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Prepublished online as a Blood First Edition Paper on August 7, 2003; DOI 10.1182/blood-2002-11-3388.
Submitted November 8, 2002
Institute of Physiology, University of Regensburg, Regensburg, Germany * Corresponding author; email: stefanie.dragon{at}vkl.uni-regensburg.de.
A characteristic process of terminal erythroid differentiation is the degradation of ribosomal RNA into mononucleotides. The pyrimidine mononucleotides can be dephosphorylated by the pyrimidine 5'-nucleotidase (P5N-I). In humans, a lack of this enzyme causes hemolytic anemia with ribosomal structures and trinucleotides retained in the red blood cells (RBC). Although the protein/nucleotide sequence of P5N-I is known in mammals, the onset and regulation of P5N-I during erythroid maturation is unknown. However, in circulating chicken embryonic RBC, the enzyme is induced together with carbonic anhydrase (CAII) and 2,3-bisphosphoglycerate (2,3-BPG) by norepinephrine (NE) and adenosine which are released by the embryo under hypoxic conditions. Here, we present the chicken P5N-I sequence and the gene expression of P5N-I during RBC maturation: the profile of gene expression follows the enzyme activity with a rise between day 13 and day 16 of embryonic development. The p5n-I expression is induced 1.) in definitive but not primitive RBC by stimulation of
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| Copyright © 2003 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
-adrenergic/adenosine receptors, and 2.) in definitive RBC by hypoxic incubation of the chicken embryo. Since embryonic RBC increase their hemoglobin oxygen affinity by degradation of nucleotides like UTP and CTP, the induction of p5n-I expression can be seen as adaptive response to hypoxia.
