulates the low survival capacity of these cells, which rapidly undergo death by apoptosis. In addition to ATP, bioenergetic metabolism generates reactive oxygen species (ROS) and intermediate metabolites that regulate a variety of cellular functions, including epigenetics changes of genomic DNA and histones. This review will briefly discuss the role of OXPHOS and the cross-talks OXPHOS-glycolysis in the differentiation process of bone cells.

Nutrigenomic regulation of sensory plasticity

Diet profoundly influences brain physiology, but how metabolic information is transmuted into neural activity and behavior changes remains elusive. Here, we show that the metabolic enzyme O-GlcNAc Transferase (OGT) moonlights on the chromatin of the D. melanogaster gustatory neurons to instruct changes in chromatin accessibility and transcription that underlie sensory adaptations to a high-sugar diet. OGT works synergistically with the Mitogen Activated Kinase/Extracellular signal Regulated Kinase (MAPK/ERK) rolled and its effector stripe (also known as EGR2 or Krox20) to integrate activity information. OGT also cooperates with the epigenetic silencer Polycomb Repressive Complex 2.1 (PRC2.1) to decrease chromatin accessibility and repress transcription in the high-sugar diet. This integration of nutritional and activity information changes the taste neurons' responses to sugar and the flies' ability to sense sweetness. Our findings reveal how nutrigenomic signaling generates neural activity and behavior in response to dietary changes in the sensory neurons.

Relevance of Indian traditional tisanes in the management of type 2 diabetes mellitus: a review

Background

Tisanes are a potential source of phytochemicals to reduce disease risk conditions and are used to protect from non-communicable diseases, globally. A few tisanes have gained more popularity than others depending on their chemical composition based on the geographical origin of the used herb. Several Indian tisanes have been claimed to have traits beneficial to people with or at a high risk of type 2 diabetes mellitus. Under the concept, the literature was reviewed and compiled into a document to highlight the chemical uniqueness of popular Indian traditional tisanes to be more informative and potent as per modern medicine to overcome type 2 diabetes mellitus.

Methods

An extensive literature survey was conducted using computerized database search engines, such as Google Scholar, PubMed, ScienceDirect, and EMBASE (Excerpta Medica database) for herbs that have been described for hyperglycemia, and involved reaction mechanism, in-vivo studies as well as clinical efficacies published since 2001 onwards using certain keywords. Compiled survey data used to make this review and all findings on Indian traditional antidiabetic tisanes are tabulated here.

Results

Tisanes render oxidative stress, counter the damage by overexposure of free radicals to the body, affect enzymatic activities, enhance insulin secretion, etc. The active molecules of tisanes also act as anti-allergic, antibacterial, anti-inflammatory, antioxidant, antithrombotic, antiviral, antimutagenicity, anti-carcinogenicity, antiaging effects, etc. WHO also has a strategy to capitalize on the use of herbals to keep populations healthy through effective and affordable alternative means with robust quality assurance and strict adherence to the product specification.

Bioinformatics Analysis of Next Generation Sequencing Data Identifies Molecular Biomarkers Associated With Type 2 Diabetes Mellitus

Background

Type 2 diabetes mellitus (T2DM) is the most common metabolic disorder. The aim of the present investigation was to identify gene signature specific to T2DM.

Methods

The next generation sequencing (NGS) dataset GSE81608 was retrieved from the gene expression omnibus (GEO) database and analyzed to identify the differentially expressed genes (DEGs) between T2DM and normal controls. Then, Gene Ontology (GO) and pathway enrichment analysis, protein-protein interaction (PPI) network, modules, miRNA (micro RNA)-hub gene regulatory network construction and TF (transcription factor)-hub gene regulatory network construction, and topological analysis were performed. Receiver operating characteristic curve (ROC) analysis was also performed to verify the prognostic value of hub genes.

Results

A total of 927 DEGs (461 were up regulated and 466 down regulated genes) were identified in T2DM. GO and REACTOME results showed that DEGs mainly enriched in protein metabolic process, establishment of localization, metabolism of proteins, and metabolism. The top centrality hub genes APP, MYH9, TCTN2, USP7, SYNPO, GRB2, HSP90AB1, UBC, HSPA5, and SQSTM1 were screened out as the critical genes. ROC analysis provides prognostic value of hub genes.

Conclusion

The potential crucial genes, especially APP, MYH9, TCTN2, USP7, SYNPO, GRB2, HSP90AB1, UBC, HSPA5, and SQSTM1, might be linked with risk of T2DM. Our study provided novel insights of T2DM into genetics, molecular pathogenesis, and novel therapeutic targets.

The Epigenetic Regulation of RNA N6-Methyladenosine Methylation in Glycolipid Metabolism

The highly conserved and dynamically reversible N6-methyladenine (m6A) modification has emerged as a critical gene expression regulator by affecting RNA splicing, translation efficiency, and stability at the post-transcriptional level, which has been established to be involved in various physiological and pathological processes, including glycolipid metabolism and the development of glycolipid metabolic disease (GLMD). Hence, accumulating studies have focused on the effects and regulatory mechanisms of m6A modification on glucose metabolism, lipid metabolism, and GLMD. This review summarizes the underlying mechanism of how m6A modification regulates glucose and lipid metabolism-related enzymes, transcription factors, and signaling pathways and the advances of m6A regulatory mechanisms in GLMD in order to deepen the understanding of the association of m6A modification with glycolipid metabolism and GLMD.

Sarcopenia in Chronic Liver Disease: A Metabolic Perspective

Sarcopenia, a condition of low muscle mass, quality, and strength, is commonly found in patients with chronic liver disease (CLD) and is associated with adverse clinical outcomes including reduction in quality of life, increased mortality, and complications. A major contributor to sarcopenia in CLD is the imbalance in muscle protein turnover wherein changes in various metabolic factors such as hyperammonemia, amino acid deprivation, hormonal imbalance, gut dysbiosis, insulin resistance, chronic inflammation, etc. have important roles. In particular, hyperammonemia is a key mediator of the liver-gut axis and is known to contribute to sarcopenia by various mechanisms including increased expression of myostatin, increased phosphorylation of eukaryotic initiation factor 2a, cataplerosis of α-ketoglutarate, mitochondrial dysfunction, increased reactive oxygen species that decrease protein synthesis and increased autophagy-mediated proteolysis. Skeletal muscle is a major organ of insulin-induced glucose metabolism, and sarcopenia is closely linked to insulin resistance and metabolic syndrome. Patients with liver cirrhosis are in a hypermetabolic state that is associated with catabolism and depletion of amino acids, particularly branched-chain amino acids. Sarcopenia can have significant implications for nonalcoholic fatty liver disease, the most common form of CLD worldwide, because of the close link between metabolic syndrome and sarcopenia. This review discusses the potential metabolic derangement as a cause or effect of sarcopenia in CLD, as well as interorgan crosstalk, which that might help identifying a novel therapeutic strategies.

Glucose metabolism in skeletal cells

The mammalian skeleton is integral to whole body physiology with a multitude of functions beyond mechanical support and locomotion, including support of hematopoiesis, mineral homeostasis and potentially other endocrine roles. Formation of the skeleton begins in the embryo and mostly from a cartilage template that is ultimately replaced by bone through endochondrial ossification. Skeletal development and maturation continue after birth in most species and last into the second decade of postnatal life in humans. In the mature skeleton, articular cartilage lining the synovial joint surfaces is vital for bodily movement and damages to the cartilage are a hallmark of osteoarthritis. The mature bone tissue undergoes continuous remodeling initiated with bone resorption by osteoclasts and completed with bone formation from osteoblasts. In a healthy state, the exquisite balance between bone resorption and formation is responsible for maintaining a stable bone mass and structural integrity, while meeting the physiological needs for minerals via controlled release from bone. Disruption of the balance in favor of bone resorption is the root cause for osteoporosis. Whereas osteoclasts pump molar quantities of hydrochloric acid to dissolve the bone minerals in a process requiring ATP hydrolysis, osteoblasts build bone mass by synthesizing and secreting copious amounts of bone matrix proteins. Thus, both osteoclasts and osteoblasts engage in energy-intensive activities to fulfill their physiological functions, but the bioenergetics of those and other skeletal cell types are not well understood. Nonetheless, the past ten years have witnessed a resurgence of interest in studies of skeletal cell metabolism, resulting in an unprecedented understanding of energy substrate utilization and its role in cell fate and activity regulation. The present review attempts to synthesize the current findings of glucose metabolism in chondrocytes, osteoblasts and osteoclasts. Advances with the other relevant cell types including skeletal stem cells and marrow adipocytes will not be discussed here as they have been extensively reviewed recently by others (van Gastel and Carmeliet, 2021). Elucidation of the bioenergetic mechanisms in the skeletal cells is likely to open new avenues for developing additional safe and effective bone therapies.

Monitoring and modelling the dynamics of the cellular glycolysis pathway: A review and future perspectives

BACKGROUND

The dynamics of the cellular glycolysis pathway underpin cellular function and dysfunction, and therefore ultimately health, disease, diagnostic and therapeutic strategies. Evolving our understanding of this fundamental process and its dynamics remains critical.

SCOPE OF REVIEW

This paper reviews the medical relevance of glycolytic pathway in depth and explores the current state of the art for monitoring and modelling the dynamics of the process. The future perspectives of label free, vibrational microspectroscopic techniques to overcome the limitations of the current approaches are considered.

MAJOR CONCLUSIONS

Vibrational microspectroscopic techniques can potentially operate in the niche area of limitations of other omics technologies for non-destructive, real-time, in vivo label-free monitoring of glycolysis dynamics at a cellular and subcellular level.

Involvement of the extracellular matrix and integrin signalling proteins in skeletal muscle glucose uptake

Whole-body euglycaemia is partly maintained by two cellular processes that encourage glucose uptake in skeletal muscle, the insulin- and contraction-stimulated pathways, with research suggesting convergence between these two processes. The normal structural integrity of the skeletal muscle requires an intact actin cytoskeleton as well as integrin-associated proteins, and thus those structures are likely fundamental for effective glucose uptake in skeletal muscle. In contrast, excessive extracellular matrix (ECM) remodelling and integrin expression in skeletal muscle may contribute to insulin resistance owing to an increased physical barrier causing reduced nutrient and hormonal flux. This review explores the role of the ECM and the actin cytoskeleton in insulin- and contraction-mediated glucose uptake in skeletal muscle. This is a clinically important area of research given that defects in the structural integrity of the ECM and integrin-associated proteins may contribute to loss of muscle function and decreased glucose uptake in type 2 diabetes.

3,3′,4,5′-Tetramethoxy-trans-stilbene Improves Insulin Resistance by Activating the IRS/PI3K/Akt Pathway and Inhibiting Oxidative Stress

The potential anti-diabetic effect of resveratrol derivative, 3,3′,4,5′-tetramethoxy-trans-stilbene (3,3′,4,5′-TMS) and its underlying mechanism in high glucose (HG) and dexamethasone (DXMS)-stimulated insulin-resistant HepG2 cells (IR-HepG2) were investigated. 3,3′,4,5′-TMS did not reduce the cell viability of IR-HepG2 cells at the concentrations of 0.5–10 µM. 3,3′,4,5′-TMS increased the potential of glucose consumption and glycogen synthesis in a concentration-dependent manner in IR-HepG2 cells. 3,3′,4,5′-TMS ameliorated insulin resistance by enhancing the phosphorylation of glycogen synthase kinase 3 beta (GSK3β), inhibiting phosphorylation of insulin receptor substrate-1 (IRS-1), and activating phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway in IR-HepG2 cells. Furthermore, 3,3′,4,5′-TMS significantly suppressed levels of reactive oxygen species (ROS) with up-regulation of nuclear factor erythroid 2-related factor 2 (Nrf2) expression. To conclude, the beneficial effect of 3,3′,4,5′-TMS against insulin resistance to increase glucose consumption and glycogen synthesis was mediated through activation of IRS/PI3K/Akt signaling pathways in the IR-HepG2 cells, accomplished with anti-oxidative activity through up-regulation of Nrf2.

Insulin: The master regulator of glucose metabolism

Insulin is the master regulator of glucose, lipid, and protein metabolism. Following ingestion of an oral glucose load or mixed meal, the plasma glucose concentration rises, insulin secretion by the beta cells is stimulated and the hyperinsulinemia, working in concert with hyperglycemia, causes: (i) suppression of endogenous (primarily reflects hepatic) glucose production, (ii) stimulation of glucose uptake by muscle, liver, and adipocytes, (iii) inhibition of lipolysis leading to a decline in plasma FFA concentration which contributes to the suppression of hepatic glucose production and augmentation of muscle glucose uptake, and (iv) vasodilation in muscle, which contributes to enhanced muscle glucose disposal. Herein, the integrated physiologic impact of insulin to maintain normal glucose homeostasis is reviewed and the molecular basis of insulin's diverse actions in muscle, liver, adipocytes, and vasculature are discussed.

Role of Endothelin-1 Receptors in Limiting Leg Blood Flow and Glucose Uptake During Hyperinsulinemia in Type 2 Diabetes

Skeletal muscle insulin resistance is a hallmark of individuals with type 2 diabetes mellitus (T2D). In healthy individuals insulin stimulates vasodilation, which is markedly blunted in T2D; however, the mechanism(s) remain incompletely understood. Investigations in rodents indicate augmented endothelin-1 (ET-1) action as a major contributor. Human studies have been limited to young obese participants and focused exclusively on the ET-1 A (ETA) receptor. Herein, we have hypothesized that ETA receptor antagonism would improve insulin-stimulated vasodilation and glucose uptake in T2D, with further improvements observed during concurrent ETA + ET-1 B (ETB) antagonism. Arterial pressure (arterial line), leg blood flow (LBF; Doppler), and leg glucose uptake (LGU) were measured at rest, during hyperinsulinemia alone, and hyperinsulinemia with (1) femoral artery infusion of BQ-123, the selective ETA receptor antagonist (n = 10 control, n = 9 T2D) and then (2) addition of BQ-788 (selective ETB antagonist) for blockade of ETA and ETB receptors (n = 7 each). The LBF responses to hyperinsulinemia alone tended to be lower in T2D (controls: ∆161 ± 160 mL/minute; T2D: ∆58 ± 43 mL/minute, P = .08). BQ-123 during hyperinsulinemia augmented LBF to a greater extent in T2D (% change: controls: 14 ± 23%; T2D: 38 ± 21%, P = .029). LGU following BQ-123 increased similarly between groups (P = .85). Concurrent ETA + ETB antagonism did not further increase LBF or LGU in either group. Collectively, these findings suggest that during hyperinsulinemia ETA receptor activation restrains vasodilation more in T2D than controls while limiting glucose uptake similarly in both groups, with no further effect of ETB receptors (NCT04907838).

Glucose Uptake by Skeletal Muscle within the Contexts of Type 2 Diabetes and Exercise: An Integrated Approach

Type 2 diabetes continues to negatively impact the health of millions. The inability to respond to insulin to clear blood glucose (insulin resistance) is a key pathogenic driver of the disease. Skeletal muscle is the primary tissue for maintaining glucose homeostasis through glucose uptake via insulin-dependent and -independent mechanisms. Skeletal muscle is also responsive to exercise-meditated glucose transport, and as such, exercise is a cornerstone for glucose management in people with type 2 diabetes. Skeletal muscle glucose uptake requires a concert of events. First, the glucose-rich blood must be transported to the skeletal muscle. Next, the glucose must traverse the endothelium, extracellular matrix, and skeletal muscle membrane. Lastly, intracellular metabolic processes must be activated to maintain the diffusion gradient to facilitate glucose transport into the cell. This review aims to examine the physiology at each of these steps in healthy individuals, analyze the dysregulation affecting these pathways associated with type 2 diabetes, and describe the mechanisms by which exercise acts to increase glucose uptake.

LDHB Deficiency Promotes Mitochondrial Dysfunction Mediated Oxidative Stress and Neurodegeneration in Adult Mouse Brain

Age-related decline in mitochondrial function and oxidative stress plays a critical role in neurodegeneration. Lactate dehydrogenase-B (LDHB) is a glycolytic enzyme that catalyzes the conversion of lactate, an important brain energy substrate, into pyruvate. It has been reported that the LDHB pattern changes in the brain during ageing. Yet very little is known about the effect of LDHB deficiency on brain pathology. Here, we have used Ldhb knockout (Ldhb^−/−) mice to test the hypothesis that LDHB deficiency plays an important role in oxidative stress-mediated neuroinflammation and neurodegeneration. LDHB knockout (Ldhb^−/−) mice were generated by the ablation of the Ldhb gene using the Cre/loxP-recombination system in the C57BL/6 genetic background. The Ldhb^−/− mice were treated with either osmotin (15 μg/g of the body; intraperitoneally) or vehicle twice a week for 5-weeks. After behavior assessments, the mice were sacrificed, and the cortical and hippocampal brain regions were analyzed through biochemical and morphological analysis. Ldhb^−/− mice displayed enhanced reactive oxygen species (ROS) and lipid peroxidation (LPO) production, and they revealed depleted stores of cellular ATP, GSH:GSSG enzyme ratio, and downregulated expression of Nrf2 and HO-1 proteins, when compared to WT littermates. Importantly, the Ldhb^−/− mice showed upregulated expression of apoptosis mediators (Bax, Cytochrome C, and caspase-3), and revealed impaired p-AMPK/SIRT1/PGC-1alpha signaling. Moreover, LDHB deficiency-induced gliosis increased the production of inflammatory mediators (TNF-α, Nf-ĸB, and NOS2), and revealed cognitive deficits. Treatment with osmotin, an adipoR1 natural agonist, significantly increased cellular ATP production by increasing mitochondrial function and attenuated oxidative stress, neuroinflammation, and neuronal apoptosis, probably, by upregulating p-AMPK/SIRT1/PGC-1alpha signaling in Ldhb^−/− mice. In brief, LDHB deficiency may lead to brain oxidative stress-mediated progression of neurodegeneration via regulating p-AMPK/SIRT1/PGC-1alpha signaling, while osmotin could improve mitochondrial functions, abrogate oxidative stress and alleviate neuroinflammation and neurodegeneration in adult Ldhb^−/− mice.

Differential expression of aerobic oxidative metabolism-related proteins in diabetic urinary exosomes

BACKGROUND

As a metabolic disease, any abnormality in the aerobic oxidation pathway of glucose may lead to the occurrence of diabetes. This study aimed to investigate the changes in proteins related to aerobic oxidative metabolism in urinary exosomes of diabetic patients and normal controls of different ages, and to further verify their correlation with the pathogenesis of diabetes.

METHODS

Samples were collected, and proteomic information of urinary exosomes was collected by LC-MS/MS. ELISA was used to further detect the expression of aerobic and oxidative metabolism-related proteins in urinary exosomes of diabetic patients and normal controls of different ages, and to draw receiver operating characteristic (ROC) curve to evaluate its value in diabetes monitoring.

RESULTS

A total of 17 proteins involved in aerobic oxidative metabolism of glucose were identified in urinary exosome proteins. Compared with normal control, the expressions of PFKM, GAPDH, ACO2 and MDH2 in diabetic patients were decreased, and the expression of IDH3G was increased. The concentrations of PFKM, GAPDH and ACO2 in urinary exosomes were linearly correlated with the expression of MDH2 (P<0.05). These four proteins vary with age, with the maximum concentration in the 45-59 age group. PFKM, GAPDH, ACO2, and MDH2 in urinary exosomes have certain monitoring value. When used in combination, the AUC was 0.840 (95% CI 0.764-0.915).

CONCLUSIONS

In diabetic patients, aerobic oxidative metabolism is reduced, and the expression of aerobic oxidative metabolism-related proteins PFKM, GAPDH, ACO2, and MDH2 in urinary exosomes is reduced, which may become potential biomarkers for monitoring changes in diabetes.

The role of Sirtuin 2 in sustaining functional integrity of the liver

AIM

Sirtuin 2 (SIRT2) is a NAD+-dependent deacetylase involved in various biological functions via deacetylation of proteins, including histone protein. Hepatic fat accumulation from aging and excess caloric intake contribute to development of non-alcoholic fatty liver disease. The study aim was to elucidate the role of SIRT2 in lipid metabolism homeostasis.

MATERIALS AND METHODS

SIRT2^+/+ (C57BL/6) and SIRT2^-/- were randomly assigned to normal diet or high-fat diet (HFD) groups and fed for 6 weeks. Histological features of the livers were evaluated by hematoxylin and eosin and Masson's trichrome staining, and the levels of selected factors were determined by quantitative reverse transcription-polymerase chain reaction and western blot analysis.

KEY FINDINGS

Although the SIRT2^-/- mice were viable, their livers exhibited higher glycogen accumulation, and skeletal muscle showed features of increased metabolic demand. The SIRT2^-/- mice attenuated HFD-induced weight gain, visceral adipose tissue formation, and fat accumulation in the liver in which the expressions of genes involved in metabolic substrate transport were modified. Additionally, the hepatocellular senescence and upregulated cell-cycle factors upon HFD intake in SIRT2^-/- livers suggested a role of SIRT2 in gene expression during abnormal metabolism. Moreover, the fibrotic phenotype of liver tissue without fat accumulation and the increased expression of genes involved in liver fibrosis in the HFD-fed SIRT2^-/- mice indicated that SIRT2 had a role in hepatocyte and hepatic stellate cell activation.

SIGNIFICANCE

Our results indicated that SIRT2 has a critical role in regulating lipid metabolic homeostasis and in sustaining liver integrity by modulating related gene expression.

Alzheimer's Disease and Diabetes Mellitus in Comparison: The Therapeutic Efficacy of the Vanadium Compound

Alzheimer’s disease (AD) is an intractable neurodegenerative disease that leads to dementia, primarily in elderly people. The neurotoxicity of amyloid-beta (Aβ) and tau protein has been demonstrated over the last two decades. In line with these findings, several etiological hypotheses of AD have been proposed, including the amyloid cascade hypothesis, the oxidative stress hypothesis, the inflammatory hypothesis, the cholinergic hypothesis, et al. In the meantime, great efforts had been made in developing effective drugs for AD. However, the clinical efficacy of the drugs that were approved by the US Food and Drug Association (FDA) to date were determined only mild/moderate. We recently adopted a vanadium compound bis(ethylmaltolato)-oxidovanadium (IV) (BEOV), which was originally used for curing diabetes mellitus (DM), to treat AD in a mouse model. It was shown that BEOV effectively reduced the Aβ level, ameliorated the inflammation in brains of the AD mice, and improved the spatial learning and memory activities of the AD mice. These finding encouraged us to further examine the mechanisms underlying the therapeutic effects of BEOV in AD. In this review, we summarized the achievement of vanadium compounds in medical studies and investigated the prospect of BEOV in AD and DM treatment.

Altered protein O-GlcNAcylation in placentas from mothers with diabetes causes aberrant endocytosis in placental trophoblast cells

Women with pre-existing diabetes have an increased risk of poor pregnancy outcomes, including disordered fetal growth, caused by changes to placental function. Here we investigate the possibility that the hexosamine biosynthetic pathway, which utilises cellular nutrients to regulate protein function via post-translationally modification with O-linked N-acetylglucosamine (GlcNAc), mediates the placental response to the maternal metabolic milieu. Mass spectrometry analysis revealed that the placental O-GlcNAcome is altered in women with type 1 (n = 6) or type 2 (n = 6) diabetes T2D (≥ twofold change in abundance in 162 and 165 GlcNAcylated proteins respectively compared to BMI-matched controls n = 11). Ingenuity pathway analysis indicated changes to clathrin-mediated endocytosis (CME) and CME-associated proteins, clathrin, Transferrin (TF), TF receptor and multiple Rabs, were identified as O-GlcNAcylation targets. Stimulating protein O-GlcNAcylation using glucosamine (2.5 mM) increased the rate of TF endocytosis by human placental cells (p = 0.02) and explants (p = 0.04). Differential GlcNAcylation of CME proteins suggests altered transfer of cargo by placentas of women with pre-gestational diabetes, which may contribute to alterations in fetal growth. The human placental O-GlcNAcome provides a resource to aid further investigation of molecular mechanisms governing placental nutrient sensing.

Glycocalyx Curving the Membrane: Forces Emerging from the Cell Exterior

Morphological transitions are typically attributed to the actions of proteins and lipids. Largely overlooked in membrane shape regulation is the glycocalyx, a pericellular membrane coat that resides on all cells in the human body. Comprised of complex sugar polymers known as glycans as well as glycosylated lipids and proteins, the glycocalyx is ideally positioned to impart forces on the plasma membrane. Large, unstructured polysaccharides and glycoproteins in the glycocalyx can generate crowding pressures strong enough to induce membrane curvature. Stress may also originate from glycan chains that convey curvature preference on asymmetrically distributed lipids, which are exploited by binding factors and infectious agents to induce morphological changes. Through such forces, the glycocalyx can have profound effects on the biogenesis of functional cell surface structures as well as the secretion of extracellular vesicles. In this review, we discuss recent evidence and examples of these mechanisms in normal health and disease.

Integration of feeding behavior by the liver circadian clock reveals network dependency of metabolic rhythms

The mammalian circadian clock, expressed throughout the brain and body, controls daily metabolic homeostasis. Clock function in peripheral tissues is required, but not sufficient, for this task. Because of the lack of specialized animal models, it is unclear how tissue clocks interact with extrinsic signals to drive molecular oscillations. Here, we isolated the interaction between feeding and the liver clock by reconstituting Bmal1 exclusively in hepatocytes (Liver-RE), in otherwise clock-less mice, and controlling timing of food intake. We found that the cooperative action of BMAL1 and the transcription factor CEBPB regulates daily liver metabolic transcriptional programs. Functionally, the liver clock and feeding rhythm are sufficient to drive temporal carbohydrate homeostasis. By contrast, liver rhythms tied to redox and lipid metabolism required communication with the skeletal muscle clock, demonstrating peripheral clock cross-talk. Our results highlight how the inner workings of the clock system rely on communicating signals to maintain daily metabolism.

Glycogen synthase kinase-3 (GSK-3) a magic enzyme: it's role in diabetes mellitus and glucose homeostasis, interactions with fluroquionlones. A mini-review

Diabetes mellitus (DM) is a non-communicable disease throughout the world in which there is persistently high blood glucose level from the normal range. The diabetes and insulin resistance are mainly responsible for the morbidities and mortalities of humans in the world. This disease is mainly regulated by various enzymes and hormones among which Glycogen synthase kinase-3 (GSK-3) is a principle enzyme and insulin is the key hormone regulating it. The GSK-3, that is the key enzyme is normally showing its actions by various mechanisms that include its phosphorylation, formation of protein complexes, and other cellular distribution and thus it control and directly affects cellular morphology, its growth, mobility and apoptosis of the cell. Disturbances in the action of GSK-3 enzyme may leads to various disease conditions that include insulin resistance leading to diabetes, neurological disease like Alzheimer's disease and cancer. Fluoroquinolones are the most common class of drugs that shows dysglycemic effects via interacting with GSK-3 enzyme. Therefore, it is the need of the day to properly understand functions and mechanisms of GSK-3, especially its role in glucose homeostasis via effects on glycogen synthase.

Drugs Interfering with Insulin Resistance and Their Influence on the Associated Hypermetabolic State in Severe Burns: A Narrative Review

It has become widely accepted that insulin resistance and glucose hypermetabolism can be linked to acute pathologies, such as burn injury, severe trauma, or sepsis. Severe burns can determine a significant increase in catabolism, having an important effect on glucose metabolism and on muscle protein metabolism. It is imperative to acknowledge that these alterations can lead to increased mortality through organ failure, even when the patients survive the initial trauma caused by the burn. By limiting the peripheral use of glucose with consequent hyperglycemia, insulin resistance determines compensatory increased levels of insulin in plasma. However, the significant alterations in cellular metabolism lead to a lack of response to insulin's anabolic functions, as well as to a decrease in its cytoprotective role. In the end, via pathological insulin signaling associated with increased liver gluconeogenesis, elevated levels of glucose are detected in the blood. Several cellular mechanisms have been incriminated in the development of insulin resistance in burns. In this context, the main aim of this review article is to summarize some of the drugs that might interfere with insulin resistance in burns, taking into consideration that such an approach can significantly improve the prognosis of the burned patient.

Pharmacological and Biological Study of Microencapsulated Probucol-Secondary Bile Acid in a Diseased Mouse Model

Probucol (PB) is a highly lipophilic drug with potential protective effects on pancreatic β-cells from inflammation and oxidation. PB has poor bioavailability and solubility, and despite many attempts, significant improvement in antidiabetic effects or absorption has yet to be discovered. Recently, the role of bile acids has been established in significant drug formulation stabilisation effects and as cell-penetrating agents. Promising results in pharmaceutical formulation studies on drug stability and release patterns when lithocholic acid (LCA) is conjugated with PB and sodium alginate (SA) have been demonstrated. Thus, this study aimed to develop and characterise PB microcapsules incorporating LCA and examine the biological effects of the microcapsules in vitro and in vivo. PB/LCA microcapsules were prepared using an encapsulation method, ionic gelation vibrational jet flow technology. LCA incorporation in PB microcapsules showed positive effects on β-cells with improved insulin release, antioxidant activity, and PB intracellular uptake. Diabetic mice gavaged LCA-PB microcapsules showed a significant reduction in diabetes signs and symptoms, better survival rate, reduced blood glucose levels, and pro-inflammatory cytokines, with an increase PB level in blood and tissues suggesting a potential therapy for treating diabetes mellitus.

An Overview of NO Signaling Pathways in Aging

Nitric Oxide (NO) is a potent signaling molecule involved in the regulation of various cellular mechanisms and pathways under normal and pathological conditions. NO production, its effects, and its efficacy, are extremely sensitive to aging-related changes in the cells. Herein, we review the mechanisms of NO signaling in the cardiovascular system, central nervous system (CNS), reproduction system, as well as its effects on skin, kidneys, thyroid, muscles, and on the immune system during aging. The aging-related decline in NO levels and bioavailability is also discussed in this review. The decreased NO production by endothelial nitric oxide synthase (eNOS) was revealed in the aged cardiovascular system. In the CNS, the decline of the neuronal (n)NOS production of NO was related to the impairment of memory, sleep, and cognition. NO played an important role in the aging of oocytes and aged-induced erectile dysfunction. Aging downregulated NO signaling pathways in endothelial cells resulting in skin, kidney, thyroid, and muscle disorders. Putative therapeutic agents (natural/synthetic) affecting NO signaling mechanisms in the aging process are discussed in the present study. In summary, all of the studies reviewed demonstrate that NO plays a crucial role in the cellular aging processes.

The hypoglycemic effect of freeze-dried fermented mulberry mixed with soybean on type 2 diabetes mellitus

Mulberry has significant hypoglycemic effect and can be used as an auxiliary food for people with type 2 diabetes. However, it is rich in carbohydrate and cannot be consumed directly by diabetic patients. In the study, we fermented the mulberry to reduce the content of glucose and fructose, and added the soybean to reduce the loss of probiotics during fermentation and then determined its hypoglycemic effect. We induced type 2 diabetes mellitus (T2DM) mice by streptozotocin and measured its blood glucose, serum biochemistry, hepatic and pancreatic histopathology, and the diversity of the gut microbiota. After 5 weeks of oral DFMS administration, the glucose tolerance was improved significantly in T2DM mice. Furthermore, there were also significant increases in superoxide dismutase activity and glutathione concentration, and marked reductions in the concentrations of malondialdehyde and free fatty acids. Moreover, DFMS also prevented histopathological changes and the increases in the activities of alanine transaminase and aspartate transaminase. DFMS treatment also markedly increased the richness of the gut microbial community. The abundance of Bacteroidetes was increased, and those of Proteobacteria, Escherichia-Shigella, and Lactobacillus were reduced. In summary, DFMS has a clear hypoglycemic effect in mice with T2DM.

Ameliorative property of Sesbania grandiflora on carbohydrate metabolic enzymes in the liver and kidney of streptozotocin-induced diabetic rats

In diabetic condition, endogenous glucose synthesis will be elevated due to defect in the action of vital enzymes involved in carbohydrate metabolism, which is the main cause for hyperglycemia. The current study was designed to explore the anti-hyperglycemic efficacy of Sesbania grandiflora flower (SGF) extract by evaluating the concentration of C-peptide, insulin, glucose, glycosylated hemoglobin (HbA1C), hemoglobin (Hb), glycogen and carbohydrate metabolic enzymes activities in diabetic rats. The study found to lower the level of glucose, HbA1C and simultaneously ameliorated concentrations of C-peptide, insulin, hemoglobin (Hb), glycogen and carbohydrate metabolic enzymes activities in SGF treated (250 mg/kg body weight for 45 days) diabetic rats. Moreover, SGF administered diabetic rats showed diminished consumption of food and water at the same time improved body weight. The results obtained from the present study were compared with glibenclamide treated (600 µg/kg body weight) diabetic rats. SGF were supplemented to normal rats to rule out toxic effect of SGF, to explore any significant alteration in the above parameters. Hence, the results depict that SGF modulated the carbohydrate metabolic enzymes activities through ameliorating the secretion of insulin and diminishing the level of glucose concentration in STZ-induced diabetic rats by its bioactive compounds.

Evaluation of Plasma AA/DHA+EPA Ratio in Obese Romanian Children

The aim of the study was to evaluate the plasma profile of arachidonic acid (AA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), as well to analyze the relationship of Omega 6/Omega 3 ratio with anthropo-metric parameters and insulin resistance markers.

Material and methods: Plasma levels of free fatty acids (FFAs) were measured using a high-throughput LC-MS AB Sciex4600 in 202 children (127 obese and 75 non-obese), age and sex-matched. Lipid and glucose profiles were assessed with current laboratory methods, while insulin resistance and beta-cell function were evaluated using HOMA-IR and HOMA-β respectively.

Results: In obese children, AA and AA/(DHA+EPA) ratio were significantly higher regardless of age and gender. In the lowest quartile of DHA, there was a clear trend for insulin resistance, with plasma insulin level, HOMA-IR, and HOMA-β significantly higher compared to the highest quartile of DHA. After adjustment for age and gender DHA remains a negative predictive factor for insulin resistance. Waist-to-height ratio (WHtR), a marker of visceral obesity was higher in children with a higher AA/(DHA+EPA) ratio.

Conclusions: In obese children, the AA is higher in concordance with insulin resistance. Additionally, children with a higher AA/(DHA+EPA) ratio have greater BMI, fat mass, waist circumference, and WHtR, important indicators of central adiposity, and cardio-metabolic disorders. LC/MS is a versatile tool for Omega ratio assessment, especially in children where the sample size is a limiting factor for metabolic and nutrition evaluation.

Exercise intervention under hypoxic condition as a new therapeutic paradigm for type 2 diabetes mellitus: A narrative review

This review aims to summarize the health benefits of exposure to hypoxic conditions during exercise in patients with type 2 diabetes mellitus (T2DM). Exposure to hypoxic conditions during exercise training positively changes the physiological response in healthy subjects. Exposure to hypoxic conditions during exercise could markedly increase skeletal muscle glucose uptake compared to that in normoxic conditions. Furthermore, post-exercise insulin sensitivity of T2DM patients increases more when exercising under hypoxic than under normoxic conditions. Regular exercise under short-term hypoxic conditions can improve blood glucose control at lower workloads than in normoxic conditions. Additionally, exercise training under short-term hypoxic conditions can maximize weight loss in overweight and obese patients. Previous studies on healthy subjects have reported that regular exercise under hypoxic conditions had a more positive effect on vascular health than exercising under normoxic conditions. However, currently, evidence indicating that exposure to hypoxic conditions could positively affect T2DM patients in the long-term is lacking. Therefore, further evaluations of the beneficial effects of exercise under hypoxic conditions on the human body, considering different cycle lengths, duration of exposures, sessions per day, and the number of days, are necessary. In this review, we conclude that there is evidence that exercise under hypoxic conditions can yield health benefits, which is potentially valuable in terms of clinical care as a new intervention for T2DM patients.

Telfairia occidentalis stimulates hepatic glycolysis and pyruvate production via insulin-dependent and insulin-independent mechanisms

Background

Telfairia occidentalis (TO), a plant consumed for its nutritional and medicinal values, exhibits hypoglycaemic effect. However, the metabolic fate of the glucose following TO-induced insulin secretion and consequent hypoglycaemia is not clear.

Objective

This study determined the effect of ethyl acetate and n-hexane fractions of TO leaf extracts on some biochemical parameters in the glucose metabolic pathway to explain the possible fate of blood glucose following TO-induced hypoglycaemia.

Methods

Eighteen male Wistar rats (180-200 g) divided into control, n-hexane TO fraction- and ethyl acetate TO fraction-treated groups (n = 6/group) were used. The control animals received normal saline while the treated groups received TO at 100 mg/kg for seven days. After 24 h following the last dose, the animals were anaesthetised using ketamine; blood samples were collected and livers harvested to determine some biochemical parameters.

Results

Ethyl acetate TO fraction significantly increased plasma insulin, liver glucokinase activity and plasma pyruvate concentration, but significantly decreased plasma glucose and liver glycogen, without significant changes in plasma lactate, glucose-6-phosphate, liver glucose-6-phosphatase and lactate dehydrogenase activities when compared with control. N-hexane TO fraction significantly reduced liver glucose-6-phosphatase activity and glycogen but significantly increased plasma pyruvate, without significant changes in plasma glucose, insulin, glucose-6-phosphate and lactate concentrations; and liver glucokinase and lactate dehydrogenase activities.

Conclusion

The present study showed that insulin-mediated TO-induced hypoglycaemia resulted in the stimulation of glycolysis and pyruvate production via insulin-dependent and insulin-independent mechanisms.

Potentiation of incretin hormones and modulation of metabolic enzymes as possible mechanisms behind the insulin sensitizing effects of cabbage-metformin treatment

In our study, we treated high fructose diet-induced insulin resistance in rats with any of metformin, cabbage (80%w/w) or combined metformin and cabbage (MetCabb), and observed the activities of glycolysis and gluconeogenesis regulatory enzymes, incretin hormones and other hormones affecting glucose homeostasis. Comparisons were made with normoglycemic noninsulin resistance rats (control) and insulin-resistant untreated rats (INres). Baseline analysis showing elevated fasting blood sugar (>250 mg/dl), insulin (>25 µIU/ml) and HOMA-IR (>10) satisfied the criteria for recruitment into the insulin-resistant groups. Treatment lasted for 12 weeks. HOMA-IR values significantly (P < 0.05) decreased from 24.7 to 5.5 and 10.6 respectively with MetCabb treatment. MetCabb normalized HOMA-IR values and mean β-cell responsiveness of the INres. Cabbage and metCabb normalized the leptin levels relative to control. The mean fasting blood sugar, insulin, and c-peptide levels with MetCabb treatment reverted to control levels. We found a strong positive linear correlation between the glucagon levels (r = 0.9145) and increasing HOMA-IR values while both incretin hormones; GLP-1 and GIP negatively regressed (r = -0.8084 and -0.8488). MetCab treatment produced comparable values of GLP-1 and GIP to the control. A strong positive correlation was found between the HOMA-IR values and the PEPCK (r = 0.9065), F-1,6-BPase (r = 0.7951), and G-6-Pase (r = 0.7893). The hexokinase (r = -0.807), PFK (r = -0.9151), and PK (r = -0.7448) levels regressed as HOMA-IR values increased. The glycolytic and gluconeogenic enzymes except PEPCK reverted to control levels with MetCabb treatment. Combination of metformin and cabbage was more effective than individual treatments.

Nuclear receptors FXR and SHP regulate protein N-glycan modifications in the liver

Nuclear receptors farnesoid X receptor (FXR) and small heterodimer partner (SHP) are key regulators of metabolism. Here, we report a previously unknown function for the hepatic FXR-SHP axis in controlling protein N-linked glycosylation. Transcriptome analysis in liver-specific Fxr-Shp double knockout (LDKO) livers revealed induction of genes encoding enzymes in the N-glycosylation pathway, including Mgat5, Fut8, St3gal6, and St6gal1 FXR activation suppressed Mgat5, while Shp deletion induced St3gal6 and St6gal1 Increased percentages of core-fucosylated and triantennary glycan moieties were seen in LDKO livers, and proteins with the "hyperglycoforms" preferentially localized to exosomes and lysosomes. This up-regulation of N-glycosylation machinery was specific to the Golgi apparatus and not the endoplasmic reticulum. The increased glycan complexity in the LDKO correlated well with dilated unstacked Golgi ribbons and alterations in the secretion of albumin, cholesterol, and triglycerides. Our findings demonstrate a role for the FXR-SHP axis in maintaining glycoprotein diversity in the liver.

Discovery through Machine Learning and Preclinical Validation of Novel Anti-Diabetic Peptides

While there have been significant advances in drug discovery for diabetes mellitus over the past couple of decades, there is an opportunity and need for improved therapies. While type 2 diabetic patients better manage their illness, many of the therapeutics in this area are peptide hormones with lengthy sequences and a molecular structure that makes them challenging and expensive to produce. Using machine learning, we present novel anti-diabetic peptides which are less than 16 amino acids in length, distinct from human signalling peptides. We validate the capacity of these peptides to stimulate glucose uptake and Glucose transporter type 4 (GLUT4) translocation in vitro. In obese insulin-resistant mice, predicted peptides significantly lower plasma glucose, reduce glycated haemoglobin and even improve hepatic steatosis when compared to treatments currently in use in a clinical setting. These unoptimised, linear peptides represent promising candidates for blood glucose regulation which require further evaluation. Further, this indicates that perhaps we have overlooked the class of natural short linear peptides, which usually come with an excellent safety profile, as therapeutic modalities.

CFTR Deficiency Affects Glucose Homeostasis via Regulating GLUT4 Plasma Membrane Transportation

Cystic Fibrosis (CF) is an autosomal recessive disorder caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. CF-related diabetes (CFRD) is one of the most prevalent comorbidities of CF. Altered glucose homeostasis has been reported in CF patients. The mechanism has not been fully elucidated. Besides the consequence of pancreatic endocrine dysfunction, we focus on insulin-responsive tissues and glucose transportation to explain glucose homeostasis alteration in CFRD. Herein, we found that CFTR knockout mice exhibited insulin resistance and glucose tolerance. Furthermore, we demonstrated insulin-induced glucose transporter 4 (GLUT4) translocation to the cell membrane was abnormal in the CFTR knockout mice muscle fibers, suggesting that defective intracellular GLUT4 transportation may be the cause of impaired insulin responses and glucose homeostasis. We further demonstrated that PI(4,5)P₂ could rescue CFTR related defective intracellular GLUT4 transportation, and CFTR could regulate PI(4,5)P₂ cellular level through PIP5KA, suggesting PI(4,5)P₂ is a down-stream signal of CFTR. Our results revealed a new signal mechanism of CFTR in GLUT4 translocation regulation, which helps explain glucose homeostasis alteration in CF patients.

Polyphenolic-rich extracts of Andrographis paniculata mitigate hyperglycemia via attenuating β-cell dysfunction, pro-inflammatory cytokines and oxidative stress in alloxan-induced diabetic Wistar albino rat

Background

This study sought to investigate anti-hyperglycemic potentials of free and bound phenolic-rich extracts of Andrographis paniculata (A. paniculata) leaves, commonly called "king of the bitter", a plant locally employed in folkloric alternative medicine.

Method

In vitro antioxidant potentials such as total phenolic and flavonoid contents were evaluated in addition to phosphomolybdenum reducing total antioxidant activity in bound and free polyphenol-rich extracts of A. paniculata. Also, following induction of diabetes through a single intraperitoneal injection of freshly prepared alloxan monohydrate (150 mg/kg body weight, b.w), diabetic rats were divided into seven (7) treatment groups with six rats each (n = 6) i.e. group 1 (normal control), 2 (diabetic untreated), 3 (5 mg/kg glibenclamide -treated control), while 4-7 were administered 50 and 100 mg/kg b.w of free and bound phenolic extracts of A. paniculata, respectively for twenty-one (21) days.

Results

There was a significant (p < 0.05) difference in hematological indices, hepatic biomarkers, total protein, antioxidant enzymes activities, total thiol and fasting blood glucose levels of diabetic groups administered polyphenolic-rich extracts of A. paniculata compared to diabetic untreated control. Similarly, serum insulin levels, hexokinase and glucose-6-phoshatase activities were significantly (p < 0.05) improved in phenolic-rich extracts of A. paniculata-treated diabetic groups compared to diabetic untreated control. A significant (p < 0.05) reduction was as well observed in the levels of inflammatory biomarkers such as interleukin-6 (IL-6) and tumor necrosis factor (TNFα) among extract of A. paniculata administered diabetic groups compared diabetic untreated group.

Conclusions

Anti-hyperglycemic activities demonstrated by polyphenolic-rich extracts of A. paniculata when compared to glibenclamide and normal control, could possibly have been occasioned by β-cell protection, restoration of glycolytic enzymes as well as mitigation of inflammatory markers via antioxidant defensive/protective properties of the extracts.

Role of Glucose Metabolism and Mitochondrial Function in Diabetic Kidney Disease

PURPOSE OF REVIEW

Diabetic kidney disease (DKD) continues to be the primary cause of chronic kidney disease in the USA and around the world. The numbers of people with DKD also continue to rise despite current treatments. Certain newer hypoglycemic drugs offer a promise of slowing progression, but it remains to be seen how effective these will be over time. Thus, continued exploration of the mechanisms underlying the development and progression of DKD is essential in order to discover new treatments. Hyperglycemia is the main cause of the cellular damage seen in DKD. But, exactly how hyperglycemia leads to the activation of processes that are ultimately deleterious is incompletely understood.

RECENT FINDINGS

Studies primarily over the past 10 years have provided novel insights into the interplay of hyperglycemia, glucose metabolic pathways, mitochondrial function, and the potential importance of what has been called the Warburg effect on the development and progression of DKD. This review will provide a brief overview of glucose metabolism and the hypotheses concerning the pathogenesis of DKD and then discuss in more detail the supporting data that indicate a role for the interplay of glucose metabolic pathways and mitochondrial function.

Stem cell fate determination through protein O-GlcNAcylation

Embryonic and adult stem cells possess the capability of self-renewal and lineage-specific differentiation. The intricate balance between self-renewal and differentiation is governed by developmental signals and cell-type-specific gene regulatory mechanisms. A perturbed intra/extracellular environment during lineage specification could affect stem cell fate decisions resulting in pathology. Growing evidence demonstrates that metabolic pathways govern epigenetic regulation of gene expression during stem cell fate commitment through the utilization of metabolic intermediates or end products of metabolic pathways as substrates for enzymatic histone/DNA modifications. UDP-GlcNAc is one such metabolite that acts as a substrate for enzymatic mono-glycosylation of various nuclear, cytosolic, and mitochondrial proteins on serine/threonine amino acid residues, a process termed protein O-GlcNAcylation. The levels of GlcNAc inside the cells depend on the nutrient availability, especially glucose. Thus, this metabolic sensor could modulate gene expression through O-GlcNAc modification of histones or other proteins in response to metabolic fluctuations. Herein, we review evidence demonstrating how stem cells couple metabolic inputs to gene regulatory pathways through O-GlcNAc-mediated epigenetic/transcriptional regulatory mechanisms to govern self-renewal and lineage-specific differentiation programs. This review will serve as a primer for researchers seeking to better understand how O-GlcNAc influences stemness and may catalyze the discovery of new stem-cell-based therapeutic approaches.

Comparative host transcriptome in response to pathogenic fungi identifies common and species-specific transcriptional antifungal host response pathways

Candidiasis, aspergillosis, and mucormycosis cause the majority of nosocomial fungal infections in immunocompromised patients. Using an unbiased transcriptional profiling in PBMCs exposed to the fungal species causing these infections, we found a core host response in healthy individuals that may govern effective fungal clearance: it consists of 156 transcripts, involving canonical and non-canonical immune pathways. Systematic investigation of key steps in antifungal host defense revealed fungal-specific signatures. As previously demonstrated, Candida albicans induced type I and Type II interferon-related pathways. In contrast, central pattern recognition receptor, reactive oxygen species production, and host glycolytic pathways were down-regulated in response to Rhizopus oryzae, which was associated with an ER-stress response. TLR5 was identified to be uniquely regulated by Aspergillus fumigatus and to control cytokine release in response to this fungus. In conclusion, our data reveals the transcriptional profiles induced by C. albicans, A. fumigatus, and R. oryzae, and describes both the common and specific antifungal host responses that could be exploited for novel therapeutic strategies.

Okra Modulates Regulatory Enzymes and Metabolites of Glucose-Utilizing Pathways in Diabetic Rats

OBJECTIVE

Using a rat diabetes model, the authors examined how substrates and products of glycolysis and key regulatory enzymes for glycolysis, gluconeogenesis, Kreb's cycle, and glycogen metabolism react to treatment with okra diet therapy, relative to glibenclamide treatment.

METHOD

The animal grouping involved normoglycemic rats, untreated diabetic rats, and diabetic rats treated with glibenclamide, 50% w/w okra sauce, exclusive okra sauce diet, or sauce without okra. Alloxan monohydrate was the diabetogenic agent. Insulin and adiponectin were assayed with enzyme-linked immunosorbent assay (ELISA) while the metabolites and enzymes were assed using standard spectrophotometric methods.

RESULTS

The exclusive diet therapy significantly (p < 0.05) improved insulin activities after 60 days and reversed the altered adiponectin activities. Glucose-6-phosphate, fructose-6-phosphate, and fructose-1,6-bisphosphate levels were depleted during diabetes, but phosphoenolpyruvate and pyruvate accumulated during the first short phase of diabetes. Rats in the glibenclamide and 100% okra diet groups showed comparable hexokinase, phosphofructokinase, and pyruvate kinase activities relative to the normoglycemic rats, while the gluconeogenic enzymes, glucose-6-phosphatase, and fructose-1,6-bisphosphatase remained altered. The authors observed that extended treatment with glibenclamide restored the activities of all the Kreb's cycle enzymes, while succinate dehydrogenase and α-ketoglutarate dehydrogenase were nonresponsive to the okra diet therapy relative to their control levels. The glycogen stores were normalized by the exclusive diet therapy, but glycogen synthase and phosphorylase activities were unresponsive.

CONCLUSIONS

Okra diet has shown insulin-sensitizing potentials with prolonged intake during diabetes as well as the potential to reverse alterations in the major carbohydrate-metabolizing enzyme.

Anti-diabetic and lipid-lowering effects of drimane sesquiterpenoids isolated from Zygogynum pancheri

Recently, it has been shown that drimane-type sesquiterpenoids isolated from Zygogynum pancheri, a species native to New Caledonia, possessed significant α-amylase inhibitory activities. To further explore their antidiabetic potential, we investigated the effect of 1β-O-(E-cinnamoyl)-6α-hydroxy-9epi-polygodial (D) and 1β-E-O-p-methoxycinnamoyl-bemadienolide (L), two of the most active compounds of the series, on diabetic model rats. Compounds D and L (2 mg kg/day) were daily and orally administrated for 30 days to streptozotocin (STZ) (150 mg/kg) induced male diabetic Wistar rats. Animals were allocated into five groups of six rats. Comparatively to diabetic rats, treatments with D and L compounds were able to significantly (P < 0.05) decrease Fasting Blood Glucose (FBG) (70.15%, 71.02%), serum total cholesterol (46.27% and 39.38%), triglycerides (56.60% and 58.15%), creatinine (37.31% and 36.49%) and uric acid levels (67.76% and 69.68%), respectively. Compounds D and L also restored the altered plasma enzyme (aspartate aminotransferase, AST (47.83% and 43.20%), alanine aminotransferase, ALT (49.76% and 48.35%, alkaline phosphatase, ALP (72.78% and 73.21%)) and lactate dehydrogenase, LDH (47.95% and 53.93%) levels to near normal, respectively. Administration of Glymepiride, significantly (p < 0.05) reduced FBG (73.94%) in STZ induced diabetic rats. Additionally, the compounds D and L exhibited inhibitory effects in vivo on lipase activity of diabetic rats (54.83% and 52.25%), respectively. The outcomes of this study suggested that these two drimanes could be considered as efficient hypoglycemic, hypolipidemic and antiobesity agents for diabetes management and its complications.

Antihyperglycemic and antihyperlipidemic activities of wild musk melon (Cucumis melo var. agrestis) in streptozotocin-nicotinamide induced diabetic rats

Objective

Wild musk melon (Cucumis melo var. agrestis, CMA) is one of the edible plants form Tamil Nadu. Traditionally, this plant was used as diabetic diet (leaves of CMA with Momordica charantia leaves), but there is no scientific report on antidiabetic action of this plant material. Hence, the current research work was designed to evaluate the antihyperglycemic and antihyperlipidemic effect of hydroalcoholic extract of CMA leaves (HALEC) in streptozotocin (STZ)-nicotinamide (NIC)-induced diabetic rats.

Methods

Diabetes was induced by administration of STZ (60 mg/kg, i.p.) after 15 min of NIC (120 mg/kg i.p.) administration. The diabetic rats were treated with HALEC (300 and 600 mg/kg, p.o., respectively) for 21 d.

Results

After the management with HALEC, blood glucose, HbA1c levels, total cholesterol, LDL cholesterol, triglycerides levels, glycogen phosphorylase and glucose-6-phosphatase levels were significantly diminished in diabetic rats. However, haemoglobin level, HDL cholesterol, liver glycogen, total protein, hexokinase, glucose-6-phosphate dehydrogenase levels were significantly increased in HALEC treated diabetic rats. The histopathological studies of the pancreas in HALEC-treated diabetic rats showed almost normal appearance. L6 cell line study revealed the increased glucose uptake activity of HALEC. High performance thin layer chromatography (HPTLC) analysis confirms the presence of active principles such as rutin, gallic acid and quercetin in HALEC.

Conclusion

The results indicated that HALEC possess significant antihyperglycemic and antihyperlipidemic activity in STZ-NIC-induced type II diabetic rats with protective effect. This research work will be useful for the isolation of active principles and development of herbal formulation in phytopharmaceuticals.

Intracellular pH Regulation of Skeletal Muscle in the Milieu of Insulin Signaling

Type 2 diabetes (T2D), along with obesity, is one of the leading health problems in the world which causes other systemic diseases, such as cardiovascular diseases and kidney failure. Impairments in glycemic control and insulin resistance plays a pivotal role in the development of diabetes and its complications. Since skeletal muscle constitutes a significant tissue mass of the body, insulin resistance within the muscle is considered to initiate the onset of diet-induced metabolic syndrome. Insulin resistance is associated with impaired glucose uptake, resulting from defective post-receptor insulin responses, decreased glucose transport, impaired glucose phosphorylation, oxidation and glycogen synthesis in the muscle. Although defects in the insulin signaling pathway have been widely studied, the effects of cellular mechanisms activated during metabolic syndrome that cross-talk with insulin responses are not fully elucidated. Numerous reports suggest that pathways such as inflammation, lipid peroxidation products, acidosis and autophagy could cross-talk with insulin-signaling pathway and contribute to diminished insulin responses. Here, we review and discuss the literature about the defects in glycolytic pathway, shift in glucose utilization toward anaerobic glycolysis and change in intracellular pH [pH]_i within the skeletal muscle and their contribution towards insulin resistance. We will discuss whether the derangements in pathways, which maintain [pH]_i within the skeletal muscle, such as transporters (monocarboxylate transporters 1 and 4) and depletion of intracellular buffers, such as histidyl dipeptides, could lead to decrease in [pH]_i and the onset of insulin resistance. Further we will discuss, whether the changes in [pH]_i within the skeletal muscle of patients with T2D, could enhance the formation of protein aggregates and activate autophagy. Understanding the mechanisms by which changes in the glycolytic pathway and [pH]_i within the muscle, contribute to insulin resistance might help explain the onset of obesity-linked metabolic syndrome. Finally, we will conclude whether correcting the pathways which maintain [pH]_i within the skeletal muscle could, in turn, be effective to maintain or restore insulin responses during metabolic syndrome.