Cited by 315Metabolism, Diabetes, and CancerAdipose Tissue and MetabolismPI3K/AKT/mTOR signaling in cancer

Distinct Signals Regulate AS160 Phosphorylation in Response to Insulin, AICAR, and Contraction in Mouse Skeletal Muscle

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Kramer, Henning F., Witczak, Carol A., Fujii, Nobuharu, Jessen, Niels, Taylor, Eric B., Arnolds, David E., Sakamoto, Kei, Hirshman, Michael F. +1 more·2006·Diabetes

Abstract

Insulin and contraction increase GLUT4 translocation in skeletal muscle via distinct signaling mechanisms. Akt substrate of 160 kDa (AS160) mediates insulin-stimulated GLUT4 translocation in L6 myotubes, presumably through activation of Akt. Using in vivo, in vitro, and in situ methods, insulin, contraction, and the AMP-activated protein kinase (AMPK) activator AICAR all increased AS160 phosphorylation in mouse skeletal muscle. Insulin-stimulated AS160 phosphorylation was fully blunted by wortmannin in vitro and in Akt2 knockout (KO) mice in vivo. In contrast, contraction-stimulated AS160 phosphorylation was only partially decreased by wortmannin and unaffected in Akt2 KO mice, suggesting additional regulatory mechanisms. To determine if AMPK mediates AS160 signaling, we used AMPK α2-inactive (α2i) transgenic mice. AICAR-stimulated AS160 phosphorylation was fully inhibited, whereas contraction-stimulated AS160 phosphorylation was partially reduced in the AMPK α2i transgenic mice. Combined AMPK α2 and Akt inhibition by wortmannin treatment of AMPK α2 transgenic mice did not fully ablate contraction-stimulated AS160 phosphorylation. Maximal insulin, together with either AICAR or contraction, increased AS160 phosphorylation in an additive manner. In conclusion, AS160 may be a point of convergence linking insulin, contraction, and AICAR signaling. While Akt and AMPK α2 activities are essential for AS160 phosphorylation by insulin and AICAR, respectively, neither kinase is indispensable for the entire effects of contraction on AS160 phosphorylation.

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  • AMPK rather than Akt is a possible candidate regulating TBC1D4 activity in response to exercise and muscle contractions.

    “AMPK rather than Akt has been proposed to be a possible candidate regulating TBC1D4 activity in response to exercise and muscle contractions given 1) Akt phosphorylation is not increased by exercise; 2) AICAR stimulates glucose uptake independently of insulin; 3) AICAR increases phosphorylation of TBC1D4 at PAS motifs in both rat [115] and mouse skeletal muscle [76]; and 4) glucose uptake is impa”

    From AMPK and Exercise: Glucose Uptake and Insulin Sensitivity (2013) · cites this paper as [76]

  • Overexpression of TBC1D4 4P mutant in mouse skeletal muscle inhibits insulin-stimulated glucose uptake in vivo by ~50%.

    “Similarly, overexpression of TBC1D4 by mutation of four predominant Akt phosphorylation sites (S318, S588, T642, and S751) (4P mutant) in mouse skeletal muscle inhibits insulin-stimulated glucose uptake in vivo by ~50% [76].”

    From AMPK and Exercise: Glucose Uptake and Insulin Sensitivity (2013) · cites this paper as [76]

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Authors
Kramer, H. F., Witczak, C. A., Fujii, N., Jessen, N., Taylor, E. B., Arnolds, D. E., Sakamoto, K., Hirshman, M. F., & Goodyear, L. J.
Affiliations
  • Joslin Diabetes Center (US)
  • Brigham and Women's Hospital (US)
Venue
Diabetes
Published
2006-07-01
Volume
55
Issue
7
Pages
2067-2076
ISSN
  • 0012-1797 (ISSN-L)
  • 1939-327X
OpenAlex
W2150889500
Cited by
315
References
30
Citations by year
2026: 2 · 2025: 2 · 2024: 3 · 2023: 3 · 2022: 5 · 2021: 15 · 2020: 9 · 2019: 14 · 2018: 15 · 2017: 13 · 2016: 17 · 2015: 19 · 2014: 22 · 2013: 17 · 2012: 20
FWCI
12.38
Type
journal article
Language
en
Open access
Locations
  • Diabetes (publishedVersion)
  • PubMed (publishedVersion)
  • UCLA - Biblioteca de Ciencias de la Salud (submittedVersion)
  • Research at the University of Copenhagen (University of Copenhagen) (submittedVersion, other-oa)
Funders
  • University of Pennsylvania
  • Joslin Diabetes Center
  • Dartmouth College
  • Pennsylvania State University
  • National Institutes of Health (AR45670, DK 36836)
  • National Institute of Diabetes and Digestive and Kidney Diseases (DK36836, P30DK036836)
  • National Institute of Arthritis and Musculoskeletal and Skin Diseases (AR45670, AR-42238, R01AR045670, F32AR051663)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Metabolism, Diabetes, and Cancer
  • Health Sciences › Medicine › Physiology › Adipose Tissue and Metabolism
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › PI3K/AKT/mTOR signaling in cancer
Keywords
AS160, Akt, AMPK, AICAR, insulin signaling, skeletal muscle contraction, GLUT4 translocation, wortmannin, glucose transport regulation, signal convergence
MeSH terms
Adenylate Kinase, Aminoimidazole Carboxamide, Animals, Female, Insulin, Kinetics, Male, Mice, Inbred C57BL, Muscle Contraction, Phosphorylation, Ribonucleotides, Signal Transduction, Muscle, Skeletal, GTPase-Activating Proteins, Protein Transport, Glucose Transporter Type 4, Mice

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