Induction of glucose transporter 1 expression through hypoxia-inducible factor 1α under hypoxic conditions in trophoblast-derived cells

Abstract

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.

Adenovirus-mediated hypoxia-targeted gene therapy using HSV thymidine kinase and bacterial nitroreductase prodrug-activating genes in vitro and in vivo

“…28 Previous studies have shown that CoCl 2 is just as efficient as low oxygen levels in inducing a hypoxic environment. In common with several previous studies, 29,30 which used both conditions in parallel, our data using either 1% oxygen or 150 mM CoCl 2 demonstrated similar results. This was the case with either HSVtk/GCV or NTR/CB1954 prodrug-activating system.…”

D-Allose Inhibits Cancer Cell Growth by Reducing GLUT1 Expression

“…HRE-driven luciferase activity was enhanced by hypoxic conditions, and GLUT1 expression was stimulated by up-regulated HRE activity (Hayashi et al 2004). Farrell et al (2010) reported that TXNIP inhibited HRE-driven luciferase activity in a SV-40 transformed alveolar epithelial cell line (MLE-12) and the expression of the HIF target gene, VEGF.…”

“…GLUT1 expression is regulated by a number of different mechanisms, for example, transcription factors such as Sp1, Sp3, and p53 (Behrooz and IsmailBeigi 1997;Schwartzenberg-Bar-Yoseph et al 2004;Hwang and Ismail-Beigi 2006). In addition, GLUT1 expression and glucose uptake are stimulated by hypoxia via induction of transcription factors, such as hypoxia induction factor 1-alpha (HIF-1-alpha), which increases GLUT1 promoter activity (Hayashi et al 2004). The binding site of HIF-1-alpha, namely the hypoxia response element (HRE), is present in the human and rat GLUT1 promoter regions (Behrooz and Ismail-Beigi 1997;Zelzer et al 1998).…”

Trypanosoma bruceimetabolite indolepyruvate decreases HIF-1α and glycolysis in macrophages as a mechanism of innate immune evasion

“…3F), even at the highest concentration of 1 mM. To confirm the role of HIF-1α in the mechanism of action of indolepyruvate, we examined two HIF-1α target genes, glucose transporter 1 (GLUT1) and lactate dehydrogenase A (LDHA) (33,34). LPS induced the mRNA of both genes and this induction was inhibited in the presence of indolepyruvate (Fig.…”