Base editing of the HBG promoter induces potent fetal hemoglobin expression with no detectable off-target mutations in human HSCs.

Reactivating silenced γ-globin expression through the disruption of repressive regulatory domains offers a therapeutic strategy for treating β-hemoglobinopathies. Here, we used transformer base editor (tBE), a recently developed cytosine base editor with no detectable off-target mutations, to disrupt transcription-factor-binding motifs in hematopoietic stem cells. By performing functional screening of six motifs with tBE, we found that directly disrupting the BCL11A-binding motif in HBG1/2 promoters triggered the highest γ-globin expression. Via a side-by-side comparison with other clinical and preclinical strategies using Cas9 nuclease or conventional BEs (ABE8e and hA3A-BE3), we found that tBE-mediated disruption of the BCL11A-binding motif at the HBG1/2 promoters triggered the highest fetal hemoglobin in healthy and β-thalassemia patient hematopoietic stem/progenitor cells while exhibiting no detectable DNA or RNA off-target mutations. Durable therapeutic editing by tBE persisted in repopulating hematopoietic stem cells, demonstrating that tBE-mediated editing in HBG1/2 promoters is a safe and effective strategy for treating β-hemoglobinopathies. Copyright © 2023 Elsevier Inc. All rights reserved.

Citation

Wenyan Han, Hou-Yuan Qiu, Shangwu Sun, Zhi-Can Fu, Guo-Quan Wang, Xiaowen Qian, Lijie Wang, Xiaowen Zhai, Jia Wei, Yichuan Wang, Yi-Lin Guo, Guo-Hua Cao, Rui-Jin Ji, Yi-Zhou Zhang, Hongxia Ma, Hongsheng Wang, Mingli Zhao, Jing Wu, Lili Bi, Qiu-Bing Chen, Zifeng Li, Ling Yu, Xiaodun Mou, Hao Yin, Li Yang, Jia Chen, Bei Yang, Ying Zhang. Base editing of the HBG promoter induces potent fetal hemoglobin expression with no detectable off-target mutations in human HSCs. Cell stem cell. 2023 Dec 07;30(12):1624-1639.e8

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PMID: 37989316

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