Tat-binding protein-1, a component of the 26S proteasome, contributes to the E3 ubiquitin ligase function of the von Hippel-Lindau protein.
von Hippel-Lindau (VHL) gene inactivation occurs in von Hippel-Lindau (VHL) disease. The protein pVHL functions in a multi-subunit E3 ubiquitin ligase that targets the hypoxia-inducible transcription factor Hif1 alpha for proteasomal degradation during normoxia. We establish that pVHL binds to Tat-binding protein-1 (TBP-1), a component of the 19S regulatory complex of the proteasome. TBP-1 associates with the beta-domain of pVHL and complexes with pVHL and Hif1 alpha in vivo. Overexpression of TBP-1 promotes degradation of Hif1 alpha in a pVHL-dependent manner that requires the ATPase domain of TBP-1. Blockade of TBP-1 expression by small interfering RNA (siRNA) causes prolonged degradation kinetics of Hif1 alpha. Several distinct mutations in exon 2 of VHL disrupt binding of pVHL to TBP-1. A pVHL mutant containing a P154L substitution coimmunoprecipitates with Hif1 alpha, but not TBP-1, and does not promote degradation of Hif1 alpha. Thus, the ability of pVHL to degrade Hif1 alpha depends in part on its interaction with TBP-1 and suggests a new mechanism for Hif1 alpha stabilization in some pVHL-deficient tumors.
Corn
Paul G
PG
Department of Medicine, Howard Hughes Medical Institute and Abramson Cancer Center, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
McDonald
E Robert
ER
Herman
James G
JG
El-Deiry
Wafik S
WS
D000074183:ATPases Associated with Diverse Cellular Activities; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D006868:Hydrolysis; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011485:Protein Binding; D034741:RNA, Small Interfering; D014157:Transcription Factors / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D051794:Von Hippel-Lindau Tumor Suppressor Protein
D004268:DNA-Binding Proteins; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D034741:RNA, Small Interfering; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D000074183:ATPases Associated with Diverse Cellular Activities; C064757:PSMC3 protein, human; C497446:VHL protein, human