5-azacytidine induction of stable mesodermal stem cell lineages from 10T1/2 cells: Evidence for regulatory genes controlling determination

5-Azacytidine converts the mouse embryonic cell line C3H10T1/2 into differentiated chondrocytes, adipocytes, and skeletal muscle. Clonal and 2D protein gel analyses demonstrate that 5-azacytidine converts 10T1/2 cells into three stably determined, but undifferentiated, stem cell lineages which can differentiate into myofibers, chondrocytes, and adipocytes. Conversion of 10T1/2 cells is accompanied by specific changes in protein synthetic patterns unique for each cell lineage. We propose that 5-azacytidine converts 10T1/2 cells by hypomethylation of “determination” regulatory loci which establish lineages of stem cells with a restricted potential to differentiate into muscle, cartilage, or fat cells. Our results suggest that these three lineages are specified by separate regulatory loci and that as few as 1–3 hypomethylation events per cell are sufficient to activate the hypothesized muscle regulatory locus. Conversion of 10T1/2 cells by 5-azacytidine provides a model for studying regulatory genes involved in cell lineage determination.