Protein synthesis in hyperoxic endothelial cells: evidence for translational defect

Area of Science:

• Cell Biology
• Biochemistry
• Physiology

Background:

• Hyperoxia, or elevated oxygen levels, can impact cellular functions.
• Protein synthesis is crucial for maintaining cellular integrity and function.
• Endothelial cells play a vital role in vascular health.

Purpose of the Study:

• To investigate the effects of hyperoxia on protein synthesis in primary porcine aortic endothelial cells.
• To identify the specific molecular mechanisms responsible for hyperoxia-induced alterations in protein synthesis.

Main Methods:

• Primary porcine aortic endothelial cells were exposed to varying oxygen concentrations and durations.
• Protein synthesis was measured by [3H]phenylalanine incorporation.
• RNA synthesis was assessed using [3H]uridine incorporation.
• Levels of free phenylalanine, tRNA-bound phenylalanine, protein degradation rates, and ribosomal activity were analyzed.

Main Results:

• Exposure to 95% O2 for 5 days inhibited protein synthesis by 71%.
• No significant changes were observed in free phenylalanine pools, tRNA charging, or protein degradation rates.
• Hyperoxia increased RNA synthesis and maintained messenger RNA efficiency for protein synthesis.
• A decrease in polypeptide chain elongation rate was identified as the primary cause of reduced protein synthesis.

Conclusions:

• Hyperoxia-induced reduction in protein synthesis is primarily due to defects in translational polypeptide chain elongation.
• These findings highlight the detrimental effects of hyperoxia on endothelial cell function at the molecular level.