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Assessment of salvage pathways utilized for incorporation of exogenous pyrimidine nucleosides into DNA of guinea pig lymphocytes stimulated by Con A
Author(s) -
Ringer David P.,
Howell Boyd A.,
Etheredge Janet L.,
Clouse Joe A.,
Kizer Donald E.
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)80422-2
Subject(s) - dna , biochemistry , pyrimidine , biology , ribonucleoside , dna synthesis , nucleoside , microbiology and biotechnology , rna , gene
The organization of specific pyrimidine pathways to channel various nucleoside precursors into DNA is poorly understood. We show that concanavalin A‐stimulated guinea pig lymphocytes incorporate [ 3 H]dThd, [ 3 H]dCyd, [ 3 H]dUrd, [ 3 H]Cyd and [ 3 H]Urd into DNA‐thymines and DNA‐cytosines in a highly conserved distribution pattern. DNA‐thymines were labeled only by dThd and dUrd, while DNA‐cytosines were labeled only by dCyd, Cyd and Urd. The kinetics for the incorporation of the [ 3 H]nucleosides were essentially identical, indicating equivalent abilities to measure DNA synthesis. Pyrazofurin inhibition of the pyrimidine de novo synthetic pathway inhibited cell proliferation and the levels of [ 3 H]nucleoside incorporation by approx. 50%, but did not alter restricted distribution of the [ 3 H]nucleosides among DNA‐thymines and DNA‐cytosines. These findings indicate the absence of Cyd and dCMP deaminase salvage pathways and suggest either subcellular compartmentalization or differential regulation of ribonucleoside diphosphoreductase which permits reduction of CDP but not UDP.