scholarly journals Loss of cortical actin filaments in insulin-resistant skeletal muscle cells impairs GLUT4 vesicle trafficking and glucose transport

2006 ◽  
Vol 291 (5) ◽  
pp. C860-C868 ◽  
Author(s):  
Alicia M. McCarthy ◽  
Kristen O. Spisak ◽  
Joseph T. Brozinick ◽  
Jeffrey S. Elmendorf
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Filamentous Actin ◽  
Cortical Actin ◽  
Insulin Resistant ◽  
Actin Structure ◽  
Insulin Responsiveness

Study has demonstrated an essential role of cortical filamentous actin (F-actin) in insulin-regulated glucose uptake by skeletal muscle. Here, we tested whether perturbations in F-actin contributed to impaired insulin responsiveness provoked by hyperinsulinemia. In L6 myotubes stably expressing GLUT4 that carries an exofacial myc-epitope tag, acute insulin stimulation (20 min, 100 nM) increased GLUT4myc translocation and glucose uptake by ∼2-fold. In contrast, a hyperinsulinemic state, induced by inclusion of 5 nM insulin in the medium for 12 h decreased the ability of insulin to stimulate these processes. Defects in insulin signaling did not readily account for the observed disruption. In contrast, hyperinsulinemia reduced cortical F-actin. This occurred concomitant with a loss of plasma membrane phosphatidylinositol 4,5-bisphosphate (PIP2), a lipid involved in cytoskeletal regulation. Restoration of plasma membrane PIP2 in hyperinsulinemic cells restored F-actin and insulin responsiveness. Consistent with these in vitro observations suggesting that the hyperinsulinemic state negatively affects cortical F-actin structure, epitrochlearis skeletal muscle from insulin-resistant hyperinsulinemic Zucker fatty rats displayed a similar loss of F-actin structure compared with that in muscle from lean insulin-sensitive littermates. We propose that a component of insulin-induced insulin resistance in skeletal muscle involves defects in PIP2/F-actin structure essential for insulin-regulated glucose transport.

Selective in vitro reversal of the insulin resistance of glucose transport in denervated rat skeletal muscle

1989 ◽  
Vol 257 (3) ◽  
pp. E418-E425 ◽  
Author(s):  
M. O. Sowell ◽  
S. L. Dutton ◽  
M. G. Buse
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Insulin Receptor ◽  
Glucose Transport ◽  
Glycogen Synthesis ◽  
Insulin Response ◽  
Medium Composition ◽  
Insulin Resistant ◽  
Denervated Muscles

Denervation (24 h) of skeletal muscle causes severe postreceptor insulin resistance of glucose transport and glycogen synthesis that is demonstrable in isolated muscles after short (30 min) preincubations. After longer preincubations (2-4 h), the insulin response of glucose transport increased to normal, whereas glycogen synthesis remained insulin resistant. Basal and insulin-stimulated amino acid transport were significantly lower in denervated muscles than in controls after short or long incubations, although the percentage stimulation of transport by insulin was not significantly different. The development of glucose transport insulin resistance after denervation was not attributable to increased sensitivity to glucocorticoids or adenosine. The selective in vitro reversal of glucose transport insulin resistance was not dependent on medium composition, did not require protein or prostaglandin synthesis, and could not be attributed to release of a positive regulator into the medium. The data suggest 1) the insulin receptor in muscle stimulates glucose transport by a signaling pathway that is not shared by other insulin-sensitive effector systems, and 2) denervation may affect insulin receptor signal transduction at more than one site.

scholarly journals In vitro anti-diabetic assessment of guavanoic acid functionalized gold nanoparticles in regulating glucose transport using L6 rat skeletal muscle cells

2020 ◽  
Vol 11 (7) ◽  
pp. 814-822
Author(s):  
K. Govindaraju ◽  
K. S. Uma Suganya
Keyword(s):  
Skeletal Muscle ◽  
Gold Nanoparticles ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Muscle Cells ◽  
Pi3k Inhibitor ◽  
Skeletal Muscle Cells ◽  
Rat Skeletal Muscle ◽  
Functionalized Gold Nanoparticles

Glucose uptake patterns of guavanoic acid and guavanoic acid functionalized gold nanoparticles in the presence of genistein (IRTK inhibitor) and wortmannin (PI3K inhibitor).

Skeletal muscle plasma membrane glucose transport and glucose transporters after exercise

1990 ◽  
Vol 68 (1) ◽  
pp. 193-198 ◽  
Author(s):  
L. J. Goodyear ◽  
M. F. Hirshman ◽  
P. A. King ◽  
E. D. Horton ◽  
C. M. Thompson ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Time Course ◽  
Plasma Membranes ◽  
Glucose Transporter ◽  
Male Rats ◽  
Intrinsic Activity ◽  
Plasma Membrane Vesicles

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.

Glucose transport in skeletal muscle membrane vesicles from control and exercised rats

1989 ◽  
Vol 257 (6) ◽  
pp. C1128-C1134 ◽  
Author(s):  
P. A. King ◽  
M. F. Hirshman ◽  
E. D. Horton ◽  
E. S. Horton
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Active Form ◽  
Membrane Vesicles ◽  
Intrinsic Activity ◽  
Muscle Membrane ◽  
Affinity Constant ◽  
Turnover Number

Skeletal muscle responds to exercise by increasing the rate of glucose uptake. Recent studies have indicated that these changes occur via mechanisms modulating the number of transporters in the plasma membrane and/or transporter intrinsic activity. In the present study, a protocol was developed for measuring the initial rate of glucose uptake by rat hindlimb skeletal muscle plasma membrane vesicles. Membranes were isolated from sedentary (control) and acutely exercised rats, and the initial rates of D- and L-glucose influx were assayed under equilibrium exchange conditions to obtain the kinetic constants for carrier-mediated transport. These values were compared with the values for transporter number measured by cytochalasin B binding, and the carrier turnover numbers were calculated. The maximum velocity (Vmax) for carrier-mediated glucose influx was increased 3.7-fold by exercise, from 3.5 nmol.mg protein-1.s-1 for the membranes from control rats to 13 nmol.mg protein-1.s-1 for the membranes from exercised animals. The mean affinity constant (K0.5; approximately 20 mM) was not different between the two groups. The number of transporters in the plasma membrane was increased to a lesser degree, 5.4 to 9.4 pmol/mg protein. As a result, the average carrier turnover number was increased almost twofold by exercise, 719 s-1 in the controls vs. 1,380 s-1 in the exercised rats. These data indicate that the response of glucose transport to exercise involves an increase in the average carrier intrinsic activity as well as a recruitment of transporters to the plasma membrane. Whether the increase in carrier turnover number is due to activation of the transporters or recruitment of a more “active” form of the carrier is unknown.

scholarly journals Rapid Reversal of Insulin-Stimulated AS160 Phosphorylation in Rat Skeletal Muscle after Insulin Exposure

2010 ◽  
pp. 71-78
Author(s):  
N Sharma ◽  
E B Arias ◽  
G D Cartee
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Time Course ◽  
Half Time ◽  
Rat Skeletal Muscle ◽  
Akt Phosphorylation ◽  
Rapid Reversal ◽  
Time Courses

Increased phosphorylation of Akt substrate of 160 kDa (AS160) is essential to trigger the full increase in insulin-stimulated glucose transport in skeletal muscle. The primary aim of this study was to characterize the time course for reversal of insulin-stimulated AS160 phosphorylation in rat skeletal muscle after insulin removal. The time courses for reversal of insulin effects both upstream (Akt phosphorylation) and downstream (glucose uptake) of AS160 were also determined. Epitrochlearis muscles were incubated in vitro using three protocols which differed with regard to insulin exposure: No Insulin (never exposed to insulin), Transient Insulin (30 min with 1.8 nmol/l insulin, then incubation without insulin for 10, 20 or 40 min), or Sustained Insulin (continuously incubated with 1.8 nmol/l insulin). After removal of muscles from insulin, Akt and AS160 phosphorylation reversed rapidly, each with a half-time of <10 min and essentially full reversal by 20 min. Glucose uptake reversed more slowly (half time between 10 and 20 min with essentially full reversal by 40 min). Removal of muscles from insulin resulted in a rapid reversal of the increase in AS160 phosphorylation which preceded the reversal of the increase in glucose uptake, consistent with AS160 phosphorylation being essential for maintenance of insulin-stimulated glucose uptake.

scholarly journals Contractile activity restores insulin responsiveness in skeletal muscle of obese Zucker rats

1993 ◽  
Vol 289 (2) ◽  
pp. 423-426 ◽  
Author(s):  
P L Dolan ◽  
E B Tapscott ◽  
P J Dorton ◽  
G L Dohm
Keyword(s):  
Skeletal Muscle ◽  
Glucose Transport ◽  
Contractile Activity ◽  
Clinical Importance ◽  
Zucker Rats ◽  
Insulin Resistant ◽  
Significant Difference ◽  
Obese Rats ◽  
Obese Zucker Rats ◽  
Insulin Responsiveness

Both insulin and contraction stimulate glucose transport in skeletal muscle. Insulin-stimulated glucose transport is decreased in obese humans and rats. The aims of this study were (1) to determine if contraction-stimulated glucose transport was also compromised in skeletal muscle of genetically obese insulin-resistant Zucker rats, and (2) to determine whether the additive effects of insulin and contraction previously observed in muscle from lean subjects were evident in muscle from the obese animals. To measure glucose transport, hindlimbs from lean and obese Zucker rats were perfused under basal, insulin-stimulated (0.1 microM), contraction-stimulated (electrical stimulation of the sciatic nerve) and combined insulin-(+)contraction-stimulated conditions. One hindlimb was stimulated to contract while the contralateral leg served as an unstimulated control. 2-Deoxyglucose transport rates were measured in the white gastrocnemius, red gastrocnemius and extensor digitorum longus muscles. As expected, the insulin-stimulated glucose transport rate in each of the three muscles was significantly slower (P < 0.05) in obese rats when compared with lean animals. When expressed as fold stimulation over basal, there was no significant difference in contraction-induced muscle glucose transport rates between lean and obese animals. Insulin-(+)contraction-stimulation was additive in skeletal muscle of lean animals, but synergistic in skeletal muscle of obese animals. Prior contraction increased insulin responsiveness of glucose transport 2-5-fold in the obese rats, but had no effect on insulin responsiveness in the lean controls. This contraction-induced improvement in insulin responsiveness could be of clinical importance to obese subjects as a way to improve insulin-stimulated glucose uptake in resistant skeletal muscle.

scholarly journals Glucose-transporter (GLUT4) protein content in oxidative and glycolytic skeletal muscles from calf and goat

1995 ◽  
Vol 305 (2) ◽  
pp. 465-470 ◽  
Author(s):  
J F Hocquette ◽  
F Bornes ◽  
M Balage ◽  
P Ferre ◽  
J Grizard ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Skeletal Muscles ◽  
Glucose Transporter ◽  
Transporter Protein ◽  
Rat Muscle ◽  
Glucose Transporter Glut4

It is well accepted that skeletal muscle is a major glucose-utilizing tissue and that insulin is able to stimulate in vivo glucose utilization in ruminants as in monogastrics. In order to determine precisely how glucose uptake is controlled in various ruminant muscles, particularly by insulin, this study was designed to investigate in vitro glucose transport and insulin-regulatable glucose-transporter protein (GLUT4) in muscle from calf and goat. Our data demonstrate that glucose transport is the rate-limiting step for glucose uptake in bovine fibre strips, as in rat muscle. Insulin increases the rate of in vitro glucose transport in bovine muscle, but to a lower extent than in rat muscle. A GLUT4-like protein was detected by immunoblot assay in all insulin-responsive tissues from calf and goat (heart, skeletal muscle, adipose tissue) but not in liver, brain, erythrocytes and intestine. Unlike the rat, bovine and goat GLUT4 content is higher in glycolytic and oxido-glycolytic muscles than in oxidative muscles. In conclusion, using both a functional test (insulin stimulation of glucose transport) and an immunological approach, this study demonstrates that ruminant muscles express GLUT4 protein. Our data also suggest that, in ruminants, glucose is the main energy-yielding substrate for glycolytic but not for oxidative muscles, and that insulin responsiveness may be lower in oxidative than in other skeletal muscles.

Biochemical and functional evidences for a GLUT-4 homologous protein in avian skeletal muscle

1999 ◽  
Vol 277 (6) ◽  
pp. R1733-R1740 ◽  
Author(s):  
Véronique Thomas-Delloye ◽  
Florence Marmonier ◽  
Claude Duchamp ◽  
Béatrice Pichon-Georges ◽  
Joël Lachuer ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Glucose Transporter ◽  
Homologous Proteins ◽  
Subsequent Increase ◽  
Homologous Protein ◽  
Glut 4 ◽  
Sarcolemmal Vesicles

The characteristics and modulation of glucose transport were investigated in skeletal muscles of 5-wk-old Muscovy ducklings ( Cairina moschata). Glucose uptake by sarcolemmal vesicles isolated from gastrocnemius muscle followed typical Michaelis-Menten kinetics with a K m value (17 mM) similar to that described in equivalent mammalian preparations. Western blot analysis of duckling sarcolemma using antibodies directed against rat GLUT-4 transporter revealed an immunoreactive protein of similar molecular mass (45 kDa) to that present in rats. When ducklings were killed in the postabsorptive state, GLUT-4 homologous protein was located predominantly (80%) in intracellular membranes. Insulin stimulation of a perfused leg muscle preparation in vitro led to the translocation of GLUT-4 homologous proteins from intracellular pools to the sarcolemma, with a subsequent increase in glucose uptake by sarcolemmal vesicles and perfused muscles. Glucose transport was positively controlled by the metabolic needs of skeletal muscle as reflected by the increased glucose uptake of sarcolemmal vesicles isolated from cold-acclimated ducklings. Present results, therefore, demonstrate, for the first time in an avian species, the existence in skeletal muscle of a glucose transporter showing molecular and functional homologies with the mammalian GLUT-4 transporter.

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