title: LEDGF hybrids efficiently retarget lentiviral integration into heterochromatin.
abstract: Correction of genetic diseases requires integration of the therapeutic gene copy into the genome of patient cells. Retroviruses are commonly used as delivery vehicles because of their precise integration mechanism, but their use has led to adverse events in which vector integration activated proto-oncogenes and contributed to leukemogenesis. Here, we show that integration by lentiviral vectors can be targeted away from genes using an artificial tethering factor. During normal lentivirus infection, the host cell-encoded transcriptional coactivator lens epithelium-derived growth factor/p75 (LEDGF/p75) binds lentiviral integrase (IN), thereby targeting integration to active transcription units and increasing the efficiency of infection. We replaced the LEDGF/p75 chromatin interaction-binding domain with CBX1. CBX1 binds histone H3 di- or trimethylated on K9, which is associated with pericentric heterochromatin and intergenic regions. The chimeric protein supported efficient transduction of lentiviral vectors and directed the integration outside of genes, near bound CBX1. Despite integration in regions rich in epigenetic marks associated with gene silencing, lentiviral vector expression remained efficient. Thus, engineered LEDGF/p75 chimeras provide technology for controlling integration site selection by lentiviral vectors.
authors.affiliation: Division of Molecular Medicine, Katholieke Universiteit Leuven, Leuven, Belgium.
authors.forename: Rik
authors.initials: R
authors.lastname: Gijsbers
authors.forename: Keshet
authors.initials: K
authors.lastname: Ronen
authors.forename: Sofie
authors.initials: S
authors.lastname: Vets
authors.forename: Nirav
authors.initials: N
authors.lastname: Malani
authors.forename: Jan
authors.initials: J
authors.lastname: De Rijck
authors.forename: Melissa
authors.initials: M
authors.lastname: McNeely
authors.forename: Frederic D
authors.initials: FD
authors.lastname: Bushman
authors.forename: Zeger
authors.initials: Z
authors.lastname: Debyser
mesh_terms: D000090266:Chromobox Protein Homolog 5; D019295:Computational Biology / Q000379:methods; D044127:Epigenesis, Genetic; D015316:Genetic Therapy / Q000379:methods; D006367:HeLa Cells; D006570:Heterochromatin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics*; D007908:Lens, Crystalline / Q000378:metabolism; D016086:Lentivirus / Q000235:genetics*; D018613:Microscopy, Confocal / Q000379:methods; D008957:Models, Genetic; D017434:Protein Structure, Tertiary; D012190:Retroviridae / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: C000715593:CBX1 protein, human; D006570:Heterochromatin; D036341:Intercellular Signaling Peptides and Proteins; C119380:lens epithelium-derived growth factor; D000090266:Chromobox Protein Homolog 5