Delayed autoregulation of glucose transport in vascular endothelial cells

Alpert, Evgenia; Gruzman, Arie; Riahi, Yael; Blejter, R.; Aharoni, P.; Weisinger, Gary; Eckel, Jürgen; Kaiser, Nurit; Sasson, Shlomo

doi:10.1007/s00125-005-1681-y

Cited by 47 publications

(37 citation statements)

References 10 publications

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“…Next we determined whether there is was any difference in glucose transporters in these cells. It has been previously established that Glut-1 and Glut-2 are the major glucose transporters found in BAECs (14,17,18,23). The Western blots of Glut-1 and Glut-2 showed that the Glut-1 is very much reduced in heat-shocked cells, whereas there was no change in Glut-2 (Fig.…”

Section: Increased Hsp90⅐enos Interactions In Heat-shocked Cells and mentioning

confidence: 71%

Hyperthermia-induced Hsp90·eNOS Preserves Mitochondrial Respiration in Hyperglycemic Endothelial Cells by Down-regulating Glut-1 and Up-regulating G6PD Activity

Presley

Vedam

Druhan

et al. 2010

Journal of Biological Chemistry

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Uncoupling of NO production from NADPH oxidation by endothelial nitric-oxide synthase (eNOS) is enhanced in hyperglycemic endothelium, potentially due to dissociation of heat shock proteins 90 (Hsp90), and cellular glucose homeostasis is enhanced by a ROS-induced positive feed back mechanism. In this study we investigated how such an uncoupling impacts oxygen metabolism and how the oxidative phosphorylation can be preserved by heat shock (42°C for 2 h, hyperthermia) in bovine aortic endothelial cells. Normal and heat-shocked bovine aortic endothelial cells were exposed to normoglycemia (NG, 5.0 mM) or hyperglycemia (30 mM). With hyperglycemia treatment, O 2 consumption rate was reduced (from V O 2 max ‫؍‬ 7.51 ؎ 0.54 to 2.35 ؎ 0.27 mm Hg/min/10 6 cells), whereas in heat-shocked cells, O 2 consumption rate remained unaltered (8.19 ؎ 1.01 mm Hg/min/10 ؋ 10 6 cells). Heat shock was found to enhance Hsp90/endothelial NOS interactions and produce higher NO. Moreover, ROS generation in the hyperglycemic condition was also reduced in heat-shocked cells. Interestingly, glucose uptake was reduced in heat-shocked cells as a result of decrease in Glut-1 protein level. Glucose phosphate dehydrogenase activity that gives rise to NADPH generation was increased by hyperthermia, and mitochondrial oxidative metabolism was preserved. In conclusion, the present study provides a novel mechanism wherein the reduced oxidative stress in heat-shocked hyperglycemic cells down-regulates Glut-1 and glucose uptake, and fine-tuning of this pathway may be a potential approach to use for therapeutic benefit of diabetes mellitus. Heat shock proteins (Hsps)2 play critical roles in endothelial function in the hyperglycemic state, although their exact function is not clearly established. Along with hyperglycemia, the production of superoxide, insulin resistance, and a decline in vascular bioavailability of nitric oxide (NO) contribute to extreme rates of morbidity and mortality (1-4). Various factors regulate endothelial nitric-oxide synthase (eNOS) signaling in endothelial cells by modulating its phosphorylation/de-phosphorylation dynamics and the coupling/uncoupling of its redox reactions. Protein kinase B (Akt) phosphorylates eNOS on serine 1177 and increases the production of NO (5), and it is found to be very critical in overall glucose metabolism and cell survival (6). Hsp90 binding to eNOS was found to be a prerequisite for successive Akt-mediated stimulation of eNOS, and indeed, Hsp90 can be considered as a scaffold between eNOS and Akt (5,7,8). Vascular endothelial growth factor enhances the recruitment of Hsp90 and facilitates Akt-dependent phosphorylation of eNOS, which results in increased NO production. NO generation is reduced under diabetic conditions due to NOS uncoupling (i.e. incomplete redox transformation of NADPH, arginine, and O 2 to NO, citrulline, and H 2 O, leading instead to the generation of reactive oxygen species) resulting in the generation of more superoxide, and Hsp levels, especially Hsp90, are reduced in hypergly...

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Section: Increased Hsp90⅐enos Interactions In Heat-shocked Cells and mentioning

confidence: 71%

Hyperthermia-induced Hsp90·eNOS Preserves Mitochondrial Respiration in Hyperglycemic Endothelial Cells by Down-regulating Glut-1 and Up-regulating G6PD Activity

Presley

Vedam

Druhan

et al. 2010

Journal of Biological Chemistry

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“…We showed that transfer of vascular cells from a high-glucose to lower glucose levels induced upregulation of glucose transport and GLUT-1 mRNA expression and that glucose-deprived cells increase the expression of GLUT-1 to ameliorate a metabolically challenging and stressful condition. 8,21,24 We also showed that GLUT-1 was a stressinducible protein belonging to the family of glucoseregulated proteins. 24 Thus, the combination of overexpression of calreticulin and high-glucose incubation of the vascular cells could markedly reduce GLUT-1 content and cause glucose deprivation-like effects, followed by a stress reaction aimed to increase GLUT-1 gene transcription and/or expression of GLUT-1 mRNA-stabilizing factors.…”

Section: Discussionmentioning

confidence: 88%

“…21 Figure 7A and 7B show a 1.8-to 2.0-fold increase in calreticulin expression and its plasma membrane abundance and reduced GLUT-1 levels in both types of cells exposed to high glucose in comparison with low glucose.…”

Section: High-glucose Augments Calreticulin Expression In Vascular Cementioning

confidence: 94%

“…The slower response of VEC agrees with our previous report on a delayed downregulatory response of these cells to high glucose. 21 Figure 3A shows, in the REMSA of the [ 32 P]-labeled 57-nt probe, 3 distinct complexes that were not apparent with the longer 203-nt probe. Similar REMSAs with CAE 2181-2190 -deleted probes were performed ( Figure 3B) The molecular mass of the [ 32 P]-labeled 57-nt probe VSMC protein complexes was determined by UV cross-linking analysis.…”

Section: Cae 2181-2190 -Cytosolic Protein-binding Interactionsmentioning

confidence: 99%

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Calreticulin Destabilizes Glucose Transporter-1 mRNA in Vascular Endothelial and Smooth Muscle Cells Under High-Glucose Conditions

Totary-Jain

Naveh-Many

Riahi

et al. 2005

Circulation Research

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Abstract-Substrate autoregulation of glucose transporter-1 (GLUT-1) mRNA and protein expression provides vascular endothelial and smooth muscle cells a sensitive mechanism to adapt their rate of glucose transport in response to changing glycemic conditions. Hyperglycemia-induced downregulation of glucose transport is particularly important in protecting these cells against an excessive influx of glucose and consequently increased intracellular protein glycation and generation of free radicals; both are detrimental in the development of vascular disease in diabetes. We aimed to investigate the molecular mechanism of high glucose-induced downregulation of GLUT-1 mRNA expression in primary bovine aortic vascular endothelial (VEC) and smooth muscle (VSMC) cell cultures. Using RNA mobility shift, UV cross-linking, and in vitro degradation assays, followed by mass-spectrometric analysis, we identified calreticulin as a specific destabilizing trans-acting factor that binds to a 10-nucleotide cis-acting element (CAE 2181(CAE -2190 ) in the 3Ј-untranslated region of GLUT-1 mRNA. Pure calreticulin accelerated the rate of GLUT-1 mRNA-probe degradation in vitro, whereas overexpression of calreticulin in vascular cells decreased significantly the total cell content of GLUT-1 mRNA and protein. The expression of calreticulin was augmented in vascular cells exposed to high glucose in comparison with low-glucose conditions. Similarly, increased expression of calreticulin was observed in aortae of diabetic Psammomys obesus in comparison with normoglycemic controls. These data suggest that CAE 2181-2190 -calreticulin complex, which is formed in VSMC and VEC exposed to hyperglycemic conditions, renders GLUT-1 mRNA susceptible to degradation. This interaction underlies the process of downregulation of glucose transport in vascular cells under high-glucose conditions. (Circ Res. 2005;97:1001-1008.)Key Words: calreticulin Ⅲ glucose transporter-1 Ⅲ hyperglycemia Ⅲ mRNA turnover Ⅲ vascular smooth muscle cells Ⅲ vascular endothelial cells H yperglycemia is a major risk factor in the development of cardiovascular complications associated with the metabolic syndrome and diabetes. 1,2 Chronic hyperglycemia alters the normal function of endothelial and smooth muscle cells in blood vessels, which undergo morphological and functional modifications, because of an excessive extra-and intracellular protein glycation and an uncontrolled production of free radicals. Collectively, these processes contribute to basement-membrane thickening, vascular occlusion, increased permeability, and initiation and progression of vascular disease and atherosclerosis. [3][4][5][6] The transport of glucose across the plasma membrane of cells is the rate-limiting step for subsequent glucose metabolism. A family of glucose transporters (GLUTs) mediates the entry of glucose into cells by facilitated diffusion. 7 Vascular endothelial (VEC) and vascular smooth muscle (VSMC) cells express predominantly the ubiquitous GLUT-1 and to a very small extent the insulin-sensi...

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“…Although GLUT-1 is known to exist in endothelial cells (2,24), the relative abundance of GLUT-1 and GLUT-4 in capillaries as opposed to myocytes has not been assessed. Previous work has identified GLUT-1 in cardiac arterioles (7) but the presence or absence of GLUT-1 in smaller vessels was not investigated.…”

Section: Glut-1 Localizationmentioning

confidence: 99%

Immunogold labeling study of the distribution of GLUT-1 and GLUT-4 in cardiac tissue following stimulation by insulin or ischemia

Davey

Garlick²,

Warley³

et al. 2007

American Journal of Physiology-Heart and Circulatory Physiology

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Whereas glucose transporter 1 (GLUT-1) is thought to be responsible for basal glucose uptake in cardiac myocytes, little is known about its relative distribution between the different plasma membranes and cell types in the heart. GLUT-4 translocates to the myocyte surface to increase glucose uptake in response to a number of stimuli. The mechanisms underlying ischemia-and insulin-mediated GLUT-4 translocation are known to be different, raising the possibility that the intracellular destinations of GLUT-4 following these stimuli also differ. Using immunogold labeling, we describe the cellular localization of these two transporters and investigate whether insulin and ischemia induce differential translocation of GLUT-4 to different cardiac membranes. Immunogold labeling of GLUT-1 and GLUT-4 was performed on left ventricular sections from isolated hearts following 30 min of either insulin, ischemia, or control perfusion. In control tissue, GLUT-1 was predominantly (76%) localized in the capillary endothelial cells, with only 24% of total cardiac GLUT-1 present in myocytes. GLUT-4 was found predominantly in myocytes, distributed between sarcolemmal and T tubule membranes (1.84 Ϯ 0.49 and 1.54 Ϯ 0.33 golds/ m, respectively) and intracellular vesicles (127 Ϯ 18 golds/ m 2 ). Insulin increased T tubule membrane GLUT-4 content (2.8 Ϯ 0.4 golds/ m, P Ͻ 0.05) but had less effect on sarcolemmal GLUT-4 (1.72 Ϯ 0.53 golds/ m). Ischemia induced greater GLUT-4 translocation to both membrane types (4.25 Ϯ 0.84 and 4.01 Ϯ 0.27 golds/ m, respectively P Ͻ 0.05). The localization of GLUT-1 suggests a significant role in transporting glucose across the capillary wall before myocyte uptake via GLUT-1 and GLUT-4. We demonstrate independent spatial translocation of GLUT-4 under insulin or ischemic stimulation and propose independent roles for T-tubular and sarcolemmal GLUT-4. glucose transporter; immunogold electron microscopy

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Delayed autoregulation of glucose transport in vascular endothelial cells

Cited by 47 publications

References 10 publications

Hyperthermia-induced Hsp90·eNOS Preserves Mitochondrial Respiration in Hyperglycemic Endothelial Cells by Down-regulating Glut-1 and Up-regulating G6PD Activity

Hyperthermia-induced Hsp90·eNOS Preserves Mitochondrial Respiration in Hyperglycemic Endothelial Cells by Down-regulating Glut-1 and Up-regulating G6PD Activity

Calreticulin Destabilizes Glucose Transporter-1 mRNA in Vascular Endothelial and Smooth Muscle Cells Under High-Glucose Conditions

Immunogold labeling study of the distribution of GLUT-1 and GLUT-4 in cardiac tissue following stimulation by insulin or ischemia

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