title: The VHL protein recruits a novel KRAB-A domain protein to repress HIF-1alpha transcriptional activity.
abstract: The von Hippel-Lindau tumor suppressor (pVHL) is a component of an E3 ubiquitin ligase and targets hypoxia-inducible factor-1alpha (HIF-1alpha) for ubiquitylation and degradation under normoxic conditions. pVHL also directly inhibits HIF-1alpha transactivation by recruiting histone deacetylases. Here, we report a novel pVHL-interacting protein that functions as a negative regulator of HIF-1alpha transactivation. This protein, generated from the ZnF197 locus by alternative splicing, contains a Kruppel-associated box (KRAB)-A domain and a SCAN domain, but lacks the 22 C2H2-type zinc fingers present in ZnF197. Therefore, we named this protein pVHL-associated KRAB-A domain-containing protein (VHLaK). We demonstrate that the KRAB-A domain in VHLaK mediates pVHL binding and functions as a transcriptional repression module. The SCAN domain mediates VHLaK homo-oligomerization, which enhances VHLaK repressive activity. pVHL can recruit VHLaK to repress HIF-1alpha transcriptional activity and HIF-1alpha-induced VEGF expression. Finally, we demonstrate that pVHL, VHLaK and KAP1/TIF-1beta can be recruited into a single complex, indicating that KAP1/TIF-1beta may participate in pVHL-mediated transcriptional repression of HIF-1alpha. Our findings provide a novel mechanism for the modulation of HIF-1alpha transactivation by pVHL.
authors.affiliation: Departments of Urology and Pathology, and The James PWilmot Cancer Center, University of Rochester Medical Center, Rochester, NY 14642, USA.
authors.forename: Zaibo
authors.initials: Z
authors.lastname: Li
authors.forename: Dakun
authors.initials: D
authors.lastname: Wang
authors.forename: Xi
authors.initials: X
authors.lastname: Na
authors.forename: Susan R
authors.initials: SR
authors.lastname: Schoen
authors.forename: Edward M
authors.initials: EM
authors.lastname: Messing
authors.forename: Guan
authors.initials: G
authors.lastname: Wu
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism; D016228:Endothelial Growth Factors / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D016147:Genes, Tumor Suppressor; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008025:Ligases / Q000235:genetics / Q000378:metabolism*; D008222:Lymphokines / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D016415:Sequence Alignment; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D000076183:Tripartite Motif-Containing Protein 28; D025521:Tumor Suppressor Proteins; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D051794:Von Hippel-Lindau Tumor Suppressor Protein
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D016228:Endothelial Growth Factors; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; C474389:ZNF197 protein, human; C101116:TRIM28 protein, human; D000076183:Tripartite Motif-Containing Protein 28; D044767:Ubiquitin-Protein Ligases; D051794:Von Hippel-Lindau Tumor Suppressor Protein; D008025:Ligases; C497446:VHL protein, human