Stem Cell Biology - Georges Lacaud

Georges graduated as a biotechnology engineer from the European Biotechnology School of Strasbourg (ESBS) in Strasbourg, France. He obtained his PhD from the University Louis Pasteur of Strasbourg, France and then did a postdoctoral fellowship at the National Jewish Medical Center in Denver, Colorado, USA studying early lymphoid cell development in Prof. Gordon Keller’s lab. Georges next moved to the Mount Sinai School of Medicine in New York, NY, USA where he worked on early hematopoietic development. In 2003, he joined the CRUK Manchester Institute as a junior group leader. He is a senior group leader and heads the Stem Cell Biology group. Georges was awarded a Professorship in Stem Cell Biology at The University of Manchester in 2018.


The genes encoding the AML1/RUNX1 transcription factor and its cofactor CBFβ are frequently rearranged or mutated in human leukaemias such as acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL). Consistent with its implication in leukaemia, RUNX1 has also been shown to be critical for haematopoietic development and adult haematopoiesis. Similarly, the transcriptional co-activator MOZ is involved in independent myeloid chromosomal translocations in human leukaemia. Our group studies the functions of RUNX1 and MOZ in haematopoietic development and maintenance in order to better understand how alterations of their functions might lead to leukaemogenesis.

Along these lines, we previously demonstrated that the first blood cells are generated by endothelial cells during embryogenesis and that AML/RUNX1 as a critical regulator of this process of endothelial to haematopoietic transition (EHT). More recently, we surveyed RUNX1 transcriptional targets and found that AML1/RUNX1 regulate a cell adhesion and migration programme during the development of the

blood system. This novel function of AML1/RUNX1 might be relevant in the proposed role of AML1/RUNX1 in metastasis of solid tumours. We subsequently identified the two GFI1 transcription repressors, and their binding partner LSD1, as absolutely required during the EHT to epigenetically silence the endothelial programme and promote the emergence of the first haematopoietic stem cells. In another study, we examined the relevance of the different isoforms of RUNX1/AML1 in adult haematopoiesis and discovered a critical role for the RUNX1C isoform in megakaryopoiesis. Regarding our work on MOZ, we established the critical requirement for MOZ histone acetyl transferase activity for the development of haematopoietic and neuronal stem cells by protecting them from replicative senescence. Finally, we recently demonstrated that fibroblasts can be reprogrammed to blood cells using a specific set of defined transcription factors. This finding suggests that reprogramming represents a putative approach to generate haematopoietic cells for patient therapies.



Genes encoding the AML1/RUNX1 transcription factor and its cofactor CBFβ are frequently rearranged or mutated in human leukaemia, such as acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL). Consistent with its implication in leukaemia, RUNX1 has also been shown to be critical for haematopoietic development. Similarly, the transcriptional co-activator MOZ is involved in independent myeloid chromosomal translocations fusing MOZ to the partner genes CBP, P300 or TIF2 in human leukaemia. Our group investigates RUNX1 and MOZ's function in haematopoietic development and maintenance to better understand how alterations of these functions might lead to leukaemogenesis. Besides these transcription factors and transcriptional activators, long noncoding RNAs (lncRNAs) have also emerged as important regulators of gene expression. In this context, we more recently started the investigation of lncRNAs essential for leukaemia.

Investigation of long noncoding RNAs in acute myeloid leukaemia

Transcription factors and epigenetic factors (writers, erasers or readers) regulate self-renewal and differentiation during normal haematopoiesis. Alterations of transcription factors and epigenetic factors are critical molecular events leading to leukaemia and other malignancies. Long noncoding RNAs (lncRNAs) are transcripts of over 200 nucleotides that display no coding potential. They represent a significant fraction of the human genome (Figure 1A). For many years, they were considered junk DNA and the result of spurious transcription. However, recent studies have revealed that lncRNAs can play essential roles in many cellular processes. Through mechanisms such as acting as tethers for the epigenetic machinery, lncRNAs have been shown to participate in gene regulation (Figure 1B). LncRNAs could therefore be essential factors in acute myeloid leukaemia (AML) development and represent a potential novel therapeutic avenue. However, our understanding of lncRNAs, and their functions in AML, is currently limited.

To identify lncRNAs important in the proliferation of leukaemic cells, we employed a CRISPR interference (CRISPRi) screening approach to induce sequence-specific repression of lncRNA expression. We selected the THP-1 cell line, a human AML cell line with an MLL-AF9 translocation, to express dCas9-KRAB (dead Cas9 fused to Krüppel associated box (KRAB) domain), which represses transcription at targeted loci. We screened 3882 lncRNAs, identifying 19 as significantly influencing cell proliferation. Within these 19 hits, we identified MIR17HG, a lncRNA that also encodes for the miR17-92a-1 cluster. The microRNAs within this cluster are essential factors in MLL-rearranged leukaemia, validating our screen's performance in identifying lncRNAs important in leukaemic maintenance.

Figure 1: LncRNAs represent an important fraction of the human genome. A. Representation of LncRNA compared to other gene biotypes. B. General mechanisms of lncRNAs in control of Gene Expression.


We have worked on characterising the phenotype, and molecular mechanism of SGOL1-AS1, which we identified from this screen. As the subcellular location of a lncRNA can influence the mechanisms by which it can act, we looked to check the localisation of this lncRNA. We have shown this noncoding RNA to be enriched within the nucleus of AML cells, localising to discrete foci within the nucleus (Figure 2A).

As well as knocking down the transcript with CRISPRi, we have also used antisense oligonucleotides (ASOs) as an orthogonal knockdown technique. This approach has allowed us to target the transcript without affecting the local chromatin. Utilising these ASOs, we have shown that both the proliferation in liquid culture and the colony-forming potential of AML cells are dependent on the expression of SGOL1-AS1 (Figure 2B). Though knockdown of SGOL1-AS1 reduced the proliferation of cells, it did not affect the cells’ differentiation or cell cycle state. Instead, reduced proliferation occurred via the induction of apoptosis. Utilising RNAseq, we identified genes that became differentially expressed upon knockdown of SGOL1-AS1. Notably, within these differentially expressed genes were those relating to innate immune programs. We showed downregulation of cytokine signalling pathways and several other programs pertaining to innate immune system cells.

Figure 2: Figure 2. SGOL1-AS1 is upregulated in AMLs. A. SGOL1-AS1 localises to discrete spots in the nuclei. B. Knockdown of SGOL1-AS1 reduces proliferation in liquid culture. C. Higher expression of SGOL1-AS1 is associated with poorer overall survival in AMLs. ASO-1 and ASO-2: anti-sense oligonucleotide against SGOL1-AS1. * p<0.05 and **** P<0.001.


Having identified the possible downstream targets of SGOL1-AS1, we looked to identify any potential mechanism by which it may work. Using in vitro transcribed biotinylated RNA, we identified several proteins associated with SGOL1-AS1. A large number of these associated proteins are important regulators of heterochromatin, including components of both telomeric and centromeric heterochromatin and members of the PRC1 complex. Altogether, these data suggest that SGOL1-AS1 regulates the expression of innate immunity genes by regulating heterochromatin formation. We are currently further investigating this mechanism.

As well as our experimental characterisation of this lncRNA, we have also investigated the expression of this lncRNA in patients and its clinical importance through mining publicly available patient data (TCGA, Blueprint, GTEx). We observed that expression of SGOL1-AS1 is increased in AMLs compared to non-malignant haematopoietic progenitor populations, such as Multipotent progenitors, Common Lymphoid progenitors and Common Myeloid progenitors. Furthermore, expression of SGOL1-AS1 is increased in AML patients compared to healthy bone marrow. We also identified a correlation between higher expression in patients and poorer overall survival (Figure 2C). Together these data show that SGOL1-AS1 is upregulated in AML and suggests this may impact AML cell characteristics.

To gain further insights into these changes, we looked at genes that showed a strong correlation in expression with SGOL1-AS1 from the patient data. Similarly to our RNAseq data from cell lines, we observed an enrichment for genes relating to innate immunity. Therefore, we conclude that upregulation of SGOL1-AS1 in AML modulates the expression of gene programs relating to innate immunity.

Antisense oligonucleotide approaches for reducing gene expression have recently entered clinics, including clinical trials in haematological malignancies. This advance in antisense therapy could allow for targeting of a lncRNA essential for AML in patients. Thus, identification and functional characterisation of LncRNAs critical for AMLs could represent potential new therapeutic avenues.

Selected Publications

Fadlullah MZ, Neo WH, Lie-A-Ling M, Thambyrajah R, Patel R, Mevel R, Aksoy I, Do Khoa N, Savatier P, Fontenille L, Baker SM, Rattray M, Kouskoff V, Lacaud G. (2022) 
Murine AGM single-cell profiling identifies a continuum of hemogenic endothelium differentiation marked by ACE. 
Blood 139(3):343-356. PubMed abstract (PMID: 34517413)

Neo WH, Meng Y, Rodriguez-Meira A, Fadlullah MZH, Booth CAG, Azzoni E, Thongjuea S, de Bruijn MFTR, Jacobsen SEW, Mead AJ, Lacaud G. (2021)
Ezh2 is essential for the generation of functional yolk sac derived erythro-myeloid progenitors.
Nature Communications 12(1):7019. PubMed abstract (PMID: 34857757)

Mevel R, Steiner I, Mason S, Galbraith LC, Patel R, Fadlullah MZ, Ahmad I, Leung HY, Oliveira P, Blyth K, Baena E, Lacaud G. (2020)
RUNX1 marks a luminal castration-resistant lineage established at the onset of prostate development.
Elife 9:e60225. PubMed abstract

Lie-A-Ling M, Marinopoulou E, Lilly AJ, Challinor M, Patel R, Lancrin C, Kouskoff V, Lacaud G. (2018)
Regulation of RUNX1 dosage is crucial for efficient blood formation from hemogenic endothelium.
Development 145(5). PubMed abstract

Draper JE, Sroczynska P, Fadlullah MZH, Patel R, Newton G, Breitwieser W, Kouskoff V, Lacaud G. (2018)
A novel prospective isolation of murine fetal liver progenitors to study in utero hematopoietic defects.
PLoS Genetics 14(1):e1007127. PubMed abstract

Stefanska M, Batta K, Patel R, Florkowska M, Kouskoff V, Lacaud G. (2017)
Primitive erythrocytes are generated from hemogenic endothelial cells.
Scientific Reports 7(1):6401. PubMed abstract

Draper JE, Sroczynska P, Leong HS, Fadlullah MZH, Miller C, Kouskoff V, Lacaud G. (2017)
Mouse RUNX1C regulates premegakaryocytic/erythroid output and maintains survival of megakaryocyte progenitors.
Blood 130(3):271-284. PubMed abstract

Thambyrajah R, Mazan M, Patel R, Moignard V, Stefanska M., Marinopoulou E, Li Y, Lancrin C, Clapes T, Möröy T, Robin C, Miller C, Cowley S, Göttgens B, Kouskoff V, Lacaud G. (2016)
GFI1 proteins orchestrate the emergence of Haematopoietic Stem Cells in the AGM through recruitment of LSD1.
Nature Cell Biology 18(1):21-32. PubMed abstract

Lie-A-Ling M, Marinopoulou E, Li Y, Patel R, Stefanska M, Bonifer C, Miller C, Kouskoff V, Lacaud G. (2014)
RUNX1 positively regulates a cell adhesion and migration program in murine hemogenic endothelium prior to blood emergence.
Blood 124(11):e11-20. PubMed abstract

Lancrin C, Sroczynska P, Stephenson C, Allen T, Kouskoff V, Lacaud G. (2009)
The haemangioblast generates haematopoietic cells through a haemogenic endothelium stage.
Nature 457(7231):892-5. PubMed abstract

Postdoctoral Fellows
Muhammad Maqbool
Neo Wenhao

Scientific Officer
Michael Lie-A-Ling
Rahima Patel

Clinical Fellow
Mathew Sheridan

Graduate Students
Liam Clayfield
Muhammad Fadlullah Wilmot
Ewan Selkirk
Steven Mayers   

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