Cited by 335Metabolism, Diabetes, and CancerPI3K/AKT/mTOR signaling in cancerMuscle metabolism and nutrition

Constitutive activation of protein kinase B alpha by membrane targeting promotes glucose and system A amino acid transport, protein synthesis, and inactivation of glycogen synthase kinase 3 in L6 muscle cells.

Hajduch, E, Alessi, D R, Hemmings, B A, Hundal, H S·1998·Diabetes

Abstract

Phosphatidylinositol 3-kinase (PI 3-kinase) has been implicated in the regulation of numerous cellular processes, including the insulin-induced regulation of glycogen synthase kinase 3 (GSK-3) and glucose transport. The hormonal-induced inactivation of GSK-3 is mediated by protein kinase B (PKB), a downstream target of PI 3-kinase, whose involvement in other insulin-stimulated responses remains poorly defined at present. In this study, we investigated whether the uptake of glucose, system A amino acid transport, and cellular protein synthesis are regulated by PKBalpha in L6 skeletal muscle cells. L6 cells stably overexpressing wild-type PKBalpha (wtPKBalpha) or a constitutively active membrane-targeted PKBalpha (mPKBalpha) showed a 3- and 15-fold increase in PKB activity, respectively. Both wtPKBalpha and mPKBalpha expression led to a significant increase in the basal uptake of glucose and methyl-aminoisobutyric acid (a substrate for the system A amino acid transporter), at least to a level seen in control cells treated with insulin. The stimulation in glucose transport was facilitated, in part, by the increased translocation of GLUT4 to the plasma membrane and also through an increase in the cellular synthesis of GLUT3. In the absence of insulin, only muscle cells expressing the constitutively active PKBalpha showed a significant increase in protein synthesis and an inhibition in GSK-3. Our results indicate that constitutive activation of PKBalpha in skeletal muscle stimulates the uptake of glucose, system A amino acids, and protein synthesis and promotes the inactivation of GSK-3. These observations imply that PKBalpha may have a role in the insulin-regulated control of these processes in skeletal muscle.

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Crossref · 10.2337/diabetes.47.7.1006

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Authors
Hajduch, E., Alessi, D. R., Hemmings, B. A., & Hundal, H. S.
Affiliations
  • Department of Anatomy and Physiology, University of Dundee, Scotland, UK.
  • University of Dundee (GB)
Venue
Diabetes
Published
1998-07-01
Volume
47
Issue
7
Pages
1006-1013
ISSN
  • 0012-1797 (ISSN-L)
  • 1939-327X
OpenAlex
W1972307668
Cited by
335
References
0
Citations by year
2025: 1 · 2024: 3 · 2023: 2 · 2022: 2 · 2021: 7 · 2020: 3 · 2019: 5 · 2018: 8 · 2017: 3 · 2016: 12 · 2015: 10 · 2014: 7 · 2013: 7 · 2012: 8
FWCI
10.23
Type
journal article
Language
en
Open access
closed
Locations
  • Diabetes (publishedVersion)
  • PubMed (publishedVersion)
Funders
Wellcome Trust
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
constitutive activation, phosphatidylinositol 3-kinase, glycogen synthase kinase-3, glucose transport, system A amino acid transport, protein synthesis, GLUT4 translocation, GLUT3, skeletal muscle, insulin signaling, L6 myoblasts
MeSH terms
Amino Acids, Animals, Biological Transport, Cell Differentiation, Cell Division, Cell Line, Cell Membrane, Enzyme Activation, Glucose, Humans, Muscle Proteins, Proto-Oncogene Proteins, Transfection, Gene Expression, Protein Serine-Threonine Kinases, Calcium-Calmodulin-Dependent Protein Kinases, Gene Targeting, Muscle, Skeletal, Glycogen Synthase Kinases, Glycogen Synthase Kinase 3, Proto-Oncogene Proteins c-akt, Rats

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