Control of erythroid differentiation: possible role of the transferrin cycle.

A monoclonal antibody to the chicken transferrin receptor (JS-8) blocked temperature-induced and spontaneous differentiation of avian erythroid cells transformed by ts- and wt-retroviral oncogenes. In cells committed to differentiate, JS-8 caused an arrest at the erythroblast or early reticulocyte stage, followed by premature cell death, whereas proliferation of noncommitted erythroid cells or other hematopoietic cells remained unaffected. JS-8 had no effect on transferrin binding or internalization, but blocked subsequent receptor-recycling resulting in reduced iron uptake. Restoration of high intracellular iron levels neutralized the action of JS-8, whereas an inhibitor of porphyrine biosynthesis (4,6-dioxoheptanoic acid) closely mimicked the effect of JS-8. This suggests that erythroid differentiation might involve coordinate synthesis of erythrocyte proteins subject to regulation by hemin or hemoglobin.