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2020
Zhang, X., Zhu, B., Chen, L. et al. Dual base editor catalyzes both cytosine and adenine base conversions in human cells. Nature Biotechnology (2020).
Although base editors are useful tools for precise genome
editing, current base editors can only convert either adenines
or cytosines. We developed a dual adenine and cytosine base
editor (A&C-BEmax) by fusing both deaminases with a Cas9
nickase to achieve C-to-T and A-to-G conversions at the same
target site. Compared to single base editors, A&C-BEmax’s
activity on adenines is slightly reduced, whereas activity on
cytosines is higher and RNA off-target activity is substan-
tially decreased.
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2020
Zhang X., Chen L., Zhu B., et al. Increasing the efficiency and targeting range of cytidine base editors through fusion of a single-stranded DNA-binding protein domain. Nature Cell Biology (2020).
Cytidine base editors are powerful genetic tools that catalyse cytidine to thymidine conversion at specific genomic loci,
and further improvement of the editing range and efficiency is critical for their broader applications. Through insertion of a
non-sequence-specific single-stranded DNA-binding domain from Rad51 protein between Cas9 nickase and the deaminases,
serial hyper cytidine base editors were generated with substantially increased activity and an expanded editing window
towards the protospacer adjacent motif in both cell lines and mouse embryos. Additionally, hyeA3A-BE4max selectively cata-
lysed cytidine conversion in TC motifs with a broader editing range and much higher activity (up to 257-fold) compared with
eA3A-BE4max. Moreover, hyeA3A-BE4max specifically generated a C-to-T conversion without inducing bystander mutations in
the haemoglobin gamma gene promoter to mimic a naturally occurring genetic variant for amelioration of β-haemoglobinopathy,
suggesting the therapeutic potential of the improved base editors.
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2020
Zeng J, Wu Y, Ren C, Bauer DE, et al. Therapeutic base editing of human hematopoietic stem cells. Nature Medicine, 2020.
Base editing by nucleotide deaminases linked to programmable DNA-binding proteins represents a
promising approach to permanently remedy blood disorders, although its application in engrafting
hematopoietic stem cells (HSCs) remains unexplored. Here we purified A3A (N57Q)-BE3 protein
for ribonucleoprotein (RNP) electroporation of human peripheral blood (PB) mobilized CD34+
hematopoietic stem and progenitor cells (HSPCs). We observed frequent on-target cytosine base
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2020
Wang L., Li L., Ma Y., et al. Reactivation of γ-globin expression through Cas9 or base editor to treat β-hemoglobinopathies. Cell Research. (2020).
