Targeted gene therapies: tools, applications, optimization

Abstract

Many devastating human diseases are caused by mutations in a single gene that prevent a somatic cell from carrying out its essential functions, or by genetic changes acquired as a result of infectious disease or in the course of cell transformation. Targeted gene therapies have emerged as potential strategies for treatment of such diseases. These therapies depend upon rare-cutting endonucleases to cleave at specific sites in or near disease genes. Targeted gene correction provides a template for homology-directed repair, enabling the cell’s own repair pathways to erase the mutation and replace it with the correct sequence. Targeted gene disruption ablates the disease gene, disabling its function. Gene targeting can also promote other kinds of genome engineering, including mutation, insertion, or gene deletion. Targeted gene therapies present significant advantages compared to approaches to gene therapy that depend upon delivery of stably expressing transgenes. Recent progress has been fueled by advances in nuclease discovery and design, and by new strategies that maximize efficiency of targeting and minimize off-target damage. Future progress will build on deeper mechanistic understanding of critical factors and pathways.

Keywords::

• Homing endonuclease
• zinc finger nuclease
• TALE nuclease
• homologous recombination
• nonhomologous end joining

Acknowledgments

We thank members of the Maizels laboratory and the Northwest Genome Engineering Consortium for valuable discussions. We apologize to the many colleagues we have been unable to cite in this review.

Declaration of interest

The authors are grateful for financial support from U.S. NIH GM RL1 084434 and R01 GM41712. O. Humbert has been supported by a Northwest Genome Engineering Consortium Interdisciplinary Training Fellowship. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this paper.

Editor: Michael M. Cox