Involvement of nuclear transcription factor Sp1 in regulating glucose transporter-1 gene expression during rat trophoblast differentiation.
Glucose transporter-1 (GLUT1) is important in placental glucose transport. However, the mechanism of regulation of placental GLUT1 expression remains to be elucidated. We show here that the level of GLUT1 protein in rat choriocarcinoma cells (Rcho-1) decreased during differentiation. To analyze the regulatory mechanism of rat GLUT1 (rGLUT1) gene expression, we transfected rGLUT1 promoter-chloramphenicol acetyltransferase constructs into Rcho-1 cells. Deletion analysis of the rGLUT1 promoter suggested that the region -76/-53 bp was essential for basal transcriptional activity. Electrophoretic mobility shift assays showed that transcription factors Sp1 and Sp3 bound two GC boxes in the region -99/-33 bp of the rGLUT1 promoter. Mutation analysis of the Sp1 binding sites revealed that the promoter-proximal site located between -76 and -53 bp was essential for basal rGLUT1 promoter activity. Furthermore, the decreased level of GLUT1 may result from a decreased level of Sp1 during differentiation. These findings suggest that Sp1 is involved in the regulation of rGLUT1 gene expression during rat trophoblast differentiation.
Okamoto
Y
Y
Department of Obstetrics and Gynecology, Osaka University, Faculty of Medicine, 2-2 Yamadaoka Suita, Osaka, 565-0871, Japan.
Sakata
M
M
Yamamoto
T
T
Nishio
Y
Y
Adachi
K
K
Ogura
K
K
Yamaguchi
M
M
Takeda
T
T
Tasaka
K
K
Murata
Y
Y
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002454:Cell Differentiation; D002822:Choriocarcinoma / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005260:Female; D005786:Gene Expression Regulation; D005947:Glucose / Q000378:metabolism; D051272:Glucose Transporter Type 1; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D051381:Rats; D020218:Response Elements / Q000235:genetics; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D051705:Sp3 Transcription Factor; D014157:Transcription Factors / Q000378:metabolism; D014327:Trophoblasts / Q000166:cytology* / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014594:Uterine Neoplasms / Q000235:genetics / Q000378:metabolism
D004268:DNA-Binding Proteins; D051272:Glucose Transporter Type 1; D009004:Monosaccharide Transport Proteins; C495679:Slc2a1 protein, rat; D016329:Sp1 Transcription Factor; C497123:Sp3 protein, rat; D014157:Transcription Factors; D051705:Sp3 Transcription Factor; D004247:DNA; D005947:Glucose