Characterization of cis-elements mediating the stimulation of glucose-6-phosphate transporter promoter activity by glucocorticoids.
The endoplasmatic glucose-6-phosphate transporter is involved in the control of hepatic glucose production and blood glucose homeostasis. In this study, the expression of a luciferase reporter gene under the control of the glucose-6-phosphate transporter gene promoter was examined in transiently transfected hepatoma cells. The promoter activity was stimulated approximately 2.5-fold by dexamethasone. Mutational analyses demonstrated that the regions nucleotide (nt) -215/-209 and nt -197/-183 relative to the translation start site were critical for this regulation. In gel electrophoretic mobility shift assays the transcription factor Fox O1, also called forkhead in rhabdomyosarcoma (FKHR), overexpressed in 293 cells, bound to a probe with the sequence nt -215/-209. The overexpression of Fox O1 stimulated the induction of glucose-6-phosphate transporter promoter activity by dexamethasone via nt -215/-209 in hepatoma cells. Recombinant glucocorticoid receptor DNA binding domain protein bound to a probe with the sequence of nt -197/-183 in gel electrophoretic mobility shift assays and an oligonucleotide with this sequence transferred glucocorticoid responsiveness to a heterologous promoter. The data indicate that the glucose-6-phosphate transporter promoter contains a glucocorticoid response unit consisting of binding sites for Fox O1 and the glucocorticoid receptor.
Department of Medical Biochemistry and Molecular Biology, University of Greifswald, Sauerbruchstr, D-17487 Greifswald, Germany.
Angela
A
Kallwellis-Opara
Xiangshan
X
Zaho
Uwe
U
Zimmermann
Terry G
TG
Unterman
Reinhard
R
Walther
Dieter
D
Schmoll
D000818:Animals; D017920:Antiporters / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D005786:Gene Expression Regulation / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000235:genetics*; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D011965:Receptors, Glucocorticoid / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics*; D013937:Thymidine Kinase / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D017920:Antiporters; D004268:DNA-Binding Proteins; C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D005938:Glucocorticoids; D009004:Monosaccharide Transport Proteins; D011965:Receptors, Glucocorticoid; D011993:Recombinant Fusion Proteins; C503531:SLC37A4 protein, human; D014157:Transcription Factors; C111261:glucose 6-phosphate(transporter); D003907:Dexamethasone; D008156:Luciferases; D013937:Thymidine Kinase