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Transcriptional Regulation in Haematopoiesis: Stem Cell Heterogeneity and Myeloid Differentiation

Research output: Book/ReportPh.D. thesisResearch

  1. Differences in Cell Cycle Status Underlie Transcriptional Heterogeneity in the HSC Compartment

    Research output: Contribution to journalJournal articleResearchpeer-review

  2. Peak-valley-peak pattern of histone modifications delineates active regulatory elements and their directionality

    Research output: Contribution to journalJournal articleResearchpeer-review

  3. Transcriptional Heterogeneity and Lineage Commitment in Myeloid Progenitors

    Research output: Contribution to journalJournal articleResearchpeer-review

  4. Initiation of MLL-rearranged AML is dependent on C/EBPα

    Research output: Contribution to journalJournal articleResearchpeer-review

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Haematopoietic stem cells (HSCs) are responsible for the formation of all of the distinct mature cell types found in the blood. HSCs can – as the only cells of the haematopoietic system – regenerate all of the blood cells when transplanted into a irradiated host, because they are endowed with the capacity to both self-renew and differentiate. This thesis is built upon two studies, which investigate two different aspects of the haematopoietic system; heterogeneity within the HSC compartment (presented in manuscript I), and the interplay between transcription factors controlling granulocyte/ monocyte differentiation (presented in manuscript II). In the first study we used a retinoic acid reporter mouse line to investigate HSC heterogeneity. Sub-fractionating HSCs into different groups depending on their reporter level showed that reporter-dim HSCs were non-proliferating and exhibited superior performance in transplantation studies. Consistent with this, transcriptome profiling revealed very low expression of cell cycle genes in these reporter-dim HSCs. Sequencing of >1200 single HSCs confirmed that the main source of transcriptional heterogeneity was the cell cycle. It also revealed a low-level expression of distinct lineage affiliated genes in the otherwise highly purified HSCs. Taken together, these studies demonstrate the use of our model as a tool for isolating superior HSCs, and show that low-level expression of mature lineage markers is inherent in the highly purified stem cell compartment. In the second study we profiled the global DNA binding sites of two major players in myeloid differentiation – PU.1 and C/EBPα - together with histone modifications in four successive stages of myeloid differentiation (LSK, preGM, GMP and mature granulocytes). Consistent with their haematopoietic expression patterns the data showed PU.1 and C/EBPα to associate with genomic enhancers exhibiting distinct kinetics. We showed that both the expression and binding pattern of PU.1 is dependent on C/EBPα, since this is highly altered in C/EBPα knock-out cells. Additionally, our data also suggest that the differentiation block occurring when C/EBPα is depleted, occurs upstream to that which was previously reported. In summary we characterise an intricate interplay between several transcription factors and provide new insights into how these factors co-operate to orchestrate myeloid
Original languageEnglish
PublisherEget Forlag
Number of pages159
Publication statusPublished - 25 Jul 2016

ID: 48378641