Genomic Characterization of Sickle Cell Mouse Models for Therapeutic Genome Editing Applications
type: CreativeWork
description: Sickle cell disease (SCD) is caused by a mutation of the β-globin gene (HBB), resulting in abnormal hemoglobin molecules that polymerize when deoxygenated, forming “sickle” shaped red blood cells (RBCs). Sickle RBCs lead to anemia, multi-organ damage and pain crises, beginning the first year of life. The onset of symptoms coincides with the developmental switch of β-like globin gene expression from fetal stage γ-globin to adult stage β-globin, resulting in a shift from fetal hemoglobin (HbF, α2γ2) to adult hemoglobin (HbA, α2β2). Some individuals harbor rare genetic variants in the extended β-globin gene cluster that cause constitutively elevated postnatal HbF, a benign condition known as hereditary persistence of fetal hemoglobin (HPFH) which alleviates symptoms of co-inherited SCD. Previously, we showed that CRISPR-Cas9-mediated genome editing can recreate a naturally occurring HPFH variant in the γ-globin (HBG1 and HBG2) promoters. Disruption of a TGACC nucleotide motif within this region by Cas9-mediated non-homologous end joining in human erythroid cells or their progenitors caused induction of HbF by interfering with recruitment of the transcriptional repressor, BCL11A. This strategy results in potent HbF induction in human cells and is a promising therapeutic strategy. However, the efficiency of genome editing and the level of HbF induction required to arrest or reverse the pathologies of SCD are unknown. In this work, we investigated the utility of humanized mouse models for SCD to answer this question. We further characterized the genomic configurations of two models: Berkeley mice, which harbor multiple tandem copies of three separate transgenes encoding human α-globin, sickle β-globin (βS) and a segment of the locus control region (LCR) a powerful enhancer that drives high-level erythroid-specific expression of linked genes; and Townes mice, in which the endogenous α-globin gene is replaced by the homologous human gene and the endogenous β-globin gene is …
abstract: Sickle cell disease (SCD) is caused by a mutation of the β-globin gene (HBB), resulting in abnormal hemoglobin molecules that polymerize when deoxygenated, forming “sickle” shaped red blood cells (RBCs). Sickle RBCs lead to anemia, multi-organ damage and pain crises, beginning the first year of life. The onset of symptoms coincides with the developmental switch of β-like globin gene expression from fetal stage γ-globin to adult stage β-globin, resulting in a shift from fetal hemoglobin (HbF, α2γ2) to adult hemoglobin (HbA, α2β2). Some individuals harbor rare genetic variants in the extended β-globin gene cluster that cause constitutively elevated postnatal HbF, a benign condition known as hereditary persistence of fetal hemoglobin (HPFH) which alleviates symptoms of co-inherited SCD. Previously, we showed that CRISPR-Cas9-mediated genome editing can recreate a naturally occurring HPFH variant in the γ-globin (HBG1 and HBG2) promoters. Disruption of a TGACC nucleotide motif within this region by Cas9-mediated non-homologous end joining in human erythroid cells or their progenitors caused induction of HbF by interfering with recruitment of the transcriptional repressor, BCL11A. This strategy results in potent HbF induction in human cells and is a promising therapeutic strategy. However, the efficiency of genome editing and the level of HbF induction required to arrest or reverse the pathologies of SCD are unknown. In this work, we investigated the utility of humanized mouse models for SCD to answer this question. We further characterized the genomic configurations of two models: Berkeley mice, which harbor multiple tandem copies of three separate transgenes encoding human α-globin, sickle β-globin (βS) and a segment of the locus control region (LCR) a powerful enhancer that drives high-level erythroid-specific expression of linked genes; and Townes mice, in which the endogenous α-globin gene is replaced by the homologous human gene and the endogenous β-globin gene is …
author: Woodard, Kaitly Jensen
keywords: gene editing, hematology, sickle cell disease, Congenital, Hereditary, and Neonatal Diseases and Abnormalities, Diseases, Hemic and Lymphatic Diseases, Medical Genetics, Medical Molecular Biology, Medical Sciences, Medicine and Health Sciences
date published: 2021-06-01T07:00:00Z
date modified: 2026-07-24T05:00:45Z
provider: University of Tennessee Health Science Center
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Tennessee Health Science Center