Expression Of Glucose Transporter Research Articles

Activation of the WNT7B/β-Catenin Pathway Initiates GLUT1 Expression and Promotes Aerobic Glycolysis in Colorectal Cancer Cells

Glucose is an important energy source for tumors, however the molecular mechanisms by which tumor cells regulate glucose uptake remain unclear. In this study, we aimed to investigate the regulation mechanism of the WNT7B/β-catenin pathway for glucose transporter 1 (GLUT1)-mediated glucose metabolism in colorectal cancer. Here, we found that WNT7B expression levels were significantly increased in colorectal cancer tissues and closely associated with the clinical stage and lymph node metastasis in patients with colorectal cancer. Next, we confirmed that WNT7B significantly increased the glucose consumption and lactic acid levels in SW480 cells by overexpressing WNT7B. Additionally, gene and protein levels of GLUT1 were increased in WNT7B-overexpressing SW480 cells. However, WNT7B knockdown reversed these effects. WNT7B also enhanced GLUT1-mediated cell proliferation, invasion, and migration. WNT7B overexpression inhibited the effect of glucose deprivation on apoptosis. The WNT/β-catenin signaling pathway inhibitor, LGK974, inhibited WNT7B secretion, leading to GLUT1 levels downregulation and promotion of cell apoptosis. Ectopic tumor xenograft model experiments revealed that WNT7B promoted tumor progression in mice. Overall, our results suggest that WNT7B promotes β-catenin entry into the nucleus to initiates GLUT1 transcription, increases glucose transport and consumption, and enhances aerobic glycolysis, thus promoting tumor progression in colorectal cancer cells.

The roles of GLUT5 in cancer progression, metastasis, and drug resistance

Emerging evidence has suggested that high fructose intake, particularly from added sugars and processed foods, is associated with increased cancer risk and progression. The fructose intake is believed to be mediated by the abnormal expression of glucose transporter 5 (GLUT5), the specific fructose transporter in cancer cells. The GLUT5-regulated fructose metabolism has shown to greatly affect cancer progression, metastasis, and drug resistance. This review aims to synchronize the current knowledge to highlight the underlying mechanisms of those impacts and understand the therapeutic potential of GULT5. First, we review the fructose metabolism and its alteration in cancer cells by comparing with glucose metabolism. Subsequently, the key contributors or biological pathways involved in GLUT5-asosociated tumor growth, cancer metastasis, and drug resistance are discussed. The contributions of specific pathways, metabolites, and key enzymes from the fructose metabolism process are also covered, such as enhanced glycolysis for tumor growth, epithelial-mesenchymal transition and angiogenesis for cancer metastasis, and efflux pump expression and activation of survival pathways for cancer drug resistance. The detailed analysis of these mechanisms will allow further understanding of the therapeutic potential of GLUT 5-mediated fructose metabolism in cancer therapy. In particular, targeting GLUT 5 and its-associated processes in fructose metabolism may offer promising strategies for improving cancer treatment outcomes through dietary interventions, specific GLUT5 inhibitors, or in combination.

Dysregulated GLUT1 results in the pathogenesis of preeclampsia by impairing the function of trophoblast cells

Preeclampsia (PE) is a common placental-origin complication of pregnancy and a major cause of morbidity and mortality among pregnant women and fetuses. However, its pathogenesis has not been elucidated. Effective strategies for prevention, screening, and treatment are still lacking. Studies have indicated that dysfunction of placental trophoblast cells, such as impaired syncytialization, proliferation, and epithelial-mesenchymal transition processes, plays a crucial role in the development of PE. Glucose transporter 1 (GLUT1) is a key protein regulating glucose transport in placental tissues. However, the effect of GLUT1 on the function of trophoblast cells in PE is not well understood. In this study, we found that GLUT1 expression is reduced in PE placental tissues. GLUT1 promotes the syncytialization process by increasing the glucose uptake ability of BeWo cells. Additionally, GLUT1 promotes the proliferation, migration, and invasion capabilities of HTR-8/SVneo cells by regulating MAPK and PI3K/AKT signaling pathways. Overall, these findings provide a new insight into understanding the biological functions of GLUT1, clarifying the pathogenesis of PE, and identifying diagnostic and therapeutic targets for PE.

Renal Sugar Metabolites and mRNA Expression of Glucose Transporters in Meat-Type Chickens with Differing Residual Water Intake.

Molecular differences exist between birds with high residual water intake (HRWI) compared to those with low residual water intake (LRWI). Residual water intake (RWI) is defined as the difference between the water intake of a bird and the expected water intake corrected for metabolic body weight, feed intake, and body weight gain. Tissue metabolomic analysis revealed significantly increased kidney glucose, fructose, and arabitol in the LRWI group compared to the HRWI group. mRNA expression analysis of apical sodium glucose cotransporters SGLT1, SGLT4, SGLT5, and SGLT6 showed decreased expression of SGLTs 1, 5, and 6 in LRWI birds (p < 0.05), whereas SGLT4 expression was increased compared with HRWI birds (p < 0.01). An analysis of basal glucose transporters GLUT1, GLUT2, GLUT5, and GLUT9 showed significantly increased GLUT2 expression in LRWI birds compared with HRWI birds (p < 0.01). We postulate that SGLT4 is the main apical transporter in chicken kidneys and that its increased expression reduces these birds' need for water, resulting in less drinking. This is balanced by the increased expression of the basal transporter GLUT2, indicating better glucose retention, which may partly explain the physiological mechanism behind why these birds drink less water. Innately driven broiler water intake could therefore be influenced by the expression of kidney solute transporters.

Fetuin-B Interacts With Insulin Receptor-β and Promotes Insulin Resistance in Retina Cells.

The purpose of this study was to investigate the correlation between insulin and Fetuin-B (FETUB) and the influence of FETUB on insulin signaling pathway in diabetic retinopathy (DR). Enzyme-linked immunosorbent assay (ELISA) was used to analyze FETUB and insulin levels in the serum and aqueous fluid of patients with DR and healthy controls. Quantitative PCR (q-PCR), Western blotting, and ELISA were used to examine FETUB expression in ARPE-19, BV2, and Müller cells under insulin stimulation. Co-immunoprecipitation was used to investigate the interaction of FETUB with insulin receptor-β (IRβ). Insulin resistance (IR)-BV2 and IR-Müller cells were treated with FETUB recombinant protein or FETUB short hairpin RNA (shRNA) to explore the influence of FETUB on insulin signaling pathway in DR. LY294002 (a PI3K pathway inhibitor) was used to determine whether FETUB affects glucose metabolism via the PI3K/Akt pathway. In aqueous fluid, FETUB concentrations were positively correlated with insulin levels. FETUB expression increased in Müller and BV2 cells under insulin regulation, and FETUB interacted with IRβ in retinal cells and mice retina. The interaction between IRβ and FETUB increased in BV2 and Müller cells under high-glucose than in controls. Insulin signaling pathway activation was suppressed in FETUB recombinant protein-treated BV2 and Müller cells but increased in FETUB shRNA-transfected cells. FETUB shRNA could not reverse LY294002-mediated inhibition of glucose transporter-4 expression. Retinal cells are the source of insulin-regulated FETUB. The FETUB interacts with IRβ and affects insulin signaling pathway in BV2 and Müller cells. FETUB may aggravate IR in BV2 and Müller cells via the PI3K/Akt pathway.

Envisioning Glucose Transporters (GLUTs and SGLTs) as Novel Intervention against Cancer: Drug Discovery Perspective and Targeting Approach.

Metabolic reprogramming and altered cellular energetics have been recently established as an important cancer hallmark. The modulation of glucose metabolism is one of the important characteristic features of metabolic reprogramming in cancer. It contributes to oncogenic progression by supporting the increased biosynthetic and bio-energetic demands of tumor cells. This oncogenic transformation consequently results in elevated expression of glucose transporters in these cells. Moreover, various cancers exhibit abnormal transporter expression patterns compared to normal tissues. Recent investigations have underlined the significance of glucose transporters in regulating cancer cell survival, proliferation, and metastasis. Abnormal regulation of these transporters, which exhibit varying affinities for hexoses, could enable cancer cells to efficiently manage their energy supply, offering a crucial edge for proliferation. Exploiting the upregulated expression of glucose transporters, GLUTs, and Sodium Linked Glucose Transporters (SGLTs), could serve as a novel therapeutic intervention for anti-cancer drug discovery as well as provide a unique targeting approach for drug delivery to specific tumor tissues. This review aims to discussthe previous and emerging research on the expression of various types of glucose transporters in tumor tissues, the role of glucose transport inhibitors as a cancer therapy intervention as well as emerging GLUT/SGLT-mediated drug delivery strategies that can be therapeutically employed to target various cancers.

6421 Imaging Phenotype May Predict Genotype In Human Pheochromocytoma: Relationships Between Genetic Mutation Clusters, Metabolite Transporter Expression, And Radiotracer Uptake

Abstract Disclosure: I. Sakuma: None. M. Fujimoto: None. D.F. Vatner: None. K. Yokote: None. T. Tanaka: None. Context [1]23I-metaiodobenzylguanidine scintigraphy (MIBG) and [1]8F-fluoro-2-doxy-D-glucose positron emission tomography (FDG-PET) are helpful for the localization of pheochromocytoma. The norepinephrine transporter (NET) and the glucose transporter 1 (GLUT1) are thought to be critical for the uptake of these radioisotopes. NET expression is activated by Paired Like Homeobox (PHOX2) and glucocorticoid receptor (GR) in neuroblastoma cells. Around 70% of pheochromocytomas carry well-known mutations. Pheochromocytoma-associated genes are divided into two clusters: the pseudohypoxia-related cluster 1 and the kinase signaling-related cluster 2. Cluster 1 mutation are associated with noradrenergic pheochromocytomas with an elevated metastatic risk. Cluster 2 tumors demonstrate an adrenergic phenotype with a less aggressive course. How mutations of cluster 1 and cluster 2 impact the expression of NET/GLUT1 and on radiotracer uptake remains unclear. Hypothesis Cluster 1 and cluster 2 will have different effects on the expression of transcription factors associated with chromaffin cell differentiation with resultant differential effects on NET/GLUT1 expression. Methods 42 patients with pheochromocytoma were evaluated by MIBG and FDG-PET. Tumor gene expression was evaluated by real-time qPCR, and mutation analyses were performed by Sanger or next-generation sequencing. Results 88% of tumors were MIBG-avid, and 67% were FDG-avid. The expression of NET in MIBG-negative tumors was 70% lower than in MIBG-positive tumors. The expression of GLUT1 in FDG-PET-negative tumors was 75% lower than in FDG-PET-positive tumors. The expression of NET positively correlated with transcription factors involved in chromaffin cell maturation, including PHOX2A, PHOX2B, GATA binding protein 3 (GATA3), GR, catecholamine synthases, and insulinoma associated 1 (INSM1). The JASPAR database for promoter analysis revealed putative responsive regions of the transcription factors PHOX2A, PHOX2B, GATA3, GR, and INSM1 on the NET gene. Seven patients (16.7%) had mutations in cluster 1, and fourteen patients (33.3%) had mutations in cluster 2. Cluster 2 exhibited elevated NET, PHOX2A, PHOX2B, GATA3, GR, and INSM1 expression levels compared to cluster 1. Cluster 1 showed a higher expression level of GLUT1 and BMP4 that is associated with early chromaffin cell differentiation. Conclusions In pheochromocytomas, MIBG and FDG uptake correlated with the expression levels of NET and GLUT1, respectively. NET expression is associated with chromaffin cell differentiation transcription factor expression. We propose that pheochromocytomas that carry Cluster 1 mutations are more likely to be missed in MIBG due to low NET expression, while pheochromocytomas that carry Cluster 2 mutations are more likely to be missed on FDG-PET due to low GLUT1 expression with a more mature chromaffin cell phenotype. Presentation: 6/2/2024

Glucose Transporter 1 Inhibitors Induce Autophagy and Synergize With Lenvatinib in Thyroid Cancer Cells.

Less differentiated thyroid cancer may upregulate the expression of glucose transporter 1 (GLUT1) and increase glycolytic activity. However, it is uncertain whether GLUT1 can be used as a target for therapy. Thyroid cancer cell lines were treated with two different GLUT1 inhibitors, STF-31 and BAY-876. Functional assays were conducted to evaluate the effects of these inhibitors on cell biology. GLUT1 inhibitors dose-dependently decreased cell growth and clonogenicity of thyroid cancer cells. Cell cycle analysis showed that these inhibitors caused G2/M arrest instead of apoptosis. Additionally, treatment with GLUT1 inhibitors led to the activation of autophagy. In both the Transwell and spheroid models, GLUT1 inhibitors significantly suppressed cell invasiveness. Moreover, GLUT1 inhibitors demonstrated synergistic interactions when combined with lenvatinib. Treatment with GLUT1 inhibitors activates autophagy and provokes cell cycle arrest, accompanied by a decrease in colony formation and invasive capacity in thyroid cancer cells.

Withanolides-enriched leaf extract of Withania somnifera exert anti-obesity effects by inducing brown adipocyte-like phenotype via tuning MAP-kinase signaling axis

Present study investigated anti-obesity potential of Withania somnifera (L.) Dunal leaf extract (WSLE). Phytochemical characterization of WSLE was performed by UPLC/MS-QToF and HPLC-based analysis. WSLE was assessed for its effect on lipid metabolism and mitochondrial biogenesis in vitro using differentiated 3 T3-L1 adipocytes. WSLE was found to contain 59 phytometabolites with a total of 10.601 μg withanolides per mg of extract. WSLE (30 μg/ml) treatment decreased basal levels of intracellular lipids and triglycerides to 13.85 % and 41.58 %, respectively. WSLE downregulated the expression of PPARγ, C/EBPα, C/EBPβ, and their target genes responsible for lipogenesis dose-dependently. An upregulation in expression of lipolytic (ATGL and HSL), thermogenic (PGC1α, UCP1, and PRDM16), and glucose transporter (GLUT4) genes was also observed. Furthermore, WSLE treatment increased glucose uptake by 1.5-fold. These beneficial effects of WSLE were abolished in presence of AMPK, p38MAPK, and ERK inhibitors. These observations were then validated in vivo using Caenorhabditis elegans as a model organism. Intriguingly, WSLE diminished fat accumulation in wild-type N2 worms as evident from reduced Oil-red-O staining and reduction in GFP expression of fat-5, 6, and 7 in transgenic strains. Overall, these results highlight anti-obesity potential of WSLE exerting its effects via alterations in AMPK/p38MAPK/ERK axis.

Structural and quantitative characterization of membrane N-glycans from MIN6 mouse pancreatic beta cells using liquid chromatography-quadrupole-Orbitrap tandem mass spectrometry

MIN6, a mouse pancreatic beta cell line, is used in diabetes research, and the cellular N-glycoproteins in membrane are important in regulating the metabolism of insulin secretion. However, the identities of N-glycans in MIN6 cells are yet to be fully elucidated. In this study, the structures of N-glycans were analyzed using liquid chromatography-electrospray ionization-higher energy collisional dissociation-tandem mass spectrometry. The abundances (%) of each N-glycan relative to the total N-glycans (100 %) were also obtained. Fifty N-glycans (with relative abundance of each > 0.5 %) were obtained, revealing 22 bisecting N-acetylglucosamine (GlcNAc; associated with cell adhesion and growth; sum of relative abundance of each: 27.1 %), 21 core-fucosylated (associated with glucose sensing and insulin secretion regulation; 28.3 %), and 16 sialylated (N-acetylneuraminic acid; related to the expression of glucose transporters and diabetes;15.5 %) N-glycans. Membranes contained higher bisecting GlcNAc and core-fucosylation, similar sialylation, but less high-mannosylation than the lysate (the cellular contents). Notably, all bisecting GlcNAc N-glycans were categorized into structures with (16.6 %) or without (10.5 %) core-fucosylation and with (6.9 %) or without (20.2 %) sialylation. The bisecting GlcNAc structures were not found in human islets; moreover, sialylation levels were 6.9 times higher than for human islets. These structural characteristics of N-glycans affect their cell adhesion and distribution through homologous interactions between beta cells, leading to increased insulin secretion efficiency. This study is the first to identify the structures and quantities of 50 N-glycans in MIN6 cell membranes that may play an important role in regulating the functions of pancreatic beta cells.

Sema4D deficiency enhances glucose tolerance through GLUT2 retention in hepatocytes

BackgroundThe glucose transporter 2 (GLUT2) is constitutively expressed in pancreatic beta cells and hepatocytes of mice. It is the most important receptor in glucose-stimulated insulin release and hepatic glucose transport. The Sema4D is a signalin receptor on cell membranes. The correlation between Sema4D and GLUT2 has not been reported previously. We investigated whether knockdown of Sema4D could exert a hypoglycemic effect based on the increased GLUT2 expression in Sema4D -/- mice hepatocytes.MethodsThe glucose tolerance test and insulin tolerance test in sema4D -/- and sema4D +/+ mice were compared before and after streptozotocin (STZ) injection; the expression of GLUT2 content on the membrane surface of both groups was verified by Western blot. Then, the levels of insulin and C-peptide in the serum of the two groups of mice after STZ injection were measured by ELISA; the differentially expressed mRNAs in the liver of the two groups of mice were analyzed by transcriptomic analysis; then the differences in the expression of GLUT2, glycogen, insulin and glucagon in the two groups of mice were compared by tissue section staining. Finally, metabolomics analysis was performed to analyze the metabolites differentially expressed in the two groups of mice.Key findingsFirst, Sema4D -/- male mice exhibited significantly greater glucose tolerance than wild-type mice in a hyperglycemic environment. Secondly, Sema4D -/- mice had more retained GLUT2 in liver membranes after STZ injection according to an immunofluorescence assay. After STZ injection, Sema4D -/- male mice did not exhibit fasting hyperinsulinemia like wild-type mice. Finally, analysis of metabolomic and immunohistochemical data also revealed that Sema4D -/- mice produce hypoglycemic effects by enhancing the pentose phosphate pathway, but not glycogen synthesis.ConclusionsThus, Sema4D may play an important role in the regulation of glucose homeostasis by affecting GLUT2 synthesis.

Gestational exposure to BPA alters the expression of glucose and lipid metabolic mediators in the placenta: Role in programming offspring for obesity

Bisphenol A (BPA) exposure during pregnancy is known to predispose offspring to obesity in later life. Our previous studies demonstrated obesogenic effects in BPA-exposed offspring, including excess body fat, increased feed efficiency, adipocyte hypertrophy, and altered leptin signaling. However, the role of the placenta in mediating these effects remained unclear. This study investigates the mechanisms by which BPA exposure affects placental glucose and lipid transporters and their impact on offspring adiposity in Wistar rats. Dams were orally gavaged with BPA [0.4 (low dose-LD) and 4.0 (high dose-HD) μg/kg body weight] from gestational day (gD) 4–14. Gestational exposure to LD BPA increased the expression of 11β hydroxysteroid dehydrogenase 1 (11β HSD1) and estrogen receptor alpha (ERα) proteins (p<0.05) in the placenta compared to control and HD BPA. Similar changes were observed in the expression of mTOR signaling mediators, fatty acid transporters, and intracellular fatty acid-binding proteins. There were no changes in the dam's body weight or lipid and glucose profiles. However, there was a dose dependent increase in glucose transporter (GLUT1) expression in the placenta. While LD BPA increased hexokinase 2 expression in the placenta, HD BPA had no effect. Both doses of BPA increased IL6 expression, but only LD BPA exposure increased PPAR-gamma expression. Additionally, BPA exposure induced ADRP expression and localization, suggesting potential lipid overload in the placenta. Furthermore, BPA exposure altered the placental epigenetic profile, with increased expression of DNA methyltransferases (DNMTs). Overall, gestational BPA exposure led to dose-specific alterations in placental glucose and lipid metabolic activities, possibly playing an role in increasing the supply of these macronutrients to the fetus and predisposing the offspring to obesity.

MEK inhibitor trametinib combined with PI3K/mTOR inhibitor BEZ-235 as an effective strategy against NSCLC through impairment of glucose metabolism

The MAPK and PI3K/AKT/mTOR pathways are aberrantly activated in non-small cell lung cancer (NSCLC) patients, but therapeutic efficacy of NSCLC using trametinib (MEK inhibitor) or BEZ-235 (dual PI3K/mTOR inhibitor) alone is still unsatisfactory. Therefore, in this study, we aimed to determine whether the combination of trametinib with BEZ-235 exerted synergistic effects against NSCLC in both in vitro and in vivo models, and we preliminarily explored the effect of this combination therapy on glucose metabolism. Our results showed that trametinib combined with BEZ-235 could better inhibit cell proliferation and colony formation, induce G0/G1 phase arrest and apoptosis, and suppress cell invasion and migration compared with the single agent. The combination index demonstrated that trametinib and BEZ-235 exerted strong synergistic effects. Additionally, trametinib and BEZ-235 exhibited synergistic antitumor effects in vivo. Furthermore, trametinib and BEZ-235 synergistically downregulated the expression of related proteins in the MAPK and PI3K/AKT/mTOR pathways, and decreased glucose consumption and lactic acid production through suppressing the expressions of glucose transporter 1 (GLUT1) and lactate dehydrogenase A (LDHA). These data imply that simultaneous inhibition of the MAPK and PI3K/AKT/mTOR pathways using trametinib combined with BEZ-235 could synergistically impair glucose metabolism, resulting in an obvious synergistic therapeutic effect against NSCLC.

Abstract P138: Diet Influences the Expression of Renal Sodium-Glucose Cotransporters in Juvenile Male Rats

Poor nutrition and metabolic dysfunction are becoming more prevalent among children, as evident by increasing childhood obesity in recent years. The kidney sodium-glucose cotransporter 2 (SGLT2) is a contributor to overall metabolic homeostasis, with inhibition of SGLT2 significantly reducing circulating glucose and lipids. The study objective was to determine if diet influences the expression of renal glucose transporters in young rats. Weanling male Wistar Kyoto rats received 1) standard laboratory chow, 2) AIN-93G diet, or 3) a high-fat diet (60% kcal, HFD). Each dietary group was then further subdivided to receive either filtered water or 5% (w/v) sucrose solution ad libitum . Four weeks later, animals were euthanized and kidneys were collected and processed. mRNA expression of Sglt1 , Sglt2 , Sqstm1 , and Nlrp3 was determined using gene specific primers and RT-PCR. Renal SGLT2 protein expression was visualized using immunohistochemistry and quantified using Imagej software. Diet significantly influenced the renal expression of both Sglt1 ( P =0.005) and Sglt2 (P=0.046), while beverage did not have a significant effect on either ( P =0.7 and P =0.4, respectively). Rats fed the HFD had more than 30% reduction in Sglt1 mRNA expression as compared to rats fed chow, and ~20% reduction in Sglt2 as compared to rats fed AIN. Preliminary data suggest that diet and beverage significantly altered renal protein expression of SGLT2, with rats fed chow having the lowest renal expression that was slightly increased with sugar consumption (1.5% versus 2.7%, respectively). Rats fed AIN had the greatest expression, but was drastically reduced in rats consuming sugar (4% versus 1.2%, respectively). To determine if autophagy and inflammasome activation is involved, the expression of Sqstm1 and Nlrp3 was measured by RT-PCR. Similarly, rats fed HFD had the lowest expression of both Sqstm1 ( P&lt;0.001) and Nlrp3 ( P=0.03). Sqstm1 and Nlrp3 mRNA expression was decreased with sugar consumption in rats fed chow and AIN, whereas Sqstm1 ( P =0.01) and Nlrp3 ( P &lt;0.001) mRNA expression was increased in rats fed HFD with sugar beverage. Our data suggest that diet significantly influences renal glucose transporter expression in juvenile rats in a way that may be mediated by autophagic impairment. The modulatory effect of sugar consumption on SGLT2 protein, Sqstm1, and Nlrp3 was diet-dependent, highlighting the importance of nutrition to renal physiology within weeks after weaning.

Increasing digesta viscosity altered nutrient transporter gene expression and decreased nutrient utilisation in Eimeria-challenged birds

ABSTRACT 1. Two experiments were conducted, the first was to investigate the effect of increasing digesta viscosity by dietary carboxymethyl cellulose (CMC) on the growth performance and intestinal morphology and characteristics of healthy birds. The second experiment evaluated the impact of increased digesta viscosity in birds during an Eimeria spp. challenge. 2. In experiment 1, a corn-soybean meal-based basal diet was supplemented with 0, 10 or 20 g/kg CMC at the expense of cornstarch and offered to seven birds in each of eight replicate cages per diet from d 8 to 22 post hatching. 3. Increasing digesta viscosity due to dietary CMC linearly reduced (p < 0.05) body weight (BW) gain and the apparent ileal digestibility of nutrients. The relative lengths of the duodenum, jejunum and ileum linearly increased (p < 0.01) with dietary CMC inclusion. 4. In experiment 2, on d 14, 256 broiler chickens were randomly assigned to eight replicate cages in a 2 × 2 factorial arrangement of treatments with two CMC concentrations (0 or 10 g CMC/kg of diet), with or without an Eimeria challenge. On d 15, birds in the challenge groups were orally gavaged with a 1 ml solution containing 25,000, 25,000 or 125,000 oocysts of E. maxima, E. tenella and E. acervulina; or 1% PBS, respectively. 5. Increasing digesta viscosity in Eimeria-challenged birds decreased the total tract digestibility of dry matter and gross energy (p < 0.05). The ileal gene expression of glucose transporters was upregulated (p < 0.05) in challenged birds that received the CMC-supplemented diet. 6. In summary, increased digesta viscosity induced changes in the expression of nutrient transporter genes and decreased nutrient utilisation in Eimeria-challenged birds.

The Role of Astrocyte-Neuron Lactate Shuttle in Neuropathic Orofacial Pain.

Inhibition of astrocytic energy metabolism alleviates neuropathic pain. To explore whether astrocyte-neuron lactate shuttle (ANLS) played any role in neuropathic orofacial pain. Rats with partial transection of the right infraorbital nerve (p-IONX) or sham operation were intrathecally injected with acetazolamide (a carbonic anhydrase inhibitor), bithionol (a soluble adenylyl cyclase inhibitor), α-cyano-4-hydroxycinnamic acid [α-CHCA, a monocarboxylate transporter (MCT) inhibitor] or vehicle once a day from postoperative day 1-14. The facial mechanical thresholds were tested on preoperative day 1 and 2 and postoperative days 1, 3, 5, 7, 10 and 14, expression of glucose transporters (GLUTs) and MCTs in the trigeminal subnucleus caudalis (Vc) were examined on the postoperative day 3 and neuronal activities in the Vc were examined in the p-IONX rats on postoperative days 3-5. Compared with the sham group, the mechanical thresholds in the p-IONX group were significantly reduced at postoperative days 1-7, and the number of astrocytes expressing GLUT1 and MCT1/4, and neurons expressing MCT2 was significantly increased on postoperative day 3. In the p-IONX groups, neurons in the Vc were sensitised, and acetazolamide, bithionol and α-CHCA reversed the central sensitisation, significantly increased the mechanical thresholds at postoperative days 1-7 and decreased the number of astrocytes expressing GLUT1 and MCT1/4, and neurons expressing MCT2 at postoperative day 3 compared with those in the vehicle-treated rats. Inhibition of ANLS alleviates p-IONX-related neuronal, behavioural and immunohistochemical changes, which suggests that ANLS plays an important role in trigeminal neuropathic pain.

The Expression and Prognostic Value of Multiple Glucose Transporters in Cutaneous Melanoma.

Over-expression of glucose transporters (GLUTs), membrane proteins that facilitate glucose transport, has been implicated in cutaneous melanomas. Our prior studies have demonstrated increased expression of GLUT1 and GLUT3 in melanomas and their association with poorer prognosis. This study aimed to investigate the expression of GLUT isoforms 4 and 8 in melanocytic lesions, examine the co-expression status of multiple GLUTs, and evaluate their prognostic significance. We analyzed 171 melanocytic lesions (97 primary melanomas, 19 metastatic melanomas, and 55 nevi) using a tissue microarray and immunohistochemistry using antibodies against GLUT4 and GLUT8. Membranous expression of GLUTs was scored using a semi-quantitative method. A combined GLUT total score was generated by summing scores from GLUT1, GLUT3, GLUT4, and GLUT8 (including data from previous studies). A significant up-regulation of GLUT4 and GLUT8 expression was found in melanomas compared to nevi (p<0.0001 for both). Concurrent over-expression of multiple GLUTs was more prevalent in melanomas compared to nevi (p<0.0001), and it was also more frequent in metastatic melanomas compared to primary melanomas (p=0.047). Importantly, high total GLUT expression scores were significantly correlated with negative prognostic factors, such as ulceration and mitoses (p=0.03 and p=0.008 respectively). Additionally, Kaplan-Meier survival curves revealed that patients with elevated GLUT total score in their melanomas had a lower disease-specific survival (p=0.006). Furthermore, analysis of multiple GLUTs improved diagnostic sensitivity. Similar to GLUT1 and GLUT3, melanoma exhibits up-regulation of GLUT 4 and GLUT8 compared to nevi. Evaluation of multiple GLUT isoforms improves diagnostic and prognostic values.

Optimal glycine allowance levels in low-protein diets and the dynamic requirement model for broilers

This study aimed to investigate the effects of different glycine levels in low-protein diets on the growth, nitrogen deposition, and expression of intestinal amino acid and glucose transporters in broilers from 29 to 42 days of age, in order to determine the optimal glycine supplementation level. A total of 240 male broilers at 29 days old were randomly assigned to 5 groups: the control group with a crude protein level of 20%, and experimental groups with low-protein diets (LP130) containing 18% crude protein, supplemented with glycine to achieve standardized ileal digestible (SID) glycine + serine to lysine ratios of 134% (LP134), 140% (LP140), and 145% (LP145). The results showed that the LP134 group had similar growth performance and slaughter performance compared to the control group (P > 0.05), whereas other low-protein diet groups had significantly lower growth performance (P < 0.05). Regression analysis determined that the optimal ratio for SID glycine + serine to lysine was 137%. A dynamic model for glycine + serine requirements was established through binary regression analysis: y = 599.051 × BW^0.75 + 8.381 × ADG (R2 = 0.998, P < 0.001). Feeding LP134, LP140, and LP145 diets significantly improved nitrogen deposition rates in broilers (P < 0.05). Low-protein diets significantly upregulated mRNA levels of b0,+AT, EAAT3, and SGLT1 genes in the duodenum (P < 0.05). In conclusion, appropriate glycine supplementation in low-protein diets can enhance growth performance, and nitrogen deposition efficiency, and regulate the expression of intestinal amino acid and glucose transporters. The optimal ratio of SID glycine + serine to lysine in low-protein diets for broilers aged 29 to 42 days is 137%.

Glucose Transporters Are Key Components of the Human Glucostat.

Mouse models are extensively utilized in metabolic studies. However, inherent differences between the species, notably their blood glucose levels, hampered data translation into clinical settings. In this study, we confirmed GLUT1 to be the predominantly expressed glucose transporter in both adult and fetal human β cells. In comparison, GLUT2 is detected in a small yet significant subpopulation of adult β cells and is expressed to a greater extent in fetal β cells. Notably, GLUT1/2 expression in INS+ cells from human stem cell-derived islet-like clusters (SC-islets) exhibited a closer resemblance to that observed in fetal islets. Transplantation of primary human islets or SC-islets, but not murine islets, lowered murine blood glucose to the human glycemic range, emphasizing the critical role of β cells in establishing species-specific glycemia. We further demonstrate the functional requirements of GLUT1 and GLUT2 in glucose uptake and insulin secretion through chemically inhibiting GLUT1 in primary islets and SCislets, and genetically disrupting GLUT2 in SC-islets. Finally, we developed a mathematical model to predict changes in glucose uptake and insulin secretion as a function of GLUT1/2 expression. Collectively, our findings illustrate the crucial roles of GLUTs in human β cells, and identify them as key components in establishing species-specific glycemic setpoints.

Increase in the Expression of Glucose Transporter 2 (GLUT2) on the Peripheral Blood Insulin-Producing Cells (PB-IPC) in Type 1 Diabetic Patients after Receiving Stem Cell Educator Therapy.

Multicenter international clinical trials demonstrated the clinical safety and efficacy by using stem cell educator therapy to treat type 1 diabetes (T1D) and other autoimmune diseases. Previous studies characterized the peripheral blood insulin-producing cells (PB-IPC) from healthy donors with high potential to give rise to insulin-producing cells. PB-IPC displayed the molecular marker glucose transporter 2 (GLUT2), contributing to the glucose transport and sensing. To improve the clinical efficacy of stem cell educator therapy in the restoration of islet β-cell function, we explored the GLUT2 expression on PB-IPC in recent onset and longstanding T1D patients. In the Food and Drug Administration (FDA)-approved phase 2 clinical studies, patients received one treatment with the stem cell educator therapy. Peripheral blood mononuclear cells (PBMC) were isolated for flow cytometry analysis of PB-IPC and other immune markers before and after the treatment with stem cell educator therapy. Flow cytometry revealed that both recent onset and longstanding T1D patients displayed very low levels of GLUT2 on PB-IPC. After the treatment with stem cell educator therapy, the percentages of GLUT2+CD45RO+ PB-IPC were markedly increased in these T1D subjects. Notably, we found that T1D patients shared common clinical features with patients with other autoimmune and inflammation-associated diseases, such as displaying low or no expression of GLUT2 on PB-IPC at baseline and exhibiting a high profile of the inflammatory cytokine interleukin (IL)-1β. Flow cytometry demonstrated that their GLUT2 expressions on PB-IPC were also markedly upregulated, and the levels of IL-1β-positive cells were significantly downregulated after the treatment with stem cell educator therapy. Stem cell educator therapy could upregulate the GLUT2 expression on PB-IPC and restore their function in T1D patients, leading to the improvement of clinical outcomes. The clinical data advances current understanding about the molecular mechanisms underlying the stem cell educator therapy, which can be expanded to treat patients with other autoimmune and inflammation-associated diseases.