6-Phosphofructo-2-kinase (pfkfb3) Gene Promoter Contains Hypoxia-inducible Factor-1 Binding Sites Necessary for Transactivation in Response to Hypoxia

Abstract

The up-regulation of glycolysis to enhance the production of energy under reduced pO 2 is a hallmark of the hypoxic response. A key regulator of glycolytic flux is fructose-2,6-bisphosphate, and its steady state concentration is regulated by the action of different isozymes product of four genes (pfkfb1-4). pfkfb3 has been found in proliferating cells and tumors, being induced by hypoxia. To understand the organization of cis-acting sequences that are responsible for the oxygen-regulated pfkfb3 gene, we have studied its 5 -flanking region. Extensive analysis of the 5 pfkfb3 promoter sequence revealed the presence of putative consensus binding sites for various transcription factors that could play an important role in pfkfb3 gene regulation. These DNA consensus sequences included estrogen receptor, hypoxia response element (HRE), early growth response, and specific protein 1 putative binding sites. Promoter deletion analysis as well as putative HREs sequences (wild type and mutated) fused to a c-fos minimal promoter unit constructs demonstrate that the sequence located from ؊1269 to ؊1297 relative to the start site is required for hypoxia-inducible factor 1 (HIF-1) induction. The effective binding of HIF-1 transcription factor to the HREs at ؊1279 and ؊1288 was corroborated by electrophoretic mobility shift assay and biotinylated oligonucleotide pull-down. In addition, HIF-1␣ null mouse embryo fibroblasts transfected with a full-length pfkfb3 promoter-luciferase reporter construct further demonstrated that HIF-1 protein was critically involved for hypoxia transactivation of this gene. Altogether, these results demonstrate that pfkfb3 is a hypoxiainducible gene that is stimulated through HIF interaction with the consensus HRE site in its promoter region.

Interleukin-6 stimulates aerobic glycolysis by regulating PFKFB3 at early stage of colorectal cancer

“…PFKFB3 is the most efficient isoform of this family and is overexpressed in various types of cancers including colon cancer (13). PFKFB3 was demonstrated to be a hypoxia inducible gene that was stimulated through HIF-1 interaction with the consensus hypoxia response element site in its promoter region (14). However, the relationship between PFKFB3 and chronic inflammation is rarely reported.…”

TP53 induced glycolysis and apoptosis regulator (TIGAR) knockdown results in radiosensitization of glioma cells

“…This metabolite is a key regulator of glycolysis and its concentration depends on the activity of different bifunctional enzymes called 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2) encoded by four genes (PFKFB1-4) [3]. In particular, it is known that the transcription of PFKFB3 is modulated by HIF-1 (Hypoxia Inducible Factor-1) and upregulated in cancer, hence the synthesis and elimination of Fru-2,6-P 2 by PFKFB3 and TIGAR are controlled by HIF-1 and p53 respectively, which points out to the relevance of metabolic regulation for tumor suppression [4].…”

Genome-wide analysis of thyroid hormone receptors shared and specific functions in neural cells

“…enzyme of glycolysis (35). Therefore, the existence of a T3/TR/ EPAS1 pathway in the developing brain provides a number of interesting working hypotheses linking two pathways with broad influence.…”