Forced enhancer-promoter rewiring to alter gene expression in animal models

• Published in: Molecular therapy. Nucleic acids Vol. 31; pp. 452 - 465
• Main Authors: Peslak, Scott A., Demirci, Selami, Chandra, Vemika, Ryu, Byoung, Bhardwaj, Saurabh K., Jiang, Jing, Rupon, Jeremy W., Throm, Robert E., Uchida, Naoya, Leonard, Alexis, Essawi, Khaled, Bonifacino, Aylin C., Krouse, Allen E., Linde, Nathaniel S., Donahue, Robert E., Ferrara, Francesca, Wielgosz, Matthew, Abdulmalik, Osheiza, Hamagami, Nicole, Germino-Watnick, Paula, Le, Anh, Chu, Rebecca, Hinds, Malikiya, Weiss, Mitchell J., Tong, Wei, Tisdale, John F., Blobel, Gerd A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 14.03.2023; American Society of Gene & Cell Therapy; Elsevier
• Subjects: enhancer-promoter interactions; fetal hemoglobin; forced chromatin looping; hemoglobin switching; MT: Oligonucleotides; Original; preclinical animal models; sickle cell disease; Therapies and Applications; vector optimization; fetal hemoglobin; hemoglobin switching; forced chromatin looping; preclinical animal models; Therapies and Applications; vector optimization; MT: Oligonucleotides; enhancer-promoter interactions; sickle cell disease
• ISSN: 2162-2531; 2162-2531
• DOI: 10.1016/j.omtn.2023.01.016

Transcriptional enhancers can be in physical proximity of their target genes via chromatin looping. The enhancer at the β-globin locus (locus control region [LCR]) contacts the fetal-type (HBG) and adult-type (HBB) β-globin genes during corresponding developmental stages. We have demonstrated previously that forcing proximity between the LCR and HBG genes in cultured adult-stage erythroid cells can activate HBG transcription. Activation of HBG expression in erythroid cells is of benefit to patients with sickle cell disease. Here, using the β-globin locus as a model, we provide proof of concept at the organismal level that forced enhancer rewiring might present a strategy to alter gene expression for therapeutic purposes. Hematopoietic stem and progenitor cells (HSPCs) from mice bearing human β-globin genes were transduced with lentiviral vectors expressing a synthetic transcription factor (ZF-Ldb1) that fosters LCR-HBG contacts. When engrafted into host animals, HSPCs gave rise to adult-type erythroid cells with elevated HBG expression. Vectors containing ZF-Ldb1 were optimized for activity in cultured human and rhesus macaque erythroid cells. Upon transplantation into rhesus macaques, erythroid cells from HSPCs expressing ZF-Ldb1 displayed elevated HBG production. These findings in two animal models suggest that forced redirection of gene-regulatory elements may be used to alter gene expression to treat disease. [Display omitted] Peslak et al. provide proof of concept that forced enhancer-promoter rewiring enables gene expression changes in two independent animal models. Expression of a synthetic transcription factor (ZF-Ldb1) that fosters contacts between the fetal hemoglobin (HBG) promoter and its enhancer allowed in vivo activation of HBG in a humanized mouse model and rhesus macaques.