title: CTF/NF1 transcription factors act as potent genetic insulators for integrating gene transfer vectors.
abstract: Gene transfer-based therapeutic approaches have greatly benefited from the ability of some viral vectors to efficiently integrate within the cell genome and ensure persistent transmission of newly acquired transgenes to the target cell progeny. However, integration of provirus has been associated with epigenetic repercussions that may influence the expression of both the transgene and cellular genes close to vector integration loci. The exploitation of genetic insulator elements may overcome both issues through their ability to act as barriers that limit transgene silencing and/or as enhancer-blockers preventing the activation of endogenous genes by the vector enhancer. We established quantitative plasmid-based assay systems to screen enhancer-blocker and barrier genetic elements. Short synthetic insulators that bind to nuclear factor-I protein family transcription factors were identified to exert both enhancer-blocker and barrier functions, and were compared to binding sites for the insulator protein CTCF (CCCTC-binding factor). Gamma-retroviral vectors enclosing these insulator elements were produced at titers similar to their non-insulated counterparts and proved to be less genotoxic in an in vitro immortalization assay, yielding lower activation of Evi1 oncogene expression and reduced clonal expansion of bone marrow cells.
authors.affiliation: Institute of Biotechnology, University of Lausanne, Lausanne, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Gaussin
authors.forename: U
authors.initials: U
authors.lastname: Modlich
authors.forename: C
authors.initials: C
authors.lastname: Bauche
authors.forename: N J
authors.initials: NJ
authors.lastname: Niederländer
authors.forename: A
authors.initials: A
authors.lastname: Schambach
authors.forename: C
authors.initials: C
authors.lastname: Duros
authors.forename: A
authors.initials: A
authors.lastname: Artus
authors.forename: C
authors.initials: C
authors.lastname: Baum
authors.forename: O
authors.initials: O
authors.lastname: Cohen-Haguenauer
authors.forename: N
authors.initials: N
authors.lastname: Mermod
mesh_terms: D000818:Animals; D001665:Binding Sites; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism; D000076246:CCCTC-Binding Factor; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D005622:Friend murine leukemia virus / Q000235:genetics / Q000378:metabolism; D020868:Gene Silencing; D018014:Gene Transfer Techniques; D005822:Genetic Vectors / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D038101:Insulator Elements; D000074008:MDS1 and EVI1 Complex Locus Protein; D051379:Mice; D008810:Mice, Inbred C57BL; D051839:NFI Transcription Factors / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D011519:Proto-Oncogenes / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation; D014162:Transfection; D019076:Transgenes; D016662:Virus Integration
chemical_list: D000076246:CCCTC-Binding Factor; C000619697:CTCF protein, human; C077305:CTF-1 transcription factor; C000619698:Ctcf protein, mouse; D004268:DNA-Binding Proteins; D000074008:MDS1 and EVI1 Complex Locus Protein; C499305:Mecom protein, mouse; D051839:NFI Transcription Factors; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D014157:Transcription Factors