Genetic analysis of erythroid differentation using non-inducible Friend cell variants

Cell differentiation rates of Friend murine erythroleukemia variants isolated by sib selection

Variants of Friend erythroleukemia cells were isolated which produced a high frequency (98%) or low frequency (2%) of hemoglobinized cells after induction with dimethylsulfoxide. Repeated subcloning and sib selection allowed enrichment of different cell lines without the use of mutagens or drug selection. The cell lines do not differ in growth rates, plating efficiencies, or chromosome numbers. The differences in inducibility phenotype were stable for more than 260 cell generations. In addition to differences in induction by dimethylsulfoxide and butyric acid, the cell lines also differ in spontaneous rates of cell differentiation. These results suggest that differences in differentiation rates are an inherited property of cells which is amplified in the presence of nonphysiological inducing agents.

Deficient heme synthesis as the cause of noninducibility of hemoglobin synthesis in a Friend erythroleukemia cell line

Friend cells of the line Fw are not induced to accumulate substantial amounts of hemoglobin and to become benzidine-positive when treated with butyric acid or other inducers, except in the presence of exogenous hemin. The cells are shown to have a deficiency in heme synthesis since they require exogenous hemin during the period of maximal hemoglobin synthesis; since endogenous heme synthesis cannot be induced to the level found in normal inducible Friend cells, even after hemoglobin synthesis has been induced by hemin and butyric acid and the hemin has then been withdrawn; since they are not inducible for ferrochelatase (heme synthetase) activity; and since they accumulate free globin chains after stimulation with butyric acid in the absence of hemlin. Comparison of globin synthesis and globin mRNA content of the cells shows that globin synthesis is not controlled by the hemin-controlled repressor of protein synthesis (HCR) nor by any specific translational control of globin synthesis by hemlin.