发布: 2017年08月05日第7卷第15期 DOI: 10.21769/BioProtoc.2425 浏览次数: 9555
评审: Longping Victor TseKanika GeraAnonymous reviewer(s)
Abstract
Minimal DNA vectors exclusively comprising therapeutically relevant sequences hold great promise for the development of novel therapeutic regimen. Dumbbell-shaped vectors represent non-viral non-integrating DNA minimal vectors which have entered an advanced stage of clinical development (Hardee et al., 2017). Spliceable introns and DNA nuclear import signals such as SV40 enhancer sequences are molecular features that have found multiple applications in plasmid vectors to improve transgene expression. In dumbbells however, effects triggered by introns were not investigated and DNA-based nuclear import sequences have not found applications yet, presumably because dumbbell vectors have continuously been minimized with regard to size. We investigated the effects of an intron and/or SV40 enhancer derived sequences on dumbbell vector driven reporter gene expression. The implementation of a spliceable intron was found to enhance gene expression unconditionally in all investigated cell lines. Conversely, the use of the SV40 enhancer improved gene expression in a cell type-dependent manner. Though both features significantly enlarge dumbbell vector size, neither the intron nor the enhancer or a combination of both revealed a negative effect on gene expression. On the contrary, both features together improved dumbbell-driven gene expression up to 160- or 56-fold compared with plasmids or control dumbbells. Thus, it is highly recommended to consider an intron and the SV40 enhancer for dumbbell vector design. Such an advanced design can facilitate pre-clinical and clinical applications of dumbbell-shaped DNA vectors.
Keywords: Dumbbell vector (哑铃形载体)Background
Although many genes have been expressed using dumbbell-shaped DNA vectors, most of these applications used the basic design comprising a promoter, the coding sequence (CDS), and a transcriptional terminator. Some vectors included a chimeric intron, however, it was not reported whether transgene expression was enhanced by this design (Schirmbeck et al., 2001). Here we studied the effects triggered by molecular features that frequently find applications in plasmid design on dumbbell-driven gene expression: 1. A chimeric intron derived from the human β-globin gene–splicing is known to facilitate RNA processing, nuclear export, and subsequently gene expression (Luo and Reed, 1999); and 2. The Simian virus 40 (SV40) enhancer which can enhance the activity of the homologous SV40 promoter and which in addition was reported to function as an active DNA nuclear import sequence (Dean, 1997; Dean et al., 1999). The proposed mechanism behind this phenomenon is that the SV40 enhancer recruits transcription factors harboring protein nuclear import signals in the cytoplasm and that the vector DNA is piggyback translocated into the nucleus with support of the protein nuclear import machinery. We generated luciferase-expressing dumbbell vectors harboring either both, only one or none of these molecular features and monitored transgene expression in HEK293T and HepG2 cells. Our data demonstrate that introns and the SV40 enhancer can substantially improve dumbbell vector design (Jiang et al., 2016).
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版权信息
© 2017 The Authors; exclusive licensee Bio-protocol LLC.
如何引用
Jiang, X. and Patzel, V. (2017). Advanced Design of Minimalistic Dumbbell-shaped Gene Expression Vectors. Bio-protocol 7(15): e2425. DOI: 10.21769/BioProtoc.2425.
分类
微生物学 > 微生物生物化学 > DNA
分子生物学 > DNA > 基因表达
分子生物学 > DNA > DNA 克隆
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