Increased levels of dihydrofolate reductase mRNA can be measured in normal, growth-stimulated mouse fibroblasts.
Levels of mRNA for the enzyme dihydrofolate reductase (EC 1.5.1.3) were determined in growth-stimulated 3T6 cells which contained wild-type dosage of the gene coding for this enzyme. As in the case of methotrexate-resistant cells having highly amplified levels of genes for dihydrofolate reductase, an increase in dihydrofolate reductase mRNA by a factor of 2-4 can be determined when cells enter the S phase. This increase is inhibited by sodium butyrate (which inhibits growth-stimulated 3T6 cells in mid G1 phase) but not by hydroxyurea (which inhibits in early S phase). We conclude that with the available methods it is possible to study the regulation of S phase-specific enzymes after growth stimulation at the level of the mRNA, even if gene amplification is not possible or desirable.
D000818:Animals; D002087:Butyrates / Q000494:pharmacology; D020148:Butyric Acid; D002453:Cell Cycle / Q000187:drug effects; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D005347:Fibroblasts / Q000502:physiology; D006918:Hydroxyurea / Q000494:pharmacology; D007700:Kinetics; D051379:Mice; D009693:Nucleic Acid Hybridization; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics*; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics*
D002087:Butyrates; D012333:RNA, Messenger; D020148:Butyric Acid; D004247:DNA; D013762:Tetrahydrofolate Dehydrogenase; D006918:Hydroxyurea