Analysis of blood stem cell lineage specification in mammalian development

Supervisor:  Prof Marella de Bruijn

The interest in stem cell-based therapies has underlined the importance of understanding how adult tissue-specific stem cells are generated and differentiate into functional end cells. Although much work has been done to understand the biology of blood stem cells in the adult, it has so far not been possible to efficiently generate these cells de novo from ES/iPS cells. In the mammalian embryo, the entire cohort of blood stem cells that is responsible for the lifelong production of mature blood cells, is generated de novo early in development from a specialized subset of endothelial cells, the so-called hemogenic endothelium (HE). Taking advantage of our unique Runx1 +23 enhancer-reporter mouse model that facilitates the visualisation and isolation of HE throughout development, our laboratory is dissecting the cellular and molecular events that underlie the birth of blood stem and progenitor cells. Our single cell functional and expression analysis has highlighted the dynamic nature of HE during mouse development, and the point at which commitment to the hematopoietic lineage is initiated (Swiers et al., Nature Communications 2013). More recently, we have performed extensive expression profiling of HE and blood stem and progenitor cells throughout early mouse development with the aim to identify and characterise the gene interacting networks and new players critical to blood cell commitment. We are particularly interested in TFs as the intrinsic regulators of cell fate, but also in interactions with the microenvironment/niche through signalling pathways and cell surface molecules, and in cell polarity/asymmetry markers and cytoskeletal proteins.

Other work in the laboratory aims to elucidate the cis-regulatory organization of the transcription factor Runx1 in developmental hematopoiesis, and identify the trans-acting factors and signals that trigger hematopoietic specification of HE. Runx1 cis-regulation is highly complex and dynamic, and is regulated through cis-regulatory elements distal to its promoters (Nottingham et al., Blood 2007, Bee et al., Blood 2009, Schutte et al., eLife 2016). Our ongoing studies in this area apply state-of-the art chromatin analysis and molecular technologies. Finally, considering the difficulty of robustly generating blood stem cells in vitro, it will be important to establish the origin(s) of HE in the mammalian embryo, as these are not well understood. This calls for identification of the cells that will give rise to HE as they pass through the primitive streak, form mesoderm and differentiate into HE, and mapping the signals that these cells receive on their journeys to their respective tissues. Knowledge obtained from these studies will not only help resolve the question of the ultimate origin of the blood stem cell lineage, but also inform mouse and human ESC/iPSC differentiation cultures.

Our laboratory is now looking for enthusiastic and motivated students to join our team in elucidating the developmental origin and gene interacting networks of the blood stem cell lineage. The successful candidate will be expected to have significant input in developing and leading their project in one of our areas of research, with the advice and guidance of the supervisor. Students will also have a thesis committee to advise them on their academic work and progress. Tailored to the specific project requirements, the successful candidate will receive training in several of the following techniques: embryo dissections, in vitro and in vivo hematopoietic assays, mouse/human ES/iPS cell culture, immunofluorescence, flow cytometry, confocal microscopy and live imaging, molecular biology, genome editing (CRISPR/Cas9), chromatin assays/gene regulation, expression profiling on single cells/small cell numbers, computational biology, and other relevant technologies. Students are also encouraged to take up a diverse array of technical and transferable skills training in the Medical Sciences Division, Oxford, or relevant courses wider afield. Attendance at (international) meetings to present and discuss data is encouraged.

The successful candidate will be part of the Developmental Hematopoiesis group in the MRC Molecular Haematology Unit of the MRC Weatherall Institute of Molecular Medicine (WIMM) at the Radcliffe Department of Medicine. In pursuing her/his project, the candidate will have ample opportunities for collaboration with other groups in the WIMM and the Radcliffe Department of Medicine working on gene regulation and epigenetics, gene editing, blood stem cell biology, and computational biology. There is an active student association in the WIMM, which organises several events throughout the year.

For further information on potential project areas, please contact Prof Marella de Bruijn