Zinc-finger nuclease-mediated gene correction using single AAV vector transduction and enhancement by Food and Drug Administration-approved drugs - PubMed (original) (raw)

Zinc-finger nuclease-mediated gene correction using single AAV vector transduction and enhancement by Food and Drug Administration-approved drugs

B L Ellis et al. Gene Ther. 2013 Jan.

Abstract

An emerging strategy for the treatment of monogenic diseases uses genetic engineering to precisely correct the mutation(s) at the genome level. Recent advancements in this technology have demonstrated therapeutic levels of gene correction using a zinc-finger nuclease (ZFN)-induced DNA double-strand break in conjunction with an exogenous DNA donor substrate. This strategy requires efficient nucleic acid delivery and among viral vectors, recombinant adeno-associated virus (rAAV) has demonstrated clinical success without pathology. However, a major limitation of rAAV is the small DNA packaging capacity and to date, the use of rAAV for ZFN gene delivery has yet to be reported. Theoretically, an ideal situation is to deliver both ZFNs and the repair substrate in a single vector to avoid inefficient gene targeting and unwanted mutagenesis, both complications of a rAAV co-transduction strategy. Therefore, a rAAV format was generated in which a single polypeptide encodes the ZFN monomers connected by a ribosome skipping 2A peptide and furin cleavage sequence. On the basis of this arrangement, a DNA repair substrate of 750 nucleotides was also included in this vector. Efficient polypeptide processing to discrete ZFNs is demonstrated, as well as the ability of this single vector format to stimulate efficient gene targeting in a human cell line and mouse model derived fibroblasts. Additionally, we increased rAAV-mediated gene correction up to sixfold using a combination of Food and Drug Administration-approved drugs, which act at the level of AAV vector transduction. Collectively, these experiments demonstrate the ability to deliver ZFNs and a repair substrate by a single AAV vector and offer insights for the optimization of rAAV-mediated gene correction using drug therapy.

PubMed Disclaimer

Conflict of interest statement

CONFLICT OF INTEREST

The authors declare no conflict of interest.

Figures

Figure 1

Figure 1

Schematic representations of the genomic contents of AAV6 ZFN2/1/D and AAV6 donor. (a) The genome of the AAV6 viral vector ZFN2/1/D, which contains DNA encoding two GFP ZFNs separated by a 2A peptide driven by the ubiquitin C promoter, and includes the eGFP gene truncated at nucleotide 37 as a donor substrate in gene targeting by homologous recombination. (b) The genome of the AAV6 viral vector donor, which contains the same truncated, non-functional form of eGFP as in (a), and is driven by the cytomegalovirus promoter. (c) Western blot from calcium phosphate transfection of ZFN2/1/D construct in the AAV backbone (lane 1), the ZFN2/1/donor* construct in a lentiviral backbone (lane 2), the ZFN2 construct in a lentiviral backbone (lane 3) and the ZFN1 construct in a lentiviral backbone (lane 4). Note that most of the protein from lane 1 is present at the monomeric weight (37 kD marker).

Figure 2

Figure 2

ZFN-mediated gene targeting in HEK 293 cells delivered by AAV6. (a) Gene targeting in HEK 293 cells with increasing MOIs of AAV6 ZFN 2/1/D virus, analyzed on day 3 for GFP by flow cytometry. (b) Gene targeting in HEK 293 cells with increasing MOIs of AAV6 donor virus and a constant MOI of 300K for the AAV6 ZFN 2/1/D virus, analyzed on day 3 for GFP by flow cytometry. (c) Kinetic analysis of gene targeting in HEK 293 cells with increasing MOIs of AAV6 ZFN 2/1/D virus analyzed by flow cytometry at the indicated time points post infection. (d) Gene targeting in HEK 293 cells with increasing MOIs of AAV6 donor virus and a constant MOI of 300K for the AAV6 ZFN 2/1/D virus, analyzed at the indicated time points for GFP by flow cytometry. *Significantly different compared with the lipofected sample. n = 3, P < 0.05 (for c and d: only evaluated at the last time point between lipofection and the infected population closest to the lipofected value).

Figure 3

Figure 3

ZFN-mediated gene targeting in Rosa 26 3T3 cells delivered by rAAV6. (a) Gene targeting in Rosa 26 3T3 cells with increasing MOIs of rAAV6 ZFN 2/1/D virus, analyzed on day 3 for GFP by flow cytometry. (b) Gene targeting in Rosa 26 3T3 cells with increasing MOIs of rAAV6 donor virus and a constant MOI of 300K for the rAAV6 ZFN 2/1/D virus, analyzed on day 3 for GFP by flow cytometry. (c) Kinetic analysis of gene targeting in Rosa 26 3T3 cells with increasing MOIs of rAAV6 ZFN 2/1/D virus, analyzed for GFP by flow cytometry. (d) Kinetic analysis of gene targeting in Rosa 26 3T3 cells with increasing MOIs of rAAV6 donor virus and a constant MOI of 300K for the rAAV6 ZFN 2/1/D virus. GFP-positive cells were then analyzed at the indicated time points by flow cytometry.*Significantly different compared with the lipofected sample. n = 3, P < 0.05 (for c and d: only evaluated at the last time point between lipofection and the infected population closest to the lipofected value).

Figure 4

Figure 4

Enhancement of gene targeting using Food and Drug Administration-approved drugs. HEK 293 cells were transduced with rAAV6 ZFN 2/1/donor at 100 000 viral genomes per cell. At the time of vector addition (co-administered) or 18 h post vector addition, cells were treated with the indicated drug (bortezomib 2 μM; sodium butyrate 1.5 μM). Two days following vector addition, cells were harvested and GFP +cells were quantitated by flow cytometry. The value determined in the presence of the drug was divided by the value determined in the absence of the drug and the data are presented as a fold change. Plasmid experiments relied on the same general strategy, however, in these cases the drug was given 4 h pos-transfection.

Similar articles

Cited by

References

    1. Fischer A, Hacein-Bey-Abina S, Cavazzana-Calvo M. 20 years of gene therapy for SCID. Nat Immunol. 2010;11:457– 460. - PubMed
    1. Cappelli B, Aiuti A. Gene therapy for adenosine deaminase deficiency. Immunol Allergy Clin North Am. 2010;30:249– 260. - PubMed
    1. Qasim W, Gaspar HB, Thrasher AJ. Progress and prospects: gene therapy for inherited immunodeficiencies. Gene Therapy. 2009;16:1285– 1291. - PubMed
    1. Liu MM, Tuo J, Chan CC. Gene therapy for ocular diseases. Br J Ophthalmol. 2011;95:604– 612. - PMC - PubMed
    1. Porteus MH, Baltimore D. Chimeric nucleases stimulate gene targeting in human cells. Science. 2003;300:763. - PubMed

Publication types

MeSH terms

Substances

Grants and funding

LinkOut - more resources