title: Role for a Zinc Finger Protein (Zfp111) in Transformation of 208F Rat Fibroblasts by Jaagsiekte Sheep Retrovirus Envelope Protein.
abstract: The native envelope gene (env) of Jaagsiekte sheep retrovirus (JSRV) also acts as an oncogene. To investigate the mechanism of transformation, we performed yeast 2-hybrid screening for cellular proteins that interact with Env. Among several candidates, we identified mouse or rat zinc finger protein 111 (zfp111). The interaction between Env and Zfp111 was confirmed through in vivo coimmunoprecipitation assays. Knockdown of endogenous Zfp111 caused a decrease in cell transformation by JSRV Env, while overexpression of Zfp111 increased overall Env transformation, supporting a role for Zfp111 in Env transformation. Knockdown of Zfp111 had no effect on the growth rate of parental rat 208F cells, while it decreased the proliferation rate of JSRV-transformed 208F cells, suggesting that JSRV-transformed cells became dependent on Zfp111. In addition, Zfp111 preferentially bound to a higher-mobility form of JSRV Env that has not been described previously. The higher-mobility form of Env (P70(env)) was found exclusively in the nuclear fraction, and size of its polypeptide backbone was the same as that of the cytoplasmic Env polyprotein (Pr80(env)). The differences in glycosylation between the two versions of Env were characterized. These results identify a novel cellular protein, Zfp111, that binds to the JSRV Env protein, and this binding plays a role in Env transformation. These results indicate that JSRV transformation also involves proteins and interactions in the nucleus.
  
  
  OBJECTIVE
  The envelope protein (Env) of Jaagsiekte sheep retrovirus (JSRV) is an oncogene, but its mechanism of cell transformation is still unclear. Here we identified seven candidate cellular proteins that can interact with JSRV Env by yeast two-hybrid screening. This study focused on one of the seven candidates, zinc finger protein 111 (Zfp111). Zfp111 was shown to interact with JSRV Env in cells and to be involved in JSRV transformation. Moreover, coexpression of JSRV Env and Zfp111 led to the identification of a novel nuclear form of the JSRV Env protein that binds Zfp111. Nuclear Env was found to differ by glycosylation from the cytoplasmic Env precursor to the virion envelope proteins. These results suggest that JSRV Env transformation may involve nuclear events such as an alteration in transcription mediated by Env-Zfp111 interactions.
authors.affiliation: Department of Molecular Biology and Biochemistry and Cancer Research Institute, University of California, Irvine, Irvine, California, USA.
authors.forename: Tom
authors.initials: T
authors.lastname: Hsu
authors.affiliation: Department of Molecular Biology and Biochemistry and Cancer Research Institute, University of California, Irvine, Irvine, California, USA.
authors.forename: An
authors.initials: A
authors.lastname: Phung
authors.affiliation: Department of Molecular Biology and Biochemistry and Cancer Research Institute, University of California, Irvine, Irvine, California, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Choe
authors.affiliation: Department of Life Science Technology, Pai Chai University, Seo-gu, Daejeon, South Korea.
authors.forename: Jung Woo
authors.initials: JW
authors.lastname: Kim
authors.affiliation: Department of Molecular Biology and Biochemistry and Cancer Research Institute, University of California, Irvine, Irvine, California, USA hyfan@uci.edu.
authors.forename: Hung
authors.initials: H
authors.lastname: Fan
mesh_terms: D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry / Q000378:metabolism / Q000821:virology; D002471:Cell Transformation, Neoplastic; D002472:Cell Transformation, Viral; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology / Q000821:virology*; D015870:Gene Expression; D005822:Genetic Vectors; D006031:Glycosylation; D054884:Host-Pathogen Interactions; D006801:Humans; D022141:Jaagsiekte sheep retrovirus / Q000737:chemistry* / Q000378:metabolism; D016086:Lentivirus / Q000235:genetics; D051379:Mice; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012756:Sheep; D015398:Signal Transduction; D020798:Two-Hybrid System Techniques; D014759:Viral Envelope Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016335:Zinc Fingers / Q000235:genetics*
chemical_list: D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D014759:Viral Envelope Proteins