Olf-1/early B cell factor is a regulator of glut4 gene expression in 3T3-L1 adipocytes.
A negative regulatory element in the 5'-flanking region of the murine glut4 gene mediates chronic insulin- and cAMP-induced repression in 3T3-L1 adipocytes. Previous work demonstrated that members of the nuclear factor 1 (NF1) family of transcription factors and an unidentified factor bind to and mediate repression from this regulatory element. By using a yeast one-hybrid screen, Olf-1/Early B cell factor (O/E-1) was isolated as a candidate for this unidentified factor. A protein complex from 3T3-L1 adipocyte nuclear extract that bound the negative regulatory element was recognized by O/E-specific antiserum, and binding activity was competed effectively by distinct O/E-binding sequences. O/E binding activity was also detected in nuclear extracts from insulin-responsive, GLUT4-expressing tissues including adipose, skeletal muscle, and heart. Mutations within the negative regulatory element that abolish binding of O/E proteins concomitantly blocked insulin-induced repression in reporter gene assays. These results suggest that one or more members of the O/E transcription factor family function as important regulators of glut4 gene expression and therefore may play a heretofore unanticipated role in glucose homeostasis and insulin signaling.
Dowell
Paul
P
Departments of Biological Chemistry and Pediatrics, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Cooke
David W
DW
D016475:3T3 Cells; D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D004247:DNA; D004268:DNA-Binding Proteins / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D051275:Glucose Transporter Type 4; D007328:Insulin / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000235:genetics*; D009124:Muscle Proteins; D011485:Protein Binding; D012689:Sequence Homology, Nucleic Acid; D015534:Trans-Activators / Q000502:physiology*; D020798:Two-Hybrid System Techniques
D004268:DNA-Binding Proteins; C489921:Ebf1 protein, mouse; D051275:Glucose Transporter Type 4; D007328:Insulin; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; C495693:Slc2a4 protein, mouse; D015534:Trans-Activators; D004247:DNA