Decreased deoxy- d-glucose transport in Friend cells during exposure to inducers of erythroid differentiation

Abstract

Various chemicals will induce Friend cells to undergo erythroid differentiation. Concurrent with this differentiation is a large increase in the synthesis of globin messenger RNA (mRNA) and hemoglobin, occurring several days after the initial exposure of the cells to inducer. An earlier change associated with the Friend cell erythroid differentiation is a decrease in the transport of the glucose analogue, 2-deoxy- d-glucose. A substantial transport drop is seen within the first 12 h of exposure to inducer, and this lowered transport rate remains as a characteristic of the induced cell. This change was seen when three different inducers were tested (dimethylsulfoxide, tetramethyl urea and hexamethylene bisacetamide). However, when non-inducible cells (chick embryo and human fibroblasts, and mouse L cells) were exposed to these inducers, no similar decrease in 2-deoxy- d-glucose transport was observed. During induction, this decrease in 2-deoxy- d-glucose transport was associated with a 3-fold drop in the transport V max (4.6-1.54 nmoles 2-deoxy- d-glucose/10 6 cells/min) while no change in the transport K m was observed. l-Glucose uptake was less than 3% of the 2-deoxy- d-glucose uptake at similar hexose concentrations in both induced and uninduced cells. Further, cytochalasin B (CB) (20 μM) inhibited greater than 90% of the deoxy- d-glucose uptake in both cell types. This indicated, most if not all of the total sugar transported was by a carrier-mediated process.