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Apoptosis in the haemopoietic system
1CRC Department of Experimental Haematology, Paterson Institute for Cancer Research, Christie (NHS Trust) Hospital, Manchester, U.K.
Summary
Haemopoietic stem cells undergo programmed cell death (apoptosis) when growth factors are withdrawn. Growth factors also promote cell survival, influencing cell fate and potentially causing hematological diseases.
Area of Science:
- Hematology
- Cell Biology
- Molecular Biology
Background:
- Haemopoietic stem cells (HSCs) undergo apoptosis upon growth factor withdrawal.
- Apoptosis is a physiological process regulating hematopoiesis and homeostasis.
- Haemopoietic growth factors act as survival signals, not just mitogenic or differentiation stimuli.
Purpose of the Study:
- To review new and old data on HSC apoptosis and growth factor signaling.
- To examine models of hematopoiesis incorporating apoptosis.
- To explore the role of growth factors in cell survival and its implications for hematological diseases.
Main Methods:
- Review of existing literature and data.
- Examination of computational models of hematopoiesis.
- Analysis of experimental data on growth factor signaling and bcl-2 expression in HSCs.
Main Results:
- Growth factors act as survival signals via membrane receptors, sharing signal transduction pathways with proliferative responses.
- Enforced bcl-2 expression in HSCs prevents apoptosis upon growth factor withdrawal, leading to differentiation without cell division.
- This suggests a stochastic model of hematopoiesis where growth factors primarily suppress apoptosis and act as mitogens.
Conclusions:
- Haemopoietic growth factors are crucial for HSC survival by suppressing apoptosis.
- Dysregulation of the cell survival/death balance may underlie certain hematological diseases.
- Understanding these mechanisms is vital for developing new therapeutic strategies.