Eicosanoids participate in the regulation of cardiac glucose transport by contribution to a rearrangement of actin cytoskeletal elements.
Intact actin microfilaments are required for insulin-regulated glucose transporter isoform 4 (GLUT4) translocation to the plasma membrane. Lipoxygenase (LO) metabolites have recently been shown to contribute to the regulation of actin cytoskeleton rearrangement. In the present investigation, ventricular cardiomyocytes were used to study the effects of two structurally different LO inhibitors (esculetin and nordihydroguaiaretic acid) on insulin signalling events, glucose uptake, GLUT4 translocation and the actin network organization. Insulin stimulation increased glucose uptake 3-fold in control cells, whereas LO inhibition completely blocked this effect. This was paralleled by a slight reduction in the insulin-induced tyrosine phosphorylation of insulin receptor substrate (IRS)-1 and IRS-2. However, inhibition of 12-LO did not affect the association of phosphatidylinositol 3-kinase with IRS-1 and the phosphorylation of Akt/protein kinase B in response to insulin. Addition of 12(S)-hydroxyeicosatetraenoic acid almost completely restored the insulin action in cells exposed to nordihydroguaiaretic acid. Insulin stimulation increased cell surface GLUT4 2-fold in control cells, whereas LO inhibition abrogated the insulin-stimulated GLUT4 translocation. LO inhibition induced a prominent disassembly of actin fibres compared with control cells. In conclusion, we show here that 12(S)-hydroxyeicosatetraenoic acid plays a role in the organization of the actin network in cardiomyocytes. LO inhibition blocks GLUT4 translocation without affecting downstream insulin signalling. These data suggest that LO metabolites participate in the regulation of glucose transport by contributing to a rearrangement of actin cytoskeletal elements.
Dransfeld
O
O
Molecular Cardiology, German Diabetes Research Institute, Auf'm Hennekamp 65, D-40225 Düsseldorf, Germany.
Rakatzi
I
I
Sasson
S
S
Gruzman
A
A
Schmitt
M
M
Häussinger
D
D
Eckel
J
J
D000199:Actins / Q000378:metabolism*; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001692:Biological Transport; D019921:Biotinylation; D015638:Cytochalasin D / Q000494:pharmacology; D003599:Cytoskeleton / Q000378:metabolism*; D015777:Eicosanoids / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4; D006352:Heart Ventricles / Q000378:metabolism; D015151:Immunoblotting; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008084:Lipoxygenase / Q000378:metabolism; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D008297:Male; D009637:Masoprocol / Q000494:pharmacology; D018613:Microscopy, Confocal; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009124:Muscle Proteins; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D017346:Protein Serine-Threonine Kinases; D021381:Protein Transport; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D014443:Tyrosine; D014468:Umbelliferones / Q000494:pharmacology
D000199:Actins; D000975:Antioxidants; D015638:Cytochalasin D; D015777:Eicosanoids; D005947:Glucose; D051275:Glucose Transporter Type 4; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008084:Lipoxygenase; D016859:Lipoxygenase Inhibitors; D009637:Masoprocol; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D014443:Tyrosine; D014468:Umbelliferones; C526296:Irs1 protein, rat; C526299:Irs2 protein, rat; C495694:Slc2a4 protein, rat; C494920:Akt1 protein, rat; C007628:esculetin