Transcriptional regulation of genes encoding glycolytic enzymes by hypoxia-inducible factor 1.

Abstract

Hypoxia-inducible factor 1 (HIF-1) activates erythropoietin gene transcription in Hep3B cells subjected to hypoxia.HIF-1 activity is also induced by hypoxia in non-erythropoietin-producing cells, suggesting a more general regulatory role.W e now report that RNAs encoding the glycolytic enzymes aldolase A (ALDA), phosphoglycerate kinase 1 (PGKl), and pyruvate kinase M were induced by exposure of Hep3B or HeLa cells to inducers of HIF-1 (1% 0,, cobalt chloride, or desferrioxamine), whereas cycloheximide blocked induction of glycolytic RNAs and HIF-1 activity.Oligonucleotides from the ALDA, PGK1, enolase 1, lactate dehydrogenase A, and phosphofructokinase L (PFKL) genes, containing sequences similar to the HIF-1 binding site in the erythropoietin enhancer, specifically bound HIF-1 present in crude nuclear extracts or affinity-purified preparations.Sequences from the ALDA, PFKL, and PGKl genes containing HIF-1 binding sites mediated hypoxia-inducible transcription in transient expression assays.These results support the role of HIF-1 as a mediator of adaptive responses to hypoxia that underlie cellular and systemic oxygen homeostasis.Homeostasis of cellular and systemic function is a consequence of genetic programs that endow individual cells with the ability to sense and respond to environmental changes.Eukaryotes require 0, for a variety of cellular processes, most notably oxidative phosphorylation, the primary metabolic pathway for ATP generation.When 0, is limiting, expression of genes encoding components of the electron transport chain is repressed, whereas transcription of genes encoding enzymes of the glycolytic pathway is activated (1, 2).Vertebrates have evolved a specialized cell type, the erythrocyte, for efficient delivery of 0, to peripheral tissues.Erythrocyte mass is determined by plasma levels of erythropoietin (EPO),' a glycoprotein hormone encoded by a gene whose transcription is regulated by 0, tension in a restricted set of cells primarily located in liver Tobacco Research U. S. A,, the Lucille P. Markey