Glucose is used aerobically and anaerobically to generate energy for cells.Glucose transporters(GLUTs)are transmembrane proteins that transport glucose across the cell membrane.Insulin promotes glucose utilization in ...Glucose is used aerobically and anaerobically to generate energy for cells.Glucose transporters(GLUTs)are transmembrane proteins that transport glucose across the cell membrane.Insulin promotes glucose utilization in part through promoting glucose entry into the skeletal and adipose tissues.This has been thought to be achieved through insulin-induced GLUT4 translocation from intracellular compartments to the cell membrane,which increases the overall rate of glucose flux into a cell.The insulin-induced GLUT4 translocation has been investigated extensively.Recently,significant progress has been made in our understanding of GLUT4 expression and translocation.Here,we summarized the methods and reagents used to determine the expression levels of Slc2a4 mRNA and GLUT4 protein,and GLUT4 translocation in the skeletal muscle,adipose tissues,heart and brain.Overall,a variety of methods such real-time polymerase chain reaction,immunohistochemistry,fluorescence microscopy,fusion proteins,stable cell line and transgenic animals have been used to answer particular questions related to GLUT4 system and insulin action.It seems that insulininduced GLUT4 translocation can be observed in the heart and brain in addition to the skeletal muscle and adipocytes.Hormones other than insulin can induce GLUT4 translocation.Clearly,more studies of GLUT4 are warranted in the future to advance of our understanding of glucose homeostasis.展开更多
Currently,glucose transporter 4(GLUT4)has been considered as the key player for the insulin-stimulated glucose transport in the muscle and adipose tissues.The development of recombinant DNA techniques allows the creat...Currently,glucose transporter 4(GLUT4)has been considered as the key player for the insulin-stimulated glucose transport in the muscle and adipose tissues.The development of recombinant DNA techniques allows the creations of genetically knockout,knockdown and transgenic animals and cells for the study of GLUT4’s physiological functions.Here,we have used key words to search the PubMed and summarized the methods used in Slc2a4 gene knockout,GLUT4 knockdown and overexpression in the whole body and tissue specific manner.The whole body GLUT4-null mice have growth retardation,but normal glucose tolerance and basal glucose turnover rates.Compared with whole body Slc2a4 knockout mice,adipose and muscle double knockout mice have impaired insulin tolerance and glucose intolerance.The results of GLUT4 knockdown in 3T3-L1 adipocytes have shown that its expression is needed for lipogenesis after,but not during,differentiation.Transgenic mice with the whole body GLUT4 overexpression have normal body weight and lowered blood glucose level.The adipose tissue specific overexpression of GLUT4 leads to increases in mouse body weight and adipose tissue weight.The insulin-stimulated GLUT4 translocation in the skeletal muscle contributes to the regulation of glucose homeostasis.Data from both transgenic overexpression and tissue specific Slc2a4 knockout indicate that GLUT4 probably plays a role in the glucose uptake in the fasting state.More studies are warranted to use advanced molecular biology tools to decipher the roles of GLUT4 in the control of glucose homeostasis.展开更多
Objective： To investigate the effects of Huanglian Jiedu Decoction （黄连解毒汤, HLJDD） on glucose transporter 4 （GLUT4） protein expressions in insulin-resistant murine target tissues. Methods： The experimental m...Objective： To investigate the effects of Huanglian Jiedu Decoction （黄连解毒汤, HLJDD） on glucose transporter 4 （GLUT4） protein expressions in insulin-resistant murine target tissues. Methods： The experimental male Wistar rats were established into insulin resistant models by injecting streptozotocin （STZ 30 mg/kg） via caudal vein and feeding them with high fat high caloric diet, and randomly divided into the model group, the aspirin group and the HLJDD group. Besides, a normal group was set up for control. Changes of body weight （BW）, levels of serum fasting blood glucose （FBG）, serum fasting insulin （FINS） and oral glucose tolerance test （OGTT） were routinely determined. The expression of GLUT4 protein in adipose and skeletal muscle tissues before and after insulin stimulation was determined with Western blot. Results： In the HLJDD group after treatment, BW and FBG got decreased, OGTT improved, and the expression and translocation of GLUT4 protein elevated obviously, either before or after insulin stimulation, as compared with those in the model group, showing significant differences respectively. Conclusion： The mechanism of improving insulin resistance by HLJDD is probably associated with its effect in elevating GLUT4 protein expression and translocation in adipose and skeletal muscle tissues of insulin resistant rats.展开更多
Background:Insulin gene enhancer protein 1,(ISL1),a LIM-homeodomain transcription factor,is involved in multiple tumors and is associated with insulin secretion and metabolic phenotypes.However,the role of ISL1 in sti...Background:Insulin gene enhancer protein 1,(ISL1),a LIM-homeodomain transcription factor,is involved in multiple tumors and is associated with insulin secretion and metabolic phenotypes.However,the role of ISL1 in stimulating glycolysis to promote tumorigenesis in gastric cancer(GC)is unclear.In this study,we aimed to characterize the expression pattern of ISL1 in GC patients and explore its molecular biological mechanism in glycolysis and tumorigenesis.Methods:We analyzed the expression and clinical significance of ISL1 in GC using immunohistochemistry and real-time polymerase chain reaction(PCR).Flow cytometry and IncuCyte assays were used to measure cell proliferation after ISL1 knockdown.RNA-sequencing was performed to identify differentially expressed genes,followed by Kyoto Encyclopedia of Genes and Genomes(KEGG)analysis and Gene Set Enrichment Analysis(GSEA)to reveal key signaling pathways likely regulated by ISL1 in GC.Alteration of the glycolytic ability of GC cells with ISL1 knockdown was validated by measuring the extracellular acidification rate(ECAR)and oxygen consumption rate(OCR)and by detecting glucose consumption and lactate production.The expression of glucose transporter 4(GLUT4)and ISL1 was assessed by Western blotting,immunohistochemistry,and immunofluorescent microscopy.The luciferase reporter activity and chromatin immunoprecipitation assays were performed to determine the transcriptional regulation of ISL1 on GLUT4.Results:High levels of ISL1 and GLUT4 expression was associated with short survival of GC patients.ISL1 knockdown inhibited cell proliferation both in vitro and in vivo.KEGG analysis and GSEA for RNA-sequencing data indicated impairment of the glycolysis pathway in GC cells with ISL1 knockdown,which was validated by reduced glucose uptake and lactate production,decreased ECAR,and increased OCR.Mechanistic investigation indicated that ISL1 transcriptionally regulated GLUT4 through binding to its promoter.Conclusion:ISL1 facilitates glycolysis and tumorigenesis in GC via the transcriptional regulation of GLUT4.展开更多
Glucose is vital to embryogenesis,as are glucose transporters.Glucose transporter 4(Glut4)is one of the glucose transporters,which is involved in rapid uptake of glucose by various cells and promotes glucose homeostas...Glucose is vital to embryogenesis,as are glucose transporters.Glucose transporter 4(Glut4)is one of the glucose transporters,which is involved in rapid uptake of glucose by various cells and promotes glucose homeostasis.Although energy metabolism in insect reproduction is well known,the molecular mechanism of Glut4 in insect reproduction is poorly understood.We suspect that Glut4 is involved in maintaining glucose concentrations in the ovaries and affecting vitellogenesis,which is critical for subsequent oocyte maturation and insect fertility.Harmonia axyridis(Pallas)is a model organism for genetic research and a natural enemy of insect pests.We studied the influence of the Glut4 gene on the reproduction and development of H.axyridis using RNA interference technology.Reverse transcription quantitative polymerase chain reaction analysis revealed that HaGlut4 was most highly expressed in adults.Knockdown of the HaGlut4 gene reduced the transcript levels of HaGlut4,and the weight and number of eggs produced significantly decreased.In addition,the transcript levels of vitellogenin receptor and vitellogenin in the fat bodies and the ovaries of H.axyridis decreased after the interference of Glut4,and decreased the triglyceride,fatty acid,total amino acid and adenosine triphosphate content of H.axyridis.This resulted in severe blockage of ovary development and reduction of yolk formation;there was no development of ovarioles in the developing oocytes.These changes indicate that a lack of HaGlut4 can impair ovarian development and oocyte maturation and result in decreased fecundity.展开更多
Insulin stimulates the production of PI(3,4,5)P3 in muscle cells, and this is required to stimulate GLUT4 fusion with the plasma membrane. Introduction of exogenous PI(3,4,5)P3 to muscle cells recapitulates insulin...Insulin stimulates the production of PI(3,4,5)P3 in muscle cells, and this is required to stimulate GLUT4 fusion with the plasma membrane. Introduction of exogenous PI(3,4,5)P3 to muscle cells recapitulates insulin's effects on GLUT4 fusion with the plasma membrane, but not glucose uptake. This study aims to explore the mechanism behind this difference. In L6-GLUT4myc muscle cells, the availability of the GLUT4 intracellular C-terminus and extracellular myc epitopes for immunoreactivity on plasma membrane lawns was detected with the corresponding antibody. The availability of the active site of GLUT4 from extracellular medium was assessed by affinity photolabeling with the cell impermeant compound Bio-LC-ATB-BMPA. 100nmol/L insulin and 10μmol/L PI(3,4,5)P3 caused myc signal gain on the plasma membrane lawns by 1.64-fold and 1.58-fold over basal, respectively. Insulin, but not PI(3,4,5)P3, increased photolabeling of GLUT4 and immunolabeling with C-terminus antibody by 2.47-fold and 2.04-fold over basal, respectively. Upon insulin stimulation, the C-terminus signal gain was greater than myc signal gain (2.04-fold vs. 1.64-fold over basal, respectively) in plasma membrane lawns. These results indicate that (i) PI(3,4,5)P3 does not make the active site of GLUT4 available from the extracellular surface despite causing GLUT4 fusion with the plasma membrane; (ii) the availability of the active site of GLUT4 from the extracellular medium and availability of the C-terminus from the cytosolic site are correlated; (iii) in addition to stimulating GLUT4 translocation, insulin stimulation displaces a protein which masks the GLUT4 C-terminus. We propose that a protein which masks the C-terminus also prevents the active site from being available for photolabelling and possibly glucose uptake after treatment with PI(3,4,5)P3.展开更多
Background: This study investigated serum Glucose transporter (GLUT) 4 levels and examined the relationship between serum GLUT4 levels and sepsis in critically ill children. Methods: This was a retrospective study of ...Background: This study investigated serum Glucose transporter (GLUT) 4 levels and examined the relationship between serum GLUT4 levels and sepsis in critically ill children. Methods: This was a retrospective study of 77 critically ill children and 33 non-diabetic healthy children (controls) who were admitted between 07/2015 and 05/2016. Patient data, clinical information, and blood samples were collected on admission, alongside a large number of laboratory parameters that were routinely assessed. Critically ill patients were divided into sepsis and non-sepsis/systemic inflammatory response syndrome (SIRS). Serum GLUT4 was measured using western blotting and enzyme-linked immunosorbent assays. Insulin resistance indexes, clinical data, laboratory parameters, and inflammatory cytokines were assessed. Results: GLUT4 serum levels were higher in critically ill children than in healthy children (90.5 vs. 30.3 μg/L, P 0.05). Compared to healthy children, hyperglycemic patients (n = 48) had elevated GLUT4 serum levels (30.3 vs. 103.7 g/L, P Conclusions: GLUT4 serum levels might be significantly increased in critically ill children compared with healthy children, particularly those in septic shock. Serum GLUT4 could predict disease severity.展开更多
Objective To evaluate the effect of low-dose insulin [1 U/(kg·d)] in combination with selenium [180 g/(kg·d)] on general physiological parameters and glucose transporter (GLUT4) level in skeletal muscle of s...Objective To evaluate the effect of low-dose insulin [1 U/(kg·d)] in combination with selenium [180 g/(kg·d)] on general physiological parameters and glucose transporter (GLUT4) level in skeletal muscle of streptozotocin (STZ)-induced diabetic rats. Methods Diabetic rats were treated with insulin,selenium,and insulin and selenium in combination for four weeks. The level of blood glucose was determined using One Touch SureStep Blood Glucose meter and the level of GLUT4 in skeletal muscle was examined by immunoblotting and immunohistochemistry. Results Our data showed that insulin in combination with selenium could significantly lower blood glucose level and restore the disturbance in GLUT4 level in skeletal muscle. Treatment with insulin was only partially effective in restoring diabetic alterations. Conclusion It can be concluded that there is a synergistic action between insulin and selenium,and that treatment of diabetic rats with combined doses of insulin and selenium is effective in the normalization of blood glucose level and correction of altered GLUT4 distribution in skeletal muscle of diabetic rats.展开更多
Nuciferine contained in lotus leaves have been confirmed to have the effect of ameliorating hyperlipemia and hyperglycemia.A laser scanning confocal microscope was used to track the translocation of glucose transporte...Nuciferine contained in lotus leaves have been confirmed to have the effect of ameliorating hyperlipemia and hyperglycemia.A laser scanning confocal microscope was used to track the translocation of glucose transporter 4(GLUT4)in L6 cells and the changes in intracellular Ca^(2+)levels in real time,and related protease inhibitors combined with western blotting were used to explore the mechanism of nuciferine.Meanwhile,KK-Ay mice,the spontaneous type 2 diabetic mice,were used to evaluate the in vivo activity of nuciferine.In this study,the in vitro studies indicated that nuciferine-induced GLUT4 translocation was regulated by G protein-PLC-PKC and AMPK pathways and nuciferine-enhanced intracellular Ca^(2+)was mediated by G protein-PLC-IP3-IP3R pathway,the increase in intracellular Ca^(2+)caused by nuciferine was not directly related to GLUT4 translocation,but both promote glucose uptake.The in vivo results suggested that nuciferine ameliorated weight gain induced by high-fat diet,abnormal lipid metabolism and the symptoms of insulin resistance in KK-Ay diabetic mice.Western blot results suggested that nuciferine increased AMPK and PKC phosphorylation levels in skeletal muscle and liver,and enhanced GLUT4 expression in skeletal muscle.Taken together,this research showed that nuciferine has the non-negligible potential in the treatment of type 2 diabetes mellitus.展开更多
Dietary flavonoids are abundant in natural plants and possess multiple pharmacological and nutritional activities.In this study,apigenin,luteolin,and baicalein were chosen to evaluate their anti-diabetic effect in hig...Dietary flavonoids are abundant in natural plants and possess multiple pharmacological and nutritional activities.In this study,apigenin,luteolin,and baicalein were chosen to evaluate their anti-diabetic effect in high-glucose and dexamethasone induced insulin-resistant(IR)HepG2 cells.All flavonoids improves the glucose consumption and glycogen synthesis abilities in IR-HepG2 cells via activating glucose transporter protein 4(GLUT4)and phosphor-glycogen synthase kinase(GSK-3β).These fl avonoids signifi cantly inhibited the production of reactive oxygen species(ROS)and advanced glycation end-products(AGEs),which were closely related to the suppression of the phosphorylation form of NF-κB and P65.The expression levels of insulin receptor substrate-1(IRS-1),insulin receptor substrate-2(IRS-2)and phosphatidylinositol 3-kinase(PI3K)/protein kinase B(Akt)pathway in IR-HepG2 cells were all partially activated by the fl avonoids,with variable effects.Furthermore,the intracellular metabolic conditions of the fl avonoids were also evaluated.展开更多
Sea cucumber and cordyceps sinensis are used as both food and traditional medicines in Asia. This study was carried out in order to investigate the hpyerglycemic effect of a mixture of sea cucumber （Apostichopusjapon...Sea cucumber and cordyceps sinensis are used as both food and traditional medicines in Asia. This study was carried out in order to investigate the hpyerglycemic effect of a mixture of sea cucumber （Apostichopusjaponicas） and cordyceps sinensis （Cor-dyceps militaris） （SCC） in diabetic rat and explore the mechanism underlining such an effect. The diabetic model rat was induced with intraperitoneal injection of streptozotocin （STZ）. The diabetic model rats were randomly divided into control group （0.9% NaC1）, low dose group （300 mg SCC.（kg body weight）-1） and high dose group （1200 mg SCC （kg body weight）-l）. Sodium chloride and SCC were intragastrically administered once a day for 35 d. Changes in fasting serum glucose and serum insulin content, oral glucose tolerance and liver and muscle glycogen content were routinely evaluated. Pancreas tissue and β-cells of islets were observed under both optical and transmission electronic microscope, respectively. The abundance of glucose metabolism-relating genes in gastrocnemius and epididymal adipose tissue was determined with either reverse transcription PCR （RT-PCR） or western blotting. Results showed that SCC significantly decreased fasting serum glucose content, improved glucose tolerance and increased serum insulin and glycogen content; repaired STZ-injured β-cells of diabetic rat, and increased the expression of phosphatidylinositol 3 kinase （PI（3）K）, protein kinase B （PKB） and glucose transporter 4 （Glut4） encoding protein in both gastroenemius and adipose tissue, and Glut4 encoding gene in peripheral tissue. Our findings demonstrated that SCC exerted an anti-hyperglycemic effect by repairing β-cells and promoting insulin-mediated signal transduction pathway in insulin-sensitive gastrocnemius and adipose tissue.展开更多
Background Retinol binding protein 4 （RBP4）, as an adipocyte secreted cytokine, was recently found to be inversely correlated with expression of glucose transporter 4 （GLUT4） in insulin resistance （IR） state and...Background Retinol binding protein 4 （RBP4）, as an adipocyte secreted cytokine, was recently found to be inversely correlated with expression of glucose transporter 4 （GLUT4） in insulin resistance （IR） state and to have an intimate relationship with IR and type 2 diabetes mellitus （T2DM）. The present study aimed to evaluate the anti-diabetic efficacy of cinnamaldehyde （Cin）, berberine （Ber）, and metformin （Met） as well as their impacts on the RBP4-GLUT4 system. Methods Rat models of T2DM were established by combination of intraperitoneal injection of low-dose streptozotocin and high fat diet induction. Rats were divided into five groups： the control group, the diabetes group, the diabetes＋Ber group, the diabetes＋Cin group, and the diabetes＋Met group. Western blotting was used to detect the serum or tissue RBP4 and GLUT4 protein levels. Results After treatment for four weeks, both Cin and Ber displayed significant hypolipidemic, hypoglycemic, and insulin sensitizing functions （P 〈0.01） compared with the control group. Their effects on lowering fasting plasma glucose （FPG）, low density lipoprotein-cholesterol （LDL-C） and homeostasis model assessment of insulin resistance （HOMA-IR） seem even better than that of Met. Cin and Ber markedly lowered serum RBP4 levels and up-regulated the expression of tissue GLUT4 protein, and Cin seemed more notable in affecting these two proteins. Conclusions Both Cin and Ber display an exciting anti-diabetic efficacy in this study and may be of great value for the treatment of type 2 diabetes. Their mechanisms involve the RBP4-GLUT4 system, during which the serum RBP4 levels are lowered and the expression of tissue GLUT4 protein is up-regulated.展开更多
OBJECTIVE: To determine the efficacy of a fermented buckwheat flower and leaf extract(EFBFL) for the reduction of blood glucose and lipid dysregulation in spontaneously obese type 2 diabetic db/db mice, and to explore...OBJECTIVE: To determine the efficacy of a fermented buckwheat flower and leaf extract(EFBFL) for the reduction of blood glucose and lipid dysregulation in spontaneously obese type 2 diabetic db/db mice, and to explore the possible mechanisms involved.METHODS: Forty 9-week-old male db/db mice were randomly allocated to a high-dose EFBFL group(EFBFL-H), a low-dose EFBFL group(EFBFL-L),a metformin hydrochloride positive control group(MEG), and a db/db control group(MG), and there was also a db/m negative control group(NCG)(n =10). Oral glucose tolerance tests(OGTT) were performed after 7 weeks of treatment. At the end of 8 weeks of treatment, random blood glucose(RBG),glycosylated hemoglobin(Hb Alc), fasting plasma glucose(FPG), fasting serum insulin(FINS), triglyceride(TG), serum total cholesterol(TC), free fatty acids(FFA), high-density lipoprotein-cholesterol, and low-density lipoprotein-cholesterol(LDL-c) were measured, the homeostasis model assessment-insulin resistance(HOMA-IR) was calculated. Immunohistochemistry and western blotting measured the expression of glucose transporter4(GLUT4) and peroxisome proliferator-activated receptor γ(PPAR-γ) by in skeletal muscle.RESULTS: The MG mice had a significantly increased in RBG, Hb Alc, the HOMA-IR level, the serum of TG, TC, LDL-c, but a decreased in glucose tolerance and the protein expression of GLUT4 and PPAR-γ compared with the NCG. Compared with the MG, EFBFL groups significantly decreased RBG, Hb Alc, and the HOMA-IR level, increased glucose tolerance. Meanwhile EFBFL groups reduced the serum TG, TC, and LDL-c in a dose-dependent manner. In addition, EFBFL increased the protein expression of GLUT4 and PPAR-γ in the skeletal muscle of db/db mice.There was significant difference between the MG group and EFBFL groups.CONCLUSION: These findings suggest that EFBFL has anti-diabetic effects in db/db mice, ameliorating glucose intolerance, lipid dysregulation, and insulin resistance.展开更多
基金We would like to thank the Department of Nutrition at the University of Tennessee at Knoxville for financial support to T.W.G.C.would like to thank Yantai Zestern Biotechnique Co.LTD for the research funding support.
文摘Glucose is used aerobically and anaerobically to generate energy for cells.Glucose transporters(GLUTs)are transmembrane proteins that transport glucose across the cell membrane.Insulin promotes glucose utilization in part through promoting glucose entry into the skeletal and adipose tissues.This has been thought to be achieved through insulin-induced GLUT4 translocation from intracellular compartments to the cell membrane,which increases the overall rate of glucose flux into a cell.The insulin-induced GLUT4 translocation has been investigated extensively.Recently,significant progress has been made in our understanding of GLUT4 expression and translocation.Here,we summarized the methods and reagents used to determine the expression levels of Slc2a4 mRNA and GLUT4 protein,and GLUT4 translocation in the skeletal muscle,adipose tissues,heart and brain.Overall,a variety of methods such real-time polymerase chain reaction,immunohistochemistry,fluorescence microscopy,fusion proteins,stable cell line and transgenic animals have been used to answer particular questions related to GLUT4 system and insulin action.It seems that insulininduced GLUT4 translocation can be observed in the heart and brain in addition to the skeletal muscle and adipocytes.Hormones other than insulin can induce GLUT4 translocation.Clearly,more studies of GLUT4 are warranted in the future to advance of our understanding of glucose homeostasis.
文摘Currently,glucose transporter 4(GLUT4)has been considered as the key player for the insulin-stimulated glucose transport in the muscle and adipose tissues.The development of recombinant DNA techniques allows the creations of genetically knockout,knockdown and transgenic animals and cells for the study of GLUT4’s physiological functions.Here,we have used key words to search the PubMed and summarized the methods used in Slc2a4 gene knockout,GLUT4 knockdown and overexpression in the whole body and tissue specific manner.The whole body GLUT4-null mice have growth retardation,but normal glucose tolerance and basal glucose turnover rates.Compared with whole body Slc2a4 knockout mice,adipose and muscle double knockout mice have impaired insulin tolerance and glucose intolerance.The results of GLUT4 knockdown in 3T3-L1 adipocytes have shown that its expression is needed for lipogenesis after,but not during,differentiation.Transgenic mice with the whole body GLUT4 overexpression have normal body weight and lowered blood glucose level.The adipose tissue specific overexpression of GLUT4 leads to increases in mouse body weight and adipose tissue weight.The insulin-stimulated GLUT4 translocation in the skeletal muscle contributes to the regulation of glucose homeostasis.Data from both transgenic overexpression and tissue specific Slc2a4 knockout indicate that GLUT4 probably plays a role in the glucose uptake in the fasting state.More studies are warranted to use advanced molecular biology tools to decipher the roles of GLUT4 in the control of glucose homeostasis.
基金National Natural Science Foundation of P. R. China (No. 30371816)Specialized Research Fund for the Doctoral Program of Higher Education (No. 20030487008)
文摘Objective： To investigate the effects of Huanglian Jiedu Decoction （黄连解毒汤, HLJDD） on glucose transporter 4 （GLUT4） protein expressions in insulin-resistant murine target tissues. Methods： The experimental male Wistar rats were established into insulin resistant models by injecting streptozotocin （STZ 30 mg/kg） via caudal vein and feeding them with high fat high caloric diet, and randomly divided into the model group, the aspirin group and the HLJDD group. Besides, a normal group was set up for control. Changes of body weight （BW）, levels of serum fasting blood glucose （FBG）, serum fasting insulin （FINS） and oral glucose tolerance test （OGTT） were routinely determined. The expression of GLUT4 protein in adipose and skeletal muscle tissues before and after insulin stimulation was determined with Western blot. Results： In the HLJDD group after treatment, BW and FBG got decreased, OGTT improved, and the expression and translocation of GLUT4 protein elevated obviously, either before or after insulin stimulation, as compared with those in the model group, showing significant differences respectively. Conclusion： The mechanism of improving insulin resistance by HLJDD is probably associated with its effect in elevating GLUT4 protein expression and translocation in adipose and skeletal muscle tissues of insulin resistant rats.
基金Natural Science Foundation of Beijing,Grant/Award Number:7132051National Natural Science Foundation of China,Grant/Award Numbers:81301874,81972758,81872502,81802471+3 种基金Interdisciplinary Medicine Seed Fund of Peking University,Grant/Award Number:BMU2018MX018Beijing Municipal Administration of Hospitals’Youth Program,Grant/Award Number:QML20181102National High Technology Research and Development Program of China,Grant/Award Number:2014AA020603Science Foundation of Peking University Cancer Hospital,Grant/Award Numbers:2017-23,2020-6。
文摘Background:Insulin gene enhancer protein 1,(ISL1),a LIM-homeodomain transcription factor,is involved in multiple tumors and is associated with insulin secretion and metabolic phenotypes.However,the role of ISL1 in stimulating glycolysis to promote tumorigenesis in gastric cancer(GC)is unclear.In this study,we aimed to characterize the expression pattern of ISL1 in GC patients and explore its molecular biological mechanism in glycolysis and tumorigenesis.Methods:We analyzed the expression and clinical significance of ISL1 in GC using immunohistochemistry and real-time polymerase chain reaction(PCR).Flow cytometry and IncuCyte assays were used to measure cell proliferation after ISL1 knockdown.RNA-sequencing was performed to identify differentially expressed genes,followed by Kyoto Encyclopedia of Genes and Genomes(KEGG)analysis and Gene Set Enrichment Analysis(GSEA)to reveal key signaling pathways likely regulated by ISL1 in GC.Alteration of the glycolytic ability of GC cells with ISL1 knockdown was validated by measuring the extracellular acidification rate(ECAR)and oxygen consumption rate(OCR)and by detecting glucose consumption and lactate production.The expression of glucose transporter 4(GLUT4)and ISL1 was assessed by Western blotting,immunohistochemistry,and immunofluorescent microscopy.The luciferase reporter activity and chromatin immunoprecipitation assays were performed to determine the transcriptional regulation of ISL1 on GLUT4.Results:High levels of ISL1 and GLUT4 expression was associated with short survival of GC patients.ISL1 knockdown inhibited cell proliferation both in vitro and in vivo.KEGG analysis and GSEA for RNA-sequencing data indicated impairment of the glycolysis pathway in GC cells with ISL1 knockdown,which was validated by reduced glucose uptake and lactate production,decreased ECAR,and increased OCR.Mechanistic investigation indicated that ISL1 transcriptionally regulated GLUT4 through binding to its promoter.Conclusion:ISL1 facilitates glycolysis and tumorigenesis in GC via the transcriptional regulation of GLUT4.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2017YFD0201000)the Hangzhou Science and Technology Development Program of China(Grant No.20190101A01).
文摘Glucose is vital to embryogenesis,as are glucose transporters.Glucose transporter 4(Glut4)is one of the glucose transporters,which is involved in rapid uptake of glucose by various cells and promotes glucose homeostasis.Although energy metabolism in insect reproduction is well known,the molecular mechanism of Glut4 in insect reproduction is poorly understood.We suspect that Glut4 is involved in maintaining glucose concentrations in the ovaries and affecting vitellogenesis,which is critical for subsequent oocyte maturation and insect fertility.Harmonia axyridis(Pallas)is a model organism for genetic research and a natural enemy of insect pests.We studied the influence of the Glut4 gene on the reproduction and development of H.axyridis using RNA interference technology.Reverse transcription quantitative polymerase chain reaction analysis revealed that HaGlut4 was most highly expressed in adults.Knockdown of the HaGlut4 gene reduced the transcript levels of HaGlut4,and the weight and number of eggs produced significantly decreased.In addition,the transcript levels of vitellogenin receptor and vitellogenin in the fat bodies and the ovaries of H.axyridis decreased after the interference of Glut4,and decreased the triglyceride,fatty acid,total amino acid and adenosine triphosphate content of H.axyridis.This resulted in severe blockage of ovary development and reduction of yolk formation;there was no development of ovarioles in the developing oocytes.These changes indicate that a lack of HaGlut4 can impair ovarian development and oocyte maturation and result in decreased fecundity.
基金the National Natural Science Foundation of China (Grant No. 30570912)the National Natural Science Foundation of China (China-Canada Joint Health Research) (Grant No. 30611120532)+1 种基金the Foundation of Tianjin Education Bureau, China to Niu Wenyan (Grant No. 20040106)the Tianjin Municipal Science and Technology Commission, China (Grant Nos. 06YFGPSH03300 and 07JCZDJC07900)
文摘Insulin stimulates the production of PI(3,4,5)P3 in muscle cells, and this is required to stimulate GLUT4 fusion with the plasma membrane. Introduction of exogenous PI(3,4,5)P3 to muscle cells recapitulates insulin's effects on GLUT4 fusion with the plasma membrane, but not glucose uptake. This study aims to explore the mechanism behind this difference. In L6-GLUT4myc muscle cells, the availability of the GLUT4 intracellular C-terminus and extracellular myc epitopes for immunoreactivity on plasma membrane lawns was detected with the corresponding antibody. The availability of the active site of GLUT4 from extracellular medium was assessed by affinity photolabeling with the cell impermeant compound Bio-LC-ATB-BMPA. 100nmol/L insulin and 10μmol/L PI(3,4,5)P3 caused myc signal gain on the plasma membrane lawns by 1.64-fold and 1.58-fold over basal, respectively. Insulin, but not PI(3,4,5)P3, increased photolabeling of GLUT4 and immunolabeling with C-terminus antibody by 2.47-fold and 2.04-fold over basal, respectively. Upon insulin stimulation, the C-terminus signal gain was greater than myc signal gain (2.04-fold vs. 1.64-fold over basal, respectively) in plasma membrane lawns. These results indicate that (i) PI(3,4,5)P3 does not make the active site of GLUT4 available from the extracellular surface despite causing GLUT4 fusion with the plasma membrane; (ii) the availability of the active site of GLUT4 from the extracellular medium and availability of the C-terminus from the cytosolic site are correlated; (iii) in addition to stimulating GLUT4 translocation, insulin stimulation displaces a protein which masks the GLUT4 C-terminus. We propose that a protein which masks the C-terminus also prevents the active site from being available for photolabelling and possibly glucose uptake after treatment with PI(3,4,5)P3.
文摘Background: This study investigated serum Glucose transporter (GLUT) 4 levels and examined the relationship between serum GLUT4 levels and sepsis in critically ill children. Methods: This was a retrospective study of 77 critically ill children and 33 non-diabetic healthy children (controls) who were admitted between 07/2015 and 05/2016. Patient data, clinical information, and blood samples were collected on admission, alongside a large number of laboratory parameters that were routinely assessed. Critically ill patients were divided into sepsis and non-sepsis/systemic inflammatory response syndrome (SIRS). Serum GLUT4 was measured using western blotting and enzyme-linked immunosorbent assays. Insulin resistance indexes, clinical data, laboratory parameters, and inflammatory cytokines were assessed. Results: GLUT4 serum levels were higher in critically ill children than in healthy children (90.5 vs. 30.3 μg/L, P 0.05). Compared to healthy children, hyperglycemic patients (n = 48) had elevated GLUT4 serum levels (30.3 vs. 103.7 g/L, P Conclusions: GLUT4 serum levels might be significantly increased in critically ill children compared with healthy children, particularly those in septic shock. Serum GLUT4 could predict disease severity.
基金supported by the National Basic Research Program of China (973Program) ( No.2007CB512005)the National Natural Science Foundation of China (No.30770785)+1 种基金the Cultivation Fund of the Key Scientific and Technological Innovation Pro-ject of the Ministry of Education of China (No.705045)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20050698012)
文摘Objective To evaluate the effect of low-dose insulin [1 U/(kg·d)] in combination with selenium [180 g/(kg·d)] on general physiological parameters and glucose transporter (GLUT4) level in skeletal muscle of streptozotocin (STZ)-induced diabetic rats. Methods Diabetic rats were treated with insulin,selenium,and insulin and selenium in combination for four weeks. The level of blood glucose was determined using One Touch SureStep Blood Glucose meter and the level of GLUT4 in skeletal muscle was examined by immunoblotting and immunohistochemistry. Results Our data showed that insulin in combination with selenium could significantly lower blood glucose level and restore the disturbance in GLUT4 level in skeletal muscle. Treatment with insulin was only partially effective in restoring diabetic alterations. Conclusion It can be concluded that there is a synergistic action between insulin and selenium,and that treatment of diabetic rats with combined doses of insulin and selenium is effective in the normalization of blood glucose level and correction of altered GLUT4 distribution in skeletal muscle of diabetic rats.
基金financially supported by National Natural Science Foundation of China grants(81573561,81911540487,31070744)the Fundamental Research Funds for the Central Universities,South-Central University for Nationalities(CZR18003).
文摘Nuciferine contained in lotus leaves have been confirmed to have the effect of ameliorating hyperlipemia and hyperglycemia.A laser scanning confocal microscope was used to track the translocation of glucose transporter 4(GLUT4)in L6 cells and the changes in intracellular Ca^(2+)levels in real time,and related protease inhibitors combined with western blotting were used to explore the mechanism of nuciferine.Meanwhile,KK-Ay mice,the spontaneous type 2 diabetic mice,were used to evaluate the in vivo activity of nuciferine.In this study,the in vitro studies indicated that nuciferine-induced GLUT4 translocation was regulated by G protein-PLC-PKC and AMPK pathways and nuciferine-enhanced intracellular Ca^(2+)was mediated by G protein-PLC-IP3-IP3R pathway,the increase in intracellular Ca^(2+)caused by nuciferine was not directly related to GLUT4 translocation,but both promote glucose uptake.The in vivo results suggested that nuciferine ameliorated weight gain induced by high-fat diet,abnormal lipid metabolism and the symptoms of insulin resistance in KK-Ay diabetic mice.Western blot results suggested that nuciferine increased AMPK and PKC phosphorylation levels in skeletal muscle and liver,and enhanced GLUT4 expression in skeletal muscle.Taken together,this research showed that nuciferine has the non-negligible potential in the treatment of type 2 diabetes mellitus.
基金supported by National Natural Science Foundation of China(32072212)Multi-Year Research Grant of University of Macao(MYRG2018-00169-ICMS)+5 种基金Science and Technology Development Fund of Macao(FDCT)(0098/2020/A)MICINN supporting the Ramón y Cajal grant for M.A.Prieto(RYC-201722891)Jianbo Xiao(RYC2020-030365-I)Xunta de Galicia supporting the Axudas Conecta Peme,the IN852A 2018/58 Neuro Food Project,the program EXCELENCIA-ED431F 2020/12the pre-doctoral grants of P.García-Oliveira(ED481A-2019/295)to Ibero-American Program on Science and Technology(CYTED-AQUA-CIBUS,P317RT0003).
文摘Dietary flavonoids are abundant in natural plants and possess multiple pharmacological and nutritional activities.In this study,apigenin,luteolin,and baicalein were chosen to evaluate their anti-diabetic effect in high-glucose and dexamethasone induced insulin-resistant(IR)HepG2 cells.All flavonoids improves the glucose consumption and glycogen synthesis abilities in IR-HepG2 cells via activating glucose transporter protein 4(GLUT4)and phosphor-glycogen synthase kinase(GSK-3β).These fl avonoids signifi cantly inhibited the production of reactive oxygen species(ROS)and advanced glycation end-products(AGEs),which were closely related to the suppression of the phosphorylation form of NF-κB and P65.The expression levels of insulin receptor substrate-1(IRS-1),insulin receptor substrate-2(IRS-2)and phosphatidylinositol 3-kinase(PI3K)/protein kinase B(Akt)pathway in IR-HepG2 cells were all partially activated by the fl avonoids,with variable effects.Furthermore,the intracellular metabolic conditions of the fl avonoids were also evaluated.
基金supported by National Marine Public Welfare Scientific Research Project of China (No.201105029)the National Key Technology S&D Program (No.2012BAD33B07)Program for Changjiang Scholars and Innovative Research Team in University (IRT1188)
文摘Sea cucumber and cordyceps sinensis are used as both food and traditional medicines in Asia. This study was carried out in order to investigate the hpyerglycemic effect of a mixture of sea cucumber （Apostichopusjaponicas） and cordyceps sinensis （Cor-dyceps militaris） （SCC） in diabetic rat and explore the mechanism underlining such an effect. The diabetic model rat was induced with intraperitoneal injection of streptozotocin （STZ）. The diabetic model rats were randomly divided into control group （0.9% NaC1）, low dose group （300 mg SCC.（kg body weight）-1） and high dose group （1200 mg SCC （kg body weight）-l）. Sodium chloride and SCC were intragastrically administered once a day for 35 d. Changes in fasting serum glucose and serum insulin content, oral glucose tolerance and liver and muscle glycogen content were routinely evaluated. Pancreas tissue and β-cells of islets were observed under both optical and transmission electronic microscope, respectively. The abundance of glucose metabolism-relating genes in gastrocnemius and epididymal adipose tissue was determined with either reverse transcription PCR （RT-PCR） or western blotting. Results showed that SCC significantly decreased fasting serum glucose content, improved glucose tolerance and increased serum insulin and glycogen content; repaired STZ-injured β-cells of diabetic rat, and increased the expression of phosphatidylinositol 3 kinase （PI（3）K）, protein kinase B （PKB） and glucose transporter 4 （Glut4） encoding protein in both gastroenemius and adipose tissue, and Glut4 encoding gene in peripheral tissue. Our findings demonstrated that SCC exerted an anti-hyperglycemic effect by repairing β-cells and promoting insulin-mediated signal transduction pathway in insulin-sensitive gastrocnemius and adipose tissue.
文摘Background Retinol binding protein 4 （RBP4）, as an adipocyte secreted cytokine, was recently found to be inversely correlated with expression of glucose transporter 4 （GLUT4） in insulin resistance （IR） state and to have an intimate relationship with IR and type 2 diabetes mellitus （T2DM）. The present study aimed to evaluate the anti-diabetic efficacy of cinnamaldehyde （Cin）, berberine （Ber）, and metformin （Met） as well as their impacts on the RBP4-GLUT4 system. Methods Rat models of T2DM were established by combination of intraperitoneal injection of low-dose streptozotocin and high fat diet induction. Rats were divided into five groups： the control group, the diabetes group, the diabetes＋Ber group, the diabetes＋Cin group, and the diabetes＋Met group. Western blotting was used to detect the serum or tissue RBP4 and GLUT4 protein levels. Results After treatment for four weeks, both Cin and Ber displayed significant hypolipidemic, hypoglycemic, and insulin sensitizing functions （P 〈0.01） compared with the control group. Their effects on lowering fasting plasma glucose （FPG）, low density lipoprotein-cholesterol （LDL-C） and homeostasis model assessment of insulin resistance （HOMA-IR） seem even better than that of Met. Cin and Ber markedly lowered serum RBP4 levels and up-regulated the expression of tissue GLUT4 protein, and Cin seemed more notable in affecting these two proteins. Conclusions Both Cin and Ber display an exciting anti-diabetic efficacy in this study and may be of great value for the treatment of type 2 diabetes. Their mechanisms involve the RBP4-GLUT4 system, during which the serum RBP4 levels are lowered and the expression of tissue GLUT4 protein is up-regulated.
基金Supported by a Grant from the Scientific Research Project of Hebei Provincial Administration for Traditional Chinese Medicine(Protective Effects and Mechanism of Extract from Fermented Buckwheat Flower and Leaf on Kidney in TypeⅡDiabetic db/db Mice,No.2017083)the Key Project Plan of Medical Science Research in Hebei Province in 2018(Protective Effects and Mechanism of Extract From Fermented Buckwheat Flower and Leaf on IsletβCells,No.201810736)。
文摘OBJECTIVE: To determine the efficacy of a fermented buckwheat flower and leaf extract(EFBFL) for the reduction of blood glucose and lipid dysregulation in spontaneously obese type 2 diabetic db/db mice, and to explore the possible mechanisms involved.METHODS: Forty 9-week-old male db/db mice were randomly allocated to a high-dose EFBFL group(EFBFL-H), a low-dose EFBFL group(EFBFL-L),a metformin hydrochloride positive control group(MEG), and a db/db control group(MG), and there was also a db/m negative control group(NCG)(n =10). Oral glucose tolerance tests(OGTT) were performed after 7 weeks of treatment. At the end of 8 weeks of treatment, random blood glucose(RBG),glycosylated hemoglobin(Hb Alc), fasting plasma glucose(FPG), fasting serum insulin(FINS), triglyceride(TG), serum total cholesterol(TC), free fatty acids(FFA), high-density lipoprotein-cholesterol, and low-density lipoprotein-cholesterol(LDL-c) were measured, the homeostasis model assessment-insulin resistance(HOMA-IR) was calculated. Immunohistochemistry and western blotting measured the expression of glucose transporter4(GLUT4) and peroxisome proliferator-activated receptor γ(PPAR-γ) by in skeletal muscle.RESULTS: The MG mice had a significantly increased in RBG, Hb Alc, the HOMA-IR level, the serum of TG, TC, LDL-c, but a decreased in glucose tolerance and the protein expression of GLUT4 and PPAR-γ compared with the NCG. Compared with the MG, EFBFL groups significantly decreased RBG, Hb Alc, and the HOMA-IR level, increased glucose tolerance. Meanwhile EFBFL groups reduced the serum TG, TC, and LDL-c in a dose-dependent manner. In addition, EFBFL increased the protein expression of GLUT4 and PPAR-γ in the skeletal muscle of db/db mice.There was significant difference between the MG group and EFBFL groups.CONCLUSION: These findings suggest that EFBFL has anti-diabetic effects in db/db mice, ameliorating glucose intolerance, lipid dysregulation, and insulin resistance.
