Attenuation of Free Fatty Acid (FFA)-Induced Skeletal Muscle Cell Insulin Resistance by Resveratrol is Linked to Activation of AMPK and Inhibition of mTOR and p70 S6K

Danja J Den Hartogh; Filip Vlavcheski; Adria Giacca; Evangelia Tsiani

doi:10.3390/ijms21144900

Attenuation of Free Fatty Acid (FFA)-Induced Skeletal Muscle Cell Insulin Resistance by Resveratrol is Linked to Activation of AMPK and Inhibition of mTOR and p70 S6K

Int J Mol Sci. 2020 Jul 11;21(14):4900. doi: 10.3390/ijms21144900.

Authors

Danja J Den Hartogh^{1

2}, Filip Vlavcheski^{1

2}, Adria Giacca^{3

4

5

6}, Evangelia Tsiani^{1

2}

Affiliations

¹ Department of Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada.
² Centre for Bone and Muscle Health, Brock University, St. Catharines, ON L2S 3A1, Canada.
³ Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.
⁴ Department of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada.
⁵ Institute of Medical Sciences, University of Toronto, Toronto, ON M5S 1A8, Canada.
⁶ Banting and Best Diabetes Centre, University of Toronto, Toronto, ON M5G 2C4, Canada.

Abstract

Insulin resistance, a main characteristic of type 2 diabetes mellitus (T2DM), is linked to obesity and excessive levels of plasma free fatty acids (FFA). Studies indicated that significantly elevated levels of FFAs lead to skeletal muscle insulin resistance, by dysregulating the steps in the insulin signaling cascade. The polyphenol resveratrol (RSV) was shown to have antidiabetic properties but the exact mechanism(s) involved are not clearly understood. In the present study, we examined the effect of RSV on FFA-induced insulin resistance in skeletal muscle cells in vitro and investigated the mechanisms involved. Parental and GLUT4myc-overexpressing L6 rat skeletal myotubes were used. [³H]2-deoxyglucose (2DG) uptake was measured, and total and phosphorylated levels of specific proteins were examined by immunoblotting. Exposure of L6 cells to FFA palmitate decreased the insulin-stimulated glucose uptake, indicating insulin resistance. Palmitate increased ser³⁰⁷ (131% ± 1.84% of control, p < 0.001) and ser^636/639 (148% ± 10.1% of control, p < 0.01) phosphorylation of IRS-1, and increased the phosphorylation levels of mTOR (174% ± 15.4% of control, p < 0.01) and p70 S6K (162% ± 20.2% of control, p < 0.05). Treatment with RSV completely abolished these palmitate-induced responses. In addition, RSV increased the activation of AMPK and restored the insulin-mediated increase in (a) plasma membrane GLUT4 glucose transporter levels and (b) glucose uptake. These data suggest that RSV has the potential to counteract the FFA-induced muscle insulin resistance.

Keywords: AMPK; Akt; GLUT4; IRS-1; free fatty acid; insulin resistance; mTOR; p70 S6K; palmitate; resveratrol.

MeSH terms

Adenylate Kinase / physiology*
Animals
Cell Line
Fatty Acids, Nonesterified / toxicity*
Glucose / metabolism
Glucose Transporter Type 4 / metabolism
Humans
Insulin Receptor Substrate Proteins / metabolism
Insulin Resistance / physiology*
Muscle Cells / drug effects
Muscle Cells / metabolism
Muscle, Skeletal / drug effects*
Muscle, Skeletal / metabolism
Palmitates / pharmacology
Palmitates / toxicity
Phosphorylation
Protein Processing, Post-Translational / drug effects
Protein Transport / drug effects
Rats
Resveratrol / pharmacology*
Ribosomal Protein S6 Kinases, 70-kDa / physiology*
Signal Transduction / drug effects
TOR Serine-Threonine Kinases / physiology*

Substances

Fatty Acids, Nonesterified
Glucose Transporter Type 4
Insulin Receptor Substrate Proteins
Irs1 protein, rat
Palmitates
Slc2a4 protein, rat
MTOR protein, human
Ribosomal Protein S6 Kinases, 70-kDa
TOR Serine-Threonine Kinases
Adenylate Kinase
Glucose
Resveratrol