Related Experiment Videos
Inhibitory effects of orotate on precursor incorporation into nucleic acids
1Department of Biochemistry and Molecular Biology, UMDNJ, New Jersey Medical School, Newark 07103.
Chemico-Biological Interactions
|January 1, 1990
Summary
Orotic acid impacts nucleic acid synthesis. Studies in mice and rats show orotic acid primarily affects nucleotide pool sizes, inhibiting RNA and DNA synthesis, particularly in liver cells.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Orotic acid is a key intermediate in pyrimidine biosynthesis.
- Dietary modifications can alter pyrimidine nucleotide synthesis rates.
- Understanding orotic acid's influence on nucleic acid metabolism is crucial.
Purpose of the Study:
- To investigate the effect of orotic acid on nucleic acid precursor incorporation in vivo and in vitro.
- To differentiate between direct inhibition of synthesis and effects on nucleotide pool sizes.
Main Methods:
- In vivo studies using mice and rats fed specific diets.
- In vitro studies with isolated cells (HTC hepatoma, rat liver epithelial cells).
- Tracer incorporation studies using radiolabeled precursors ([3H]orotate, [3H]adenosine, [3H]thymidine, [3H]deoxyadenosine).
Main Results:
- Dietary orotate differentially affected RNA incorporation in mouse kidney vs. liver, and rat liver vs. kidney.
- Orotate's effects in mice appeared to be on ribonucleotide pool sizes, not direct RNA synthesis inhibition.
- Orotate inhibited DNA synthesis and cellular proliferation in cultured cells, independent of dTTP pool size.
- Orotate increased UTP levels in HTC cells while inhibiting DNA synthesis.
Conclusions:
- Orotic acid influences nucleic acid synthesis through effects on nucleotide pool sizes and direct inhibition of DNA synthesis.
- Species- and tissue-specific differences exist in orotic acid's impact on RNA metabolism.
- Orotate's inhibitory effect on DNA synthesis is evident even when precursor pools are not elevated.