Induction of mutation in mouse FM3A cells by N4-aminocytidine-mediated replicational errors

Mol Cell Biol. 1988 Jan;8(1):347-52. doi: 10.1128/mcb.8.1.347-352.1988.


To explore the potential use of a nucleoside analog, N4-aminocytidine, in studies of cellular biology, the mechanism of mutation induced by this compound in mouse FM3A cells in culture was studied. On treatment of cells in suspension with N4-aminocytidine, the mutation to ouabain resistance was induced. The major DNA-replicating enzyme in mammalian cells, DNA polymerase alpha, was used to investigate whether the possible cellular metabolite of N4-aminocytidine, N4-aminodeoxycytidine 5'-triphosphate (dCamTP), can be incorporated into the DNA during replication. Using [3H]dCamTP in an in vitro DNA-synthesizing system, we were able to show that this nucleotide analog can be incorporated into newly formed DNA and that it can serve as a substitute for either dCTP or dTTP. dCamTP in the absence of dCTP maintained the activated calf thymus DNA-directed polymerization of deoxynucleoside triphosphates as efficiently as in its presence. Even in the presence of dCTP, dCamTP was incorporated into the polynucleotide. When dCamTP was used as a single substrate in the poly(dA)-oligo(dT)-directed polymerase reaction, it was incorporated into the polynucleotide fraction. The extent of incorporation was 4% of that of dTTP incorporation when dTTP was used as a single substrate. Even in the presence of dTTP, dCamTP incorporation was observed. A copolymer containing N4-aminocytosine residues was shown to incorporate guanine residues opposite the N4-aminocytosines. However, we were unable to observe adenine incorporation opposite N4-aminocytosine in templates. These cell-free experiments show that an AT-to-GC transition can take place in the presence of dCamTP during DNA synthesis, strongly suggesting that the mutation induced in the FM3A cells by N4-aminocytidine is due to replicational errors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Survival / drug effects
  • Cells, Cultured
  • Cytidine / analogs & derivatives*
  • Cytidine / pharmacology
  • DNA / biosynthesis
  • DNA Polymerase II / metabolism
  • DNA Replication / drug effects*
  • Hydrogen Bonding
  • Mice
  • Mutagens*
  • Mutation / drug effects*
  • Templates, Genetic


  • Mutagens
  • N(4)-aminocytidine
  • Cytidine
  • DNA
  • DNA Polymerase II