Chuah Marinee K, VandenDriessche Thierry
1 Department of Gene Therapy & Regenerative Medicine, Faculty of Medicine & Pharmacy, Free University of Brussels , Brussels B-1090, Belgium .
Hum Gene Ther Methods. 2013 Dec;24(6):329-32. doi: 10.1089/hgtb.2013.166.
Genome engineering can be accomplished by designer nucleases. They are specifically designed to cleave double-stranded DNA at the desired target locus. This double-strand break subsequently engages the DNA repair pathway through nonhomologous end-joining (NHEJ), resulting in either gene disruption or gene repair. Alternatively, the presence of homologous donor DNA allows for targeted integration of this exogenous donor DNA in this target locus through homology-directed DNA repair. The key bottleneck in genome engineering relates to the delivery and expression of the designer nucleases. One of the most attractive vector platforms for genome engineering is based on integration-defective lentiviral vectors (IDLVs). The intrinsic episomal nature of IDLVs is well suited to ensure transient expression of designer nucleases and minimize potential risks associated with their sustained expression. Unfortunately, their expression is compromised because of epigenetic silencing that interferes with the transcriptional competence of IDLVs. In this issue, Pelascini and colleagues now showed that this bottleneck could be overcome by interfering with chromatin remodeling using histone deacetylase (HDAC) inhibitors. HDAC inhibition restored expression of designer nucleases from IDLVs and rescued their ability to achieve efficient targeted gene disruption by NHEJ comparable with that achieved with bona fide integrating lentiviral vectors. This study has implications for the ex vivo use of IDLVs for gene repair and gene targeting.
基因组工程可通过定制核酸酶来实现。这些核酸酶经过专门设计，能在所需的靶位点切割双链DNA。这种双链断裂随后通过非同源末端连接（NHEJ）参与DNA修复途径，导致基因破坏或基因修复。另外，同源供体DNA的存在使得该外源供体DNA能够通过同源定向DNA修复在该靶位点进行靶向整合。基因组工程的关键瓶颈在于定制核酸酶的递送和表达。基因组工程中最具吸引力的载体平台之一是基于整合缺陷型慢病毒载体（IDLV）。IDLV的固有游离性质非常适合确保定制核酸酶的瞬时表达，并将与其持续表达相关的潜在风险降至最低。不幸的是，由于表观遗传沉默干扰了IDLV的转录能力，其表达受到影响。在本期杂志中，佩拉斯奇尼及其同事现在表明，通过使用组蛋白脱乙酰酶（HDAC）抑制剂干扰染色质重塑可以克服这一瓶颈。HDAC抑制恢复了IDLV中定制核酸酶的表达，并挽救了它们通过NHEJ实现高效靶向基因破坏的能力，这与真正整合型慢病毒载体所实现的能力相当。这项研究对IDLV在基因修复和基因靶向的体外应用具有启示意义。
