title: The GATA1-HS2 enhancer allows persistent and position-independent expression of a β-globin transgene.
abstract: Gene therapy of genetic diseases requires persistent and position-independent expression of a therapeutic transgene. Transcriptional enhancers binding chromatin-remodeling and modifying complexes may play a role in shielding transgenes from repressive chromatin effects. We tested the activity of the HS2 enhancer of the GATA1 gene in protecting the expression of a β-globin minigene delivered by a lentiviral vector in hematopoietic stem/progenitor cells. Gene expression from proviruses carrying GATA1-HS2 in both LTRs was persistent and resistant to silencing at most integration sites in the in vivo progeny of human hematopoietic progenitors and murine long-term repopulating stem cells. The GATA1-HS2-modified vector allowed correction of murine β-thalassemia at low copy number without inducing clonal selection of erythroblastic progenitors. Chromatin immunoprecipitation studies showed that GATA1 and the CBP acetyltransferase bind to GATA1-HS2, significantly increasing CBP-specific histone acetylations at the LTRs and β-globin promoter. Recruitment of CBP by the LTRs thus establishes an open chromatin domain encompassing the entire provirus, and increases the therapeutic efficacy of β-globin gene transfer by reducing expression variegation and epigenetic silencing.
authors.affiliation: H. San Raffaele-Telethon Institute for Gene Therapy (HSR-TIGET), Istituto Scientifico H. San Raffaele, Milan, Italy.
authors.forename: Annarita
authors.initials: A
authors.lastname: Miccio
authors.forename: Valentina
authors.initials: V
authors.lastname: Poletti
authors.forename: Francesca
authors.initials: F
authors.lastname: Tiboni
authors.forename: Claudia
authors.initials: C
authors.lastname: Rossi
authors.forename: Antonella
authors.initials: A
authors.lastname: Antonelli
authors.forename: Fulvio
authors.initials: F
authors.lastname: Mavilio
authors.forename: Giuliana
authors.initials: G
authors.lastname: Ferrari
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D044127:Epigenesis, Genetic; D050982:GATA1 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000166:cytology; D006801:Humans; D016086:Lentivirus / Q000235:genetics; D051379:Mice; D010641:Phenotype; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D019076:Transgenes; D055544:beta-Globins / Q000235:genetics; D017086:beta-Thalassemia / Q000378:metabolism*
chemical_list: D050982:GATA1 Transcription Factor; C494688:GATA1 protein, human; C494689:Gata1 protein, mouse; D055544:beta-Globins; D049452:Green Fluorescent Proteins