Induction of glucose transporter 1 expression through hypoxia-inducible factor 1alpha under hypoxic conditions in trophoblast-derived cells.
Glucose transporter 1 (GLUT1) plays an important role in the transport of glucose in the placenta. During early pregnancy, placentation occurs in a relatively hypoxic environment that is essential for appropriate embryonic development, and GLUT1 expression is enhanced in response to oxygen deficiency in the placenta. Hypoxia-inducible factor-1 (HIF-1)alpha is involved in the induction of GLUT1 expression in other cells. The present study was designed to test whether HIF-1alpha is involved in hypoxia-induced activation of GLUT1 expression using trophoblast-derived human BeWo and rat Rcho-1 cells as models. GLUT1 mRNA and protein expression were elevated under 5% O2 or in the presence of cobalt chloride, which has been shown to mimic hypoxia. Using rat GLUT1 (rGLUT1) promoter-luciferase constructs, we showed that this up-regulation was mediated at the transcriptional level. Deletion mutant analysis of the rGLUT1 promoter indicated that a 184 bp hypoxia-responsive element (HRE) of the promoter was essential to increase GLUT1 reporter gene expression in response to low-oxygen conditions. BeWo and Rcho-1 cells cultured under 5% O2 or with CoCl2 showed increased expression of HIF-1alpha protein compared with those cultured under 20% O2. To test whether this factor is directly involved in hypoxia-induced GLUT1 promoter activation, BeWo and Rcho-1 cells were transiently transfected with an HIF-1alpha expression vector. Exogeneous HIF-1alpha markedly increased the GLUT1 promoter activity from constructs containing the HRE site, while the GLUT1 promoter constructs lacking the HRE site were not activated by exogenous HIF-1alpha These data demonstrate that GLUT1 is up-regulated under 5% O2 or in the presence of CoCl2 in the placental cell lines through HIF-1alpha interaction with a consensus HRE site of the GLUT1 promoter.
Hayashi
Masami
M
Department of Obstetrics and Gynecology, Osaka University Faculty of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
Sakata
Masahiro
M
Takeda
Takashi
T
Yamamoto
Toshiya
T
Okamoto
Yoko
Y
Sawada
Kenjiro
K
Kimura
Akiko
A
Minekawa
Ryoko
R
Tahara
Masahiro
M
Tasaka
Keiichi
K
Murata
Yuji
Y
D015152:Blotting, Northern / Q000379:methods; D045744:Cell Line, Tumor; D003035:Cobalt / Q000494:pharmacology; D003847:Deoxyglucose / Q000378:metabolism; D005260:Female; D051272:Glucose Transporter Type 1; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D015151:Immunoblotting / Q000379:methods; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D010100:Oxygen / Q000494:pharmacology; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis; D020218:Response Elements / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism*; D014327:Trophoblasts / Q000378:metabolism*
D051272:Glucose Transporter Type 1; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009004:Monosaccharide Transport Proteins; D012333:RNA, Messenger; C495677:SLC2A1 protein, human; D014157:Transcription Factors; D003035:Cobalt; D003847:Deoxyglucose; C018021:cobaltous chloride; D010100:Oxygen