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Multilineage embryonic hematopoiesis requires hypoxic ARNT activity
D M Adelman1, E Maltepe, M C Simon
1Department of Pathology, and the Howard Hughes Medical Institute (HHMI), University of Chicago, Chicago, Illinois 60637, USA.
Genes & Development
|October 16, 1999
Summary
Embryonic hematopoietic progenitor proliferation is regulated by hypoxia via HIF-1 signaling. This pathway, dependent on ARNT and VEGF, is crucial for blood cell development in early embryos.
Area of Science:
- Developmental Biology
- Hematopoiesis
- Cellular Physiology
Background:
- Most cells arrest growth during hypoxia, but some, like endothelial cells, proliferate.
- The role of hypoxia in embryonic hematopoietic progenitor regulation was previously unclear.
Purpose of the Study:
- To investigate the role of hypoxia-induced signaling pathways in embryonic hematopoietic progenitor proliferation.
- To determine the involvement of HIF-1 (hypoxia-inducible factor 1) in this process.
Main Methods:
- Utilized Arnt(-/-) embryoid bodies and embryos to study hypoxia response.
- Assessed hematopoietic progenitor numbers and proliferation under hypoxic conditions.
- Measured Vascular Endothelial Growth Factor (VEGF) expression and rescue experiments.
Main Results:
- Hypoxia stimulates proliferation of embryonic hematopoietic progenitors through a HIF-1-dependent pathway.
- Arnt(-/-) embryoid bodies and embryos lack hypoxia-mediated progenitor proliferation.
- Defects in Arnt(-/-) embryos include reduced yolk sac hematopoietic progenitors, linked to decreased ARNT-dependent VEGF expression, which can be rescued by exogenous VEGF.
Conclusions:
- Physiologic hypoxia is essential for the proliferation and survival of embryonic hematopoietic precursors.
- The HIF-1/ARNT/VEGF axis plays a critical role in regulating early hematopoiesis during embryonic development.