β-haemoglobinopathies such as sickle-cell anaemia and β-thalassemia are among the world’s most common monogenic diseases. These diseases are associated with mutations within the β-globin genes that code for adult haemoglobin, resulting in impaired oxygen transport. Current treatments to alleviate symptoms are limited and only offer short-term relief with lifelong administration required. As 5% of the world population are carriers for haemoglobinopathies, a gene therapeutic approach to cure these diseases may be an effective approach. It has been shown that in individuals with a β-haemoglobinopathy, elevation of foetal haemoglobin levels leads to ameliorated symptoms. Thus, reactivation of the developmentally silenced foetal γ-globin genes offers a promising approach to treat β-haemoglobinopathies.
Key transcriptional regulators have been identified in recent years that control the developmental switch between foetal and adult haemoglobin. The aim of our research is to explore a transcriptional repressor called Zinc Finger and BTB Domain Containing 7A (ZBTB7A) that has been discovered to repress the foetal γ-globin genes. Knocking out the Zbtb7a gene in an erythroid adult-like cell model dramatically increases γ-globin levels. While the mechanism of repression is still unknown, we hypothesise that ZBTB7A’s ability to homodimerize via its BTB/POZ domain plays a key role in its binding to the foetal γ-globin genes to mediate γ-globin repression in adulthood.
Therefore, this study aims to investigate the functional importance of ZBTB7A homodimerisation. One amino acid within the BTB/POZ domain of ZBTB7A has been shown to be crucial for homodimerisation. By introducing an amino acid substitution into endogenous Zbtb7a using CRISPR/Cas9-mediated genome editing in an erythroid cell model, we aim to abrogate ZBTB7A homodimerization and elicit the mechanism and role in its ability to transcriptionally repress genes, with a particular focus on γ-globin repression.