scholarly journals Stimulation of glucose transport in L6 muscle cells by long-term intermittent stretch-relaxation

FEBS Letters ◽  
1992 ◽  
Vol 301 (1) ◽  
pp. 94-98 ◽  
Author(s):  
Yasuhide Mitsumoto ◽  
Gregory P. Downey ◽  
Amira Klip
Keyword(s):  
Glucose Transport ◽  
Muscle Cells ◽  
L6 Muscle Cells ◽  
Stimulation Of

scholarly journals Unique mechanism of GLUT3 glucose transporter regulation by prolonged energy demand: increased protein half-life

1998 ◽  
Vol 333 (3) ◽  
pp. 713-718 ◽  
Author(s):  
Zayna A. KHAYAT ◽  
Anthony L. McCALL ◽  
Amira KLIP
Keyword(s):  
Glucose Uptake ◽  
Protein Content ◽  
Glucose Transport ◽  
Half Life ◽  
Glucose Transporter ◽  
Muscle Cells ◽  
Mrna Levels ◽  
Glut1 Protein ◽  
L6 Muscle Cells

L6 muscle cells survive long-term (18 h) disruption of oxidative phosphorylation by the mitochondrial uncoupler 2,4-dinitrophenol (DNP) because, in response to this metabolic stress, they increase their rate of glucose transport. This response is associated with an elevation of the protein content of glucose transporter isoforms GLUT3 and GLUT1, but not GLUT4. Previously we have reported that the rise in GLUT1 expression is likely to be a result of de novo biosynthesis of the transporter, since the uncoupler increases GLUT1 mRNA levels. Unlike GLUT1, very little is known about how interfering with mitochondrial ATP production regulates GLUT3 protein expression. Here we examine the mechanisms employed by DNP to increase GLUT3 protein content and glucose uptake in L6 muscle cells. We report that, in contrast with GLUT1, continuous exposure to DNP had no effect on GLUT3 mRNA levels. DNP-stimulated glucose transport was unaffected by the protein-synthesis inhibitor cycloheximide. The increase in GLUT3 protein mediated by DNP was also insensitive to cycloheximide, paralleling the response of glucose uptake, whereas the rise in GLUT1 protein levels was blocked by the inhibitor. The GLUT3 glucose transporter may therefore provide the majority of the glucose transport stimulation by DNP, despite elevated levels of GLUT1 protein. The half-lives of GLUT3 and GLUT1 proteins in L6 myotubes were determined to be about 15 h and 6 h respectively. DNP prolonged the half-life of both proteins. After 24 h of DNP treatment, 88% of GLUT3 protein and 57% of GLUT1 protein had not turned over, compared with 25% in untreated cells. We conclude that the long-term stimulation of glucose transport by DNP arises from an elevation of GLUT3 protein content associated with an increase in GLUT3 protein half-life. These findings suggest that disruption of the oxidative chain of L6 muscle cells leads to an adaptive response of glucose transport that is distinct from the insulin response, involving specific glucose transporter isoforms that are regulated by different mechanisms.

Is intracellular Ca2+ involved in insulin stimulation of sugar transport? Fact and prejudice

1984 ◽  
Vol 62 (11) ◽  
pp. 1228-1236 ◽  
Author(s):  
Amira Klip
Keyword(s):  
Plasma Membrane ◽  
Glucose Transport ◽  
Insulin Action ◽  
Sugar Transport ◽  
Muscle Cells ◽  
Fat Tissue ◽  
Insulin Stimulation ◽  
Hormonal Response ◽  
L6 Muscle Cells ◽  
Stimulation Of

Insulin stimulates the rate of glucose transport in muscle and fat tissue by incorporation of transporters from internal membranes into the plasma membrane. It is conceivable that cell Ca2+ ions could play a role in transporter translocation. Indeed Ca2+ has been thought to mediate insulin action, but the evidence remains highly controversial. Experiments to this effect include (i) determinations of a requirement for extracellular Ca2+ in the hormonal response, (ii) stimulation of glucose transport by agents thought to elevate cytosolic Ca2+, [Ca2+]i, and (iii) determinations of Ca2+ efflux. Actual measurements of the effect of insulin on [Ca2+]i were missing until recently. Current methods to measure [Ca2+]i include Ca2+-selective intracellular electrodes, metallochromic dyes, and photoproteins. Main drawbacks of these procedures have been the requirement of microinjection for their incorporation, which restricts their use to large cells, and their interaction with cytoplasmic Mg2+ and H+. Recently, a fluorescent Ca2+ chelator, quin-2, has been devised, which circumvents these difficulties. A permeable, non-chelating precursor of quin-2 penetrates cells and once in the cytosol becomes an impermeant, fluorescent Ca2+ chelator. With this technique it was shown that insulin does not change [Ca2+]i while stimulating glucose transport in L6 muscle cells.

scholarly journals Differential regulation of the GLUT-1 and GLUT-4 glucose transport systems by glucose and insulin in L6 muscle cells in culture

1991 ◽  
Vol 266 (4) ◽  
pp. 2615-2621 ◽  
Author(s):  
U M Koivisto ◽  
H Martinez-Valdez ◽  
P J Bilan ◽  
E Burdett ◽  
T Ramlal ◽  
...  
Keyword(s):  
Glucose Transport ◽  
Muscle Cells ◽  
Differential Regulation ◽  
Transport Systems ◽  
Glut 1 ◽  
Glut 4 ◽  
Cells In Culture ◽  
L6 Muscle Cells

scholarly journals Triiodothyronine Acutely Stimulates Glucose Transport into L6 Muscle Cells Without Increasing Surface GLUT4, GLUT1, or GLUT3

Thyroid ◽  
2012 ◽  
Vol 22 (7) ◽  
pp. 747-754 ◽  
Author(s):  
Silvania Silva Teixeira ◽  
Akhilesh K. Tamrakar ◽  
Francemilson Goulart-Silva ◽  
Caroline Serrano-Nascimento ◽  
Amira Klip ◽  
...  
Keyword(s):  
Glucose Transport ◽  
Muscle Cells ◽  
L6 Muscle Cells

Characterization of the role of the AMP-activated protein kinase in the stimulation of glucose transport in skeletal muscle cells

2002 ◽  
Vol 363 (1) ◽  
pp. 167-174 ◽  
Author(s):  
Lee G.D. FRYER ◽  
Fabienne FOUFELLE ◽  
Kay BARNES ◽  
Stephen A. BALDWIN ◽  
Angela WOODS ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Phorbol Ester ◽  
Hyperosmotic Stress ◽  
Amp Activated Protein Kinase ◽  
Stimulation Of ◽  
Constitutively Active

Stimulation of AMP-activated protein kinase (AMPK) in skeletal muscle has been correlated with an increase in glucose transport. Here, we demonstrate that adenoviral-mediated expression of a constitutively active mutant of AMPKα leads to activation of glucose transport in a skeletal-muscle cell line, similar to that seen following treatment with 5-amino-imidazolecarboxamide (AICA) riboside, hyperosmotic stress or insulin. In contrast, expression of a dominant-negative form of AMPK blocked the stimulation of glucose transport by both AICA riboside and hyperosmotic stress, but was without effect on either insulin or phorbol-ester-stimulated transport. These results demonstrate that activation of AMPK is sufficient for stimulation of glucose uptake into muscle cells, and is a necessary component of the AICA riboside- and hyperosmotic-stress-induced pathway leading to increased glucose uptake. On the other hand, AMPK is not required in the insulin- or phorbol-ester-mediated pathways. Long-term (5 days) expression of the constitutively active AMPK mutant increased protein expression of GLUT1, GLUT4 and hexokinase II, consistent with previous reports on the chronic treatment of rats with AICA riboside. Expression of constitutively active AMPK had no detectable effect on p38 mitogen-activated protein kinase levels, although interestingly the level of protein kinase B was decreased. These results demonstrate that long-term activation of AMPK is sufficient to cause increased expression of specific proteins in muscle. Our results add further support to the hypothesis that long-term activation of AMPK is involved in the adaptive response of muscle to exercise training.

Effect of dieckol from Ecklonia cava on glucose transport in L6 muscle cells

Planta Medica ◽  
2011 ◽  
Vol 77 (12) ◽  
Author(s):  
J Guan ◽  
Z Cui ◽  
D Lee ◽  
Y Lee ◽  
D Park
Keyword(s):  
Glucose Transport ◽  
Muscle Cells ◽  
Ecklonia Cava ◽  
L6 Muscle Cells

Rapid stimulation of glucose transport by mitochondrial uncoupling depends in part on cytosolic Ca2+ and cPKC

1998 ◽  
Vol 275 (6) ◽  
pp. C1487-C1497 ◽  
Author(s):  
Zayna A. Khayat ◽  
Theodoros Tsakiridis ◽  
Atsunori Ueyama ◽  
Romel Somwar ◽  
Yousuke Ebina ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Protein Kinase ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Energy Demand ◽  
Plasma Membranes ◽  
Muscle Cells ◽  
Atp Production ◽  
Pkc Β ◽  
Stimulation Of

2,4-Dinitrophenol (DNP) uncouples the mitochondrial oxidative chain from ATP production, preventing oxidative metabolism. The consequent increase in energy demand is, however, contested by cells increasing glucose uptake to produce ATP via glycolysis. In L6 skeletal muscle cells, DNP rapidly doubles glucose transport, reminiscent of the effect of insulin. However, glucose transport stimulation by DNP does not require insulin receptor substrate-1 phosphorylation and is wortmannin insensitive. We report here that, unlike insulin, DNP does not activate phosphatidylinositol 3-kinase, protein kinase B/Akt, or p70 S6 kinase. However, chelation of intra- and extracellular Ca2+ with 1,2-bis(2-aminophenoxy)ethane- N, N, N′, N′-tetraacetic acid-AM in conjunction with EGTA inhibited DNP-stimulated glucose uptake by 78.9 ± 3.5%. Because Ca2+-sensitive, conventional protein kinase C (cPKC) can activate glucose transport in L6 muscle cells, we examined whether cPKC may be translocated and activated in response to DNP in L6 myotubes. Acute DNP treatment led to translocation of cPKCs to plasma membrane. cPKC immunoprecipitated from plasma membranes exhibited a twofold increase in kinase activity in response to DNP. Overnight treatment with 4-phorbol 12-myristate 13-acetate downregulated cPKC isoforms α, β, and γ and partially inhibited (45.0 ± 3.6%) DNP- but not insulin-stimulated glucose uptake. Consistent with this, the PKC inhibitor bisindolylmaleimide I blocked PKC enzyme activity at the plasma membrane (100%) and inhibited DNP-stimulated 2-[3H]deoxyglucose uptake (61.2 ± 2.4%) with no effect on the stimulation of glucose transport by insulin. Finally, the selective PKC-β inhibitor LY-379196 partially inhibited DNP effects on glucose uptake (66.7 ± 1.6%). The results suggest interfering with mitochondrial ATP production acts on a signal transduction pathway independent from that of insulin and partly mediated by Ca2+ and cPKCs, of which PKC-β likely plays a significant role.

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