TY - BOOK
T1 - Transcriptional Regulation in Haematopoiesis:
T2 - Stem Cell Heterogeneity and Myeloid Differentiation
AU - Lauridsen, Felicia K B
PY - 2016/7/25
Y1 - 2016/7/25
N2 - 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
AB - 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
M3 - Ph.D. thesis
BT - Transcriptional Regulation in Haematopoiesis:
PB - Eget Forlag
ER -