Nerlov Group - Hematopoietic Stem Cell Genetics

About the Research

The Nerlov laboratory studies the fundamental processes by which blood stem cells sustain blood cell production throughout life, and how ageing and haematological malignancies perturb this process. We use single cell genomic technologies (ATAC-seq and RNA-seq) to study hematopoietic stem– and progenitor cells in normal development and during ageing, and explore the knowledge generated to unravel the cellular and molecular pathways through which hematopoietic stem- and progenitor cells are specified. We use this knowledge to generate therapeutic strategies for conditions where cell types are under- or overproduced (anaemia, hypereosinophilia, mastocytosis), and to identify the cells and molecular mechanisms involved in the aetiology of acute myeloid leukaemia (AML) and myeloproliferative disorders (MPD). We combine studies of genetically modified mice (lineage tracing, conditional and knock-in mutagenesis, fluorescent reporters, genetic disease models) with molecular and functional analysis of human haematopoiesis, including samples from patients with blood cancer, with the aim of developing pharmacological strategies to treat malignancies and counteract the adverse effects of ageing on the hematopoietic system and overall human physiology.

Myeloid lineage specification:

We recently generated a revised hierarchical model of murine and human hematopoiesis (Drissen, Nat. Immunol. 2016; Drissen, Sci. Immunol. 2019). This model identifies two previously unrecognized developmental checkpoints where cell fate decisions are made. This project will use conditional CRISPR/Cas9 technology to screen for transcription factors that promote specific cell fates at these checkpoints. This will be combined with ATAC-seq and chromatin conformation analysis to identify the cis-regulatory elements that mediate cross-regulatory interactions between transcription factors, which will be validated using Perturb-seq to construct the gene regulatory networks (GRNs) that control cell fate decisions. Key translational aims are to identify the cell types from which haematological malignancies originate, and to use the GRNs identified to devise therapeutic strategies for conditions where specific blood cell types are over-produced (such as hypereosinophilia, mastocytosis).

Hematopoietic stem cell heterogeneity:

Hematopoietic stem cells (HSCs) sustain life-long production of lymphocytes, granulocytes, monocytes, erythrocytes and platelets. The classical view of HSCs is that each HSC generates all blood cell types. However, by combining single cell RNAseq with single HSC transplantation we have identified HSC subtypes with restricted cellular output, platelet and platelet/myeloid-restricted HSCs (Sanjuan-Pla, Nature 2013; Carrelha, Nature 2018). It is, however, not known what the physiological roles of these different HSCs are. This project will use advanced genetics (HSC subtype-specific reporters, intersectional lineage tracing) to determine the physiological role of these of HSC subtypes and progenitor subsets during steady state, stress haematopoiesis (e.g. after blood loss, infection or during inflammation), and the development of myeloid malignancies (AML and myeloproliferative disorders; in collaboration with the Psaila Group). Parallel studies on human HSCs (collaboration with the Vyas Group) will use barcoding, HSC xenografting and single cell HSC profiling (ATAC-seq, RNA-seq) to identify the equivalent human HSC subtypes and their associated transcriptional and epigenetic programs. 

The role of ageing in leukaemia development and immune decline:

Ageing is associated with decreased production of lymphocytes and erythrocytes, leading to anaemia and declining adaptive immunity. We previously showed that a key feature of hematopoietic ageing is increased platelet-lineage bias of HSCs, which directly suppresses lymphopoiesis (Grover et al., Nat Comms. 2016). Through comprehensive molecular profiling of both hematopoietic and stromal cell types from young and aged mice we have shown that increased TGFb1 and IL-6 signalling in the aged bone marrow regulates this process (Valletta et al., Nat Comms. 2020). We are now investigating how interfering with these signals can counteract ageing of HSCs and associated alterations in the production of blood cells, as well as decrease susceptibility to myeloid malignancies. We are also using genetically accurate models of AML to identify the age-associated changes that contribute to increased prevalence and poor prognosis of AML in elderly patients, with a particular focus on secreted factors that support leukemia progression as putative therapeutic targets.

Bi-directional c-Kit–mKitL signalling in hematopoiesis and cancer:

We previously identified bi-directional signalling by c-Kit and membrane-associated KitL (mKitL) as a novel signalling system that is critical for the post-natal expansion of the thymus (Buono et al., Nat. Cell Biol. 2016) and showed that it works by activating the AKT/mTOR pathway downstream of mKitL (Buono et al., Nat. Comms. 2018).  Subsequently, we have shown that mKitL is expressed in a range of human cancers, and that signalling through mKitL is critical for triple-negative breast cancer progression. Our next aim is to develop mKitL as a therapeutic target across multiple cancers, using genetic targeting in xenograft models of human cancer, and the development of first-in-class small-molecule mKitL inhibitors. 

Projects are available in all these areas, including single cell analysis of human myeloid malignancies; the development of pharmacological strategies to counteract hematopoietic ageing; the identification of transcriptional and epigenetic mechanisms that specify normal and malignant HSC and progenitor cell populations; the role of ageing in development of myeloid malignancies; and the study of mKitL in human cancer models and development of mKitL small molecule inhibitors.

Additional supervision will be given by Professor Paresh Vyas and Associate Professor Bethan Psaila.

Please see the Weatherall Institute for Molecular Medicine (WIMM) for information about applications for a DPhil in Medical Sciences with groups based in the WIMM.

Training Opportunities

Training is available in the areas of HSC and progenitor biology, biology of ageing, transcription factor biology, cytokine biology, single cell analysis of HSC/progenitor function, single cell functional genomics (RNAseq, ATACseq), advanced flow cytometry, advanced mouse genetics, CRISPR/Cas9-based genome editing and library screening technologies and advanced bioinformatics.

Students will be enrolled on the MRC WIMM DPhil Course, which takes place in the autumn of their first year. Running over several days, this course helps students to develop basic research and presentation skills, as well as introducing them to a wide-range of scientific techniques and principles, ensuring that students have the opportunity to build a broad-based understanding of differing research methodologies.

Generic skills training is offered through the Medical Sciences Division's Skills Training Programme. This programme offers a comprehensive range of courses covering many important areas of researcher development: knowledge and intellectual abilities, personal effectiveness, research governance and organisation, and engagement, influence and impact. Students are actively encouraged to take advantage of the training opportunities available to them.

As well as the specific training detailed above, students will have access to a wide-range of seminars and training opportunities through the many research institutes and centres based in Oxford.

All MRC WIMM graduate students are encouraged to participate in the successful mentoring scheme of the Radcliffe Department of Medicine, which is the host department of the MRC WIMM. This mentoring scheme provides an additional possible channel for personal and professional development outside the regular supervisory framework. The RDM also holds an Athena SWAN Silver Award in recognition of our efforts to build a happy and rewarding environment where all staff and students are supported to achieve their full potential.

PUBLICATIONS