title: Identification of a novel binding protein of FAT10: eukaryotic translation elongation factor 1A1.
abstract: BACKGROUND
  FAT10 is known to execute its functions mainly through conjugation to different substrates, and these known functions include cytokine responses, apoptosis, mitosis, and tumorigenesis. Nonetheless, the known binding proteins of FAT10 cannot explain all its known functions. As such, the aim of this study was to identify unidentified conjugation proteins of FAT10.
  
  
  METHODS
  The yeast two-hybrid system was employed in this study. FAT10 was used as the bait protein for screening of a cDNA library from a human hepatocellular carcinoma cell line, Hep3B. Protein interactions were confirmed based on localization studies and co-immunoprecipitation assays. The expression of mRNA and protein was determined using real-time polymerase chain reaction and western blot analyses, respectively.
  
  
  RESULTS
  In this study, we identified eukaryotic elongation factor 1A1 (eEF1A1) as a FAT10-specific binding protein. The binding between FAT10 and eEF1A1 was confirmed both in vivo and in vitro. We also found that, when the expression of FAT10 was reduced by siRNA knockdown, this resulted in downregulation of eEF1A1 expression at both the mRNA and protein levels in human hepatocellular carcinoma cells.
  
  
  CONCLUSIONS
  We propose a model in which eEF1A1 serves as a substrate of FAT10 to accomplish, in part, its functions in regulating the biological behavior of tumor cells. Since both eEF1A1 and FAT10 are important for tumorigenesis and development, comprehending the mechanisms of this interaction can provide clues for identification of novel strategic targets for drug screening and molecular typing, and possibly in the development of new effective therapeutic strategies against hepatocellular carcinoma.
authors.affiliation: The Department of Hepatobiliary Surgery, The Second Affiliated Hospital of Nanchang University, Nanchang 330006, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Yu
authors.forename: Xiuxia
authors.initials: X
authors.lastname: Liu
authors.forename: Tiande
authors.initials: T
authors.lastname: Liu
authors.forename: Kui
authors.initials: K
authors.lastname: Hong
authors.forename: Jun
authors.initials: J
authors.lastname: Lei
authors.forename: Rongfa
authors.initials: R
authors.lastname: Yuan
authors.forename: Jianghua
authors.initials: J
authors.lastname: Shao
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D045744:Cell Line, Tumor; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D020648:Peptide Elongation Factor 1 / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering; D020798:Two-Hybrid System Techniques; D014452:Ubiquitins / Q000235:genetics / Q000378:metabolism*
chemical_list: C094814:EEF1A1 protein, human; D020648:Peptide Elongation Factor 1; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C109184:UBD protein, human; D014452:Ubiquitins