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Hypoxia inducible factor-alpha binding and ubiquitylation by the von Hippel-Lindau tumor suppressor protein.
J BIOL CHEM
25733 - 25741.
The von Hippel-Lindau tumor suppressor protein (pVHL) has emerged as a key factor in cellular responses to oxygen availability, being required for the oxygen-dependent proteolysis of alpha subunits of hypoxia inducible factor-1 (HIF), Mutations in VHL cause a hereditary cancer syndrome associated with dysregulated angiogenesis, and up-regulation of hypoxia inducible genes, Here we investigate the mechanisms underlying these processes and show that extracts from VHL-deficient renal carcinoma cells have a defect in HIF-alpha ubiquitylation activity which is complemented by exogenous pVHL, This defect was specific for HIF-alpha among a range of substrates tested. Furthermore, HIF-alpha subunits were the only pVHL-associated proteasomal substrates identified by comparison of metabolically labeled anti-pVHL immunoprecipitates from proteosomally inhibited cells and normal cells. Analysis of pVHL/HIF-alpha interactions defined short sequences of conserved residues within the internal transactivation domains of HIF-alpha molecules sufficient for recognition by pVHL, In contrast, while full-length pVHL and the p19 variant interact with HIF-alpha, the association was abrogated by further N-terminal and C-terminal truncations. The interaction was also disrupted by tumor-associated mutations in the beta-domain of pVHL and loss of interaction was associated with defective HIF-alpha ubiquitylation and regulation, defining a mechanism by which these mutations generate a constitutively hypoxic pattern of gene expression promoting angiogenesis, The findings indicate that pVHL regulates HIF-alpha proteolysis by acting as the recognition component of a ubiquitin ligase complex, and support a model in which its beta domain interacts with short recognition sequences in HIF-alpha subunits.
|Title:||Hypoxia inducible factor-alpha binding and ubiquitylation by the von Hippel-Lindau tumor suppressor protein|
|Open access status:||An open access publication|
|Keywords:||FACTOR 1-ALPHA HIF-1-ALPHA, IRON-REGULATORY PROTEIN-2, DEPENDENT PROTEOLYSIS, UBIQUITIN LIGASE, GENE-PRODUCT, ELONGIN-B, DEGRADATION, ACTIVATION, COMPLEX, FACTOR-1-ALPHA|
|UCL classification:||UCL > School of Life and Medical Sciences > Faculty of Medical Sciences > Medicine (Division of)|
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