Analysis of gene expression in subpopulations of murine hematopoietic stemand progenitor cells

Objective. The aim of the present work was to study how functional differen ces between subsets of the murine hematopoietic stem/progenitor cell compar tment are manifested on the level of different patterns of gene expression in these subsets. Materials and Methods. Amplified 3' terminal total cDNA fragment population s from four stem and progenitor cell fractions sorted using differential st aining with Rhodamine 123 were prepared, and gene expression patterns were analyzed by Southern hybridization with a panel of gene markers. Results. For the vast majority of lineage-specific markers, no expression w as detected in the long-term repopulating stem cell fraction. Expression of a number of key genes positively regulating entry and progression through the cell cycle was down-regulated in long-term repopulating cells, in accor dance with the quiescent state of the latter. In contrast, certain but not all cell division kinase inhibitors were significantly up-regulated in long - and short-term repopulating stem cell fractions. Expression of several ge nes important for entry into the apoptotic pathway was moderately reduced i n long-term repopulating cells. Messenger RNA levels of the transcription f actors GATA-1, GATA-2, c-Myb and SCL were down-regulated in longterm repopu lating cells, as compared to more mature stem/progenitor cells. Finally, ex pression of the MDR1a gene encoding the Pgp efflux pump was highest in long -term repopulating cells, and progressively decreased with maturation. Conclusion. The patterns of gene expression in the stem/progenitor cell fra ctions are In good correlation with the known properties of adult hematopoi etic stem/progenitor cells and may provide insight into molecular mechanism s underlying stem cell physiology. (C) 2000 International Society for Exper imental Hematology. Published by Elsevier Science Inc.