Glucose Transporter Gene Expression Research Articles

Mixed-Lineage Leukaemia Gene Regulates Glucose-Sensitive Gene Expression and Insulin Secretion in Pancreatic Beta Cells.

The escalating prevalence of diabetes mellitus underscores the need for a comprehensive understanding of pancreatic beta cell function. Interest in glucose effectiveness has prompted the exploration of novel regulatory factors. The myeloid/lymphoid or mixed-lineage leukaemia gene (MLL) is widely recognised for its role in leukemogenesis and nuclear regulatory mechanisms through its histone methyltransferase activity in active chromatin. However, its function within pancreatic endocrine tissues remains elusive. Herein, we unveil a novel role of MLL in glucose metabolism and insulin secretion. MLL knockdown in βHC-9 pancreatic beta cells diminished insulin secretion in response to glucose loading, paralleled by the downregulation of the glucose-sensitive genes SLC2a1 and SLC2a2. Similar observations were made in MLL heterozygous knockout mice (MLL+/-), which exhibited impaired glucose tolerance and reduced insulin secretion without morphological anomalies in pancreatic endocrine cells. The reduction in insulin secretion was independent of changes in beta cell mass or insulin granule morphology, suggesting the regulatory role of MLL in glucose-sensitive gene expression. The current results suggest that MLL interacts with circadian-related complexes to modulate the expression of glucose transporter genes, thereby regulating glucose sensing and insulin secretion. Our findings shed light on insulin secretion control, providing potential avenues for therapeutics against diabetes.

Salvia officinalis Improves Glycemia and Suppresses Pro-inflammatory Features in Obese Rats with Metabolic Syndrome.

Obesity is regarded as the main cause of metabolic diseases and a core factor for all-cause mortality in the general population, notably from cardiovascular disease. The majority of people with type 2 diabetes have obesity and insulin resistance. Some evidence indicates that an individual with obesity is approximately 10 times more likely to develop type 2 diabetes than someone with moderate body weight. One of the most significant therapeutic herbs, Salvia officinalis (Lamiaceae) (SAGE), possesses potent medicinal importance. The aim of this article was to evaluate the anti-diabetic and antiobesity activity of SAGEAE against HFD-induced obesity in rats. Thirty adult albino rats were randomly divided into five equal groups: control, High-fat Diet (HFD) administrated rats, HFD + Salvia officinalis Aqueous Extract (SAGEAE) (150 mg/kg.bw.), HFD + SAGEAE (300 mg/kg.bw.) and HFD + metformin (500 mg/kg.bw.). Body weight, plasma biochemical parameters, oxidative stress, inflammatory indicators, hepatic Phosphoenolpyruvate Carboxykinase 1 (PCK1), Glucokinase (GK), brain Leptin Receptor (LepRb), Glucose Transporter-4 (GLUT4), Sirtuin 1 (SIRT1) and mRNA33-5P gene signalling mRNA levels were all assessed after 8 weeks. A histological examination of the liver was also performed to check for lipid accumulation. The administration of HFD resulted in increased body weight, glucose, insulin, leptin, Total Cholesterol (TC), Triglycerides (TG), Thiobarbaturic Acid Reactive Substances (TBARS), Monocyte Chemoattractant Protein-1 (MCP1), Interleukine-6 (IL-6) and tumor necrosis factor-α (TNF- α) as well as hepatic PCK1, brain LepRb and adipose tissue mRNA33-5P gene expression. However, our findings revealed a significant reduction in adiponectin, High-density Lipoproteincholesterol (HDL-C), reduced glutathione (GSH) and Superoxide Dismutase (SOD) levels as well as the expression of hepatic GK and adipose tissue SIRT1 and GLUT4 genes. Also, administration of SAGEAE significantly normalized body weight, glucose, insulin, leptin, adiponectin, TC, TG, HDL-C, TBARs, SOD, IL-6, MCP-1 and TNF-α in plasma and liver tissue of HFD-treated rats. On the other hand, PCK1, GK, LepRb, SIRT1, GLUT4 and mRNA33-5P gene expression was enhanced in obese rats when administrated with SAGEAE. Histological and US studies support the biochemical, PCR and electrophoretic results. The findings imply that SAGEAE could be used as a new pharmaceutical formula in the treatment of obesity.

High Glucose Is a Stimulation Signal of the Salt-Tolerant Yeast Zygosaccharomyces rouxii on Thermoadaptive Growth.

The salt-tolerant yeast Zygosaccharomyces rouxii is a typical aroma-producing yeast used in food brewing, but its mechanism of high temperature tolerance is still unclear. In this study, the response mechanism of Z. rouxii to glucose under high temperature stress at 40 °C was explored, based on the total synthetic lowest-nutrient medium. The results of the growth curves and scanning electron microscopy showed that high glucose was necessary for Z. rouxii to restore growth under high temperature stress, with the biomass at 300 g/L of glucose (OD600, 120h = 2.44 ± 0.26) being 8.71 times higher than that at 20 g/L (OD600, 120h = 0.28 ± 0.08). The results of the transcriptome analysis, combined with RT-qPCR, showed that the KEGG analysis of differentially expressed genes was enriched in pathways related to glucose metabolism, and high glucose (300 g/L) could effectively stimulate the gene expression of glucose transporters, trehalose synthesis pathways, and xylitol synthesis pathways under a high temperature, especially the expression of the glucose receptor gene RGT2 (up-regulated 193.7 times at 12 h). The corresponding metabolic characteristics showed that the contents of intracellular metabolites, such as glucose (Cmax, 6h = 6.50 ± 0.12 mg/g DCW), trehalose (Cmax, 8h = 369.00 ± 17.82 μg/g DCW), xylitol (Cmax, 8h = 1.79 ± 0.27 mg/g DCW), and glycerol (Cmax, 8h = 268.10 ± 44.49 μg/g DCW), also increased with time. The accumulation of acetic acid, as the main product of overflow metabolism under high temperature stress (intracellular Cmax, 2h = 126.30 ± 10.96 μg/g DCW; extracellular Cmax, 12h = 499.63 ± 27.16 mg/L), indicated that the downstream glycolysis pathway was active. Compared with the normal physiological concentration of glucose, a high glucose concentration can effectively stimulate the gene expression and metabolism of salt-tolerant Z. rouxii under high-temperature conditions to restore growth. This study helps to deepen the current understanding of the thermoadaptive growth mechanism of salt-tolerant Z. rouxii.

Intestinal Morphology and Glucose Transporter Gene Expression under a Chronic Intake of High Sucrose.

Sucrose is a disaccharide that is degraded into fructose and glucose in the small intestine. High-sucrose and high-fructose diets have been reported, using two-dimensional imaging, to alter the intestinal morphology and the expression of genes associated with sugar transport, such as sodium glucose co-transporter 1 (SGLT1), glucose transporter 2 (GLUT2), and glucose transporter 5 (GLUT5). However, it remains unclear how high-fructose and high-sucrose diets affect the expression of sugar transporters and the intestinal morphology in the whole intestine. We investigate the influence of a chronic high-sucrose diet on the expression of the genes associated with sugar transport as well as its effects on the intestinal morphology using 3D imaging. High sucrose was found to increase GLUT2 and GLUT5 mRNA levels without significant changes in the intestinal morphology using 3D imaging. On the other hand, the delay in sucrose absorption by an α-glucosidase inhibitor significantly improved the intestinal morphology and the expression levels of SGLT1, GLUT2, and GLUT5 mRNA in the distal small intestine to levels similar to those in the proximal small intestine, thereby improving glycemic control after both glucose and sucrose loading. These results reveal the effects of chronic high-sugar exposure on glucose absorption and changes in the intestinal morphology.

Glucose Regulates Glucose Transport and Metabolism via mTOR Signaling Pathway in Bovine Placental Trophoblast Cells.

It has been confirmed that improving the energy level of the diet contributed to the greater reproductive performance and birth weight of calves in periparturient dairy cows. To investigate the effect of glucose on nutrient transport during fetal development, the bovine placental trophoblast cells (BPTCs) were cultured in media with different glucose concentrations (1, 2, 4, 8, or 16 mg/mL). Subsequently, the BPTCs were cultured in media with 1, 8 mg/mL glucose and 8 mg/mL glucose plus 100 nmol/L rapamycin (the inhibitor of mTOR pathway). Compared with the 1 mg/mL glucose, the addition of 8 mg/mL glucose stimulated cell proliferation, upregulated the mRNA abundance of the glucose transporter GLUT1 and GLUT4, and increased the activity of glucose metabolism-related enzyme glucose-6-phosphate dehydrogenease (G6PD), lactate dehydrogenase (LDHA) and phosphoglycerate kinase 1 (PGK1), as well as adenosine-triphosphate (ATP) content (p < 0.05).Furthermore, compared with the treatment of 1 mg/mL glucose, adding 8 mg/mL of glucose-upregulated gene expression in the mTOR signaling pathway, including phosphatidylinositol3-kinase (PI3K), protein kinase B (Akt), mammalian target of rapamycin (mTOR) and 70 kDa ribosomal protein S6 kinase 2 (P70S6K) (p < 0.05).The supplementation of rapamycin downregulated the gene and protein expression of the mTOR signaling pathway, including mTOR, P70S6K, EIF4E-binding protein 1 (4EBP1), hypoxia-inducible factor 1-alpha (HIF-1α) and gene expression of glucose transporter upregulated by 8 mg/mL glucose (p < 0.05). Thus, these results indicated that the addition of 8 mg/mL glucose regulated the glucose transport and metabolism in BPTCs through the mTOR signaling pathway, thereby promoting the supply of nutrients to fetus.

Lactobacillus amylovorus Promotes Lactose Utilization in Small Intestine and Enhances Intestinal Barrier Function in Intrauterine Growth Restricted Piglets

BackgroundIntrauterine growth restriction (IUGR) resulted in high mortality and many physiological defects of piglets, causing huge economic loss in the swine industry. Lactobacillus amylovorus (L. amylovorus) was identified as one of the main differential bacteria between IUGR and normal piglets. However, the effects of L. amylovorus on the growth performance and intestinal health in IUGR piglets remained unclear. ObjectivesThis study aimed to investigate the promoting effects of L. amylovorus Mafic1501, a new strain isolated from normal piglets, on the growth performance and intestinal barrier functions in IUGR piglets. MethodsNewborn mice or piglets were assigned into 3 groups: CON (normal birth weight, control), IUGR (low birth weight), and IUGR+L. amy (low birth weight), administered with sterile saline or L. amylovorus Mafic1501, respectively. Growth performance, lactose content in the digesta, intestinal lactose transporter, and barrier function parameters were profiled. IPEC-J2 cells were cultured to verify the effects of L. amylovorus Mafic1501 on lactose utilization and intestinal barrier functions. ResultsL. amylovorus Mafic1501 elevated body weight and average daily gain of IUGR mice and piglets (P < 0.05). The lactose content in the ileum was decreased, whereas gene expression of glucose transporter 2 (GLUT2) was increased by L. amylovorus Mafic1501 in IUGR piglets during suckling period (P < 0.05). Besides, L. amylovorus Mafic1501 promoted intestinal barrier functions by increasing the villus height and relative gene expressions of tight junctions (P < 0.05). L. amylovorus Mafic1501 and its culture supernatant decreased the lactose level in the medium and upregulated gene expressions of transporter GLUT2 and tight junction protein Claudin-1 of IPEC-J2 cells (P < 0.05). ConclusionL. amylovorus Mafic1501 improved the growth performance of IUGR piglets by promoting the lactose utilization in small intestine and enhancing intestinal barrier functions. Our results provided the new evidence of L. amylovorus Mafic1501 for its application in the swine industry.

Sangyod rice extract inhibits adipocyte growth and differentiation via mTOR, Akt, and AMPK pathways

This study aimed to evaluate Sangyod rice extract (SRE) in two aspects: its effect on 3T3-L1 cell proliferation during early adipocyte differentiation and its anti-adipogenic properties. Initially, SRE reduced 3T3-L1 preadipocyte proliferation by downregulating mTOR and Akt expression. In later stages, it significantly inhibited adipogenesis, lowering lipid accumulation and triglyceride levels. SRE achieved these effects by suppressing key adipogenic transcription factors (PPAR-γ, C/EBPα, C/EBPβ, SREBP-1c, SREBP-2) and lipogenic genes (perilipin, aP2, ACC, FasN, LPL, HSL, ATGL), as well as adipokine genes (leptin, resistin, AdipoQ, AdipoQ-R1, AdipoQ-R2). AMPK activation played a crucial role in SRE's mechanism, hindering adipogenesis. Moreover, SRE was found to decrease glucose uptake by suppressing the gene expression of glucose transporter 4 (Glut4) and the insulin receptor (IsnR). This research highlights the potential of SRE as an anti-obesity agent, particularly in alleviating insulin resistance and obesity. This suggests that SRE could be formulated into a functional food product with these advantageous properties.

Astragalus polysaccharide restores insulin secretion impaired by lipopolysaccharides through the protein kinase B /mammalian target of rapamycin/glucose transporter 2 pathway

BackgroundLipopolysaccharide (LPS)-induced dysfunction of pancreatic β-cells leads to impaired insulin (INS) secretion. Astragalus polysaccharide (APS) is a bioactive heteropolysaccharide extracted from Astragalus membranaceus and is a popular Chinese herbal medicine. This study aimed to elucidate the mechanisms by which APS affects INS secretion from β-cells under LPS stress.MethodsRat insulinoma (INS-1) cells were treated with LPS at a low, medium, or high concentration of APS. Glucose-stimulated insulin secretion (GSIS) was evaluated using an enzyme-linked immunosorbent assay (ELISA). Transcriptome sequencing was used to assess genome-wide gene expression. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis was used to determine the signaling pathways affected by APS. Quantitative reverse transcription–polymerase chain reaction (qRT-PCR) was performed to evaluate the gene expression of glucose transporter 2 (GLUT2), glucokinase (GCK), pancreatic duodenal homeobox-1 (PDX-1), and INS. Western blot analysis was used to detect the protein expression of phosphorylated protein kinase B (p-Akt), total Akt (t-Akt), phosphorylated mammalian target of rapamycin (p-mTOR), total mTOR (t-mTOR), and GLUT2.ResultsLPS decreased GLUT2, GCK, PDX-1, and INS expression and reduced GSIS. These LPS-induced decreases in gene expression and GSIS were restored by APS treatment. In addition, transcriptome sequencing in combination with KEGG enrichment analysis revealed changes in the INS signaling pathway following APS treatment. LPS decreased p-Akt and p-mTOR expression, which was restored by APS treatment. The restorative effects of APS on GSIS as well as on the expression of GLUT2, GCK, PDX-1, and INS were abolished by treatment with the Akt inhibitor MK2206 or the mTOR inhibitor rapamycin (RPM).ConclusionsAPS restored GSIS in LPS-stimulated pancreatic β-cells by activating the Akt/mTOR/GLUT2 signaling pathway.

GLUT1 Mediates the Metabolic Reprogramming and Inflammation of CCR2$^+$ Monocytes/Macrophages from Patients with DCM.

Macrophages expressing CC chemokine receptor 2 (CCR2) possess characteristics and performance akin to M1 polarized macrophages, which promote inflammation. Advanced heart failure (HF) patients with higher abundance of CCR2+ macrophages are more likely to experience adverse remodeling. The precise mechanism of CCR2+ macrophages in how they affect the progression of dilated cardiomyopathy remains unknown. Cardiac biopsy samples from dilated cardiomyopathy patients (DCM) were used for immunohistochemistry and immunofluorescence staining. PCR is employed to identify the IL-1β, IL-6, TNF-α, TGF-β, MMP2, MMP9, PKM1, PKM1, GLUT1, GLUT2, GLUT3, GLUT4, PDK1, PFKFB3, PFK1 and HK2 mRNA expression of CCR2+ monocytes/macrophages from the peripheral blood of DCM patients. Seahorse was used to evaluate the oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) of CCR2+ monocytes/macrophages. 2-DG was used to simulate a lack of glucose. Lentivirus containing GLUT1 inhibitory sequence was used to knockdown GLUT1 gene expression of CCR2+ monocytes/macrophages. Western Blot and immunofluorescence staining was used to evaluate the expression of NLRP3. Immunostaining results of cardiac biopsy tissue from dilated cardiomyopathy (DCM) patients demonstrated that the progression to HF was associated with an increase in the number of CCR2+ macrophages. PCR results demonstrated that CCR2 monocytes and macrophages derived from the blood of DCM patients expressed elevated levels of inflammatory factors and up regulation of glycolysis related genes. In addition, OCR and glucose uptake experiments confirmed that increased glucose uptake of these cells was associated with greater inflammation and correlated with a worsening of cardiac function. limiting the glucose supply to CCR2+ monocytes and macrophages, or suppressing the activity of glucose transporter 1 (GLUT1) could reduce inflammation levels. These results suggest that CCR2+ monocytes and macrophages rely on metabolic reprogramming to trigger inflammatory response and contribute to myocardial injury and the progression of DCM.

Exercise increases MEF2A abundance in rat cardiac muscle by downregulating microRNA-223-5p

Exercise plays an important role in cardiac health and enhances the transport of glucose in cardiac muscle by increasing the glucose transporter-4 (GLUT4) content at the cell membrane. The GLUT4 gene is a target of myocyte enhancer transcription factor 2A (MEF2A). Several transcription factors are regulated by microRNAs (miRs), small non-coding RNAs that control gene expression at the posttranscriptional level. In this study we tested the hypothesis that exercise regulates the expression of miR-223 and that MEF2A is a direct target of miR-223. Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and western blot experiments showed that GLUT4 gene expression and protein abundance increased by 30 and 23%, respectively, in the microsomal fraction immediately after exercise, and had returned to control levels after 18 h. In contrast, the increase in GLUT4 in the membrane fraction was delayed. Exercise also increased the protein abundance of transcription factors involved in GLUT4 expression. Immediately after exercise, the protein abundance of MEF2A, nuclear respiratory factor 1 (NRF1), and forkhead box O1 (FOXO1) increased by 18, 30, and 40%, respectively. qRT-PCR experiments showed that miR-223-3p and miR-223-5p expression decreased immediately after exercise by 60 and 30%, respectively, and luciferase assays indicated that MEF2A is a target of the 5p strand of miR-223. Overexpression of miR-223-5p in H9c2 cells decreased the protein abundance of MEF2A. Our results suggest that the exercise-induced increase in GLUT4 content in cardiac muscle is partly due to the posttranscriptional increase in MEF2A protein abundance caused by the decrease in miR-223-5p expression. The exercise-induced decrease in miR-223-3p expression likely contributes to the increases in NRF1 and FOXO1 abundance and GLUT4 content.

Non-monotonic dose-response of di-(2-ethylhexyl) phthalate isolated from Penicillium citrinum XT6 on adipogenesis and expression of PPARγ and GLUT4 in 3T3-L1 adipocytes.

Adipogenesis is the fat cell formation process regulated by peroxisome proliferator-activated receptors (PPARγ). The insulin-responsive glucose transporter 4 (GLUT4) has a major role in glucose uptake and metabolism in insulin target tissues (i.e.,adipose and muscle cells). The interplay between PPARγ and GLUT4 is essential for proper glucose homeostasis. This study aimed to isolate, elucidate, and investigate the effect of an isolated compound from Penicillium citrinum XT6 on adipogenesis, PPARγ, and GLUT4 expression in 3T3-L1 adipocytes. The isolated compound was determined by analyzing spectroscopic data (LC-MS, FT-IR, Spectrophotometry UV-Vis, and NMR). The adipogenesis activity of the isolated compound in 3T3-L1 cells was determined by the Oil Red O staining method. RT-PCR was used to analyze the gene expression of PPARγ and GLUT4. Di-(2-ethylhexyl)-phthalate (DEHP) was the isolated compound from P.citrinum XT6. The results revealed adipogenesis stimulation and inhibition, as well as PPARγ and GLUT4 expressions. DEHP showed a non-monotonic dose-response (NMDR) effect on adipogenesis and PPARγ and GLUT4 expression. It is the first study that reveals DEHP's NMDR effects on lipid and glucose metabolism in adipocytes.

Low rumen degradable starch promotes the growth performance of goats by increasing protein synthesis in skeletal muscle via the AMPK-mTOR pathway.

Since starch digestion in the small intestine provides more energy than digestion in the rumen of ruminants, reducing dietary rumen degradable starch (RDS) content is beneficial for improving energy utilization of starch in ruminants. The present study tested whether the reduction of rumen degradable starch by restricting dietary corn processing for growing goats could improve growth performance, and further investigated the possible underlying mechanism. In this study, twenty-four 12-wk-old goats were selected and randomly allocated to receive either a high RDS diet (HRDS, crushed corn-based concentrate, the mean of particle sizes of corn grain=1.64mm, n=12) or a low RDS diet (LRDS, non-processed corn-based concentrate, the mean of particle sizes of corn grain >8mm, n=12). Growth performance, carcass traits, plasma biochemical indices, gene expression of glucose and amino acid transporters, and protein expression of the AMPK-mTOR pathway were measured. Compared to the HRDS, LRDS tended to increase the average daily gain (ADG, P=0.054) and decreased the feed-to-gain ratio (F/G, P<0.05). Furthermore, LRDS increased the net lean tissue rate (P<0.01), protein content (P<0.05) and total free amino acids (P<0.05) in the biceps femoris (BF) muscle of goats. LRDS increased the glucose concentration (P<0.01), but reduced total amino acid concentration (P<0.05) and tended to reduce blood urea nitrogen (BUN) concentration (P=0.062) in plasma of goats. The mRNA expression of insulin receptors (INSR), glucose transporter 4 (GLUT4), L-type amino acid transporter 1 (LAT1) and 4F2 heavy chain (4F2hc) in BF muscle, and sodium-glucose cotransporters 1 (SGLT1) and glucose transporter 2 (GLUT2) in the small intestine were significantly increased (P<0.05) in LRDS goats. LRDS also led to marked activation of p70-S6 kinase (S6K) (P<0.05), but lower activation of AMP-activated protein kinase (AMPK) (P<0.05) and eukaryotic initiation factor 2α (P<0.01). Our findings suggested that reducing the content of dietary RDS enhanced postruminal starch digestion and increased plasma glucose, thereby improving amino acid utilization and promoting protein synthesis in the skeletal muscle of goats via the AMPK-mTOR pathway. These changes may contribute to improvement in growth performance and carcass traits in LRDS goats.

Plant Polyphenol Gossypol Induced Cell Death and Its Association with Gene Expression in Mouse Macrophages

Gossypol is a complex plant polyphenol reported to be cytotoxic and anti-inflammatory, but little is known about its effect on gene expression in macrophages. The objective of this study was to explore gossypol's toxicity and its effect on gene expression involved in the inflammatory response, glucose transport and insulin signaling pathways in mouse macrophages. Mouse RAW264.7 macrophages were treated with multiple concentrations of gossypol for 2-24 h. Gossypol toxicity was estimated by MTT assay and soluble protein content. qPCR analyzed the expression of anti-inflammatory tristetraprolin family (TTP/ZFP36), proinflammatory cytokine, glucose transporter (GLUT) and insulin signaling genes. Cell viability was greatly reduced by gossypol, accompanied with a dramatic reduction in soluble protein content in the cells. Gossypol treatment resulted in an increase in TTP mRNA level by 6-20-fold and increased ZFP36L1, ZFP36L2 and ZFP36L3 mRNA levels by 26-69-fold. Gossypol increased proinflammatory cytokine TNF, COX2, GM-CSF, INFγ and IL12b mRNA levels up to 39-458-fold. Gossypol treatment upregulated mRNA levels of GLUT1, GLUT3 and GLUT4 genes as well as INSR, AKT1, PIK3R1 and LEPR, but not APP genes. This study demonstrated that gossypol induced macrophage death and reduced soluble protein content, which was accompanied with the massive stimulation of anti-inflammatory TTP family and proinflammatory cytokine gene expression, as well as the elevation of gene expression involved in glucose transport and the insulin signaling pathway in mouse macrophages.

Aberrant lipid accumulation in the mouse visceral yolk sac resulting from maternal diabetes and obesity.

Maternal diabetes and obesity in pregnancy are well-known risk factors for structural birth defects, including neural tube defects and congenital heart defects. Progeny from affected pregnancies are also predisposed to developing cardiometabolic disease in later life. Based upon in vitro embryo cultures of rat embryos, it was postulated that nutrient uptake by the yolk sac is deficient in diabetic pregnancies. In contrast, using two independent mouse models of maternal diabetes, and a high-fat diet-feeding model of maternal obesity, we observed excessive lipid accumulation at 8.5days in the yolk sac. The numbers as well as sizes of intracellular lipid droplets were increased in yolk sacs of embryos from diabetic and obese pregnancies. Maternal metabolic disease did not affect expression of lipid transporter proteins, including ApoA1, ApoB and SR-B1, consistent with our earlier report that expression of glucose and fatty acid transporter genes was also unchanged in diabetic pregnancy-derived yolk sacs. Colocalization of lipid droplets with lysosomes was significantly reduced in the yolk sacs from diabetic and obese pregnancies compared to yolk sacs from normal pregnancies. We therefore conclude that processing of lipids is defective in pregnancies affected by maternal metabolic disease, which may lead to reduced availability of lipids to the developing embryo. The possible implications of insufficient supply of lipids -and potentially of other nutrients-to the embryos experiencing adverse pregnancy conditions are discussed.

Smilax china L. Polyphenols Improves Insulin Resistance and Obesity in High-fat Diet-induced Mice Through IRS/AKT-AMPK and NF-κB Signaling Pathways.

Smilax china L. is an important herb used in traditional Chinese medicine. In this study, the mechanism of Smilax china L. polyphenols (SCP) on insulin resistance and anti-obesity in mice induced by a high-fat diet (HFD) was investigated. Fifty female mice were randomly divided into five groups: control, HFD and low, medium, and high doses of SCP for 70 d. SCP significantly decreased intraperitoneal adipose tissue index, body weight gain, liver lipids, and serum inflammatory factor levels. Blood glucose and insulin concentrations, as well as insulin resistance index in SCP, were significantly lower than those in HFD. In addition, SCP markedly up-regulated the gene expression of glucose transporter 4 (GLUT4), insulin receptor substrate 1 (IRS1), insulin receptor substrate 2 (IRS2), serine-threonine kinase (AKT), Acyl-CoA oxidase (ACO), and protein kinase A (PKA), and down-regulated the expression of mammalian target of rapamycin complex 1 (mTORC1), sterol-responsive element-binding protein-1c (SREBP1c), fatty acid synthase (FAS), 3-hydroxy-3-methyl glutaryl coenzyme A reductase (HMGCR), and forkhead box protein O1 (FOXO1). SCP significantly increased the protein expression of AKT, GLUT4, AMP-activated protein kinase (AMPK), phosphorylated-AMPK (p-AMPK), phosphorylated-AKT (p-AKT), and uncoupling protein 1 (UCP-1), and decreased the expression of SREBP1c, FAS, HMGCR, phosphorylation of IKBα (p-IKBα), and nuclear factor kappa B subunit p65 (P65) in the liver. Overall, SCP effectively reduced HFD-induced insulin resistance and obesity in mice, partly through NF-κB and IRS/AKT-AMPK signaling pathways to regulate inflammatory factors. Therefore, SCP may improve lifestyle diseases.

Improvement of obesity by Liupao tea is through the IRS-1/PI3K/AKT/GLUT4 signaling pathway according to network pharmacology and experimental verification

BackgroundObesity is a state of accumulating excessive body fat, charactering by a high blood lipid and associating with various metabolic diseases. As a kind of dark tea, many studies revealed that long-term drinking Liupao tea (LT) can reduce weight (Liu et al., 2014). However, the anti-obesity mechanism and active ingredients of LT are not known. MethodsLiquid chromatography-mass spectrometry (LC-MS) combined with network pharmacology was used to screen the active components and related targets of Liupao tea water extract (LTWE). The key anti-obesity targets and pathways of LTWE were predicted by protein-protein interaction (PPI) networks, and enrichment analyses using Kyoto Encyclopedia of Genes and Genomes and Gene Ontology databases. Then, the active components selected by high-performance liquid chromatography (HPLC) fingerprinting were used together with LTWE in an adipogenic model and insulin resistance (IR) model in vitro. ResultsMost of the compounds identified from LTWE were flavonofids, esters, and amides. Key targets such as RAC-alpha serine/threonine-protein kinase, insulin, and tumor necrosis factor (TNF) were involved in the phosphatidylinositol-3-kinase-protein kinase B (PI3K-AKT) signaling pathway, pathways in cancer, and other pathways. Four active components were screened by network pharmacology combined with HPLC fingerprinting. The in vitro experiment of LTWE and its four active components showed that in insulin-resistant 3T3-L1 cells, LTWE, (−)-epigallocatechin gallate (EGCG) and gallic acid (GA) inhibited adipocyte differentiation. Three factors could inhibit the differentiation of 3T3-L1 cells by decreasing gene expression of peroxisome proliferators-activated receptor γ (PPARγ), fatty acid synthase (FAS), CCAAT/enhancer binding proteins-α (C/EBPα) and interleukin-6 (IL-6). Caffeine and ellagic acid (EA) showed opposite results, but their effects on promoting adipose differentiation diminished with increasing concentrations of drug. In dexamethasone-induced insulin-resistant 3T3-L1 cells, the fluorescence intensity of 2-Deoxy-2-[(7-nitro-2,1,3-Benzoxadiazol-4-yl)amino]-d-glucose revealed that LTWE, GA, EGCG, caffeine, and EA significantly promoted glucose consumption. LTWE, GA, and EA improved insulin resistance in adipocytes by upregulating gene expression of insulin receptor substrate-1 (IRS-1), PI3K, AKT, and glucose transporter 4 (GLUT4). ConclusionLC-MS combined with network pharmacology preliminarianized that LTWE acts mainly on the PI3K-AKT signaling pathway. Cell experiments revealed that the anti-obesity effect of LTWE is the result of multi-component action, which inhibits the proliferation and differentiation of preadipocytes by regulating gene expression of adipogenic transcription factors and proinflammatory factors, and improves IR by activating the IRS-1/PI3K/AKT/GLUT4 pathway.

Antidiabetic activity of Solanum torvum fruit extract in streptozotocin-induced diabetic rats.

Solanum torvum Swartz, a medicinal plant belonging to the family Solanaceae, is an important medicinal plant widely distributed throughout the world and used as medicine to treat diabetes, hypertension, tooth decay, and reproductive problems in traditional systems of medicine around the world including Malaysia. The objective of this study was to investigate hypoglycemic, antilipidemic, and hepatoprotective activities, histopathology of the pancreas, and specific glucose regulating gene expression of the ethanolic extract of S. torvum fruit in streptozotocin-induced diabetic Sprague-Dawley rats. Acute toxicity study was done according to OECD-423 guidelines. Diabetes was induced by intraperitoneal (i.p.) injection of streptozotocin (55 mg/kg) in male Sprague-Dawley rats. Experimental diabetic rats were divided into six different groups; normal, diabetic control, and glibenclamide at 6 mg/kg body weight, and the other three groups of animals were treated with oral administration of ethanolic extract of S. torvum fruit at 120, 160, and 200 mg/kg for 28 days. The effect of ethanolic extract of S. torvum fruit on body weight, blood glucose, lipid profile, liver enzymes, histopathology of pancreas, and gene expression of glucose transporter 2 (slc2a2), and phosphoenolpyruvate carboxykinase (PCK1) was determined by RT-PCR. Acute toxicity studies showed LD50 of ethanolic extract of S. torvum fruit to be at the dose of 1600 mg/kg body weight. Blood glucose, total cholesterol, triglycerides, low-density lipoproteins, very low-density lipoproteins, serum alanine aminotransferase, and aspartate aminotransferase were significantly reduced, whereas high-density lipoproteins were significantly increased in S. torvum fruit (200 mg/kg)-treated rats. Histopathological study of the pancreas showed an increase in number, size, and regeneration of β-cell of islets of Langerhans. Gene expression studies revealed the lower expression of slc2a2 and PCK1 in treated animals when compared to diabetic control. Ethanolic extract of S. torvum fruits showed hypoglycemic, hypolipidemic, and hepatoprotective activity in streptozocin-induced diabetic rats. Histopathological studies revealed regeneration of β cells of islets of Langerhans. Gene expression studies indicated lower expression of slc2a2 and PCK1 in treated animals when compared to diabetic control, indicating that the treated animals prefer the gluconeogenesis pathway.

Venous Wall of Patients with Chronic Venous Disease Exhibits a Glycolytic Phenotype

Chronic venous disease (CVeD) is a rising medical condition characterized by a broad spectrum of disorders in the venous system. Varicose veins (VVs) represent a frequent clinical manifestation of CVeD, particularly in the lower limbs. Prior histopathological studies have defined a set of alterations observed in the venous wall of patients with VVs, affecting their structure and behavior. Metabolic changes in the veins appear to be a critical biological mechanism aiding our understanding of the pathogenesis of CVeD. In this sense, previous studies have identified a potential role of a glycolytic phenotype in the development of different vascular disorders; however, its precise role in CVeD remains to be fully explored. Thus, the aim of the present study was to analyze the gene and protein expression of glucose transporter 1 (GLUT-1) and the glycolytic enzymes PGK-1, ALD, GA3PDH and LDH in the VVs of patients with CVeD (n = 35) in comparison to those expressed in healthy subjects. Our results display enhanced gene and protein expression of GLUT-1, PGK-1, ALD, GA3PDH and LDH in patients with CVeD, suggesting a glycolytic switch of the venous tissue. Greater understanding of the impact of this glycolytic switch in patients with CVeD is required to define a possible pathophysiological role or therapeutic implications of these changes.

Antidiabetic potential of Lysiphyllum strychnifolium (Craib) A. Schmitz compounds in human intestinal epithelial Caco-2 cells and molecular docking-based approaches

BackgroundLysiphyllum strychnifolium (Craib) A. Schmitz, a traditional Thai medicinal plant, is mainly composed of polyphenols and flavonoids and exhibits several pharmacological activities, including antioxidant, anticancer, antimicrobial, and antidiabetic activities. However, the mechanism by which pure compounds from L. strychnifolium inhibit glucose catalysis in the small intestine and their effect on the glucose transporter remain unknown.MethodsThe objectives of this research were to examine the effect of 3,5,7-trihydroxychromone-3-O-\U0001d6fc-L-rhamnopyranoside (compound 1) and 3,5,7,3’,5’-pentahydroxy-flavanonol-3-O-\U0001d6fc-L-rhamnopyranoside (compound 2) on the inhibition of α-amylase and α-glucosidase, as well as glucose transporters, such as sodium-glucose cotransporter 1 (SGLT1), glucose transporter 2 (GLUT2), and glucose transporter 5 (GLUT5), using Caco-2 cells as a model of human intestinal epithelial cells. Additionally, the binding affinity and interaction patterns of compounds against two receptor proteins (SGLT1 and GLUT2) were determined for the first time utilizing a molecular docking approach.ResultsIn the α-amylase inhibition assay, a concentration-dependent inhibitory response was observed against the enzyme. The results indicated that compound 1 inhibited α-amylase activity in a manner similar to that of acarbose (which exhibit IC50 values of 3.32 ± 0.30 µg/mL and 2.86 ± 0.10 µg/mL, respectively) in addition to a moderate inhibitory effect for compound 2 (IC50 = 10.15 ± 0.53 µg/mL). Interestingly, compounds 1 and 2 significantly inhibited α-glucosidase and exhibited better inhibition than that of acarbose, with IC50 values of 5.35 ± 1.66 µg/mL, 510.15 ± 1.46 µg/mL, and 736.93 ± 7.02 µg/mL, respectively. Additionally, α-glucosidase activity in the supernatant of the Caco-2 cell monolayer was observed. In comparison to acarbose, compounds 1 and 2 inhibited α-glucosidase activity more effectively in Caco-2 cells without cytotoxicity at a concentration of 62.5 µg/mL. Furthermore, the glucose uptake pathways mediated by SGLT1, GLUT2, and GLUT5- were downregulated in Caco-2 cells treated with compounds 1 and 2. Additionally, molecular modeling studies revealed that compounds 1 and 2 presented high binding activity with SGLT1 and GLUT2.ConclusionIn summary, our present study was the first to perform molecular docking with compounds present in L. strychnifolium extracts. Our findings indicated that compounds 1 and 2 reduced glucose uptake in Caco-2 cells by decreasing the expression of glucose transporter genes and inhibiting the binding sites of SGLT1 and GLUT2. Therefore, compounds 1 and 2 may be used as functional foods in dietary therapy for postprandial hyperglycemia modulation of type 2 diabetes.

Changes in tear glucose and insulin concentrations following an oral glucose tolerance test

ABSTRACT Clinical relevance Tear glucose and insulin are responsible for the health of the ocular surface; thus, it is important for clinicians to detect the tear glucose and insulin using point-of-care methods. Aim To determine if changes in blood glucose and insulin levels following an oral glucose tolerance test are reflected in the tears and to test the association between gene expression and tear insulin and glucose. Methods Twenty healthy young adults were enrolled. Basal tears and peripheral blood samples were collected to assess glucose and insulin using a point-of-care glucometer and ELISA assays in fasted subjects, and 1.5 and 3 h after an oral glucose challenge. Conjunctival impression cytology was collected to determine gene expression of insulin receptor (INSR) and glucose transporters (GLUT1 and GLUT4). Changes were examined using non-parametric one-way ANOVA. Spearman tests were conducted to examine associations between variables. Results Glucose and insulin levels increased 1.5 h after oral glucose in both blood (P < 0.001) and tears (P < 0.049) and returned to near baseline values after 3 h. There was a positive correlation between glucose levels in the blood and tears (rho = 0.57, P < 0.001), but not between blood and tear insulin levels (P = 0.18). Glucose and insulin levels in tears were correlated (rho = 0.32, P = 0.048). Tear glucose concentration at 1.5 h after oral glucose was associated with INSR expression (rho = 0.49, P = 0.03), and there was a trend with GLUT1 (P = 0.06) but not GLUT4. Conclusion Tear glucose reflected blood glucose levels but this correspondence was not observed for insulin. Further studies are required to determine the role of glucose and insulin on the ocular surface in both health and diabetes.