Oxygen-dependent regulation of erythropoietin gene expression in rat hepatocytes.

The essential role of the glycoprotein hormone erythropoietin (Epo) in the control of red blood cell production is well established. Synthesis of Epo is induced in response to low oxygen (hypoxia). In response to stimulation, increases in serum Epo levels are paralleled by changes in the abundance of Epo mRNA. These changes indicate that the level of Epo mRNA is the major determinant of hormone production rate [1-3]. Studies of the organ distribution of Epo mRNA [4, 5] have confirmed the results of organ ablation studies, which demonstrated that in adults the kidney is the major organ responsible for the Epo production, but the liver is capable of Epo production as well [6, 7]. More sensitive detection methods of Epo mRNA have demonstrated small quantities in testis, brain, lung, and spleen of rodents [3, 8].