Fig. 7.
The chiaroscuro stem cell model.
As early marrow stem cells move through cell cycle transit, chromatin coverage changes, resulting in activation of different transcription regions and thus different gene expression. This change underlies the reversibly shifting phenotype of stem cells. Here stem cells are shown altering their phenotype from hematopoietic engraftable stem cell (S) to hematopoietic progenitor 1 (P1) to hematopoietic progenitor 2 (P2) with different phenotypes (eg, proteopodia) and back to hematopoietic engraftable stem cell. Cylinders represent DNA chromatin coverage; boxes, active transcription factors.
