# Mechanisms of cis-acting HbF regulation in sickle cell anemia

> **NIH NIH R01** · BOSTON MEDICAL CENTER · 2020 · $426,000

## Abstract

ABSTRACT
Sickle cell anemia is one of mankind's most common hereditary monogenic diseases and a global health
burden. A therapeutic goal is to increase fetal hemoglobin concentration to protect erythrocytes from sickle
polymer-induced injury. Fetal hemoglobin gene expression is regulated by cis-and trans-acting loci. Although
the trans-acting loci have been intensively studied and BCL11A is being targeted genetically, less attention has
been paid to cis-acting regulators, which in some instances might be of paramount importance. Herein we
focus on novel cis-acting loci that we found to be associated with elevated fetal hemoglobin in the Arab-Indian
haplotype of sickle cell anemia. Our central hypothesis is: Variants in the β-globin gene cluster locus control
region in sickle cell anemia with the Arab-Indian haplotype modulate fetal hemoglobin gene expression by
differential looping of the locus control region to globin gene promoters and account, in part, for the variance in
fetal hemoglobin levels associated with different HBB haplotypes. We will use an induced pluripotent stem cell
(iPSC)-based system capable of recapitulating both fetal and adult-type blood cell production that provides a
flexible model for mechanistic studies to validate this hypothesis. We propose three specific aims:
Aim 1: Genetically modify sickle cell disease haplotype-specific iPSCs to assess the effects of putative
cis-acting regulators of fetal hemoglobin expression. We will use gene editing to target selected cis-acting
elements to modulate fetal hemoglobin gene expression in adult-type erythroblasts derived from sickle cell
anemia patients with the high Arab-Indian and low Benin fetal hemoglobin HBB gene cluster haplotypes.
Aim 2: Functionally validate novel cis-acting fetal hemoglobin modulators using the directed
differentiation of sickle cell disease-specific iPSCs into fetal and adult-type blood cells. Directed
differentiation of sickle iPSCs into fetal and adult hemoglobin-expressing erythroblasts will allow us to explore
the cell intrinsic effects of modified regulatory regions.
Aim 3: Dissect the effects of cis-activating fetal hemoglobin modulators in iPSC-derived erythroid cells
using chromosome conformation capture, chromatin immunoprecipitation, and global transcriptional
analyses. We will define the mechanism of cis-acting regulation through assays examining the effects of
engineered changes on the expression of globin genes, fetal hemoglobin synthesis and chromosomal looping.
 The proposed studies use both established and novel systems and strategies to: 1) evaluate the role of
novel, cis-acting fetal hemoglobin modulators in iPSC-derived erythroid cells, 2) reveal the basic biology
behind globin switching during blood cell development, and 3) lay the groundwork for the development and
testing of novel, patient-specific therapeutics. These transdisciplinary studies will be carried out in the
complementing laboratories of three investigators with experti...

## Key facts

- **NIH application ID:** 9926298
- **Project number:** 5R01HL133350-04
- **Recipient organization:** BOSTON MEDICAL CENTER
- **Principal Investigator:** GEORGE J MURPHY
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $426,000
- **Award type:** 5
- **Project period:** 2017-04-01 → 2023-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9926298

## Citation

> US National Institutes of Health, RePORTER application 9926298, Mechanisms of cis-acting HbF regulation in sickle cell anemia (5R01HL133350-04). Retrieved via AI Analytics 2026-06-01 from https://api.ai-analytics.org/grant/nih/9926298. Licensed CC0.

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