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Science 3 March 1972:
Vol. 175. no. 4025, pp. 955 - 961
DOI: 10.1126/science.175.4025.955
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Articles

Protein Synthesis: Its Control in Erythropoiesis

Paul A. Marks 1 and Richard A. Rifkind 2

1 College of Physicians and Surgeons, Columbia University, New York 10032
2 Departments of Human Genetics and Development and of Medicine at the university

Erythropoiesis in the fetal mouse provides a model to study several important aspects of the regulation of cell differentiation and differentiated protein synthesis. Changes in the patterns of hemoglobins formed during fetal and postfetal development are shown to be associated with the substitution of the liver erythroid cell line. In the course of differentiation of yolk sac erythroid cells there are at least two classes of proteins distinguishable with respect to dependence on continued RNA formatoin. The bulk of nuclear proteins, "nondifferentiated" proteins, appear to be dependent on relatively short-lived messenger RNA while synthesis of differentiated proteins, the hemoglobins, proceeds on relatively stable molecules of messenger RNA. Hemoglobin formation occurs in those cells which are actively synthesizing DNA and dividing. On the average, two to three cell divisions may occur after the formation and stabilization of the messenger RNA for globin. Yolk sac erythropoiesis, at least from day 10 of gestation, is unresponsive to erythropoietin. By comparison, in fetal liver erythropoiesis, the hormone, erythropoietin, acts selectively on the most immature erythroid cell precursor to induce differentiation, cell replication, and hemoglobin formation. The erythropoietin responsive cell in the liver is apparently differentiated from the progenitor, pluripotential stem cell and committed to erythroblast formation and hemoglobin synthesis on exposure to the hormone. The initial effects of erythropoietin on macromolecular synthesis are to stimulate RNA synthesis, which temporally is followed by cell replication and the increase in hemoglobin formation. During liver erythropoiesis, there appears to be a transition from hemoglobin synthesis dependent on RNA formation to hemoglobin synthesis directed by relatively stable messenger RNA.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Hemoglobin Concentration in Normal Diploid and Intersex Triploid Chickens: Genetic Inactivation or Canalization?.
F. Abdel-Hameed (1972)
Science 178, 864-865
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