双向逆转录病毒整合位点PCR方法和定量数据分析工作流程
Summary
该手稿描述了可以同时分析上游和下游载体 – 宿主连接DNA的双向整合位点测定的实验程序和软件分析。双向PCR产品可用于任何下游测序平台。所得数据对于综合DNA靶标的高通量，定量比较是有用的。
Abstract
整合位点（IS）测定是逆转录病毒整合位点研究的关键组成部分及其生物学意义。在最近的逆转录病毒基因治疗研究中，IS测定结合下一代测序已被用作细胞跟踪工具来表征共享相同IS的克隆干细胞群体。为了准确比较不同样品内和跨越不同样品的干细胞克隆，检测灵敏度，数据重现性和高通量能力均为最重要的检测标准之一。这项工作为双向IS分析提供了详细的协议和数据分析工作流程。双向测定可以同时排列上游和下游载体 – 宿主结。与常规单向IS测序方法相比，双向方法显着提高了IS检测率和t两端积分事件的表征他瞄准DNA。这里描述的数据分析流程通过多个比较步骤准确地识别和列举相同的IS序列，将IS序列映射到参考基因组上并确定测序误差。使用优化的测定程序，我们最近在恒河猴猕猴移植后发表了数千个造血干细胞（HSC）克隆的详细重新填充模式，首次证实了HSC重新增殖的精确时间点和HSC在功能异质性中的功能异质性灵长类动物系统。以下协议描述了准确识别和量化相同的IS序列的逐步实验过程和数据分析工作流程。
Introduction
逆转录病毒将其基因组DNA插入各个位点的宿主基因组。这种独特的性质可能有助于癌症和其他形式的病毒发病机制的发展，具有使这些病毒高度适应细胞工程用于基因治疗和基础生物学研究的讽刺意义。病毒整合位点（IS） – 整合了外来DNA（病毒）的宿主基因组上的位置 – 对整合的病毒和宿主细胞的命运具有重要意义。 IS测定已经用于各种生物和临床研究环境，以研究逆转录病毒整合位点选择和发病机理，癌症发展，干细胞生物学和发育生物学1,2,3,4 。检测灵敏度低，数据重现性差，交叉污染频繁将IS测定应用限制在当前和计划研究中的关键因素。
已经开发了许多IS分析技术。包括连接介导的（LM）聚合酶链反应（PCR） 5 ，逆PCR 6和线性扩增介导（LAM）PCR 7的限制性酶基整合位点测定法是最广泛使用的。然而，使用位点特异性限制性酶在IS的检索期间产生偏倚，仅允许在限制性位点附近恢复4个整合到宿主基因组内的整合子（集成到宿主基因组中的外来DNA） 4 。最近几年也引入了更综合评估载体IS的分析技术。这些测定采用各种策略，包括Mu转座子介导的PCR 8 ，非限制性（nr）-LAM PCR 9 ，II型限制性内切酶缓冲消化10 ，机械剪切11和随机六聚体基因PCR（Re-free PCR） 12 ，以克隆基因组DNA并扩增IS。目前的技术具有不同程度的检测灵敏度，基因组覆盖率，靶特异性，高通量能力，测定程序的复杂性以及检测目标位点相对频率的偏差。鉴于现有测定的不同质量和可以使用的各种目的，应仔细选择最佳测定方法。
该工作提供了详细的实验程序和双向测定的计算数据分析工作流程，通过同时分析整合的靶DNA的上游和下游IS，显着提高检测率和序列定量准确度（参见图1的测定程序示意图）。这种方法也提供了是表征逆转录病毒整合过程的手段（例如，靶位点重复的保真度和上游和下游插入的基因组序列的变化）。其他双向方法主要用于克隆和测序目标DNA 11,13,14的两端。使用公认的LM-PCR方法和计算分析映射以及用于量化上游和下游连接点，广泛优化用于载体标记克隆的高通量和可重复定量的测定。已经证明使用TaqαI酶的双向分析对于干细胞基因治疗临床前研究中的高通量克隆定量是有用的。本文介绍了一种使用更频繁的切割器（RsaI / CviQI-主题：GTAC）的修改方法，使两倍与基于TaqαI的测定相比，他检测到整合素的机会。描述了使用GTAC基序酶用于慢病毒（NL4.3及其衍生物）和γ-逆转录病毒（pMX载体）载体IS分析的详细实验和数据分析程序。测定中使用的寡核苷酸列于表1中 。用于IS序列分析的内部编程脚本在补充文档中提供。
Protocol
Representative Results
Discussion
双向测定能够同时分析上游（左）和下游（右）载体 – 宿主DNA连接序列，并且可用于许多基因治疗，干细胞和癌症研究应用。与以前的基于TCGA基序的酶（ TaqαI ）为基础的检测2,15和其他方法相比，使用GTAC基序酶（RsaI和CviQI）和双向PCR方法显着提高了检测内含子（或克隆群体）的机会单向LM-PCR方法5 。双向测定改善了IS的分析，特别是在临床或小动物模型研究中经常?…
Disclosures
The authors have nothing to disclose.
Acknowledgements
资助由美国国家卫生研究院R00-HL116234，U19 AI117941和R56 HL126544提供;国家科学基金会授予DMS-1516675;韩国国家研究基金会（NRF-2011-0030049，NRF-2014M3C9A3064552）;和KRIBB倡议计划。
Materials
| Thermostable DNA polymerase | Agilent | 600424 | PicoMaxx Polymerase |
| Thermostable DNA polymerase buffer | Agilent | 600424 | PicoMaxx Polymerase buffer |
| Deoxynucleotide (dNTP) solution mix | New England Biolabs | N0447L | dNTP solution mix (10mM each) |
| PCR tubes | VWR International | 53509-304 | PCR Strip Tubes With Individual Attached Caps |
| 2ml microcentrifuge tube | Molecular Bioproducts | 3453 | microcentrifuge tubes |
| PCR purification kit | Qiagen | 28106 | |
| RsaI | New England Biolabs | R0167L | restriction enzyme |
| CviQI | New England Biolabs | R0639L | restriction enzyme |
| Buffer A | New England Biolabs | B7204S | NEB CutSmart buffer |
| DNA Polymerase I large (klenow) fragment | New England Biolabs | M0210L | Blunting |
| streptavidin beads solution | Invitrogen | 60101 | Dynabeads kilobaseBINDER kit |
| Binding Solution | Invitrogen | 60101 | Dynabeads kilobaseBINDER kit |
| Washing Solution | Invitrogen | 60101 | Dynabeads kilobaseBINDER kit |
| magnetic stand | ThermoFisher | 12321D | DynaMag™-2 Magnet |
| T4 DNA ligase | New England Biolabs | M0202L | T4 DNA ligase |
| 10X T4 DNA ligase buffer | New England Biolabs | B0202S | T4 DNA ligase reaction buffer |
| 5X T4 DNA ligase buffer | Invitrogen | 46300-018 | T4 DNA ligase buffer with polyethylene glycol-8000 |
| UV-Vis spectrophotometer | Fisher Scientific | S06497 | Nanodrop 2000 |
| pvuII | new England Biolabs | R0151L | restriction enzyme |
| sfoI | new England Biolabs | R0606L | restriction enzyme |
| Buffer B | new England Biolabs | B7203S | NEB buffer 3.1 |
| Nuclease free water | Integrated DNA Technologies | 11-05-01-14 | |
| Capillary electrophoresis | Qiagen | 9001941 | QIAxcel capillary electrophoresis |
| Veriti 96-well Fast Thermal Cycler | Thermo Fisher Scientific | 4375305 | PCR Instrument |
| Rotating wheel (or Roller) | Eppendorf | M10534004 | Cell Culture Roller Drums |
| DNA size marker | Qiagen | 929559 | QX size marker (100-2,500 bp) |
| DNA size marker | Qiagen | 929554 | QX size marker (50-1,500 bp) |
| DNA alignment markers | Qiagen | 929524 | QX DNA Alignment Marker |
| genomc DNA | Not Available | Not Available | Sample genomc DNA from in vivo or in vitro experiments |
References
- Serrao, E., Engelman, A. N. Sites of Retroviral DNA Integration: From Basic Research to Clinical Applications. Crit. Rev. Biochem. Mol. Bio. 51 (1), 26-42 (2016).
- Kim, S., et al. Dynamics of HSPC Repopulation in Nonhuman Primates Revealed by a Decade-Long Clonal-Tracking Study. Cell Stem Cell. 14 (4), 473-485 (2014).
- Bushman, F. Retroviral integration and human gene therapy. J. Clin. Invest. 117 (8), 2083-2086 (2007).
- Bystrykh, L. V., Verovskaya, E., Zwart, E., Broekhuis, M., de Haan, G. Counting stem cells: methodological constraints. Nat Meth. 9 (6), 567-574 (2012).
- Schröder, A., et al. HIV-1 integration in the human genome favors active genes and local hotspots. Cell. 110 (4), 521-529 (2002).
- Silver, J., Keerikatte, V. Novel use of polymerase chain reaction to amplify cellular DNA adjacent to an integrated provirus. J. Virol. 64, 3150 (1990).
- Schmidt, M., et al. High-resolution insertion-site analysis by linear amplification-mediated PCR (LAM-PCR). Nat. Meth. 4 (12), 1051-1057 (2007).
- Brady, T., et al. A method to sequence and quantify DNA integration for monitoring outcome in gene therapy. Nucleic Acids Res. 39 (11), e72 (2011).
- Gabriel, R., et al. Comprehensive genomic access to vector integration in clinical gene therapy. Nat. Med. 15 (12), 1431-1436 (2009).
- Kim, S., Kim, Y., Liang, T., Sinsheimer, J., Chow, S. A high-throughput method for cloning and sequencing human immunodeficiency virus type 1 integration sites. J. Virol. 80 (22), 11313-11321 (2006).
- Maldarelli, F., et al. Specific HIV integration sites are linked to clonal expansion and persistence of infected cells. Science. 345 (6193), 179-183 (2014).
- Wu, C., et al. High Efficiency Restriction Enzyme-Free Linear Amplification-Mediated Polymerase Chain Reaction Approach for Tracking Lentiviral Integration Sites Does Not Abrogate Retrieval Bias. Hum. Gene. Ther. 24 (1), 38-47 (2013).
- Aker, M., Tubb, J., Miller, D. G., Stamatoyannopoulos, G., Emery, D. W. Integration Bias of Gammaretrovirus Vectors following Transduction and Growth of Primary Mouse Hematopoietic Progenitor Cells with and without Selection. Mol. Ther. 14 (2), 226-235 (2006).
- Gabriel, R., Kutschera, I., Bartholomae, C. C., von Kalle, C., Schmidt, M. Linear Amplification Mediated PCR; Localization of Genetic Elements and Characterization of Unknown Flanking DNA. J Vis Exp. (88), e51543 (2014).
- Kim, S., et al. High-throughput, sensitive quantification of repopulating hematopoietic stem cell clones. J. Virol. 84 (22), 11771-11780 (2010).
- Mitchell, R., et al. Retroviral DNA integration: ASLV, HIV, and MLV show distinct target site preferences. PLoS Biol. 2 (8), e234 (2004).
- Melkus, M., et al. Humanized mice mount specific adaptive and innate immune responses to EBV and TSST-1. Nat. Med. 12 (11), 1316-1322 (2006).
- Bystrykh, L. V. A combinatorial approach to the restriction of a mouse genome. BMC Res Notes. 6, 284 (2013).
- Beard, B. C., Adair, J. E., Trobridge, G. D., Kiem, H. -. P. High-throughput genomic mapping of vector integration sites in gene therapy studies. Methods Mol Biol. , 321-344 (2014).
- Gabriel, R., et al. Comprehensive genomic access to vector integration in clinical gene therapy. Nat. Med. 15 (12), 1431-1436 (2009).
- Qin, X., An, D., Chen, I., Baltimore, D. Inhibiting HIV-1 infection in human T cells by lentiviral-mediated delivery of small interfering RNA against CCR5. Proc Natl Acad Sci U S A. 100 (1), 183-188 (2003).
- Kitamura, T., et al. Retrovirus-mediated gene transfer and expression cloning: powerful tools in functional genomics. Exp. Hematol. 31 (11), 1007-1014 (2003).
- Cartier, N., et al. Hematopoietic stem cell gene therapy with a lentiviral vector in X-linked adrenoleukodystrophy. Science. 326 (5954), 818-823 (2009).
