LOSS OF GLUCOSE TRANSPORTERS IS AN EARLY EVENT IN DIFFERENTIATION OF HD3 CELLS

The HD3 cell, a chicken erythroblast cell line infected with a tempera ture-sensitive avian erythroblastosis virus, becomes committed to diff erentiate to an erythrocyte upon temperature shift in presence of indu cers. Before induction, the HD3 cell transports glucose and 2-deoxyglu cose (2-DG). 3-O-methylglucose is poorly taken up. Upon induction of d ifferentiation, glucose and 2-DG transport activity fall. Twenty-four hours postinduction, up to 75% of the glucose transport activity may d isappear. By use of cDNA probes for chicken glucose transporters, two species of mRNA of 3.1 and 1.7 kb (equivalent to mammalian GLUT1 and G LUT3 mRNA, respectively) are detected. Both messages virtually disappe ar within 48 h after induction. Run-on assays show the cessation of sy nthesis of the corresponding RNAs parallel to the loss of glucose tran sport. In contrast to the glucose transporters, the nucleoside transpo rter level increases after induction of hematopoiesis. This developmen tal pattern is consistent with earlier studies showing that mature chi cken erythrocytes have little glucose transport activity but retain ap preciable levels of the nucleoside transporter and that nucleosides an d glutamine provide major sources of oxidizable carbon compounds to su stain metabolism in circulating chicken erythrocytes.