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Polyamine regulatory processes and oxidative stress in monocrotaline-treated pulmonary artery endothelial cells
S M Aziz1, M Toborek, B Hennig
1Department of Pharmacy Services, Henry Ford Hospital, Detroit, MI 48202-2689, USA.
Abstract:
Alterations in polyamine metabolism may be a critical mechanism of monocrotaline (MCT)-induced structural remodeling of the pulmonary vasculature. In the present study, the hypothesis that MCT, through the induction of oxidative stress, modulates cellular polyamine regulatory mechanisms which in turn might be involved in the upregulation of fibronectin production in pulmonary artery endothelial cells (PAEC) was examined. A 24-h treatment with MCT significantly increased PAEC polyamine concentrations as compared to vehicle-treated cells. In addition, exposure to MCT caused an increase in abundance of ornithine decarboxylase (ODC) mRNA, upregulation of ODC activity and enhancement of spermidine import into PAEC. Inhibition of de novo polyamine synthesis further increased spermidine uptake in MCT-treated cells. The depletion of cellular polyamine contents through the blockade of both de novo polyamine biosynthesis and polyamine transport prevented MCT-induced increases in the medium level of fibronectin. In addition, PAEC treatment with MCT stimulated cellular oxidative stress as determined by increased levels of thiobarbituric acid reactive substances, enhanced dichlorofluorescein fluorescence and activation of NF-kappa B. A co-treatment with dimethylthiourea, an oxygen radical scavenger, prevented MCT-induced increases in cellular oxidation and attenuated disturbances in polyamine metabolism. These data suggest that MCT can stimulate polyamine regulatory processes in PAEC possibly through an increase in cellular oxidative stress. The present study may have significant implication in understanding mechanisms of MCT-induced pulmonary hypertension and remodeling of pulmonary vasculature.
Insights
Monocrotaline (MCT) induces pulmonary hypertension by increasing polyamine metabolism and oxidative stress in pulmonary artery endothelial cells (PAEC). Blocking polyamine synthesis and transport prevents fibronectin production, suggesting a key role in vascular remodeling.
Area of Science:
- Cardiovascular Biology
- Cellular Metabolism
- Pulmonary Hypertension Research
Background:
- Polyamines are crucial for cell growth and differentiation.
- Alterations in polyamine metabolism are implicated in cardiovascular diseases.
- Monocrotaline (MCT) is a known toxin causing pulmonary hypertension and vascular remodeling.
Purpose of the Study:
- To investigate the role of polyamine metabolism in MCT-induced pulmonary artery endothelial cell (PAEC) remodeling.
- To determine if MCT-induced oxidative stress modulates polyamine regulation and fibronectin production in PAEC.
- To explore the therapeutic potential of targeting polyamine pathways in MCT-induced pulmonary hypertension.
Main Methods:
- PAEC were treated with MCT, and polyamine concentrations, ornithine decarboxylase (ODC) activity, and mRNA levels were measured.
- Fibronectin production was assessed after inhibiting de novo polyamine synthesis and transport.
- Oxidative stress markers (thiobarbituric acid reactive substances, dichlorofluorescein fluorescence, NF-kappa B activation) were evaluated.
- The effect of an oxygen radical scavenger (dimethylthiourea) was examined.
Main Results:
- MCT significantly increased PAEC polyamine concentrations, ODC activity, and spermidine uptake.
- Inhibition of polyamine synthesis and transport prevented MCT-induced fibronectin upregulation.
- MCT exposure led to increased oxidative stress and NF-kappa B activation in PAEC.
- Dimethylthiourea attenuated MCT-induced oxidative stress and normalized polyamine metabolism.
Conclusions:
- MCT stimulates polyamine regulatory processes in PAEC, potentially via oxidative stress induction.
- Modulation of polyamine metabolism is a critical mechanism in MCT-induced pulmonary vascular remodeling.
- Targeting polyamine pathways may offer a novel therapeutic strategy for pulmonary hypertension.