Unequal accumulation of alpha- and beta-globin mRNA in erythropoietic mouse spleen.

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Abstract
At times after injection of mice with phenylhydrazine, .alpha.- and .beta.-globin m[messenger]RNAs were separated by gel electrophoresis and quantitated by densitometric scanning of stained gels. At 66 h after injection, the ratio of .beta. to .alpha. mRNA was about 1.2. By 138 h, total globin mRNA was 5-fold greater in spleen cells, and the .beta. to .alpha. mRNA ratio approached 2. This ratio remained around 1 in reticulocytes throughout this period. Analyses of globin products directed by these mRNAs from spleen cells and reticulocytes in the ascites cell-free system reflected the .beta. to .alpha. mRNA ratio observed by electrophoresis. Relative rates of synthesis of globin mRNAs were estimated after incubation of spleen cells with either [3H]uridine or [3H]adenosine. Although synthesis of both mRNAs was maximal at 114 h and then declined sharply, .beta. mRNA was synthesized at a greater rate than .alpha. mRNA at every developmental stage. In contrast to the excess accumulation of .beta. mRNA in spleen cells, synthesis of .alpha.- and .beta.-globin chains remained balanced throughout erythroid development. During erythropoiesis in this system, equal synthesis of .alpha. and .beta. globin may involve regulation at both transcriptional and post-transcriptional levels.