Cited by 149Metabolism, Diabetes, and CancerPI3K/AKT/mTOR signaling in cancerMuscle metabolism and nutrition

Insulin, but Not Contraction, Activates Akt/PKB in Isolated Rat Skeletal Muscle

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Brozinick, Joseph T., Birnbaum, Morris J.·1998·Journal of Biological Chemistry

Abstract

Insulin and muscle contraction potently stimulate glucose uptake in mammalian skeletal muscle. Studies in muscle and adipose tissue have shown that insulin induces its receptor-dependent phosphorylation of insulin receptor substrates 1 and 2, which leads to activation of polyphosphatidylinositol (PI) 3'-kinase. In contrast, muscle contraction stimulates glucose transport via a mechanism that is independent of insulin, but the two pathways may converge downstream at the level of stimulation of GLUT4 translocation. In the present study, we have examined the role of Akt, an insulin-activated serine threonine kinase that has previously been shown to increase glucose transport in adipocytes. Either insulin or in vitro muscle contraction significantly elevated glucose transport in isolated rat epitrochlearis and soleus muscles. However, Akt kinase activity was significantly stimulated by insulin and not contraction. Moreover, wortmannin, an inhibitor of PI 3'-kinase, completely blocked the insulin-stimulated increase in Akt activity and glucose transport but did not alter either of these parameters in contracting muscles. The increases in Akt activity were paralleled by a decrease in the electrophoretic mobility of Akt, indicative of phosphorylation of Akt by an upstream kinase. These changes in Akt mobility appeared to be at least partially because of phosphorylation of Akt on serine 473. A putative downstream target of Akt, p70 S6 kinase, showed similar changes in mobility in response to insulin but not contraction. These data support the view that Akt is a downstream target of PI 3'-kinase and is involved in the signaling pathways involved in insulin but not contraction stimulation of glucose transport in skeletal muscle. These data provide further evidence that two distinct pathways exist for the stimulation of glucose transport in mammalian skeletal muscle.

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Crossref · 10.1074/jbc.273.24.14679

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  • PI3 kinase inhibitor wortmannin inhibits insulin but not contraction-stimulated glucose uptake.

    “1) PI3 kinase inhibitor wortmannin inhibits insulin but not contraction-stimulated glucose uptake. Contraction does not promote IRS-1 autophosphorylation or increase PI3 kinase activity [103-106].”

    From AMPK and Exercise: Glucose Uptake and Insulin Sensitivity (2013) · cites this paper as [106]

  • Contraction does not promote IRS-1 autophosphorylation or increase PI3 kinase activity.

    “1) PI3 kinase inhibitor wortmannin inhibits insulin but not contraction-stimulated glucose uptake. Contraction does not promote IRS-1 autophosphorylation or increase PI3 kinase activity [103-106].”

    From AMPK and Exercise: Glucose Uptake and Insulin Sensitivity (2013) · cites this paper as [106]

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Authors
Brozinick, J. T., & Birnbaum, M. J.
Affiliations
Howard Hughes Medical Institute (US)
Corresponding author
  • Brozinick, Joseph T.
  • Birnbaum, Morris J.
Venue
Journal of Biological Chemistry
Publisher
Elsevier BV
Published
1998-06
Volume
273
Issue
24
Pages
14679-14682
ISSN
0021-9258 (ISSN-L)
OpenAlex
W2040466763
Cited by
149
References
32
Citations by year
2025: 2 · 2022: 5 · 2021: 3 · 2020: 4 · 2019: 2 · 2018: 6 · 2017: 1 · 2016: 1 · 2015: 1 · 2014: 3 · 2013: 2 · 2012: 8
FWCI
4.25
Type
journal article
Language
en
Open access
Locations
  • Journal of Biological Chemistry (publishedVersion, cc-by)
  • PubMed (publishedVersion)
Funders
  • National Institutes of Health (5r01dk039615-03)
  • National Institute of Diabetes and Digestive and Kidney Diseases (DK 39615)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Metabolism, Diabetes, and Cancer
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › PI3K/AKT/mTOR signaling in cancer
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Muscle metabolism and nutrition
Keywords
insulin signaling, Akt, skeletal muscle glucose transport, muscle contraction, PI3-kinase, wortmannin, GLUT4 translocation, p70 S6 kinase, epitrochlearis muscle, soleus muscle
MeSH terms
Wortmannin, Phosphoinositide-3 Kinase Inhibitors, Androstadienes, Animals, Biological Transport, Enzyme Activation, Enzyme Inhibitors, Glucose, Insulin, Male, Muscle Contraction, Phosphorylation, Phosphoserine, Proto-Oncogene Proteins, Signal Transduction, Rats, Wistar, Protein Serine-Threonine Kinases, Muscle, Skeletal, Ribosomal Protein S6 Kinases, Proto-Oncogene Proteins c-akt, Rats

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