HSC · Migration of HSCs from the AGM region to other haemopoietic organs during mouse ontogeny
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2007-03-06 → 2008-07-05
- EU contribution
- €157,063
- Participants
- 1
- Scheme
- EIF
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Results in brief
Final Activity Report Summary - HSC (Migration of HSCs from the AGM region to other haemopoietic organs during mouse ontogeny)
The haemopoietic stem cells (HSCs) are the foundation of the adult haemopoietic system and give rise to all mature blood cells. In mammals distinct sites of haemopoietic activity have been identified during ontogeny. Quantitative temporal measurement of various haemopoietic activities present in the yolk sac, AGM and foetal liver suggests that the foetal liver activity is a consequence of colonisation by cells emigrating from the AGM and yolk sac (Kumaravelu, 2002). However, there is only limited experimental data where this migration was shown (Emambokus, 2003; Gothert, 2004; Samokhvalov 2007). Therefore, to investigate whether HSCs generated in the AGM are able to migrate and seed other haemopoietic organs, such as foetal liver and bone marrow we followed a different approach using a more tightly regulated and inducible TetON system and Cre-lox technology. We attempted to mark HSCs with the fluorescent protein YFP at the time of their generation in the AGM and track marked cells through development. For the specific cell lineage expression of Cre recombinase the Sca-1 expression cassette, generated by the host laboratory, was used (Miles,1997; Ma, 2001). Sca-1 (stem cell antigen-1) is a widely used HSC marker (Spangrude,1988). One part of the TetON system (rtTAM2) was expressed under the control of the Sca-1 locus and several transgenic mouse lines were established. Subsequently these mice were supposed to be bred against two other transgenic mouse lines, TetO-Cre mice and ROSAYFP reporter mice. In the presence of doxycycline, rtTAM2 should activate the TetO-Cre promoter allowing the expression of Cre-recombinase. Active Cre-recombinase would then delete a stop cassette, flanked by loxP sites, and lead to the generation of the fluorescent protein YFP as a permanent mark. Unfortunately, a careful characterisation of all established transgenic rtTAM2 mouse lines revealed that none of the lines was expressing the rtTAM2 protein in HSCs.
Data: CORDIS, © European Union
Project objective
During my PhD I concentrated on the transcriptional regulation of growth control and terminal differentiation in megakaryocytes leading to platelet release. All mature blood cells including platelets have a limited life-span and need to be constantly replaced during life.As haemopoietic stem cells (HSCs) are the foundation for this life-long production, I became interested in the specification of the haemopoietic system from HSCs during ontogeny. In mammals the first adult-type HSCs arise in the Aorta-Gona d-Mesonephros (AGM) region at E10.5 of embryonic development. With the onset of circulation, these cells are believed to travel and seed other haemopoietic organs (fetal liver and bone marrow) later in development.Once settled in the bone marrow, HSCs produce all mature blood cells during adult life. However, to date the path of migration of HSCs from the AGM to bone marrow or other haemopoietic sites has not been shown. Experiments outlined in this proposal will attempt to answer this question by generating compound mutant animals from three transgenic mouse strains.HSCs will be specifically labelled with GFP at the time of their generation in the AGM region. If the hypothesis is correct, labelled GFP+ cells should migrate to the fetal liver and adult bon e marrow and give rise to other haemopoietic cells.This would prove for the first time that AGM HSCs are able to migrate and serve as a source for mature blood cells throughout adult life. As the host institute has a long-standing interest and expertise i n the field of HSC biology it will provide excellent training and allow me to become an independent researcher in this field.
Original text from CORDIS.
Participants
- DEPARTMENT OF CELLULAR BIOLOGYERASMUS UNIVERSITY · ROTTERDAMCoordinatorCity levelNetherlands
Links
Data: CORDIS, © European Union