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Search Results (210)

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Keywords = glucose transporter 2 (GLUT2)

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31 pages, 1732 KiB  
Review
GLUT4 Trafficking and Storage Vesicles: Molecular Architecture, Regulatory Networks, and Their Disruption in Insulin Resistance
by Hana Drobiova, Ghadeer Alhamar, Rasheed Ahmad, Fahd Al-Mulla and Ashraf Al Madhoun
Int. J. Mol. Sci. 2025, 26(15), 7568; https://doi.org/10.3390/ijms26157568 - 5 Aug 2025
Abstract
Insulin-regulated glucose uptake is a central mechanism in maintaining systemic glucose homeostasis, primarily occurring in skeletal muscle and adipose tissue. This process relies on the insulin-stimulated translocation of the glucose transporter, GLUT4, from specialized intracellular compartments, known as GLUT4 storage vesicles (GSVs), to [...] Read more.
Insulin-regulated glucose uptake is a central mechanism in maintaining systemic glucose homeostasis, primarily occurring in skeletal muscle and adipose tissue. This process relies on the insulin-stimulated translocation of the glucose transporter, GLUT4, from specialized intracellular compartments, known as GLUT4 storage vesicles (GSVs), to the plasma membrane. Disruption of this pathway is a hallmark of insulin resistance and a key contributor to the pathogenesis of type 2 diabetes. Recent advances have provided critical insights into both the insulin signalling cascades and the complex biogenesis, as well as the trafficking and fusion dynamics of GSVs. This review synthesizes the current understanding of the molecular mechanisms governing GSV mobilization and membrane fusion, highlighting key regulatory nodes that may become dysfunctional in metabolic disease. By elucidating these pathways, we propose new therapeutic avenues targeting GSV trafficking to improve insulin sensitivity and combat type 2 diabetes. Full article
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11 pages, 508 KiB  
Article
Bromelain Improves Hypothalamic Control of Energy Homeostasis in High-Fat Diet-Induced Obese Rats
by Raviye Ozen Koca, Mustafa Berk Basaran, Hatice Solak and Zulfikare Isik Solak Gormus
Curr. Issues Mol. Biol. 2025, 47(8), 607; https://doi.org/10.3390/cimb47080607 - 1 Aug 2025
Viewed by 132
Abstract
Obesity remains a major global health challenge with limited therapeutic options. Bromelain, a proteolytic enzyme complex derived from pineapple, has been recognized for its natural anti-inflammatory, anti-edematous, and appetite-suppressing properties. This study aimed to investigate the effects of bromelain on hypothalamic neuropeptides and [...] Read more.
Obesity remains a major global health challenge with limited therapeutic options. Bromelain, a proteolytic enzyme complex derived from pineapple, has been recognized for its natural anti-inflammatory, anti-edematous, and appetite-suppressing properties. This study aimed to investigate the effects of bromelain on hypothalamic neuropeptides and metabolic markers in a high-fat diet (HFD)-induced obesity model in rats. Thirty-six male Wistar albino rats were randomly divided into four groups: standard diet (SD), standard diet with bromelain (SDBro), high-fat diet (HFD), and high-fat diet with bromelain (HFDBro). Obesity was induced by a 3-month HFD regimen, followed by bromelain supplementation (200 mg/kg/day, orally) for one month. Hypothalamic tissues were analyzed via ELISA for neuropeptide Y (NPY), pro-opiomelanocortin (POMC), glucose transporter 2 (GLUT2), fibroblast growth factor 2 (FGF2), and insulin-like growth factor 1 receptor (IGF1R). While NPY levels showed no significant changes, POMC increased in the HFD and was normalized with bromelain. GLUT2 was downregulated in the HFD and significantly restored by bromelain. FGF2 levels remained unchanged. IGF1R was upregulated in the HFD but reduced by bromelain, with an unexpected increase in SDBro. Overall, bromelain partially reversed HFD-induced disruptions in hypothalamic energy-regulating pathways, particularly affecting GLUT2 and POMC. These findings highlight bromelain’s potential role in central metabolic regulation under dietary stress. Full article
(This article belongs to the Section Bioorganic Chemistry and Medicinal Chemistry)
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19 pages, 4441 KiB  
Article
In Silico and In Vivo Pharmacological Evaluation of Iridoid Compounds: Geniposide and Asperuloside Profile Study Through Molecular Docking Assay and in the Caenorhabditis elegans Model
by Mariana Uczay, Péterson Alves Santos, Pricila Pflüger, Gilsane von Poser, José Brea, Maria Isabel Loza, Patrícia Pereira and José Angel Fontenla
Biomolecules 2025, 15(8), 1105; https://doi.org/10.3390/biom15081105 - 31 Jul 2025
Viewed by 259
Abstract
Iridoids are compounds recognized for their neuroprotective properties and their potential application in the treatment of neurodegenerative diseases. Geniposide (GP) and asperuloside (ASP) are iridoids that have demonstrated some biological activities. In this study, the potential neuroprotective effects of these iridoids were evaluated [...] Read more.
Iridoids are compounds recognized for their neuroprotective properties and their potential application in the treatment of neurodegenerative diseases. Geniposide (GP) and asperuloside (ASP) are iridoids that have demonstrated some biological activities. In this study, the potential neuroprotective effects of these iridoids were evaluated through in silico and in vivo assays, using Caenorhabditis elegans (C. elegans) strains CF1553 (sod-3::GFP), GA800 (cat::GFP), and CL2166 (gst-4::GFP). The results suggested that neither compound appears to have good passive permeability through the blood–brain barrier (BBB). However, an active transport mechanism involving the glucose transporter GLUT-1 may be present, as both compounds contain glucose in their molecular structure. In addition, they can inhibit the activity of both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). GP at 1 and 2 mM reversed the H2O2-induced increase in sod-3 expression, while ASP at 1 and 2 mM reversed the increase in gst-4 expression. Worm survival was more adversely affected by higher concentrations of GP than ASP, although both similarly reduced acetylcholinesterase activity. These findings suggest that GP and ASP exhibit very low toxicity both in silico and in vivo in C. elegans, and positively modulate key enzymes involved in antioxidant pathways, highlighting their potential for neuroprotective applications. Full article
(This article belongs to the Section Natural and Bio-derived Molecules)
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19 pages, 1867 KiB  
Article
Compare the Decrease in Visceral Adipose Tissue in People with Obesity and Prediabetes vs. Obesity and Type 2 Diabetes Treated with Liraglutide
by Rosa Nayely Hernández-Flandes, María de los Ángeles Tapia-González, Liliana Hernández-Lara, Eduardo Osiris Madrigal-Santillán, Ángel Morales-González, Liliana Aguiano-Robledo and José A. Morales-González
Diabetology 2025, 6(7), 67; https://doi.org/10.3390/diabetology6070067 - 4 Jul 2025
Viewed by 857
Abstract
Obesity is considered a global pandemic. In Mexico, 7/10 adults, 4/10 adolescents, and 1/3 children are overweight or obese, and it is estimated that 90% of cases of type 2 diabetes (T2D) are attributable to these pathologies. Visceral adipose tissue (VAT) presents increased [...] Read more.
Obesity is considered a global pandemic. In Mexico, 7/10 adults, 4/10 adolescents, and 1/3 children are overweight or obese, and it is estimated that 90% of cases of type 2 diabetes (T2D) are attributable to these pathologies. Visceral adipose tissue (VAT) presents increased lipolysis, lower insulin sensitivity, and greater metabolic alterations. Glucagon-like peptide-1 (GLP-1) is a polypeptide incretin hormone that stimulates insulin secretion dependent on the amount of oral glucose consumed, reduces plasma glucagon concentrations, slows gastric emptying, suppresses appetite, improves insulin synthesis and secretion, and increases the sensitivity of β cells to glucose. Liraglutide is a synthetic GLP-1 analog that reduces VAT and improves the expression of Glucose transporter receptor type 4 (GLUT 4R), Mitogen-activated protein (MAP kinases), decreases Fibroblast growth factor type β (TGF-β), reactivates the peroxisome proliferator-activated receptor type ɣ (PPAR-ɣ) pathway, and decreases chronic inflammation. Currently, there are many studies that explain the decrease in VAT with these medications, but there are no studies that compare the decrease in patients with obesity and prediabetes vs. obesity and type 2 diabetes to know which population obtains a greater benefit from treatment with this pharmacological group; this is the reason for this study. The primary objective was to compare the difference in the determination of visceral adipose tissue in people with obesity and type 2 diabetes vs. obesity and prediabetes treated with liraglutide. Methods: A quasi-experimental, analytical, prolective, non-randomized, non-blinded study was conducted over a period of 6 months in a tertiary care center. A total of 36 participants were divided into two arms; group 1 (G1: Obesity and prediabetes) and group 2 (G2: Obesity and type 2 diabetes) for 6 months. Inclusion criteria: men and women ≥18 years with type 2 diabetes, prediabetes, and obesity. Exclusion criteria: Glomerular filtration rate (GFR) < 60 mL/min/1.73 m2 elevated transaminases (>5 times the upper limit of normal), and use of non-weight-modifying antidiabetic agents. Conclusions: No statistically significant difference was found in the decrease in visceral adipose tissue when comparing G1 (OB and PD) with G2 (OB and T2D). When comparing intragroup in G2 (OB and T2D), greater weight loss was found [(−3.78 kg; p = 0.012) vs. (−3.78 kg; p = 0.012)], as well differences in waist circumference [(−3.9 cm; p = 0.049) vs. (−3.09 cm; p = 0.017)], and glucose levels [(−1.75 mmol/L; p = 0.002) vs. (−0.56 mmol/L; p = 0.002)], A1c% [(−1.15%; p = 0.001) vs. (−0.5%; p = 0.000)]. Full article
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11 pages, 1636 KiB  
Article
Triterpenoid CDDO-EA Protects from Hyperglycemia, Hyperinsulinemia, and Obesity by Decreasing Energy Intake
by Austin E. Cantu, Cordelia Rasa, Shizue Mito, Denae Cantu, Juan Carlos Lopez-Alvarenga, Leslie L. Rivera-Lopez, Israel Rios, Ashley Abrego-Gonzalez and Sara M. Reyna
Int. J. Mol. Sci. 2025, 26(12), 5485; https://doi.org/10.3390/ijms26125485 - 7 Jun 2025
Viewed by 620
Abstract
Obesity is a significant factor in the development of type 2 diabetes (T2D). Treatment of obesity is pivotal in the prevention and management of T2D, and the development of new pharmacological therapies are studied for improving insulin resistance and glucose intolerance. Oleanolic acid-derived [...] Read more.
Obesity is a significant factor in the development of type 2 diabetes (T2D). Treatment of obesity is pivotal in the prevention and management of T2D, and the development of new pharmacological therapies are studied for improving insulin resistance and glucose intolerance. Oleanolic acid-derived triterpenoids, 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acids (CDDOs), are studied to elucidate the mechanisms by which they protect against obesity. However, fundamental knowledge gaps remain regarding the physiological and molecular mechanisms by which CDDOs protect against obesity. Our recently published studies showed that CDDO-ethyl amide (CDDO-EA) prevents skeletal muscle inflammation by inhibiting activation of nuclear factor-kappa B (NF-κB) signaling. Moreover, CDDO-EA induced translocation of glucose transporter 4, GLUT4, in skeletal muscle cells. We hypothesized that CDDO-EA protects from obesity-induced hyperglycemia in mice fed a high-fat diet (HFD). Our results show that CDDO-EA protects from HFD-induced obesity but has no effect on body weight in mice fed a low-fat diet (LFD). Our data show that CDDO-EA inhibition of weight gain is associated with reduced caloric intake and glucose and insulin levels in mice fed an HFD. This highlights the potential of CDDO-EA as a therapeutic agent for obesity treatment and the protection against the development of T2D. Full article
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24 pages, 3890 KiB  
Article
Dietary Insulinogenic Amino Acid Restriction Improves Glucose Metabolism in a Neonatal Piglet Model
by Matthew W. Gorton, Parniyan Goodarzi, Xia Lei, Michael Anderson, Mohammad Habibi, Nedra Wilson and Adel Pezeshki
Nutrients 2025, 17(10), 1675; https://doi.org/10.3390/nu17101675 - 15 May 2025
Viewed by 772
Abstract
Background: Dietary consumption of insulinogenic amino acids (IAA) is known to contribute to the development of insulin resistance. It remains to be studied whether dietary IAA restriction improves glucose metabolism and insulin sensitivity and whether this improvement is related to alterations in glucose [...] Read more.
Background: Dietary consumption of insulinogenic amino acids (IAA) is known to contribute to the development of insulin resistance. It remains to be studied whether dietary IAA restriction improves glucose metabolism and insulin sensitivity and whether this improvement is related to alterations in glucose metabolism in peripheral tissues. The objective of this study was to examine the effect of IAA restriction on glucose metabolism in a piglet model. Methods: Following the acclimation period, thirty-two seven-day-old male piglets were randomly assigned into one of three groups for three weeks as follows (n = 10–11/group): (1) NR (control): basal diet without IAA restriction; (2) R50: basal diet with IAA restricted by 50%; (3) R75: basal diet with IAA restricted by 75%. IAA were alanine (Ala), arginine (Arg), isoleucine (Ile), leucine (Leu), lysine (Lys), threonine (Thr), phenylalanine (Phe), and valine (Val) as suggested by previous studies. Thermal images, body weight, and growth parameters were recorded weekly, oral glucose tolerance tests were performed on week 2 of the study, and blood and tissue samples were collected on week 3 after a meal test. Results: R75 improved glucose tolerance and, together with R50, reduced blood insulin concentration and homeostatic model assessment for insulin resistance (HOMA-IR) value, which is suggestive of improved insulin sensitivity following IAA restriction. R75 increased thermal radiation and decreased adipocyte number in white adipose tissue (WAT). R75 had a greater transcript of glucose transporter 1 (GLUT1), phosphofructokinase, liver type (PFKL), and pyruvate kinase, liver, and RBC (PKLR) in the liver and glucokinase (GCK) in WAT indicating a higher uptake of glucose in the liver and greater glycolysis in both liver and WAT. R75 increased the mRNA abundance of insulin receptor substrate 1 (IRS1) and protein kinase B (AKT1) in skeletal muscle suggestive of enhanced insulin signaling. Further, R75 had a higher mRNA of fibroblast growth factor 21 (FGF-21) in both the liver and hypothalamus and its upstream molecules such as activating transcription factor 4 (ATF4) and inhibin subunit beta E (INHBE) which may contribute to increased energy expenditure and improved glucose tolerance during IAA restriction. Conclusions: IAA restriction improves glucose tolerance and insulin sensitivity in piglets while not reducing body weight, likely through improved hepatic glycolysis and insulin signaling in skeletal muscle, and induced FGF-21 signaling in both the liver and hypothalamus. Full article
(This article belongs to the Section Proteins and Amino Acids)
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22 pages, 2221 KiB  
Article
Luminal Sweet Sensing and Enteric Nervous System Participate in Regulation of Intestinal Glucose Transporter, GLUT2
by Andrew W. Moran, Miran Alrammahi, Kristian Daly, Darren Weatherburn, Catherine Ionescu, Alexandra Blanchard and Soraya P. Shirazi-Beechey
Nutrients 2025, 17(9), 1547; https://doi.org/10.3390/nu17091547 - 30 Apr 2025
Viewed by 686
Abstract
Background/Objectives: Dietary glucose is transported across the intestinal absorptive cell into the systemic circulation by the apically located Na+-dependent glucose transporter 1 (SGLT1, SLC5A1) and basally residing Na+-independent glucose transporter 2 (GLUT2, SLC2A2). Whilst recent experimental evidence [...] Read more.
Background/Objectives: Dietary glucose is transported across the intestinal absorptive cell into the systemic circulation by the apically located Na+-dependent glucose transporter 1 (SGLT1, SLC5A1) and basally residing Na+-independent glucose transporter 2 (GLUT2, SLC2A2). Whilst recent experimental evidence has shown that sensing of sweet compounds by the gut-expressed sweet taste receptor T1R2–T1R3 and glucagon-like peptide-2 receptor signalling are components of the pathway controlling SGLT1 expression, little is known about the mechanisms involved in the regulation of GLUT2. In this study, we tested the hypothesis that T1R2–T1R3 and its downstream signalling pathway participate in the regulation of intestinal GLUT2. Methods: We used in vivo and in vitro approaches employing a weaning pig model, a heterologous expression assay, and knockout mice for elucidating the regulation of GLUT2 by luminal sugars. Results: A plant-based sweetener formulation included in piglets’ diet led to a marked increase in GLUT2 expression in piglets’ intestine, compared to controls. The sweeteners that do not activate pig T1R2–T1R3 failed to upregulate GLUT2. There was a significant increase in GLUT2 expression when the sweetener sucralose, which activates T1R2–T1R3, was included in the drinking water of wild-type mice. However, in knockout mice, in which the genes for the sweet receptor subunit T1R3 and the associated G-protein gustducin were deleted, there was no upregulation of GLUT2 expression in response to sucralose supplementation. There was a notable increase in GLUT2 expression in wild-type mice fed a high-carbohydrate diet compared to when maintained on a low-carbohydrate diet. However, in GLP-2 receptor knockout mice kept on the high-carbohydrate diet, there was no enhancement in GLUT2 expression. Conclusions: The experimental evidence suggests that luminal sweet sensing via T1R2–T1R3 and the enteroendocrine-derived GLP-2 are constituents of the regulatory pathway controlling GLUT2 expression. Full article
(This article belongs to the Special Issue The Interaction Between Flavor and Diet)
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11 pages, 3234 KiB  
Article
Improved Differentiation Towards Insulin Producing Beta-Cells Derived from Healthy Canine Pancreatic Ductal Organoids
by Boyd H. T. Gouw, Flavia C. M. Oliveira, Hans S. Kooistra, Bart Spee, Lisa van Uden and Louis C. Penning
Vet. Sci. 2025, 12(4), 362; https://doi.org/10.3390/vetsci12040362 - 13 Apr 2025
Cited by 1 | Viewed by 746
Abstract
Background: Diabetes mellitus (DM) is a common potentially life-threatening endocrine disorder in pets and humans. Since only symptomatic treatment is available, a more sustainable treatment is urgently needed. Objective: The aim of this study is to establish functional differentiated canine pancreatic β-cells that [...] Read more.
Background: Diabetes mellitus (DM) is a common potentially life-threatening endocrine disorder in pets and humans. Since only symptomatic treatment is available, a more sustainable treatment is urgently needed. Objective: The aim of this study is to establish functional differentiated canine pancreatic β-cells that release insulin upon glucose stimulus. Methods: Pancreatic tissue was obtained from surplus material of healthy dogs (n = 4), euthanized for non-pancreatic related research. Ductal cells were isolated and expanded in dog pancreas expansion media (dpEM) and differentiated and maturated in five sequentially added pancreas differentiation media (PDMs). Gene expression was analyzed by reversed transcriptase qPCR (RT-qPCR), and insulin release was analyzed with a canine-specific ELISA. Results: Canine pancreatic ductal cells (LGR5 and SOX9 expression) were differentiated into β-cells expressing key β-cell-related genes: Pancreatic and duodenal homeobox 1 (PDX1), NK6 Homeobox 1 (NKX6.1), Glucose Transporter Type 2 (GLUT2), Proprotein convertase subtilisin/kexin type 1 (PCSK1), and low levels of insulin. Neither Glucagon (α-cells) nor LGR5 and SOX9 were expressed, and somatostatin was expressed at low levels. The differentiated cells released insulin upon glucose stimulation. Conclusion and implications: The step-by-step differentiation protocol, mimicking pancreatic organogenesis, resulted in β-cells secreting insulin levels suitable for β-cell disease modelling. It remains to be seen if stem cells from diseased animals behave similarly. Full article
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17 pages, 3401 KiB  
Article
Induced Types 2 and 3 Deiodinase in Non-Thyroidal Illness Syndrome and the Implications to Critical Illness-Induced Myopathy—A Prospective Cohort Study
by André Cardoso Braun, Thaliane Carvalho Oliveira, Ludmilla C. D. Thomazini, Gustavo Argenti, Bruno Jaskulski Kotzian, Valentina Machado, João Henrique M. Conte, Carolina Zanfir, Amanda C. A. Souto, Bruna Ulian, Josi Vidart and Simone Magagnin Wajner
Int. J. Mol. Sci. 2025, 26(6), 2410; https://doi.org/10.3390/ijms26062410 - 7 Mar 2025
Viewed by 692
Abstract
Loss of muscle mass and strength is a common condition associated with adverse outcomes in critically ill patients. Here, we determined the correlation between non-thyroidal illness (NTIS) and molecular alterations in the muscle of critically ill individuals. We evaluated deiodinase expression, intramuscular triiodothyronine [...] Read more.
Loss of muscle mass and strength is a common condition associated with adverse outcomes in critically ill patients. Here, we determined the correlation between non-thyroidal illness (NTIS) and molecular alterations in the muscle of critically ill individuals. We evaluated deiodinase expression, intramuscular triiodothyronine (T3) levels, and mitochondria and sarcoplasmic reticulum components. The cellular colocalization of the enzymes and its influence on myocytes and genes regulated by T3 were shown, including those of mitochondria. A prospective cohort of 96 patients. Blood and muscular samples were collected on admission to the intensive care unit (ICU), as well as clinical data and ultrasonographic measurements. Patients with NTIS showed increased oxidative stress markers associated with critical illness in muscle biopsy, such as carbonyl content and low sulfhydryl and GSH. The distribution pattern of deiodinases in muscle and its biochemical properties showed significant pathophysiological linkage between NTIS and muscle loss, as type 3-deiodinase (D3) was highly expressed in stem cells, preventing their differentiation in mature myocytes. Despite the high type 2-deiodinase (D2) expression in muscle tissue in the acute phase of critical illness, T3 was unmeasurable in the samples. In this scenario, we also demonstrated impaired expression of glucose transporters GLUT4, IRS1, and 2, which are involved in muscle illness. Here, we provide evidence that altered thyroid hormone metabolism contributes to stem cell dysfunction and further explain the mechanisms underlying critical illness-induced myopathy. Full article
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23 pages, 41936 KiB  
Article
Flavonoid-Rich Extracts from Chuju (Asteraceae Chrysanthemum L.) Alleviate the Disturbance of Glycolipid Metabolism on Type 2 Diabetic Mice via Modulating the Gut Microbiota
by Yu Yin, Wen Nie, Zheng-Quan Tang and Shuang-Jie Zhu
Foods 2025, 14(5), 765; https://doi.org/10.3390/foods14050765 - 24 Feb 2025
Cited by 2 | Viewed by 1173
Abstract
Type 2 diabetes mellitus (T2DM) and its associated complications represent a significant public health issue affecting hundreds of millions of people globally; thus, measures to prevent T2DM are urgently needed. Chuju has been proven to possess antihyperglycemic activity. However, the bioactive ingredients in [...] Read more.
Type 2 diabetes mellitus (T2DM) and its associated complications represent a significant public health issue affecting hundreds of millions of people globally; thus, measures to prevent T2DM are urgently needed. Chuju has been proven to possess antihyperglycemic activity. However, the bioactive ingredients in chuju that contribute to its antihyperglycemic activity, as well as the relationship between its antihyperglycemic activity and the gut microbiota, remain unclear. To understand the potential effects that it has on T2DM, the glycolipid metabolism and gut microbiota regulation of flavonoid-rich extracts from chuju (CJE) were investigated. The results showed that the top ten flavonoid compounds in CJE are Apigenin 6, 8-digalactoside, Apigenin 6-C-glucoside 8-C-arabinoside, Luteolin-4′-O-glucoside, Isoshaftoside, Scutellarin, Quercetin 3-O-malonylglucoside, Chrysoeriol 7-O-glucoside, Quercetin-3,4′-O-di-beta-glucoside, Luteolin 6-C-glucoside 8-C-arabinoside, and Homoorientin. Furthermore, CJE mitigated hyperglycemia and glycolipid metabolism by reducing the abundance of Faecalibaculum, Coriobacteriaceae, and Romboutsia and increasing the abundance of Alistipes. In addition, the results of Western blot analysis showed that CJE could enhance glycogen synthesis and glucose transport by up-regulating the phosphorylation of IRS1-PI3K-Akt and AMPK-GLUT4. Simultaneously, CJE could decrease gluconeogenesis by down-regulating the phosphorylation of FoxO1/GSK 3β. In conclusion, the findings of this study provide new evidence supporting the hypothesis that CJE can be used as part of a therapeutic approach for treating disturbances in glycolipid metabolism via regulating the gut microbiota and mediating the IRS1-PI3K-Akt-FoxO1/GSK 3β and AMPK-GLUT4 pathways. Full article
(This article belongs to the Section Nutraceuticals, Functional Foods, and Novel Foods)
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29 pages, 7525 KiB  
Article
Impact of Glucose, Inflammation and Phytochemicals on ACE2, TMPRSS2 and Glucose Transporter Gene Expression in Human Intestinal Cells
by Rizliya Visvanathan, Michael J. Houghton and Gary Williamson
Antioxidants 2025, 14(3), 253; https://doi.org/10.3390/antiox14030253 - 21 Feb 2025
Viewed by 889
Abstract
Inflammation is associated with the pathophysiology of type 2 diabetes and COVID-19. Phytochemicals have the potential to modulate inflammation, expression of SARS-CoV-2 viral entry receptors (angiotensin-converting enzyme 2 (ACE2) and transmembrane protease, serine 2 (TMPRSS2)) and glucose transport in the gut. This study [...] Read more.
Inflammation is associated with the pathophysiology of type 2 diabetes and COVID-19. Phytochemicals have the potential to modulate inflammation, expression of SARS-CoV-2 viral entry receptors (angiotensin-converting enzyme 2 (ACE2) and transmembrane protease, serine 2 (TMPRSS2)) and glucose transport in the gut. This study assessed the impact of phytochemicals on these processes. We screened 12 phytochemicals alongside 10 pharmaceuticals and three plant extracts, selected for known or hypothesised effects on the SARS-CoV-2 receptors and COVID-19 risk, for their effects on the expression of ACE2 or TMPRSS2 in differentiated Caco-2/TC7 human intestinal epithelial cells. Genistein, apigenin, artemisinin and sulforaphane were the most promising ones, as assessed by the downregulation of TMPRSS2, and thus they were used in subsequent experiments. The cells were then co-stimulated with pro-inflammatory cytokines interleukin-1 beta (IL-1β) and tumour necrosis factor-alpha (TNF-α) for ≤168 h to induce inflammation, which are known to induce multiple pathways, including the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway. Target gene expression (ACE2, TMPRSS2, SGLT1 (sodium-dependent glucose transporter 1) and GLUT2 (glucose transporter 2)) was measured by droplet digital PCR, while interleukin-1 (IL-6), interleukin-1 (IL-8) and ACE2 proteins were assessed using ELISA in both normal and inflamed cells. IL-1β and TNF-α treatment upregulated ACE2, TMPRSS2 and SGLT1 gene expression. ACE2 increased with the duration of cytokine exposure, coupled with a significant decrease in IL-8, SGLT1 and TMPRSS2 over time. Pearson correlation analysis revealed that the increase in ACE2 was strongly associated with a decrease in IL-8 (r = −0.77, p < 0.01). The regulation of SGLT1 gene expression followed the same pattern as TMPRSS2, implying a common mechanism. Although none of the phytochemicals decreased inflammation-induced IL-8 secretion, genistein normalised inflammation-induced increases in SGLT1 and TMPRSS2. The association between TMPRSS2 and SGLT1 gene expression, which is particularly evident in inflammatory conditions, suggests a common regulatory pathway. Genistein downregulated the inflammation-induced increase in SGLT1 and TMPRSS2, which may help lower the postprandial glycaemic response and COVID-19 risk or severity in healthy individuals and those with metabolic disorders. Full article
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13 pages, 11166 KiB  
Article
The Abnormal Expression of Tubular SGLT2 and GULT2 in Diabetes Model Mice with Malocclusion-Induced Hyperglycemia
by Koichiro Kajiwara, Sachio Tamaoki and Yoshihiko Sawa
Biomedicines 2025, 13(2), 267; https://doi.org/10.3390/biomedicines13020267 - 22 Jan 2025
Viewed by 899
Abstract
Background: A relationship between malocclusion and the promotion of diabetes has been suggested. In hyperglycemia, the expression of sodium–glucose cotransporter 2 (SGLT2) and the facilitative glucose transporter 2 (GLUT2) is upregulated in proximal tubular cells, leading to an increase in renal glucose reabsorption. [...] Read more.
Background: A relationship between malocclusion and the promotion of diabetes has been suggested. In hyperglycemia, the expression of sodium–glucose cotransporter 2 (SGLT2) and the facilitative glucose transporter 2 (GLUT2) is upregulated in proximal tubular cells, leading to an increase in renal glucose reabsorption. The present study aimed to investigate whether malocclusion contributes to diabetic exacerbation. Methods: Streptozotocin (STZ)-induced diabetic mice with malocclusion due to cutting molars were investigated based on increased blood glucose levels. PCR and immunohistochemical analyses were performed on diabetic mice kidneys to investigate the expression of SGLT2 and GLUT2. Results: Animal experiments were performed using 32 mice for 21 days. The time to reach a diabetic condition in STZ-administered mice was shorter with malocclusion than without malocclusion. The increase and mean blood glucose levels in STZ-administered mice were steeper and higher with malocclusion than without malocclusion. Urea albumin, BUN, and CRE levels were higher in diabetic mice with malocclusion than in diabetic mice without. Immunoreaction with anti-SGLT2 and anti-GLUT2 in the renal tissue of STZ-administered mice was stronger with malocclusion than without malocclusion. The amounts of SGLT2 and GLUT2 mRNA in the renal tissue in STZ-administered mice were higher with malocclusion than without malocclusion. The amounts of TNF-a and IL-6 mRNA in the large intestinal tissue in STZ-administered mice were higher with malocclusion than without malocclusion. Conclusions: Our results indicate that malocclusion accelerates the tubular expression of SGLT2 and GLUT2 under hyperglycemia. Malocclusion may be a diabetes-exacerbating factor with increased poor glycemic control due to shortened occlusion time resulting from swallowing food without chewing. Full article
(This article belongs to the Special Issue Advanced Research in Diabetic Kidney Disease)
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22 pages, 4034 KiB  
Article
Dopamine-Sensitive Anterior Cingulate Cortical Glucose-Monitoring Neurons as Potential Therapeutic Targets for Gustatory and Other Behavior Alterations
by Edina Hormay, Bettina László, István Szabó, Kitti Mintál, Beáta Berta, Tamás Ollmann, László Péczely, Bernadett Nagy, Attila Tóth, Kristóf László, László Lénárd and Zoltán Karádi
Biomedicines 2024, 12(12), 2803; https://doi.org/10.3390/biomedicines12122803 - 10 Dec 2024
Viewed by 1043
Abstract
Background: The anterior cingulate cortex (ACC) is known for its involvement in various regulatory functions, including in the central control of feeding. Activation of local elements of the central glucose-monitoring (GM) neuronal network appears to be indispensable in these regulatory processes. Destruction [...] Read more.
Background: The anterior cingulate cortex (ACC) is known for its involvement in various regulatory functions, including in the central control of feeding. Activation of local elements of the central glucose-monitoring (GM) neuronal network appears to be indispensable in these regulatory processes. Destruction of these type 2 glucose transporter protein (GLUT2)-equipped chemosensory cells results in multiple feeding-associated functional alterations. Methods: In order to examine this complex symptomatology, (1) dopamine sensitivity was studied in laboratory rats by means of the single-neuron-recording multibarreled microelectrophoretic technique, and (2) after local bilateral microinjection of the selective type 2 glucose transporter proteindemolishing streptozotocin (STZ), open-field, elevated plus maze, two-bottle and taste reactivity tests were performed. Results: A high proportion of the anterior cingulate cortical neurons changed their firing rate in response to microelectrophoretic administration of D-glucose, thus verifying them as local elements of the central glucose-monitoring network. Approximately 20% of the recorded cells displayed activity changes in response to microelectrophoretic application of dopamine, and almost 50% of the glucose-monitoring units here proved to be dopamine-sensitive. Moreover, taste stimulation experiments revealed even higher (80%) gustatory sensitivity dominance of these chemosensory cells. The anterior cingulate cortical STZ microinjections resulted in extensive behavioral and taste-associated functional deficits. Conclusions: The present findings provided evidence for the selective loss of glucose-monitoring neurons in the anterior cingulate cortex leading to motivated behavioral and gustatory alterations. This complex dataset also underlines the varied significance of the type 2 glucose transporter protein-equipped, dopamine-sensitive glucose-monitoring neurons as potential therapeutic targets. These units appear to be indispensable in adaptive control mechanisms of the homeostatic–motivational–emotional–cognitive balance for the overall well-being of the organism. Full article
(This article belongs to the Special Issue Dopamine Signaling Pathway in Health and Disease—2nd Edition)
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16 pages, 37876 KiB  
Article
Circ_0000284 Is Involved in Arsenite-Induced Hepatic Insulin Resistance Through Blocking the Plasma Membrane Translocation of GLUT4 in Hepatocytes via IGF2BP2/PPAR-γ
by Shiqing Xu, Zhida Hu, Yujie Wang, Qiyao Zhang, Zhi Wang, Teng Ma, Suhua Wang, Xiaohui Wang and Li Wang
Toxics 2024, 12(12), 883; https://doi.org/10.3390/toxics12120883 - 4 Dec 2024
Cited by 1 | Viewed by 1541
Abstract
Arsenic exposure can induce liver insulin resistance (IR) and diabetes (DM), but the underlying mechanisms are not yet clear. Circular RNAs (circRNAs) are involved in the regulation of the onset of diabetes, especially in the progression of IR. This study aimed to investigate [...] Read more.
Arsenic exposure can induce liver insulin resistance (IR) and diabetes (DM), but the underlying mechanisms are not yet clear. Circular RNAs (circRNAs) are involved in the regulation of the onset of diabetes, especially in the progression of IR. This study aimed to investigate the role of circRNAs in arsenic-induced hepatic IR and its underlying mechanism. Male C57BL/6J mice were given drinking water containing sodium arsenite (0, 0.5, 5, or 50 ppm) for 12 months. The results show that sodium arsenite increased circ_0000284 expression, decreased insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2) and peroxisome proliferator-activated receptor-γ (PPAR-γ), and inhibited cell membrane protein levels of insulin-responsive glucose transporter protein 4 (GLUT4) in the mouse livers, indicating that arsenic exposure causes liver damage and disruptions to glucose metabolism. Furthermore, sodium arsenite reduced glucose consumption and glycogen levels, increased the expression of circ_0000284, reduced the protein levels of IGF2BP2 and PPAR-γ, and inhibited GLUT4 protein levels in the cell membranes of insulin-treated HepG2 cells. However, a circ_0000284 inhibitor reversed arsenic exposure-induced reductions in IGF2BP2, PPAR-γ, and GLUT4 levels in the plasma membrane. These results indicate that circ_0000284 is involved in arsenite-induced hepatic insulin resistance through blocking the plasma membrane translocation of GLUT4 in hepatocytes via IGF2BP2/PPAR-γ. This study provides a scientific basis for finding early biomarkers for the control of arsenic exposure and type 2 diabetes mellitus (T2DM), and discovering new prevention and control measures. Full article
(This article belongs to the Special Issue Health Effects of Exposure to Environmental Pollutants)
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21 pages, 10876 KiB  
Article
Inhibition of IRAP Enhances the Expression of Pro-Cognitive Markers Drebrin and MAP2 in Rat Primary Neuronal Cells
by Frida Stam, Sara Bjurling, Erik Nylander, Esther Olaniran Håkansson, Nicholas Barlow, Johan Gising, Mats Larhed, Luke R. Odell, Alfhild Grönbladh and Mathias Hallberg
Int. J. Mol. Sci. 2024, 25(22), 12016; https://doi.org/10.3390/ijms252212016 - 8 Nov 2024
Cited by 1 | Viewed by 1299
Abstract
The insulin-regulated aminopeptidase (IRAP; oxytocinase) is part of the M1 aminopeptidase family and is highly expressed in many tissues, including the neocortex and hippocampus of the brain. IRAP is involved in various physiological functions and has been identified as a receptor for the [...] Read more.
The insulin-regulated aminopeptidase (IRAP; oxytocinase) is part of the M1 aminopeptidase family and is highly expressed in many tissues, including the neocortex and hippocampus of the brain. IRAP is involved in various physiological functions and has been identified as a receptor for the endogenous hexapeptide Angiotensin IV (Ang IV). The binding of Ang IV inhibits the enzymatic activity of IRAP and has been proven to enhance learning and memory in animal models. The macrocyclic compound 9 (C9) is a potent synthetic IRAP inhibitor developed from the previously reported inhibitor HA08. In this study, we have examined compound C9 and its effects on cognitive markers drebrin, microtubule-associated protein 2 (MAP2), and glial fibrillary acidic protein (GFAP) in primary hippocampal and cortical cultures. Cells from Sprague Dawley rats were cultured for 14 days before treatment with C9 for 4 consecutive days. The cells were analysed for protein expression of drebrin, MAP2, GFAP, glucose transporter type 4 (GLUT4), vesicular glutamate transporter 1 (vGluT1), and synapsin I using immunocytochemistry. The gene expression of related proteins was determined using qPCR, and viability assays were performed to evaluate toxicity. The results showed that protein expression of drebrin and MAP2 was increased, and the corresponding mRNA levels were decreased after treatment with C9 in the hippocampal cultures. The ratio of MAP2-positive neurons and GFAP-positive astrocytes was altered and there were no toxic effects observed. In conclusion, the IRAP inhibitor compound C9 enhances the expression of the pro-cognitive markers drebrin and MAP2, which further confirms IRAP as a relevant pharmaceutical target and C9 as a promising candidate for further investigation. Full article
(This article belongs to the Section Molecular Neurobiology)
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