Facilitative glucose transporters (GLUT) are proteins that mediate glucose transmembrane transport in the form of facilitated diffusion, which play an important role in regulating cell energy metabolism. There are many breakthroughs in researches of facilitative GLUT in recent years. It has been known that there are 14 subtypes of facilitative GLUT with obvious tissue specificity in distribution and physiological function. In the present review, the tissue and cellular distribution, subcellular localization, expression regulation, physiological function and the relationship to diseases of facilitative GLUT subtypes were summarized, in order to further understand their physiological and pathophysiological significances.
Biological Transport ; Disease ; Energy Metabolism ; Glucose ; Glucose Transport Proteins, Facilitative ; physiology ; Humans

BACKGROUND: Malignant cells exhibit increased glycolytic metabolism, and in many cases increased glucose transporter gene expression. The authors hypothesized that GLUT1 glucose transporter expression is increased in gallbladder carcinoma, and the degree of expression might have prognostic significance. METHODS: To evaluate a possible prognostic factor, we studied the expression of GLUT1 glucose transporter by an immunohistochemical method in 56 gallbladder carcinomas from patients and we compared these results with established prognostic factors. RESULTS: Of the 56 cases, 34 (60.7%) were positive for GLUT1. The expression of GLUT1 was not associated with patient age, sex and histologic type. Whereas the expression of GLUT1 was significantly correlated with depth of tumor invasion and lymph node and distant metastases. CONCLUSIONS: GLUT1 glucose transporter expression is strongly associated with poor prognostic factors of the gallbladder carcinoma and the assessment of the extent of GLUT1 immunostaining identifies patient with poorer prognosis.
Gallbladder* ; Gene Expression ; Glucose Transport Proteins, Facilitative* ; Glucose* ; Humans ; Lymph Nodes ; Metabolism ; Neoplasm Metastasis ; Prognosis

OBJECTIVETo study the expression level and significance of glucose transporter 1 (Glut-1) in normal breast tissue, adenosis, adenoma and breast carcinoma.

METHODSA total of 147 cases of female breast tissue samples, including 92 cases of invasive ductal carcinoma, 26 cases of breast fibroadenoma, 24 cases of breast adenosis and 5 cases of normal breast tissues, were collected for quantitative detection of the expression of Glut-1 protein by immunohistochemistry (EnVision method) and Western blot, and its mRNA by reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTSIn normal breast tissue and benign lesions of the breast, Glut-1 was undetectable or only weakly detectable in cytoplasm of ductal and acinar epithelia. In contrast, the intensity of Glut-1 staining was significantly higher in invasive ductal carcinomas (P = 0.0002) with protein expression predominantly in cellular membrane and lesser in cytoplasm. Western blot and RT-PCR analyses showed that the expression of Glut-1 protein and mRNA were significantly increased in invasive ductal carcinoma than fibroadenoma (P =0.001 for protein; P <0.05 for mRNA) and adenosis (P =0.001 for protein; P < 0.05 for mRNA). There was a significant difference among groups (P = 0.0002 for protein; P = 0.0001 for mRNA).

CONCLUSIONSGlucose transport activity, as indicated by Glut-1 protein and its mRNA expression, significantly increases in breast carcinoma than non-cancerous lesions. The over-expression of Glut-1 in breast carcinoma is tightly coupled with tumor cell proliferation, invasion and metastasis, implying that Glut-1 may serve as a new marker in the early diagnosis and prognostication of breast malignancy as well as a new therapeutic target.

Breast Neoplasms ; metabolism ; Carcinoma, Ductal, Breast ; metabolism ; Female ; Gene Expression Regulation, Neoplastic ; Glucose ; physiology ; Glucose Transport Proteins, Facilitative ; genetics ; metabolism ; Glucose Transporter Type 1 ; genetics ; metabolism ; Humans ; Prognosis

Fanconi-Bickel syndrome is a rare autosomal recessive disorder caused by a mutation in the facilitative glucose transporter 2 gene (GLUT2 or SLC2A2 gene) that codes for the glucose transporter protein 2 expressed in hepatocytes, pancreatic beta-cells, enterocytes, and renal tubular cells. Mutation of this gene leads to defective carbohydrate metabolism, hepatomegaly, glucose intolerance, proximal renal tubular dysfunction, and hypophosphatemic rickets. We report a case of Fanconi-Bickel syndrome in an 18-year-old man who presented due to renal glycosuria; a mutation was identified in the GLUT2 gene (c.482C > A + c.1556G > A). To the best of our knowledge, unlike previous reports of Fanconi-Bickel syndrome, this case was relatively unusual in that it caused only mild clinical signs.
Carbohydrate Metabolism ; Enterocytes ; Fanconi Syndrome ; Glucose Intolerance ; Glucose Transport Proteins, Facilitative ; Glucose Transporter Type 2 ; Hepatocytes ; Hepatomegaly ; Hypophosphatemic Rickets, X-Linked Dominant

Fanconi-Bickel syndrome is a rare autosomal recessive disorder of the carbohydrate metabolism recently demonstrated to be caused by mutations in GLUT2, the gene for the glucose transporter protein 2 expressed in the liver, pancreatic beta islet-cells, intestine and kidney. Typical clinical and laboratory findings of Fanconi-Bickel syndrome are hepatomegaly secondary to glycogen accumulation, glucose and galactose intolerance, fasting hypoglycemia, a characteristic proximal tubular nephropathy and severe short stature. Several cases have been reported in other countries after Fanconi and Bickel in Switzerland first reported this syndrome in 1949. We experienced the first Korean case of Fanconi-Bickel syndrome in a neonate presented with hyperglycemia and hypergalactosemia that was initially diagnosed as transient neonatal diabetes mellitus and galactosemia. We also identified a novel mutation(K5X) in the GLUT2 gene.
Carbohydrate Metabolism ; Diabetes Mellitus* ; Fanconi Syndrome* ; Galactose ; Galactosemias* ; Glucose ; Glucose Transport Proteins, Facilitative ; Glycogen ; Hepatomegaly ; Humans ; Hyperglycemia ; Hypoglycemia ; Infant, Newborn ; Intestines ; Kidney ; Liver ; Switzerland

BACKGROUND/AIMS: Malignant cells exhibit increased glycolytic metabolism, and in many cases increased glucose transporter gene expression. We studied the expression of the glucose transporters in hepatocellular carcinoma(HCC) and intrahepatic cholangiocarcinoma(CC). also, examined the usefulness of Glut-1 glucose transporter in the discrimination of HCC from CC. METHODS AND RESULTS: 23 HCC, 15 CC and 8 normal liver tissues were investigated immunohistochemically with Glut-1 glucose transporter. Immunostaning was regarded as positive when more than 5% of cells were stained. Among 38 liver tumor cases, Glut-1 was stained in 15(40%). in 2(9%) of 23 HCC and in 13(87%) of 15 CC were positive.(P=0.001) In HCC, underlying cirrhosis, 18(78%) were negative.(P=0.04) Other prognostic factors: histologic type, lymph node metastasis, distant metastasis did not show any significant correlation. CONCLUSION: Differential diagnosis between HCC and CC could be made by Glut-1 glucose transporter expression
Carcinoma, Hepatocellular* ; Cholangiocarcinoma* ; Diagnosis, Differential ; Discrimination (Psychology) ; Fibrosis ; Gene Expression ; Glucose Transport Proteins, Facilitative* ; Glucose* ; Liver ; Lymph Nodes ; Metabolism ; Neoplasm Metastasis

BACKGROUND: Previous studies have shown that 17beta-estradiol activates AMP-activated protein kinase (AMPK) in rodent muscle and C2C12 myotubes and that acute 17beta-estradiol treatment rapidly increases AMPK phosphorylation possibly through non-genomic effects but does not stimulate glucose uptake. Here, we investigated whether 24-hour 17beta-estradiol treatment stimulated glucose uptake and regulated the expression of genes associated with glucose and energy metabolism through the genomic effects of estrogen receptor (ER) in C2C12 myotubes. METHODS: C2C12 myotubes were treated with 17beta-estradiol for 24 hours, and activation of AMPK, uptake of glucose, and expression of genes encoding peroxisome proliferator-activated receptor γ coactivator 1α, carnitine palmitoyltransferase 1β, uncoupling protein 2, and glucose transporter 4 were examined. Furthermore, we investigated whether AMPK inhibitor (compound C) or estrogen receptor antagonist (ICI182.780) treatment reversed 17beta-estradiol-induced changes. RESULTS: We found that 24-hour treatment of C2C12 myotubes with 17beta-estradiol stimulated AMPK activation and glucose uptake and regulated the expression of genes associated with glucose and energy metabolism. Treatment of C2C12 myotubes with the estrogen receptor antagonist (ICI182.780) reversed 17beta-estradiol-induced AMPK activation, glucose uptake, and changes in the expression of target genes. Furthermore, treatment with the AMPK inhibitor (compound C) reversed 17beta-estradiol-induced glucose uptake and changes in the expression of target genes. CONCLUSION: Our results suggest that 17beta-estradiol stimulates AMPK activation and glucose uptake and regulates the expression of genes associated with glucose and energy metabolism in C2C12 myotubes through the genomic effects of ER.
AMP-Activated Protein Kinases ; Carnitine O-Palmitoyltransferase ; Energy Metabolism ; Estrogens ; Glucose Transport Proteins, Facilitative ; Glucose ; Muscle Fibers, Skeletal ; Peroxisomes ; Phosphorylation ; Rodentia

PURPOSE: To characterize the relationship between serum estradiol levels and the expression of glucose transporter type 4 (Glut4) in the pubococcygeus and iliococcygeus muscles in female rats. METHODS: The muscles were excised from virgin rats during the metestrus and proestrus stages of the estrous cycle, and from sham and ovariectomized rats implanted with empty or estradiol benzoate–filled capsules. The expression of estrogen receptors (ERs) was inspected in the muscles at metestrus and proestrus. Relative Glut4 expression, glycogen content, and serum glucose levels were measured. Appropriate statistical tests were done to identify significant differences (P≤0.05). RESULTS: The pubococcygeus and iliococcygeus muscles expressed ERα and ERβ. Glut4 expression and glycogen content in the pubococcygeus muscle were higher at proestrus than at metestrus. No significant changes were observed in the iliococcygeus muscle. In ovariectomized rats, the administration of estradiol benzoate increased Glut4 expression and glycogen content in the pubococcygeus muscle alone. CONCLUSIONS: High serum estradiol levels increased Glut4 expression and glycogen content in the pubococcygeus muscle, but not in the iliococcygeus muscle.
Animals ; Benzoates ; Blood Glucose ; Capsules ; Estradiol* ; Estrous Cycle ; Female ; Glucose Transport Proteins, Facilitative* ; Glucose Transporter Type 4* ; Glucose* ; Glycogen ; Humans ; Metabolism ; Metestrus ; Muscles* ; Ovariectomy ; Pelvic Floor* ; Proestrus ; Rats* ; Receptors, Estrogen

Previous studies have shown that ginsenoside Rb1 (Rb1), one of active components in ginseng, can activate insulin signaling pathway and promote translocation of glucose transporters (GLUTs) to increase glucose uptake in adipocytes. However, the effect of Rb1 on the expressions of GLUTs remains unknown. In this study, the effects of Rb1 on GLUT1 and GLUT4 were observed in 3T3-L1 adipocytes and epididymal adipose tissue of db/db obese diabetic mice. Male db/db mice were treated with Rb1 by intraperitoneal injection at the dosage of 20 mg x kg(-1) for 14 d. Rb1 reduced HOMA-IR significantly (P < 0.05, n = 5), and FBG and FINS sowed declining trend after treatment with Rb1. Rb1 recovered the expressions of GLUT1 and GLUT4 and phosphorylation of AKT in adipose tissue of db/db mice. In vitro, glucose consumption in 3T3-L1 adipocytes treated with 10 micromol x L(-1) Rb1 for 24 h was elevated (P < 0.05, n=3), and mRNA of GLUT1 and GLUT4 were up-regulated (P < 0.05, n=3) and proteins of GLUT1 and GLUT4 were also increased. AKT was activated in adipocytes treated with Rb1 for 3 h. It can be concluded that ginsenoside Rb1 can up-regulate the expression of GLUTs in adipose tissue, in addition to activate insulin signalling pathway, which may partially account for its insulin sensitizing activity and regulating effect of glucose metabolism.
3T3 Cells ; Adipocytes ; drug effects ; Animals ; Cell Line ; Diabetes Mellitus, Experimental ; metabolism ; Ginsenosides ; pharmacology ; Glucose ; metabolism ; Glucose Transport Proteins, Facilitative ; metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Inbred NOD ; Up-Regulation ; drug effects

D-glucose is an essential fuel for metabolism in mammalian cells and the predominant fuel source for the brain. Transport of glucose across tissue barriers is mediated by stereospecific transporter proteins. Glut-1 is a major glucose transporter expressed on vascular endothelial cells comprising the blood brain barrier and is responsible for glucose entry into the brain. Impaired glucose transport across the blood brain barrier results in Glut-1 deficiency syndrome(DS). It is caused by haploinsufficiency of the blood brain barrier hexose carrier. Heterozygous mutations or hemizygosity of the GLUT-1 gene cause Glut-1 DS. It is characterized by infantile seizures refractory to anticonvulsants, developmental delay, acquired microcephaly, spasticity, ataxia, opsoclonus and other paroxysmal neurological phenomena, often occurring prior to meals. The diagnosis of Glut-1 DS is established in neurologically impaired patients with reduced cerebrospinal glucose concentration(hypoglycorrhachia) and lactate concentration in the absence of hypoglycemia. Decreased 3-O-methyl-D-glucose uptake in erythrocytes also supports the diagnosis of Glut-1 DS. Several treatment strategies have been pursued, none optimal, as it relates to the developmental encephalopahty associated with this clinical syndrome. Ketogenic diet has been effective in controlling seizures but has had little measurable effects on the associated cognitive impairments and behavioral disturbance. Current treatment is inadequate, and future studies should be directed at the mechanisms designed to upreglulate GLUT-1 expression, thereby increasing residual Glut-1 activity to 75 to 100%.
3-O-Methylglucose ; Anticonvulsants ; Ataxia ; Blood-Brain Barrier ; Brain ; Diagnosis ; Endothelial Cells ; Epilepsy ; Erythrocytes ; Glucose Transport Proteins, Facilitative* ; Glucose Transporter Type 1* ; Glucose* ; Haploinsufficiency ; Humans ; Hypoglycemia ; Ketogenic Diet ; Lactic Acid ; Meals ; Metabolism ; Microcephaly ; Muscle Spasticity ; Ocular Motility Disorders ; Seizures