Cell Lineage Specificity of Chromatin Configuration and Gene Expression in Haemopoietic Progenitor Cells

Haemopoietic stem cells have the potential to activate up to eight distinct cell lineage specific genetic programmes [1]. The mechanisms of cell lineage choice or commitment are fundamental to developmental biology in general and are beginning to be unravelled at least in invertebrates (e.g., Drosophila, Nematodes, slime moulds). Transacting DNA binding proteins that directly or indirectly regulate gene transcription are central players in the game [2], as are inductive cellular interactions [3]. In haemopoietic differentiation, it is clear that selective progenitor-stromal cell interactions involving both adhesive and growth factor recognition [4–7] are playing a role in early decision-making but the basic mechanisms whereby uni-lineage adoption is made are still obscure.