title: Widespread expression of BORIS/CTCFL in normal and cancer cells.
abstract: BORIS (CTCFL) is the paralog of CTCF (CCCTC-binding factor; NM_006565), a ubiquitously expressed DNA-binding protein with diverse roles in gene expression and chromatin organisation. BORIS and CTCF have virtually identical zinc finger domains, yet display major differences in their respective C- and N-terminal regions. Unlike CTCF, BORIS expression has been reported only in the testis and certain malignancies, leading to its classification as a "cancer-testis" antigen. However, the expression pattern of BORIS is both a significant and unresolved question in the field of DNA binding proteins. Here, we identify BORIS in the cytoplasm and nucleus of a wide range of normal and cancer cells. We compare the localization of CTCF and BORIS in the nucleus and demonstrate enrichment of BORIS within the nucleolus, inside the nucleolin core structure and adjacent to fibrillarin in the dense fibrillar component. In contrast, CTCF is not enriched in the nucleolus. Live imaging of cells transiently transfected with GFP tagged BORIS confirmed the nucleolar accumulation of BORIS. While BORIS transcript levels are low compared to CTCF, its protein levels are readily detectable. These findings show that BORIS expression is more widespread than previously believed, and suggest a role for BORIS in nucleolar function.
authors.affiliation: Queen Mary University of London, Centre for Neuroscience and Trauma, Blizard Institute, Barts and the London School of Medicine and Dentistry, London, United Kingdom.
authors.forename: Tania A
authors.initials: TA
authors.lastname: Jones
authors.forename: Babatunji W
authors.initials: BW
authors.lastname: Ogunkolade
authors.forename: Jaroslaw
authors.initials: J
authors.lastname: Szary
authors.forename: Johan
authors.initials: J
authors.lastname: Aarum
authors.forename: Muhammad A
authors.initials: MA
authors.lastname: Mumin
authors.forename: Shyam
authors.initials: S
authors.lastname: Patel
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Pieri
authors.forename: Denise
authors.initials: D
authors.lastname: Sheer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000076246:CCCTC-Binding Factor; D045744:Cell Line, Tumor; D002466:Cell Nucleolus / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism*; D021382:Protein Sorting Signals; D021381:Protein Transport; D012097:Repressor Proteins / Q000378:metabolism
chemical_list: D000076246:CCCTC-Binding Factor; C000619697:CTCF protein, human; C456540:CTCFL protein, human; D002868:Chromosomal Proteins, Non-Histone; C000619698:Ctcf protein, mouse; C499208:Ctcfl protein, mouse; D004268:DNA-Binding Proteins; D021382:Protein Sorting Signals; D012097:Repressor Proteins; C047458:fibrillarin