Expression of growth factor receptors by haematopoietic stem and progenitor cells

• Main Author: Mooney, Ciarán James
• Published: University of Birmingham 2017
• Subjects: 616.1; RC Internal medicine
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.707678

The mechanisms that govern the lineage commitment of haematopoietic stem and progenitor cells (HSPCs) have been a topic of debate since the 1960s. Two models of lineage commitment have been described; a permissive model, in which haematopoietic growth factors (HGFs) stimulate proliferation and survival of distinct HSPC subpopulations to permit stochastic lineage-specification, and a deterministic model, which proposes that HGFs instruct HSPCs to differentiate towards a specific cell lineage. To provide further insight into whether HGFs provide instructive cues or act in a selective manner, this study has investigated the expression of fms-like tyrosine kinase 3 (Flt3), and the receptors for erythropoietin (EpoR) and macrophage-colony stimulating factor (M-CSFR) by single HSPCs within the bone marrow. Using single-cell qRT-PCR and flow cytometry, a large number of novel HSPC subpopulations have been identified based on receptor expression. Importantly, multiplex analysis of protein and mRNA expression revealed that the above receptors are rarely co-expressed during the early stages of haematopoiesis. Furthermore, Flt3 expression was identified within the haematopoietic stem cell compartment and in vitro analysis demonstrated that Flt3 ligand primarily acts on a subpopulation of downstream progenitors. These findings suggest that Flt3, EpoR and M-CSFR differentially regulate distinct early HSPC subpopulations.