Regulation of glucose transporter expression in cardiac myocytes: p38 MAPK is a strong inducer of GLUT4

• Published in: Cardiovascular research 2004-10, Vol.64 (1), p.94-104
• Main Authors: MONTESSUIT, Christophe, ROSENBLATT-VELIN, Nathalie, PAPAGEORGIOU, Irène, CAMPOS, Lis, PELLIEUX, Corinne, PALMA, Tatiana, LERCH, René
• Format: Article
• Language: English
• Subjects: Animals; Animals, Newborn; Biological and medical sciences; Cardiology. Vascular system; Cells, Cultured; Electrophoretic Mobility Shift Assay; Enzyme Activation; Fibroblast Growth Factor 2 - analysis; Fibroblast Growth Factor 2 - metabolism; Fluorescent Antibody Technique; Genetic Engineering; Glucose Transporter Type 1; Glucose Transporter Type 4; Immunoblotting - methods; Insulin-Like Growth Factor I - analysis; Insulin-Like Growth Factor I - metabolism; Luciferases - genetics; Male; MAP Kinase Signaling System - physiology; Medical sciences; Mitogen-Activated Protein Kinases - metabolism; Monosaccharide Transport Proteins - analysis; Monosaccharide Transport Proteins - genetics; Monosaccharide Transport Proteins - metabolism; Muscle Proteins - analysis; Muscle Proteins - genetics; Muscle Proteins - metabolism; Myocytes, Cardiac - metabolism; p38 Mitogen-Activated Protein Kinases - metabolism; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction
• ISSN: 0008-6363; 1755-3245
• DOI: 10.1016/j.cardiores.2004.06.005

In vivo differentiation of cardiac myocytes is associated with downregulation of the glucose transporter isoform GLUT1 and upregulation of the isoform GLUT4. Adult rat cardiomyocytes in primary culture undergo spontaneous dedifferentiation, followed by spreading and partial redifferentiation, which can be influenced by growth factors. We used this model to study the signaling mechanisms modifying the expression of GLUT4 in cardiac myocytes. Adult rat cardiomyocytes in primary culture exhibited spontaneous upregulation of GLUT1 and downregulation of GLUT4, suggesting resumption of a fetal program of GLUT gene expression. Treatment with IGF-1 and, to a minor extent, FGF-2 resulted in restored expression of GLUT4 protein and mRNA. Activation of p38 MAPK mediated the increased expression of GLUT4 in response to IGF-1. Transient transfection experiments in neonatal cardiac myocytes confirmed that p38 MAPK could activate the glut4 promoter. Electrophoretic mobility shift assay in adult rat cardiomyocytes and transient transfection experiments in neonatal cardiac myocytes indicated that MEF2 was the main transcription factor transducing the effect of p38 MAPK activation on the glut4 promoter. Spontaneous dedifferentiation of adult rat cardiomyocytes in vitro is associated with downregulation of GLUT4, which can be reversed by treatment with IGF-1. The effect of IGF-1 is mediated by the p38 MAPK/MEF2 axis, which is a strong inducer of GLUT4 expression.