Regulation of the human GLUT4 gene promoter: interaction between a transcriptional activator and myocyte enhancer factor 2A.
The GLUT4 gene is subject to complex tissue-specific and metabolic regulation, with a profound impact on insulin-mediated glucose disposal. We have shown, by using transgenic mice, that the human GLUT4 promoter is regulated through the cooperative function of two distinct regulatory elements, domain 1 and the myocyte enhancer factor 2 (MEF2) domain. The MEF2 domain binds transcription factors MEF2A and MEF2D in vivo. Domain I binds a transcription factor, GLUT4 enhancer factor (GEF). In this report, we show a restricted pattern of GEF expression in human tissues, which overlaps with MEF2A only in tissues expressing high levels of GLUT4, suggesting the hypothesis that GEF and MEF2A function together to activate GLUT4 transcription. Data obtained from transiently transfected cells support this hypothesis. Neither GEF nor MEF2A alone significantly activated GLUT4 promoter activity, but increased promoter activity 4- to 5-fold when expressed together. Deletion of the GEF-binding domain (domain I) and the MEF2-binding domain prevented activation, strengthening the conclusion that promoter regulation occurs through these elements. GEF and MEF2A, isolated from nuclei of transfected cells, bound domain I and the MEF2 domain, respectively, which is consistent with activation through these regulatory elements. Finally, GEF and MEF2A coimmunoprecipitated in vivo, strongly supporting a mechanism of GLUT4 transcription activation that depends on this protein-protein interaction.
Knight
John B
JB
Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, P.O. Box 26901, Room 853-BMSB, Oklahoma City, OK 73190, USA.
Eyster
Craig A
CA
Griesel
Beth A
BA
Olson
Ann Louise
AL
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D005947:Glucose / Q000378:metabolism; D051275:Glucose Transporter Type 4; D005982:Glutathione Transferase / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D026161:MADS Domain Proteins; D064326:MEF2 Transcription Factors; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D009004:Monosaccharide Transport Proteins / Q000235:genetics*; D009124:Muscle Proteins; D018006:Myogenic Regulatory Factors; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014018:Tissue Distribution; D014157:Transcription Factors / Q000096:biosynthesis* / Q000737:chemistry* / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
D004268:DNA-Binding Proteins; D051275:Glucose Transporter Type 4; D008164:Luminescent Proteins; D026161:MADS Domain Proteins; D064326:MEF2 Transcription Factors; C578035:MEF2A protein, human; C578043:MEF2D protein, human; C578036:Mef2a protein, mouse; C578044:Mef2d protein, mouse; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D018006:Myogenic Regulatory Factors; D011993:Recombinant Fusion Proteins; C495692:SLC2A4 protein, human; C480633:SLC2A4RG protein, human; C495693:Slc2a4 protein, mouse; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D005982:Glutathione Transferase; D005947:Glucose