AZT as HDR Inhibitors

Biological Activity

Approved by the FDA in 1987,^[1] and still used in combination treatment, azidothymidine (AZT) is a thymidine (nucleoside) analogue that is phosphorylated in the host (by enzymes of the thymidine-phosphorylation pathway) to AZT-triphosphate, which inhibits viral (HIV-1) reverse transcriptase activity about 100-fold better than cellular polymerase α. ^[1,2,3] AZT was also found to decrease CRISPR/Cas9-mediated HDR outcomes. ^[4]

Successful Applications in CRISPR 

AZT decreased the HDR efficiency in mouse embryonic stem cells (ESCs) by 3-fold or by more than 10-fold as detected by flow cytometry or sequencing respectively. At AZT’s optimal concentration of 5 μM, no or very mild toxicity was observed, and optimal activity was achieved within the first 24-hour window postelectroporation.

Moreover, AZT increased the knockout efficiency (in the absence of a donor template) in a clonal mouse ESC line. For example, in the case of sgGFP-1, the knockout efficiency increased by more than 1.8-fold.^{[ 4 ]}



Reference:

1. Broder, S. (2010). The development of antiretroviral therapy and its impact on the HIV-1/AIDS pandemic. Antiviral research, 85(1), 1–18. 

2. Mitsuya, H., Weinhold, K. J., Furman, P. A., St Clair, M. H., Lehrman, S. N., Gallo, R. C., Bolognesi, D., Barry, D. W., & Broder, S. (1985). 3'-Azido-3'-deoxythymidine (BW A509U): an antiviral agent that inhibits the infectivity and cytopathic effect of human T-lymphotropic virus type III/lymphadenopathy-associated virus in vitro. Proceedings of the National Academy of Sciences of the United States of America, 82(20), 7096–7100. 

3. Furman, P. A., Fyfe, J. A., St Clair, M. H., Weinhold, K., Rideout, J. L., Freeman, G. A., Lehrman, S. N., Bolognesi, D. P., Broder, S., Mitsuya, H. (1986). Phosphorylation of 3'-azido-3'-deoxythymidine and selective interaction of the 5'-triphosphate with human immunodeficiency virus reverse transcriptase. Proceedings of the National Academy of Sciences of the United States of America, 83(21), 8333-8337. 

4. Yu, C., Liu, Y., Ma, T., Liu, K., Xu, S., Zhang, Y., Liu, H., La Russa, M., Xie, M., Ding, S., & Qi, L. S. (2015). Small molecules enhance CRISPR genome editing in pluripotent stem cells. Cell stem cell, 16(2), 142–147. 

Related Product: