Stabilization of hypoxia-inducible factor-1alpha protein in hypoxia occurs independently of mitochondrial reactive oxygen species production.

Abstract

The transcription factor hypoxia-inducible factor-1α (HIF-1α) is a master regulator of the cellular response to low oxygen. HIF-1α protein accumulates in hypoxia due to inhibition of prolyl hydroxylase enzymes, which under normoxic conditions use molecular oxygen to hydroxylate HIF-1α on two conserved proline residues (Pro(402) and Pro(564)), thus targeting the protein for 26 S proteasome-dependent degradation. A functional mitochondrial electron transport chain is known to be necessary for HIF-1α stabilization in hypoxia. It has been reported that reactive oxygen species (ROS), produced under hypoxia by complex III of the mitochondrial electron transport chain, play a critical role in the stabilization of the HIF-1α protein, possibly by directly inhibiting prolyl hydroxylase enzymes. In contrast, we found that ROS production by complex III is not required for hypoxia-induced HIF-1α stabilization. Thus, reestablishing mitochondrial oxygen consumption in the presence of a complex III inhibitor by using an artificial electron donor to complex IV or by overexpressing Ciona intestinalis alternative oxidase results in HIF-1α protein stabilization in hypoxia. Furthermore, five inhibitors that target different sites of the mitochondrial electron transport chain have similar effects on the HIF-1α protein half-life in hypoxia but vary in their effects on mitochondrial ROS production. Finally, ROS do not regulate prolyl hydroxylase activity directly. We conclude that HIF-1α protein stabilization in hypoxia occurs independently of mitochondrial ROS production. However, mitochondria can modulate the cellular hypoxic response through altered respiratory activity, likely by regulating the cellular oxygen availability.

• Authors: Yee Liu Chua, Eric Dufour, Emmanuel P Dassa, Pierre Rustin, Howard T Jacobs, Cormac T Taylor, Thilo Hagen
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 285 Issue 41 Pg. 31277-84 (Oct 08 2010) ISSN: 1083-351X [Electronic] United States
• PMID: 20675386 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• HIF1A protein, human
• Hif1a protein, mouse
• Hypoxia-Inducible Factor 1, alpha Subunit
• Reactive Oxygen Species
• Procollagen-Proline Dioxygenase
• Proteasome Endopeptidase Complex
• ATP dependent 26S protease
• Electron Transport Complex III

Topics

• Animals
• Cell Hypoxia (physiology)
• Cell Line, Tumor
• Ciona intestinalis (genetics, metabolism)
• Electron Transport Complex III (genetics, metabolism)
• Humans
• Hypoxia-Inducible Factor 1, alpha Subunit (genetics, metabolism)
• Mice
• Mitochondria, Liver (genetics, metabolism)
• Procollagen-Proline Dioxygenase (genetics, metabolism)
• Proteasome Endopeptidase Complex (genetics, metabolism)
• Protein Stability
• Reactive Oxygen Species (metabolism)