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Allylamine enhances c-Ha-ras protooncogene expression in rat aortic smooth muscle cells
1Department of Physiology and Pharmacology, College of Veterinary Medicine, Texas A & M University, College Station 77843-4466.
Abstract:
Studies were conducted to evaluate the mechanisms involved in the deregulation of proliferative control induced by allylamine (AAM) in rat aortic smooth muscle cells (SMCs). Subcultured SMCs from animals treated with AAM (70 mg/kg) or tap water for 20 days were processed for measurements of [3H]thymidine incorporation and c-Ha-ras mRNA levels. Pre-confluent AAM cells stimulated with 10% fetal bovine serum exhibited enhanced mitogenic responsiveness relative to control cells. Decreased [3H]thymidine incorporation was observed in post-confluent cultures of both cell types relative to pre-confluent counterparts. A 5-fold increase in c-Ha-ras transcript levels was observed in pre-confluent/cycling cultures of AAM cells relative to controls. C-Ha-ras expression was markedly reduced in post-confluent cultures of both cell types as compared to pre-confluent counterparts. No difference between control and AAM cells was observed during G1-synchronization of pre- or post-confluent cultures. These results suggest that the enhanced proliferative capacity induced by AAM is associated with alterations in cell cycle-related expression of the c-Ha-ras protooncogene.
Insights
Allylamine (AAM) exposure in rat aortic smooth muscle cells (SMCs) increases proliferation by altering c-Ha-ras protooncogene expression during the cell cycle. This suggests a link between AAM-induced cell growth and changes in ras gene activity.
Area of Science:
- Cell Biology
- Molecular Biology
- Toxicology
Background:
- Proliferative control is crucial for maintaining vascular homeostasis.
- Deregulation of smooth muscle cell (SMC) proliferation contributes to cardiovascular diseases.
- Allylamine (AAM) is a known inducer of vascular damage.
Purpose of the Study:
- To investigate the mechanisms underlying AAM-induced proliferative control deregulation in rat aortic SMCs.
- To examine the role of c-Ha-ras protooncogene expression in AAM-mediated SMC proliferation.
Main Methods:
- Primary rat aortic SMCs were cultured and treated with AAM (70 mg/kg) or tap water for 20 days.
- [3H]thymidine incorporation was measured to assess DNA synthesis and proliferation.
- c-Ha-ras mRNA levels were quantified using molecular techniques.
Main Results:
- AAM-treated SMCs showed enhanced mitogenic responsiveness when stimulated.
- c-Ha-ras transcript levels were significantly increased in pre-confluent/cycling AAM cells.
- Both control and AAM cells exhibited decreased proliferation and c-Ha-ras expression in post-confluent cultures.
Conclusions:
- AAM exposure enhances SMC proliferative capacity.
- Alterations in cell cycle-related c-Ha-ras protooncogene expression are associated with AAM-induced proliferation.
- These findings provide insight into the molecular mechanisms of AAM-induced vascular SMC deregulation.