title: U19/Eaf2 binds to and stabilizes von hippel-lindau protein.
abstract: Studies have firmly established a key regulatory role for the tumor suppressor pVHL in the regulation of the vascular system and normal spermatogenesis. Here, we report that knockout of the newly identified tumor suppressor U19/Eaf2 also caused vascular system abnormalities and aspermatogenesis, suggesting a potential link between U19/Eaf2 and pVHL. Coimmunoprecipitation and in vitro binding assays showed an association between U19/Eaf2 and pVHL, whereas deletion mutagenesis revealed the requirement of the NH(2) terminus of U19/Eaf2 and both the alpha and beta domains of pVHL for this binding. U19/Eaf2 stabilizes pVHL, as shown by protein stability and pulse-chase studies. Testes and mouse embryonic fibroblasts (MEF) derived from U19/Eaf2 knockout mice expressed reduced levels of pVHL, indicating that full in vivo expression of pVHL indeed requires U19/Eaf2. As expected, U19/Eaf2 knockout MEF cells exhibited an increased level and activity of hypoxia-inducible factor 1alpha (HIF1alpha), a protein typically regulated via a pVHL-mediated degradation pathway. Furthermore, angiogenesis in a Matrigel plug assay was significantly increased in U19/Eaf2 knockout mice. The above observations argue that U19/Eaf2 can modulate HIF1alpha and angiogenesis, possibly via direct binding and stabilization of pVHL.
authors.affiliation: Department of Urology and University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Wuhan
authors.initials: W
authors.lastname: Xiao
authors.forename: Junkui
authors.initials: J
authors.lastname: Ai
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Habermacher
authors.forename: Olga
authors.initials: O
authors.lastname: Volpert
authors.forename: Ximing
authors.initials: X
authors.lastname: Yang
authors.forename: Ai-Yuan
authors.initials: AY
authors.lastname: Zhang
authors.forename: Junghyun
authors.initials: J
authors.lastname: Hahn
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Cai
authors.forename: Zhou
authors.initials: Z
authors.lastname: Wang
mesh_terms: D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D017353:Gene Deletion; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018919:Neovascularization, Physiologic; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D051794:Von Hippel-Lindau Tumor Suppressor Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: C483108:FESTA protein, mouse; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009687:Nuclear Proteins; D015534:Trans-Activators; D051794:Von Hippel-Lindau Tumor Suppressor Protein