Background: Human globin genes, coding for hemoglobin, are differentially activated in the embryonic, fetal and adult stages of hematopoiesis. Mutations in adult globin genes result in hemoglobinopathies such as sickle cell anemia. Reactivating fetal hemoglobin (HbF) genes to replace the mutated adult globin chain is a major therapeutic goal in hemoglobinopathies. Understanding the molecular mechanisms of HbF repression in adults is of paramount importance in identifying novel therapeutic targets.
Aims: Our recent work with single-cell transcriptomics showed that the small proportion of adult human erythroid precursors expressing HbF (F cells) exist in three distinct groups depending on the combination of the two fetal globin genes they are expressing (Fig1). The main aim of the project is to unravel the molecular mechanism(s) regulating the persistent patterns of fetal globin expression in F cells, with the goal of identifying novel therapeutic targets.
Approach: Hematopoietic stem and progenitor cells (CD34+) cells will be isolated from blood samples of subjects with ‘hHPFH’ (heterocellular hereditary persistence of fetal haemoglobin) mutations, which produce large numbers of F cells, and subjected to single cell transcriptomics (Year 1). CD34+ cells will be terminally differentiated in-vitro and analysed for epigenetic regulation of globin gene expression by single-cell ATAC-Seq, H3K27me3, H3K27Ac and H3K4me3 histone marks (CUT&Tag), transcription factor binding (CUT&Tag) (Years 1 and 2), functional assays in CD34+ cells and in human erythroid cell lines by gene editing (Year 3).
Skills: Single cell transcriptomics, (epi)genomics, CUT&Tag, bioinformatics, in-vitro CD34+ differentiation, flow cytometry, genetics, gene editing.
Figure 1:
We have recently discovered that HbF containing red blood cells and their precursors exist in three different groups according to their γ globin chain expression, which we named A-F, G-F and AG-F cells. (generated on BD Rhapsody platform)