1
|
Maldonado-Cervantes MI, Galicia OG, Moreno-Jaime B, Zapata-Morales JR, Montoya-Contreras A, Bautista-Perez R, Martinez-Morales F. Autocrine modulation of glucose transporter SGLT2 by IL-6 and TNF-α in LLC-PK(1) cells. J Physiol Biochem 2012; 68:411-20. [PMID: 22351116 DOI: 10.1007/s13105-012-0153-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 01/31/2012] [Indexed: 10/28/2022]
Abstract
We determined in cultured kidney epithelial cells (LLC-PK(1)) the effects of high glucose, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) on mRNA and protein expression of the renal glucose transporters SGLT1 and SGLT2. Cultured monolayers were incubated with similar concentrations of IL-6 and TNF-α to those produced by LLC-PK(1) in the presence of 20 mM glucose. Confluent monolayers with either 5 (controls, C) or 20 mM glucose (high glucose, HG) were incubated in the presence of 5 mM glucose, 20 mM glucose, 10 pg/ml IL-6, or TNF-α alone or in combination. Separate groups with IL-6 and TNF-α were incubated with antibodies to their respective receptors. HG induced an increased SGLT1 mRNA at 48 h (p<0.05 vs. C) and protein expression in 120 h (p<0.05 vs. C). HG also induced an increased SGLT2 mRNA at 72 and 96 h (P<0.05 vs. C) and SGLT2 protein expression at 120 h (p<0.05 vs. C). In C, 10 pg/ml IL-6 or TNF-α did not modify SGLT1 mRNA (n.s vs. in the absence of cytokines). In contrast, cytokines induced an increased expression of SGLT1 protein at 120 h (p<0.05 vs. in the absence of cytokines), and SGLT2 mRNA and protein were increased at 96 and 120 h, respectively (p<0.05 vs. in absence of cytokines). No changes were observed when cells were incubated with cytokines and HG (n.s vs. C). In conclusion, this study showed that SGLT2 increased in the presence of IL-6 and TNF-α, indicating an autocrine modulation of the expression of this transporter by cytokines.
Collapse
Affiliation(s)
- M I Maldonado-Cervantes
- Department of Pharmacology, School of Medicine, Universidad Autonoma de San Luis Potosi, San Luis Potosi, Mexico
| | | | | | | | | | | | | |
Collapse
|
2
|
Sabino-Silva R, Mori R, David-Silva A, Okamoto M, Freitas H, Machado U. The Na+/glucose cotransporters: from genes to therapy. Braz J Med Biol Res 2010; 43:1019-26. [DOI: 10.1590/s0100-879x2010007500115] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 10/18/2010] [Indexed: 11/22/2022] Open
|
3
|
Schmidt C, Höcherl K, Bucher M. Regulation of renal glucose transporters during severe inflammation. Am J Physiol Renal Physiol 2006; 292:F804-11. [PMID: 17032938 DOI: 10.1152/ajprenal.00258.2006] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Severe sepsis is accompanied by acute renal failure (ARF) with renal tubular dysfunction and glucosuria. In this study, we aimed to determine the regulation of renal tubular glucose transporters during severe experimental inflammation. Male C57BL/6J mice were injected with LPS or proinflammatory cytokines, and renal perfusion, glomerular filtration rate (GFR), fractional glucose excretion, and expression of tubular glucose transporters were determined. We found a decreased plasma glucose concentration with impaired renal tissue perfusion and GFR and increased fractional glucose excretion associated with decreased expression of SGLT2, SGLT3, and GLUT2 after LPS injection. Similar alterations were observed after application of TNF-alpha, IL-1beta, IL-6, or IFN-gamma. To clarify the role of proinflammatory cytokines, we performed LPS injections in knockout mice with deficiencies for TNF-alpha, IL-1 receptor type 1, IFN-gamma, or IL-6 as well as LPS injections in glucocorticoid-treated wild-type mice. LPS-induced alterations of glucose transporters also were present in single-cytokine knockout mice. In contrast, glucocorticoid treatment clearly attenuated LPS-induced changes in renal glucose transporter expression and improved GFR and fractional glucose excretion. LPS-induced decrease of renal perfusion was not improved by glucocorticoids, indicating a minor role of ischemia in the development of septic renal dysfunction. Our results demonstrate modifications of tubular glucose transporters during severe inflammation that are probably mediated by proinflammatory cytokines and account for the development of ARF with increased fractional glucose excretion. In addition, our findings provide an explanation why single anti-cytokine strategies fail in the therapy of septic patients and contribute to an understanding of the beneficial effects of glucocorticoids on septic renal dysfunction.
Collapse
Affiliation(s)
- Christoph Schmidt
- Dept. of Anesthesiology, Regensburg University, 93042 Regensburg, Germany
| | | | | |
Collapse
|
4
|
Schaan BD, Irigoyen MC, Lacchini S, Moreira ED, Schmid H, Machado UF. Sympathetic modulation of the renal glucose transporter GLUT2 in diabetic rats. Auton Neurosci 2005; 117:54-61. [PMID: 15620570 DOI: 10.1016/j.autneu.2004.11.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2004] [Revised: 10/28/2004] [Accepted: 11/02/2004] [Indexed: 10/26/2022]
Abstract
We have previously shown that the abolition of renal sympathetic nervous activity (RSNA) can influence cortical GLUT1 expression in diabetic rats. However, no study has examined the effects of nervous activity on expression of GLUT2, the major glucose transporter in proximal renal tubules, which participates in renal glucose handling. The aim of this study was to determine whether sympathetic activity modulates renal GLUT2 content. We studied diabetic and nondiabetic rats with normal, low, or high RSNA. The low-RSNA experiment used four groups of Wistar male rats: Wistar sham-operated, Wistar renal-denervated, Diabetic sham-operated, and Diabetic renal-denervated. The high-RSNA experiment used four groups of Wistar-Kyoto male rats: WKY (control), WKY-Diabetic, SHR (spontaneously hypertensive rats), and SHR-Diabetic. Renal denervation was confirmed by a decrease in intrarenal norepinephrine levels and sympathetic hyperactivity, by measurement of RSNA. Western blotting was used to determine the renal cortical GLUT2 protein content, and 24-h urinary sodium and glucose levels were also evaluated. Compared with controls (Wistar and WKY), diabetes increased the GLUT2 protein content in normal-RSNA Diabetics (47%) and WKY-Diabetics (83%). The renal denervation-induced decrease in RSNA reduced the GLUT2 content in both normal and diabetic rats (-21% and -15%, respectively). Compared to WKY rats, SHR presented elevated RSNA and also showed an increase in renal GLUT2 content (17%). Diabetes caused a major increase in GLUT2 protein (52%) in the SHR. These results demonstrate a direct relationship between RSNA and GLUT2 levels; they also reveal an additive effect of sympathetic hyperactivity and diabetes on GLUT2 expression, suggesting a new mechanism for modulating protein expression in renal tissue.
Collapse
Affiliation(s)
- Beatriz D'Agord Schaan
- Instituto de Cardiologia do RS/Fundação Universitária de Cardiologia, Porto Alegre, RS, CEP 90620-001, Brazil.
| | | | | | | | | | | |
Collapse
|
5
|
Fladeby C, Skar R, Serck-Hanssen G. Distinct regulation of glucose transport and GLUT1/GLUT3 transporters by glucose deprivation and IGF-I in chromaffin cells. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1593:201-8. [PMID: 12581864 DOI: 10.1016/s0167-4889(02)00390-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Effects of prolonged metabolic (glucose deprivation) and hormonal [insulin-like growth factor I (IGF-I)] challenge on regulation of glucose transporter (GLUT) expression, glucose transport rate and possible signaling pathways involved were studied in the neuroendocrine chromaffin cell. The results show that bovine chromaffin cells express both GLUT1 and GLUT3. Glucose deprivation and IGF-I activation led to an elevation of GLUT1 and GLUT3 mRNA, the strongest effect being that of IGF-I on GLUT3 mRNA. Both types of stimulus increased the GLUT1 protein content in a cycloheximide (CHX)-sensitive manner, and the glucose transport rate was elevated by 3- to 4-fold after 48 h under both experimental conditions. IGF-I-induced glucose uptake was totally suppressed by CHX. In contrast, only approximately 50% of transport activation in glucose-deprived cells was sensitive to the protein synthesis inhibitor. Specific inhibitors of mTOR/FRAP and p38 MAPK each partially blocked IGF-I-stimulated glucose transport, but had no effect on transport rate in glucose-deprived cells. The results are consistent with IGF-I-activated transport being completely dependent on new GLUT protein synthesis while the enhanced transport in glucose-deprived cells was partially achieved independent of new synthesis of proteins, suggesting a mechanism relying on preexisting transporters.
Collapse
Affiliation(s)
- Cathrine Fladeby
- Department of Physiology, University of Bergen, 5009, Bergen, Norway.
| | | | | |
Collapse
|
6
|
Aft RL, Zhang FW, Gius D. Evaluation of 2-deoxy-D-glucose as a chemotherapeutic agent: mechanism of cell death. Br J Cancer 2002; 87:805-12. [PMID: 12232767 PMCID: PMC2364258 DOI: 10.1038/sj.bjc.6600547] [Citation(s) in RCA: 201] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2001] [Revised: 06/05/2002] [Accepted: 07/22/2002] [Indexed: 12/28/2022] Open
Abstract
Nutrient deprivation has been shown to cause cancer cell death. To exploit nutrient deprivation as anti-cancer therapy, we investigated the effects of the anti-metabolite 2-deoxy-D-glucose on breast cancer cells in vitro. This compound has been shown to inhibit glucose metabolism. Treatment of human breast cancer cell lines with 2-deoxy-D-glucose results in cessation of cell growth in a dose dependent manner. Cell viability as measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide conversion assay and clonogenic survival are decreased with 2-deoxy-D-glucose treatment indicating that 2-deoxy-D-glucose causes breast cancer cell death. The cell death induced by 2-deoxy-D-glucose was found to be due to apoptosis as demonstrated by induction of caspase 3 activity and cleavage of poly (ADP-ribose) polymerase. Breast cancer cells treated with 2-deoxy-D-glucose express higher levels of Glut1 transporter protein as measured by Western blot analysis and have increased glucose uptake compared to non-treated breast cancer cells. From these results we conclude that 2-deoxy-D-glucose treatment causes death in human breast cancer cell lines by the activation of the apoptotic pathway. Our data suggest that breast cancer cells treated with 2-deoxy-D-glucose accelerate their own demise by initially expressing high levels of glucose transporter protein, which allows increased uptake of 2-deoxy-D-glucose, and subsequent induction of cell death. These data support the targeting of glucose metabolism as a site for chemotherapeutic intervention by agents such as 2-deoxy-D-glucose.
Collapse
Affiliation(s)
- R L Aft
- Department of Surgery, Alvin J. Siteman Cancer Center, Washington University School of Medicine, St. Louis, Missouri, MO 63110, USA.
| | | | | |
Collapse
|
7
|
McMahon RJ, Hwang JB, Frost SC. Glucose deprivation does not affect GLUT1 targeting in 3T3-L1 adipocytes. Biochem Biophys Res Commun 2000; 273:859-64. [PMID: 10891337 DOI: 10.1006/bbrc.2000.2985] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have previously demonstrated that glucose deprivation alters the glycosylation of the GLUT1 glucose transporter in 3T3-L1 adipocytes. Many aberrantly glycosylated proteins are retained in the endoplasmic reticulum by interaction with chaperones. Herein, we use three independent procedures to show that GLUT1 is targeted to the plasma membrane, despite alterations in glycosylation. While earlier experiments revealed that plasma membrane targeting of aglyco GLUT 1 transporter was significantly reduced, our data show for the first time that altered glycosylation provides sufficient information to drive appropriate trafficking.
Collapse
Affiliation(s)
- R J McMahon
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32610, USA
| | | | | |
Collapse
|
8
|
Carver FM, Shibley IA, Miles DS, Pennington JS, Pennington SN. Increased intracellular localization of brain GLUT-1 transporter in response to ethanol during chick embryogenesis. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:E750-9. [PMID: 10516136 DOI: 10.1152/ajpendo.1999.277.4.e750] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fetal exposure to ethanol is associated with growth retardation of the developing central nervous system. We have previously described a chick model to study the molecular mechanism of ethanol effects on glucose metabolism in ovo. Total membrane fractions were prepared from day 4, day 5, and day 7 chick embryos exposed in ovo to ethanol or to vehicle. By Western blotting analysis, ethanol exposure caused a mean 7- to 10-fold increase in total GLUT-1 and a 2-fold increase in total GLUT-3. However, glucose uptake by ethanol-treated cells increased by only 10%. Analysis of isolated plasma (PM) and intracellular (IM) membranes from day 5 cranial tissue revealed a mean 25% decrease in GLUT-1 in the PM and a 66% increase in the IM in the ethanol group vs. control. The amount of PM GLUT-3 was unchanged but that of IM GLUT-3 was significantly decreased. The data suggest that GLUT-3 cell surface expression may be resistant to the suppressive effects of ethanol in the developing brain of ethanol-treated embryos. The overall increase in GLUT-1 may reflect a deregulation of the transporter induced by ethanol exposure. The increased IM localization and decreased amount of PM GLUT-1 may be a mechanism used by the ethanol-treated cell to maintain normal glucose uptake despite the overall increased level of the transporter.
Collapse
Affiliation(s)
- F M Carver
- Department of Biochemistry, School of Medicine, East Carolina University, Greenville, North Carolina 27858, USA.
| | | | | | | | | |
Collapse
|
9
|
Viñals F, Gross A, Testar X, Palacín M, Rösen P, Zorzano A. High glucose concentrations inhibit glucose phosphorylation, but not glucose transport, in human endothelial cells. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1450:119-29. [PMID: 10354504 DOI: 10.1016/s0167-4889(99)00035-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Glucose uptake is autoregulated in a variety of cell types and it is thought that glucose transport is the major step that is subjected to control by sugar availability. Here, we examined the effect of high glucose concentrations on the rate of glucose uptake by human ECV-304 umbilical vein-derived endothelial cells. A rise in the glucose concentration in the medium led a dose-dependent decrease in the rate of 2-deoxyglucose uptake. The effect of high glucose was independent of protein synthesis and the time-course analysis indicated that it was relatively slow. The effect was not due to inhibition of glucose transport since neither the expression nor the subcellular distribution of the major glucose transporter GLUT1, nor the rate of 3-O-methylglucose uptake was affected. The total in vitro assayed hexokinase activity and the expression of hexokinase-I were similar in cells treated or not with high concentrations of glucose. In contrast, exposure of cells to a high glucose concentration caused a marked decrease in phosphorylated 2-deoxyglucose/free 2-deoxyglucose ratio. This suggests the existence of alterations in the rate of in vivo glucose phosphorylation in response to high glucose. In summary, we conclude that ECV304 human endothelial cells reduce glucose utilization in response to enhanced levels of glucose in the medium by inhibiting the rate of glucose phosphorylation, rather than by blocking glucose transport. This suggests a novel metabolic effect of high glucose on cellular glucose utilization.
Collapse
Affiliation(s)
- F Viñals
- Departament de Bioquimica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 645, 08028, Barcelona, Spain
| | | | | | | | | | | |
Collapse
|
10
|
Howard RL. Down-regulation of glucose transport by elevated extracellular glucose concentrations in cultured rat aortic smooth muscle cells does not normalize intracellular glucose concentrations. THE JOURNAL OF LABORATORY AND CLINICAL MEDICINE 1996; 127:504-15. [PMID: 8621988 DOI: 10.1016/s0022-2143(96)90068-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Vascular disease is a prominent complication of diabetes mellitus, and hyperglycemia has been implicated as a risk factor for the development of these vascular complications. It has previously been suggested that down-regulation of glucose transport in response to hyperglycemia might serve a protective role by decreasing intracellular glucose concentrations. In the present study, regulation of glucose transport by extracellular glucose concentrations was investigated in cultured rat vascular smooth muscle cells (VSMCs). Confluent quiescent VSMCs were exposed to medium containing either normal (5 mmol/L) or elevated (20 mmol/L) extracellular glucose concentrations for 24 hours. VSMCs exposed to elevated extracellular glucose concentrations (with or without serum) for 24 hours exhibited significant decreases in 2-deoxyglucose (2-DG) and D-glucose uptake rates. This decreased glucose transport was associated with a decrease in the Vmax of D-glucose transport without a change in KM. In the absence of serum, a decrease in the quantity of GLUT-1 transport protein at the plasma membrane was noted in cells exposed to elevated extracellular glucose concentrations for 24 hours. Intracellular glucose concentrations were estimated by using two methods, and the results revealed significantly higher intracellular glucose concentrations in the cells exposed to elevated extracellular glucose concentrations for 24 hours. These results suggest that down-regulation of glucose transport in cultured VSMCs exposed to elevated extracellular glucose concentrations for 24 hours does not occur to an extent that normalizes intracellular glucose concentrations. This prolonged increase in intracellular glucose concentrations and the potential associated toxicity may explain the increased incidence of vascular complications in patients with diabetes mellitus.
Collapse
Affiliation(s)
- R L Howard
- Department of Medicine, Indiana University School of Medicine, Wishard Memorial Hospital, Indianapolis 46202-2879, USA
| |
Collapse
|
11
|
McMahon RJ, Frost SC. Glycogen: a carbohydrate source for GLUT-1 glycosylation during glucose deprivation of 3T3-L1 adipocytes. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 270:E640-5. [PMID: 8928771 DOI: 10.1152/ajpendo.1996.270.4.e640] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In 3T3-L1 adipocytes, the glycosylation of the GLUT-1 transporter is altered beyond 12 h of glucose deprivation. To determine whether glycogen degradation provides substrate for normal protein glycosylation during this delay, we measured the glycogen content of 3T3-L1 adipocytes. From an initial value of 0.537 +/- 0.097 mumol glucose/10(6) cells, glycogen was depleted in a time-dependent manner in response to glucose deprivation, exhibiting a half-time of 6 h. Surprisingly, fructose did not prevent glycogen depletion. However, in such glycogen-depleted adipocytes, the alteration of GLUT-1 glycosylation in response to glucose deprivation was more rapid than in normal adipocytes. Chinese hamster ovary (CHO) cells, which synthesize abbreviated dolichol-linked oligosaccharides within minutes of glucose deprivation (J. I. Rearick, A. Chapman, and S. Kornfeld. J. Biol. Chem. 256: 6255-6261, 1981), contained only 1% of the level of glycogen found in 3T3-L1 adipocytes. Glycosylation of GLUT-1 was altered in CHO cells within 3 h of glucose deprivation. These data demonstrate that, during glucose stress, glycogen may serve as a buffer for oligosaccharide biosynthesis and provide a potential explanation for varying sensitivities of different cell types to glucose deprivation.
Collapse
Affiliation(s)
- R J McMahon
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville 32610, USA
| | | |
Collapse
|
12
|
Zheng Q, Levitsky LL, Mink K, Rhoads DB. Glucose regulation of glucose transporters in cultured adult and fetal hepatocytes. Metabolism 1995; 44:1553-8. [PMID: 8786723 DOI: 10.1016/0026-0495(95)90074-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
GLUT2 is the major glucose transporter of adult hepatocytes. In vivo, membrane GLUT1 is localized to a ring of perivenous cells and increases slightly after fasting or insulin deprivation. GLUT1 also increases in vitro after prolonged culture of isolated adult hepatocytes. We have previously shown that GLUT1 mRNA, protein, and activity are present in the rat fetal hepatocyte, and that both GLUT1 and GLUT2 are important for the pattern of glucose transport in the fetal hepatocyte. We tested the hypothesis that the hypothesis that the postnatal increase in circulating glucose is one of the regulators of the changed pattern of GLUT1 and GLUT2 in the hepatocyte after the fetal to neonatal transition. Fetal and adult rat hepatocytes were cultured for 45 hours in supplemented Dulbecco's modified Eagle's medium at glucose concentrations of 1, 8.3, or 30 mmol/L. Culture at 8.3 and 30 mmol/L glucose diminished GLUT1 mRNA levels were lower in adult versus fetal hepatocyte cultures at 8.3 and 30 mmol/L (P < .05). Similarly, GLUT1 protein levels were significantly diminished in hepatocytes cultured at higher medium glucose (P < .05 for fetal cells at 30 v 1 mmol/L; P < .05 for adult cells at 8.3 and 30 v 1 mmol/L). GLUT2 mRNA abundance was enhanced by medium glucose in adult hepatocytes (P < .05 at 8.3 and 30 v 1 mmol/L) and was unchanged by medium glucose in fetal hepatocytes. In contrast, GLUT2 protein level was unchanged by medium glucose in adult hepatocytes, and was diminished at 30 mmol/L as compared with mmol/L glucose in fetal hepatocytes (P < .05). In confirmation of these findings, uptake of 2-deoxyglucose (2-DOG) by fetal hepatocytes was significantly diminished after culture in 8.3 or 30 mmol/L glucose versus 1 mmol/L glucose (P < .05 and < .01, respectively). These studies confirm that the fetal hepatocyte glucose transporter pattern could be maintained in part by low fetal portal glucose levels. However, the resistance of the fetal hepatocyte glucose transporter pattern as compared with that of the adult hepatocyte to the effects of hyperglycemia suggests additional undefined control mechanisms.
Collapse
Affiliation(s)
- Q Zheng
- Pediatric Endocrine Unit, Massachusetts General Hospital
| | | | | | | |
Collapse
|
13
|
Haber RS, Wilson CM, Weinstein SP, Pritsker A, Cushman SW. Thyroid hormone increases the partitioning of glucose transporters to the plasma membrane in ARL 15 cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1995; 269:E605-10. [PMID: 7573440 DOI: 10.1152/ajpendo.1995.269.3.e605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The stimulation of glucose transport by 3,5,3'-triiodo-L-thyronine (T3) in the liver-derived ARL 15 cell line is only partly attributable to increased GLUT-1 glucose transporter gene expression. To test the hypothesis that T3 increases the partitioning of GLUT-1 to the cell surface, we quantitated surface GLUT-1 using the photolabel ATB-[3H]BMPA. In control cells only approximately 20% of total cellular GLUT-1 was present at the cell surface. T3 treatment (100 nM) for 6 h increased the rate of 2-deoxy-[3H]glucose (2-DG) uptake by 30, 92, and 95% in three experiments and increased surface GLUT-1 photolabeling by 17, 81, and 72%, respectively, with no increase in total cellular GLUT-1. T3 treatment for 48 h increased 2-DG uptake by 143, 172, and 216% in three experiments and increased cell surface GLUT-1 photolabeling by 88, 161, and 184%, respectively, with smaller increases in total cellular GLUT-1. T3 treatment for 48 h thus increased the fraction of cellular GLUT-1 at the plasma membrane from 21 +/- 2 to 35 +/- 3% (SE). We conclude that most of the early (6-h) stimulation of glucose transport by T3 in ARL 15 cells is mediated by an increase in the partitioning of GLUT-1 to the plasma membrane. With more chronic T3 treatment (48 h), the enhanced surface partitioning of GLUT-1 is persistent and is superimposed on an increase in total cellular GLUT-1, accounting for a further increase in glucose transport.
Collapse
Affiliation(s)
- R S Haber
- Department of Medicine, Mount Sinai School of Medicine, New York, New York 10029, USA
| | | | | | | | | |
Collapse
|
14
|
McMahon RJ, Frost SC. Nutrient control of GLUT1 processing and turnover in 3T3-L1 adipocytes. J Biol Chem 1995; 270:12094-9. [PMID: 7744857 DOI: 10.1074/jbc.270.20.12094] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Metabolic labeling and immunoprecipitation were used to analyze the glucose-dependent regulation of GLUT1 synthesis, processing, and turnover in a murine adipocyte cell line. Metabolically labeled GLUT1 from control cells migrated as a 46-kDa protein, while GLUT1 from cells deprived of glucose for more than 12 h migrated as a 37-kDa protein. On the basis of tunicamycin sensitivity, both GLUT1 species arose from a common protein migrating at 36 kDa. In addition, the rate of synthesis of GLUT1 in control and glucose-deprived cells was similar. In short pulse-chase experiments, we distinguished two species arising from the core GLUT1 protein in control cells; an intermediate and the mature 46-kDa species. In contrast, only one glycoform, the 37-kDa species, arose from the core protein in glucose-deprived cells, which was not further processed in either the presence or absence of glucose. Although 12-18 h of glucose deprivation were required to affect GLUT1 glycosylation, glucose-deprived cells quickly recovered the ability to correctly glycosylate GLUT1 upon the readdition of glucose (t1/2 < 1 h). GLUT1 in control adipocytes exhibited a half-life of approximately 14 h, while that in glucose-deprived adipocytes was greater than 50 h. This effect was readily reversed upon the readdition of glucose. In total, these data show that glucose deprivation alters both the processing (glycosylation) and turnover (degradation) of GLUT1. These results are discussed in light of transport function.
Collapse
Affiliation(s)
- R J McMahon
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville 32610, USA
| | | |
Collapse
|
15
|
Lu Z, Xia L, Mesmer OT, Lo TC. Use of hexose transport mutants to examine the expression and properties of the rat myoblast GLUT 1 transport process. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1234:155-65. [PMID: 7696290 DOI: 10.1016/0005-2736(94)00279-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Rat L6 myoblasts were recently shown to possess the GLUT 1, 3 and 4 transporters, and not the GLUT 2 isoform [1]. This investigation examined the expression and properties of the GLUT 1 isoform. GLUT 1 transcript level was significantly reduced in cells grown at high densities and during myogenic differentiation. A comparison of the GLUT 1 and 4 transcript levels in myogenesis-competent and impaired cells revealed an inverse relationship between these two isoforms. This relationship was confirmed by studies using two independent spontaneous GLUT 3- GLUT 4- mutants, M1 and M3. These mutants possessed very high level of the GLUT 1 isoform, but negligible amount of the GLUT 3 and 4 isoforms. GLUT 1 expression was also subject to positive regulation. Glucose starvation was found to increase not only the levels of the GLUT 1 transcript and transporter, but also the intrinsic activity of the GLUT 1 transporter. Studies with M1 and M3 mutants revealed that the GLUT 1 transporter was not functional in glucose-grown cells, even though it was present at a very high level in the plasma membrane. This transporter became functional when cells were starved for glucose. The functional GLUT 1 transporter had an apparent Km value of around 0.9 mM, and was sensitive to cytochalasin B, phloretin, phlorizin and pCMBS.
Collapse
Affiliation(s)
- Z Lu
- Department of Biochemistry, University of Western Ontario, London, Canada
| | | | | | | |
Collapse
|
16
|
Honkanen RA, McBath H, Kushmerick C, Callender GE, Scarlata SF, Fenstermacher JD, Haspel HC. Barbiturates inhibit hexose transport in cultured mammalian cells and human erythrocytes and interact directly with purified GLUT-1. Biochemistry 1995; 34:535-44. [PMID: 7819247 DOI: 10.1021/bi00002a019] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Barbiturates reduce cerebral blood flow, metabolism, and Glc transfer across the blood-brain barrier. The effect of barbiturates on hexose transport in cultured mammalian cell lines and human erythrocytes was studied. Pentobarbital inhibits [3H]-2-dGlc uptake in 3T3-C2 murine fibroblasts by approximately 95% and approximately 50% at 10 and 0.5 mM, respectively. Uptake of [3H]-2-dGlc is linear with time in the presence or absence of pentobarbital, and the percent inhibition is constant. This suggests that hexose transport, not phosphorylation, is inhibited by barbiturates. Inhibition by pentobarbital of hexose transport in 3T3-C2 cells is rapid (< 1 min), is not readily reversible, is not altered by the presence of albumin [1% (w/v)], and is independent of temperature (4-37 degrees C) and the level of cell surface GLUT-1. The IC50's for inhibition of hexose transport in 3T3-C2 cells by pentobarbital, thiobutabarbital, and barbital are 0.8, 1.0, and 4 mM, respectively. This is consistent with both the Meyer-Overton rule and the pharmacology of barbiturates. Neither halothane (< or = 10 mM) nor ethanol [< or = 0.4% (v/v)] significantly inhibits hexose transport. Inhibition by pentobarbital (0.5 mM) of [3H]-2-dGlc uptake by 3T3-C2 cells decreases the apparent Vmax (approximately 50%) but does not alter the apparent Km (approximately 0.5 mM). Inhibition of hexose transport by barbiturates, but not ethanol [< or = 0.4% (v/v)], is also observed in human erythrocytes and four other cultured mammalian cell lines. Pentobarbital quenches (Qmax approximately 75%) the intrinsic fluorescence of purified and reconstituted GLUT-1 (Kd approximately 3 mM). Quenching is independent of Glc occupancy, is unchanged by mild proteolytic inactivation, and does not appear to directly involve perturbations of the lipid bilayer. We propose that barbiturates can interact directly with GLUT-1 and inhibit the intrinsic activity of the carrier. Glc crosses the blood-brain barrier primarily via the GLUT-1 of the endothelial cells of cerebral capillaries. Partial inhibition of this process by barbiturates may be of significance to cerebral protection.
Collapse
Affiliation(s)
- R A Honkanen
- Department of Anesthesiology, Henry Ford Hospital, Detroit, Michigan 48202
| | | | | | | | | | | | | |
Collapse
|
17
|
Nagamatsu S, Sawa H, Inoue N, Nakamichi Y, Takeshima H, Hoshino T. Gene expression of GLUT3 glucose transporter regulated by glucose in vivo in mouse brain and in vitro in neuronal cell cultures from rat embryos. Biochem J 1994; 300 ( Pt 1):125-31. [PMID: 8198523 PMCID: PMC1138133 DOI: 10.1042/bj3000125] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
This study was designed to determine whether glucose regulates the gene expression of glucose transporter GLUT3 in neurons. We examined the regulation of GLUT3 mRNA by glucose in vivo in mouse brain and in vitro by using neuronal cultures from rat embryos. Hypoglycaemia (< 30 mg/dl), produced by 72 h of starvation, increased GLUT3 mRNA in mouse brain by 2-fold. Hybridization studies in situ demonstrated that hypoglycaemia-induced increases in GLUT3 mRNA expression were observed selectively in brain regions including the hippocampus, dentate gyrus, cerebral cortex and piriform cortex, but not the cerebellum. Primary neuronal cultures from rat embryos deprived of glucose for 48 h also showed an increase (4-fold over control) in GLUT3 mRNA, indicating that glucose can directly regulate expression of GLUT3 mRNA. In contrast with hypoglycaemia, hyperglycaemia produced by streptozotocin did not alter the expression of GLUT3 mRNA. We also confirmed previous findings that hypoglycaemia increases GLUT1 mRNA expression in brain. The increase in GLUT1 expression was probably limited to the blood-brain barrier in vivo, since GLUT1 mRNA could not be detected in neurons of the mouse cerebrum. Thus we conclude that up-regulation of neuronal GLUT3 in response to glucose starvation represents a protective mechanism against energy depletion in neurons.
Collapse
Affiliation(s)
- S Nagamatsu
- Department of Biochemistry, Kyorin University School of Medicine, Tokyo, Japan
| | | | | | | | | | | |
Collapse
|
18
|
Ortiz PA, Haspel HC. Differential control of the functional cell surface expression and content of hexose transporter GLUT-1 by glucose and glucose metabolism in murine fibroblasts. Biochem J 1993; 295 ( Pt 1):67-72. [PMID: 8216241 PMCID: PMC1134821 DOI: 10.1042/bj2950067] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The present paper evaluates the contributions of glucose and its metabolites to the post-translational regulation of hexose transport and GLUT-1 content in murine fibroblasts. The effects of 3-O-methylglucose, a nearly non-metabolizable glucose analogue, on 2-deoxyglucose-uptake, cell-surface expression and content of GLUT-1, glucose 6-phosphate levels, and phosphoglucose isomerase (PGI) and hexokinase activities of murine fibroblasts were compared with those of glucose and fructose. Glucose (EC50 approximately 6 mM) or 3-O-methylglucose (EC50 approximately 12 mM), which are substrates of GLUT-1, but not fructose, which is not transported by GLUT-1, are able to prevent the glucose-deprivation-induced increases in both hexose transport and cell-surface expression of GLUT-1. In contrast, glucose (EC50 approximately 6 mM), but not 3-O-methylglucose or fructose, prevents the glucose-deprivation-induced accumulation of total GLUT-1 polypeptides. Glucose (> or = 5 mM), but not fructose or 3-O-methylglucose, leads to significant glucose 6-phosphate accumulation. Although 3-O-methylglucose is weakly phosphorylated by fibroblasts, accumulation of phosphorylated product does not correlate with hexose-transport regulation. The activities of hexokinase and PGI are not altered by glucose, fructose or 3-O-methylglucose. We suggest that, in murine fibroblasts: (i) hexose transport and GLUT-1 content are differentially regulated; (ii) substrates of GLUT-1 and/or their immediate metabolites regulate the cell-surface expression of functional GLUT-1; and (iii) glucose metabolism is required for the regulation of GLUT-1 content.
Collapse
Affiliation(s)
- P A Ortiz
- Department of Physiology and Biophysics, State University of New York, Stony Brook 11794-8661
| | | |
Collapse
|
19
|
Ortiz PA, Honkanen RA, Klingman DE, Haspel HC. Regulation of the functional expression of hexose transporter GLUT-1 by glucose in murine fibroblasts: role of lysosomal degradation. Biochemistry 1992; 31:5386-93. [PMID: 1606164 DOI: 10.1021/bi00138a021] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The nature of the membrane compartments involved in the regulation by glucose of hexose transport is not well defined. The effect of inhibitors of lysosomal protein degradation on hexose transport (i.e., uptake of [3H]-2-deoxy-D-glucose) and hexose transporter protein GLUT-1 (i.e., immunoblotting with antipeptide serum) in glucose-fed and -deprived cultured murine fibroblasts (3T3-C2 cells) was studied. The acidotropic amines chloroquine (20 microM) and ammonium chloride (10 mM) cause accumulation (both approximately 4-fold) of GLUT-1 protein and a small increase (both approximately 25%) in hexose transport in glucose-fed fibroblasts (24 h). The endopeptidase inhibitor, leupeptin (100 microM) causes accumulation (approximately 4-fold) of GLUT-1 protein in glucose-fed fibroblasts (24 h) without changing hexose transport (less than or equal to 5%). These agents do not greatly alter the electrophoretic mobility of GLUT-1. Neither chloroquine nor leupeptin augment the glucose deprivation (24 h) induced increases in hexose transport (approximately 4-fold) and GLUT-1 content (approximately 7-fold). In contrast, chloroquine or leupeptin diminish the reversal by glucose refeeding of the glucose deprivation induced accumulation of GLUT-1 protein but fail to alter the return of hexose transport to control levels.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- P A Ortiz
- Department of Physiology and Biophysics, State University of New York, Stony Brook 11794
| | | | | | | |
Collapse
|
20
|
Maher F, Davies-Hill TM, Lysko PG, Henneberry RC, Simpson IA. Expression of two glucose transporters, GLUT1 and GLUT3, in cultured cerebellar neurons: Evidence for neuron-specific expression of GLUT3. Mol Cell Neurosci 1991; 2:351-60. [DOI: 10.1016/1044-7431(91)90066-w] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/1991] [Indexed: 11/26/2022] Open
|