Multiple splice variants of the human HIF-3 alpha locus are targets of the von Hippel-Lindau E3 ubiquitin ligase complex.

Abstract

Functional inactivation of the von Hippel-Lindau (VHL) tumor suppressor protein is the cause of familial VHL disease and sporadic kidney cancer. The VHL gene product (pVHL) is a component of an E3 ubiquitin ligase complex that targets the hypoxia-inducible factor (HIF) 1 and 2 alpha subunits for polyubiquitylation. This process is dependent on the hydroxylation of conserved proline residues on the alpha subunits of HIF-1/2 in the presence of oxygen. In our effort to identify orphan HIF-like proteins in the data base that are potential targets of the pVHL complex, we report multiple splice variants of the human HIF-3 alpha locus as follows: hHIF-3 alpha 1, hHIF-3 alpha 2 (also referred to as hIPAS; human inhibitory PAS domain protein), hHIF-3 alpha 3, hHIF-3 alpha 4, hHIF-3 alpha 5, and hHIF-3 alpha 6. We demonstrate that the common oxygen-dependent degradation domain of hHIF-3 alpha 1-3 splice variants is targeted for ubiquitylation by the pVHL complex in vitro and in vivo. This activity is enhanced in the presence of prolyl hydroxylase and is dependent on a proline residue at position 490. Furthermore, the ubiquitin conjugation occurs on lysine residues at position 465 and 568 within the oxygen-dependent degradation domain. These results demonstrate additional targets of the pVHL complex and suggest a growing complexity in the regulation of hypoxia-inducible genes by the HIF family of transcription factors.

• Authors: Mindy A Maynard, Heng Qi, Jacky Chung, Eric H L Lee, Yukihiro Kondo, Shuntaro Hara, Ronald C Conaway, Joan W Conaway, Michael Ohh
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 278 Issue 13 Pg. 11032-40 (Mar 28 2003) ISSN: 0021-9258 [Print] United States
• PMID: 12538644 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Apoptosis Regulatory Proteins
• Basic Helix-Loop-Helix Transcription Factors
• DNA Primers
• HIF3A protein, human
• Repressor Proteins
• Transcription Factors
• Tumor Suppressor Proteins
• Ubiquitin-Protein Ligases
• Von Hippel-Lindau Tumor Suppressor Protein
• Ligases
• VHL protein, human
• Oxygen

Topics

• Alternative Splicing
• Apoptosis Regulatory Proteins
• Base Sequence
• Basic Helix-Loop-Helix Transcription Factors
• DNA Primers
• Humans
• Ligases (metabolism)
• Oxygen (metabolism)
• Protein Binding
• Repressor Proteins
• Transcription Factors (genetics, metabolism)
• Tumor Cells, Cultured
• Tumor Suppressor Proteins
• Ubiquitin-Protein Ligases
• Von Hippel-Lindau Tumor Suppressor Protein