scholarly journals Glucose transport and GLUT4 protein distribution in skeletal muscle of GLUT4 transgenic mice

1996 ◽  
Vol 313 (1) ◽  
pp. 133-140 ◽  
Author(s):  
Joseph T. BROZINICK ◽  
Benedict B. YASPELKIS ◽  
Cindy M. WILSON ◽  
Kristen E. GRANT ◽  
E. Michael GIBBS ◽  
...  

The aim of the present investigation was to determine whether the subcellular distribution and insulin-stimulated translocation of the GLUT4 isoform of the glucose transporter are affected when GLUT4 is overexpressed in mouse skeletal muscle, and if the overexpression of GLUT4 alters maximal insulin-stimulated glucose transport and metabolism. Rates of glucose transport and metabolism were assessed by hind-limb perfusion in GLUT4 transgenic (TG) mice and non-transgenic (NTG) controls. Glucose-transport activity was determined under basal (no insulin), submaximal (0.2 m-unit/ml) and maximal (10 m-units/ ml) insulin conditions using a perfusate containing 8 mM 3-O-methyl-D-glucose. Glucose metabolism was quantified by perfusing the hind limbs for 25 min with a perfusate containing 8 mM glucose and 10 m-units/ml insulin. Under basal conditions, there was no difference in muscle glucose transport between TG (1.10±0.10 μmol/h per g; mean±S.E.M.) and NTG (0.93±0.16 μmol/h per g) mice. However, TG mice displayed significantly greater glucose-transport activity during submaximal (4.42±0.49 compared with 2.69±0.33 μmol/h per g) and maximal (11.68±1.13 compared with 7.53±0.80 μmol/h per g) insulin stimulation. Nevertheless, overexpression of the GLUT4 protein did not alter maximal rates of glucose metabolism. Membrane purification revealed that, under basal conditions, plasma-membrane (~ 12-fold) and intracellular-membrane (~ 4-fold) GLUT4 protein concentrations were greater in TG than NTG mice. Submaximal insulin stimulation did not increase plasma-membrane GLUT4 protein concentration whereas maximal insulin stimulation increased this protein in both NTG (4.1-fold) and TG (2.6-fold) mice. These results suggest that the increase in insulin-stimulated glucose transport following overexpression of the GLUT4 protein is limited by factors other than the plasma-membrane GLUT4 protein concentration. Furthermore, GLUT4 overexpression is not coupled to glucose-metabolic capacity.

1991 ◽  
Vol 70 (4) ◽  
pp. 1593-1600 ◽  
Author(s):  
G. D. Cartee ◽  
A. G. Douen ◽  
T. Ramlal ◽  
A. Klip ◽  
J. O. Holloszy

Hypoxia caused a progressive cytochalasin B-inhibitable increase in the rate of 3-O-methylglucose transport in rat epitrochlearis muscles to a level approximately six-fold above basal. Muscle ATP concentration was well maintained during hypoxia, and increased glucose transport activity was still present after 15 min of reoxygenation despite repletion of phosphocreatine. However, the increase in glucose transport activity completely reversed during a 180-min-long recovery in oxygenated medium. In perfused rat hindlimb muscles, hypoxia caused an increase in glucose transporters in the plasma membrane, suggesting that glucose transporter translocation plays a role in the stimulation of glucose transport by hypoxia. The maximal effects of hypoxia and insulin on glucose transport activity were additive, whereas the effects of exercise and hypoxia were not, providing evidence suggesting that hypoxia and exercise stimulate glucose transport by the same mechanism. Caffeine, at a concentration too low to cause muscle contraction or an increase in glucose transport by itself, markedly potentiated the effect of a submaximal hypoxic stimulus on sugar transport. Dantrolene significantly inhibited the hypoxia-induced increase in 3-O-methylglucose transport. These effects of caffeine and dantrolene suggest that Ca2+ plays a role in the stimulation of glucose transport by hypoxia.


1994 ◽  
Vol 297 (3) ◽  
pp. 539-545 ◽  
Author(s):  
J T Brozinick ◽  
G J Etgen ◽  
B B Yaspelkis ◽  
J L Ivy

The effect of electrically induced muscle contraction, insulin (10 m-units/ml) and electrically-induced muscle contraction in the presence of insulin on insulin-regulatable glucose-transporter (GLUT-4) protein distribution was studied in female Sprague-Dawley rats during hindlimb perfusion. Plasma-membrane cytochalasin B binding increased approximately 2-fold, whereas GLUT-4 protein concentration increased approximately 1.5-fold above control with contractions, insulin, or insulin + contraction. Microsomal-membrane cytochalasin B binding and GLUT-4 protein concentration decreased by approx. 30% with insulin or insulin + contraction, but did not significantly decrease with contraction alone. The rate of muscle glucose uptake was assessed by determining the rate of 2-deoxy[3H]glucose accumulation in the soleus, plantaris, and red and white portions of the gastrocnemius. Both contraction and insulin increased glucose uptake significantly and to the same degree in the muscles examined. Insulin + contraction increased glucose uptake above that of insulin or contraction alone, but this effect was only statistically significant in the soleus, plantaris and white gastrocnemius. The combined effects of insulin + contraction of glucose uptake were not fully additive in any of the muscles investigated. These results suggest that (1) insulin and muscle contraction are mobilizing two separate pools of GLUT-4 protein, and (2) the increase in skeletal-muscle glucose uptake due to insulin + contraction is not due to an increase in plasma-membrane GLUT-4 protein concentration above that observed for insulin or contraction alone.


1994 ◽  
Vol 107 (3) ◽  
pp. 487-496 ◽  
Author(s):  
I. Guillet-Deniau ◽  
A. Leturque ◽  
J. Girard

Skeletal muscle regeneration is mediated by the proliferation of myoblasts from stem cells located beneath the basal lamina of myofibres, the muscle satellite cells. They are functionally indistinguishable from embryonic myoblasts. The myogenic process includes the fusion of myoblasts into multinucleated myotubes, the biosynthesis of proteins specific for skeletal muscle and proteins that regulates glucose metabolism, the glucose transporters. We find that three isoforms of glucose transporter are expressed during foetal myoblast differentiation: GLUT1, GLUT3 and GLUT4; their relative expression being dependent upon the stage of differentiation of the cells. GLUT1 mRNA and protein were abundant only in myoblasts from 19-day-old rat foetuses or from adult muscles. GLUT3 mRNA and protein, detectable in both cell types, increased markedly during cell fusion, but decreased in contracting myotubes. GLUT4 mRNA and protein were not expressed in myoblasts. They appeared only in spontaneously contracting myotubes cultured on an extracellular matrix. Insulin or IGF-I had no effect on the expression of the three glucose transporter isoforms, even in the absence of glucose. The rate of glucose transport, assessed using 2-[3H]deoxyglucose, was 2-fold higher in myotubes than in myoblasts. Glucose deprivation increased the basal rate of glucose transport by 2-fold in myoblasts, and 4-fold in myotubes. The cellular localization of the glucose transporters was directly examined by immunofluorescence staining. GLUT1 was located on the plasma membrane of myoblasts and myotubes. GLUT3 was located intracellularly in myoblasts and appeared also on the plasma membrane in myotubes. Insulin or IGF-I were unable to target GLUT3 to the plasma membrane. GLUT4, the insulin-regulatable glucose transporter isoform, appeared only in contracting myotubes in small intracellular vesicles. It was translocated to the plasma membrane after a short exposure to insulin, as it is in skeletal muscle in vivo. These results show that there is a switch in glucose transporter isoform expression during myogenic differentiation, dependent upon the energy required by the different stages of the process. GLUT3 seemed to play a role during cell fusion, and could be a marker for the muscle's ability to regenerate.


1989 ◽  
Vol 257 (4) ◽  
pp. E520-E530
Author(s):  
M. F. Hirshman ◽  
L. J. Wardzala ◽  
L. J. Goodyear ◽  
S. P. Fuller ◽  
E. D. Horton ◽  
...  

We studied the mechanism for the increase in glucose transport activity that occurs in adipose cells of exercise-trained rats. Glucose transport activity, glucose metabolism, and the subcellular distribution of glucose transporters were measured in adipose cells from rats raised in wheel cages for 6 wk (mean total exercise 350 km/rat), age-matched sedentary controls, and young sedentary controls matched for adipose cell size. Basal rates of glucose transport and metabolism were greater in cells from exercise-trained rats compared with young controls, and insulin-stimulated rates were greater in the exercise-trained rats compared with both age-matched and young controls. The numbers of plasma membrane glucose transporters were not different among groups in the basal state; however, with insulin stimulation, cells from exercise-trained animals had significantly more plasma membrane transporters than young controls or age-matched controls. Exercise-trained rats also had more low-density microsomal transporters than control rats in the basal state. When the total number of glucose transporters/cell was calculated, the exercise-trained rats had 42% more transporters than did either control group. These studies demonstrate that the increased glucose transport and metabolism observed in insulin-stimulated adipose cells from exercise-trained rats is due, primarily, to an increase in the number of plasma membrane glucose transporters translocated from an enlarged intracellular pool.


1998 ◽  
Vol 337 (1) ◽  
pp. 51-57 ◽  
Author(s):  
Garret J. ETGEN ◽  
William J. ZAVADOSKI ◽  
Geoffrey D. HOLMAN ◽  
E. Michael GIBBS

Skeletal muscle glucose transport was examined in transgenic mice overexpressing the glucose transporter GLUT1 using both the isolated incubated-muscle preparation and the hind-limb perfusion technique. In the absence of insulin, 2-deoxy-d-glucose uptake was increased ∼ 3–8-fold in isolated fast-twitch muscles of GLUT1 transgenic mice compared with non-transgenic siblings. Similarly, basal glucose transport activity was increased ∼ 4–14-fold in perfused fast-twitch muscles of transgenic mice. In non-transgenic mice insulin accelerated glucose transport activity ∼ 2–3-fold in isolated muscles and to a much greater extent (∼ 7–20-fold) in perfused hind-limb preparations. The observed effect of insulin on glucose transport in transgenic muscle was similarly dependent upon the technique used for measurement, as insulin had no effect on isolated fast-twitch muscle from transgenic mice, but significantly enhanced glucose transport in perfused fast-twitch muscle from transgenic mice to ∼ 50–75% of the magnitude of the increase observed in non-transgenic mice. Cell-surface glucose transporter content was assessed via 2-N-4-(l-azi-2,2,2-trifluoroethyl)benzoyl-1,3-bis-(d -mannos-4-yloxy)-2-propylamine photolabelling methodology in both isolated and perfused extensor digitorum longus (EDL). Cell-surface GLUT1 was enhanced by as much as 70-fold in both isolated and perfused EDL of transgenic mice. Insulin did not alter cell-surface GLUT1 in either transgenic or non-transgenic mice. Basal levels of cell-surface GLUT4, measured in either isolated or perfused EDL, were similar in transgenic and non-transgenic mice. Interestingly, insulin enhanced cell-surface GLUT4 ∼ 2-fold in isolated EDL and ∼ 6-fold in perfused EDL of both transgenic and non-transgenic mice. In summary, these results reveal differences between isolated muscle and perfused hind-limb techniques, with the latter method showing a more robust responsiveness to insulin. Furthermore, the results demonstrate that muscle overexpressing GLUT1 has normal insulin-induced GLUT4 translocation and the ability to augment glucose-transport activity above the elevated basal rates.


1993 ◽  
Vol 264 (1) ◽  
pp. C146-C150 ◽  
Author(s):  
J. M. Ren ◽  
C. F. Semenkovich ◽  
J. O. Holloszy

Feeding rats beta-guanidinopropionic acid (beta-GPA), a creatine analogue, results in depletion of creatine and phosphocreatine and induces increases in mitochondrial oxidative enzymes and hexokinase in skeletal muscle. Comparisons of different muscle types and studies of the adaptation to exercise suggest that 1) the levels of the insulin-responsive glucose transporter (GLUT-4), mitochondrial oxidative enzymes, and hexokinase may be coregulated and 2) GLUT-4 content can determine maximal glucose transport activity in muscle. To further evaluate these possibilities, we examined the effects of feeding rats 1% beta-GPA in their diet for 6 wk on muscle GLUT-4 expression and glucose transport activity. beta-GPA feeding induced 40-50% increases in cytochrome c concentration, citrate synthase activity, and hexokinase activity in plantaris muscle. GLUT-4 protein concentration was increased approximately 50% in plantaris and epitrochlearis muscles, while GLUT-4 mRNA was increased approximately 40% in plantaris muscles of beta-GPA-fed rats. Glucose transport activity maximally stimulated by insulin was increased in parallel with GLUT-4 protein concentration in the epitrochlearis. These results provide evidence that chronic creatine depletion increases GLUT-4 expression by pretranslational mechanisms. They support the hypothesis that the levels of mitochondrial enzymes, hexokinase, and GLUT-4 protein are coregulated in striated muscles. They also support the concept that the GLUT-4 content of a muscle determines its maximal glucose transport activity when the signaling pathways for glucose transport activation are intact.


2020 ◽  
Vol 53 (1) ◽  
Author(s):  
Yuri Okazaki ◽  
Jennifer Murray ◽  
Ali Ehsani ◽  
Jessica Clark ◽  
Robert H. Whitson ◽  
...  

Abstract Background Skeletal muscle has an important role in regulating whole-body energy homeostasis, and energy production depends on the efficient function of mitochondria. We demonstrated previously that AT-rich interactive domain 5b (Arid5b) knockout (Arid5b−/−) mice were lean and resistant to high-fat diet (HFD)-induced obesity. While a potential role of Arid5b in energy metabolism has been suggested in adipocytes and hepatocytes, the role of Arid5b in skeletal muscle metabolism has not been studied. Therefore, we investigated whether energy metabolism is altered in Arid5b−/− skeletal muscle. Results Arid5b−/− skeletal muscles showed increased basal glucose uptake, glycogen content, glucose oxidation and ATP content. Additionally, glucose clearance and oxygen consumption were upregulated in Arid5b−/− mice. The expression of glucose transporter 1 (GLUT1) and 4 (GLUT4) in the gastrocnemius (GC) muscle remained unchanged. Intriguingly, the expression of TBC domain family member 1 (TBC1D1), which negatively regulates GLUT4 translocation to the plasma membrane, was suppressed in Arid5b−/− skeletal muscle. Coimmunofluorescence staining of the GC muscle sections for GLUT4 and dystrophin revealed increased GLUT4 localization at the plasma membrane in Arid5b−/− muscle. Conclusions The current study showed that the knockout of Arid5b enhanced glucose metabolism through the downregulation of TBC1D1 and increased GLUT4 membrane translocation in skeletal muscle.


1990 ◽  
Vol 68 (1) ◽  
pp. 193-198 ◽  
Author(s):  
L. J. Goodyear ◽  
M. F. Hirshman ◽  
P. A. King ◽  
E. D. Horton ◽  
C. M. Thompson ◽  
...  

Recent reports have shown that immediately after an acute bout of exercise the glucose transport system of rat skeletal muscle plasma membranes is characterized by an increase in both glucose transporter number and intrinsic activity. To determine the duration of the exercise response we examined the time course of these changes after completion of a single bout of exercise. Male rats were exercised on a treadmill for 1 h (20 m/min, 10% grade) or allowed to remain sedentary. Rats were killed either immediately or 0.5 or 2 h after exercise, and red gastrocnemius muscle was used for the preparation of plasma membranes. Plasma membrane glucose transporter number was elevated 1.8- and 1.6-fold immediately and 30 min after exercise, although facilitated D-glucose transport in plasma membrane vesicles was elevated 4- and 1.8-fold immediately and 30 min after exercise, respectively. By 2 h after exercise both glucose transporter number and transport activity had returned to nonexercised control values. Additional experiments measuring glucose uptake in perfused hindquarter muscle produced similar results. We conclude that the reversal of the increase in glucose uptake by hindquarter skeletal muscle after exercise is correlated with a reversal of the increase in the glucose transporter number and activity in the plasma membrane. The time course of the transport-to-transporter ratio suggests that the intrinsic activity response reverses more rapidly than that involving transporter number.


1997 ◽  
Vol 273 (1) ◽  
pp. E185-E191 ◽  
Author(s):  
R. S. Streeper ◽  
E. J. Henriksen ◽  
S. Jacob ◽  
J. Y. Hokama ◽  
D. L. Fogt ◽  
...  

The racemic mixture of the antioxidant alpha-lipoic acid (ALA) enhances insulin-stimulated glucose metabolism in insulin-resistant humans and animals. We determined the individual effects of the pure R-(+) and S-(-) enantiomers of ALA on glucose metabolism in skeletal muscle of an animal model of insulin resistance, hyperinsulinemia, and dyslipidemia: the obese Zucker (fa/fa) rat. Obese rats were treated intraperitoneally acutely (100 mg/kg body wt for 1 h) or chronically [10 days with 30 mg/kg of R-(+)-ALA or 50 mg/kg of S-(-)-ALA]. Glucose transport [2-deoxyglucose (2-DG) uptake], glycogen synthesis, and glucose oxidation were determined in the epitrochlearis muscles in the absence or presence of insulin (13.3 nM). Acutely, R-(+)-ALA increased insulin-mediated 2-DG-uptake by 64% (P < 0.05), whereas S-(-)-ALA had no significant effect. Although chronic R-(+)-ALA treatment significantly reduced plasma insulin (17%) and free fatty acids (FFA; 35%) relative to vehicle-treated obese animals, S-(-)-ALA treatment further increased insulin (15%) and had no effect on FFA. Insulin-stimulated 2-DG uptake was increased by 65% by chronic R-(+)-ALA treatment, whereas S-(-)-ALA administration resulted in only a 29% improvement. Chronic R-(+)-ALA treatment elicited a 26% increase in insulin-stimulated glycogen synthesis and a 33% enhancement of insulin-stimulated glucose oxidation. No significant increase in these parameters was observed after S-(-)-ALA treatment. Glucose transporter (GLUT-4) protein was unchanged after chronic R-(+)-ALA treatment but was reduced to 81 +/- 6% of obese control with S-(-)-ALA treatment. Therefore, chronic parenteral treatment with the antioxidant ALA enhances insulin-stimulated glucose transport and non-oxidative and oxidative glucose metabolism in insulin-resistant rat skeletal muscle, with the R-(+) enantiomer being much more effective than the S-(-) enantiomer.


1995 ◽  
Vol 73 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Patricia A. King ◽  
Mary N. Rosholt ◽  
Kenneth B. Storey

One of the critical adaptations for freeze tolerance by the wood frog, Rana sylvatica, is the production of large quantities of glucose as an organ cryoprotectant during freezing exposures. Glucose export from the liver, where it is synthesized, and its uptake by other organs is dependent upon carrier-mediated transport across plasma membranes by glucose-transporter proteins. Seasonal changes in the capacity to transport glucose across plasma membranes were assessed in liver and skeletal muscle of wood frogs; summer-collected (June) frogs were compared with autumn-collected (September) cold-acclimated (5 °C for 3–4 weeks) frogs. Plasma membrane vesicles prepared from liver of autumn-collected frogs showed 6-fold higher rates of carrier-mediated glucose transport than vesicles from summer-collected frogs, maximal velocity (Vmax) values for transport being 72 ± 14 and 12.0 + 2.9 nmol∙mg protein−1∙s−1, respectively (at 10 °C). However, substrate affinity constants for carrier-mediated glucose transport (K1/2) did not change seasonally. The difference in transport rates was due to greater numbers of glucose transporters in liver plasma membranes from autumn-collected frogs. The total number of transporter sites, as determined by cytochalasin B binding, was 8.5-fold higher in autumn than in summer. Glucose transporters in wood frog liver membranes cross-reacted with antibodies to the rat GluT-2 glucose transporter (the mammalian liver isoform), and Western blots further confirmed a large increase in transporter numbers in liver membranes from autumn- versus summer-collected frogs. By contrast with the liver, however, there were no seasonal changes in glucose-transporter activity or numbers in plasma membranes isolated from skeletal muscle. We conclude that an enhanced capacity for glucose transport across liver, but not muscle, plasma membranes during autumn cold-hardening is an important adaptation that anticipates the need for rapid export of cryoprotectant from liver during natural freezing episodes.


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