Structural and functional analysis of hypoxia-inducible factor 1

Area of Science:

• Molecular Biology
• Cellular Biology
• Genetics

Background:

• Hypoxia-inducible factor 1 (HIF-1) is a transcription factor regulating genes involved in cellular response to low oxygen.
• HIF-1 controls genes for erythropoietin, vascular endothelial growth factor, and glycolytic enzymes.

Purpose of the Study:

• To elucidate the structure and function of HIF-1.
• To investigate the regulation of HIF-1 alpha and HIF-1 beta (ARNT) protein and mRNA expression under hypoxic conditions.

Main Methods:

• Co-transfection of expression vectors and reporter genes.
• Analysis of HIF-1 binding site activity.
• Measurement of HIF-1 alpha and HIF-1 beta protein and mRNA levels in various cell lines and organs.
• Gene mapping of HIF1A.

Main Results:

• HIF-1 is a heterodimer of HIF-1 alpha and HIF-1 beta (ARNT).
• Dimerization requires HLH and PAS domains; DNA binding involves the basic domain.
• Hypoxia induces HIF-1 alpha and HIF-1 beta protein levels in all cell lines examined.
• HIF-1 DNA-binding activity increases with decreasing oxygen tension.
• HIF-1 alpha and HIF-1 beta mRNAs are widely distributed and modestly induced by hypoxia in vivo.

Conclusions:

• HIF-1 plays a critical role in the cellular oxygen response.
• Hypoxia significantly regulates HIF-1 at the protein level.
• The HIF1A gene is located on human chromosome 14 and mouse chromosome 12.