Instruction, Not Selection

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Science Signaling  14 Jul 2009:
Vol. 2, Issue 79, pp. ec234
DOI: 10.1126/scisignal.279ec234

Although they play a vital role in the generation of all of the blood cell types that derive from pluripotent hematopoietic progenitor cells, it has been unclear whether cytokines instruct hematopoietic cell fate or whether they promote survival of cells that are already lineage-restricted. Rieger et al. addressed this question using live imaging of differentiating cultured mouse granulocyte-macrophage precursors (GMPs) that expressed a green fluorescent protein (GFP) reporter once they became committed to either the granulocyte (G) or macrophage (M) lineage. The authors observed no cell death in cultures treated with either macrophage or granulocyte colony-stimulating factor (M-CSF or G-CSF), suggesting that these cytokines instructed the lineage commitment decision rather than selectively promoting the survival of cells already committed to one lineage or the other.

M. A. Rieger, P. S. Hoppe, B. M. Smejkal, A. C. Eitelhuber, T. Schroeder, Hematopoietic cytokines can instruct lineage choice. Science 325, 217–218 (2009). [Abstract] [Full Text]