INDUCTION OF DELTA-AMINOLEVULINIC-ACID DEHYDRATASE IN MOUSE FRIEND VIRUS-TRANSFORMED ERYTHROLEUKEMIA-CELLS DURING ERYTHROID-DIFFERENTIATION

  • 1 January 1984
    • journal article
    • research article
    • Vol. 64  (1) , 64-70
Abstract
The activity of .delta.-aminolevulinic acid (ALA) dehydratase, an enzyme involved in heme biosynthesis, was shown to increase in Friend virus-transformed murine erythroleukemia (MEL) cells during erythroid differentiation. In this study, the nature of the increase in ALA dehydratase activity in MEL cells was examined using a monospecific antibody directed to the enzyme. A 7-fold increase in ALA dehydratase activity was observed after cells had been treated with 1.5% dimethyl sulfoxide (Me2SO) for 5 days. Ouchterlony double immunodiffusion analysis showed that lysates from untreated and Me2SO-treated MEL cells formed a single precipitin line with rabbit IgG directed to the normal mouse liver ALA dehydratase. A single arc of identity was also observed with the lysates from normal mouse erythrocytes, spleen, liver and lysates from both uninduced and induced MEL cells. Rocket immunoelectrophoresis demonstrated that lysates from both uninduced and induced cells formed rockets with the IgG and that the peak height of the rocket was proportional to the ALA dehydratase activity applied. The slope of linear plots of rocket peak heights vs. ALA dehydratase activity was identical for lysates from uninduced and Me2SO-induced cells. Succinylacetone, a potent inhibitor of ALA dehydratase, was shown to markedly inhibit the activity of the enzyme, but did not interfere with the synthesis of ALA dehydratase induced by Me2SO treatment. Me2SO-induced increases in ALA dehydratase activity and the enzyme protein were both blocked by the simultaneous treatment of cells with 5-bromo-2''-deoxyuridine (BrdU). BrdU-mediated repression of ALA dehydratase was partially overcome by treating the cells with thymidine. Evidently, increased ALA dehydratase activity in MEL cells undergoing erythroid differentiation after Me2SO treatment is due to de novo synthesis of the same enzyme protein present in uninduced MEL cells as well as in normal erythrocytes. This represents the 1st direct demonstration of an increase in a heme biosynthetic pathway enzyme protein in erythroid cells undergoing differentiation.