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PLoS One. 2011;6(12):e27955. doi: 10.1371/journal.pone.0027955. Epub 2011 Dec 2.

The GATA1-HS2 enhancer allows persistent and position-independent expression of a β-globin transgene.

Author information

1
H. San Raffaele-Telethon Institute for Gene Therapy (HSR-TIGET), Istituto Scientifico H. San Raffaele, Milan, Italy.

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.

PMID:
22164220
PMCID:
PMC3229501
DOI:
10.1371/journal.pone.0027955
[Indexed for MEDLINE]
Free PMC Article

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