Abstract
Targeted nucleases, including zinc-finger nucleases (ZFNs), transcription activator-like (TAL) effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9), have provided researchers with the ability to manipulate nearly any genomic sequence in human cells and model organisms. However, realizing the full potential of these genome-modifying technologies requires their safe and efficient delivery into relevant cell types. Unlike methods that rely on expression from nucleic acids, the direct delivery of nuclease proteins to cells provides rapid action and fast turnover, leading to fewer off-target effects while maintaining high rates of targeted modification. These features make nuclease protein delivery particularly well suited for precision genome engineering. Here we describe procedures for implementing protein-based genome editing in human embryonic stem cells and primary cells. Protocols for the expression, purification and delivery of ZFN proteins, which are intrinsically cell-permeable; TALEN proteins, which can be internalized via conjugation with cell-penetrating peptide moieties; and Cas9 ribonucleoprotein, whose nucleofection into cells facilitates rapid induction of multiplexed modifications, are described, along with procedures for evaluating nuclease protein activity. Once they are constructed, nuclease proteins can be expressed and purified within 6 d, and they can be used to induce genomic modifications in human cells within 2 d.
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Acknowledgements
We thank S.J. Sirk for critical reading of the manuscript. This work was supported by the National Institutes of Health (DP1CA174426 to C.F.B.), The Skaggs Institute for Chemical Biology (to C.F.B.), the Institute for Basic Science (IBS-R021-D1 to J.-S.K.) and ShanghaiTech University (to J.L.). Molecular graphics were generated by PyMol.
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J.L., T.G. and C.F.B. conceived the study; J.L., T.G., C.F.B. and J.-S.K. designed the research; J.L., Y.Y., N.W., S.S., S.K. and C.N.K. performed the experiments; and T.G., J.L. and J.-S.K. wrote the manuscript.
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J.-S.K. is a co-founder of ToolGen.
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Liu, J., Gaj, T., Yang, Y. et al. Efficient delivery of nuclease proteins for genome editing in human stem cells and primary cells. Nat Protoc 10, 1842–1859 (2015). https://doi.org/10.1038/nprot.2015.117
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DOI: https://doi.org/10.1038/nprot.2015.117
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