Secreted tyrosine sulfated-eIF5A mediates oxidative stress-induced apoptosis

Area of Science:

• Biochemistry
• Cell Biology
• Cardiovascular Research

Background:

• Oxidative stress is implicated in ischemia/reperfusion injury, atherosclerosis, and aging.
• The precise mechanisms by which oxidative stress induces apoptosis in cardiac myocytes remain unclear.
• Hypoxia/reoxygenation of cardiac myocytes releases factors that promote apoptosis.

Purpose of the Study:

• To identify a humoral factor responsible for apoptosis induction in cardiac myocytes.
• To investigate the role of this factor in oxidative stress-related conditions.
• To evaluate the therapeutic potential of targeting this factor.

Main Methods:

• Collected conditioned medium from cardiac myocytes subjected to hypoxia/reoxygenation.
• Identified and characterized the apoptosis-inducing factor using biochemical techniques.
• Utilized anti-eIF5A neutralizing monoclonal antibodies (mAbs) in vitro and in vivo models.
• Measured plasma eIF5A levels in myocardial ischemia/reperfusion models.

Main Results:

• Identified eIF5A as a secreted factor from hypoxic/reoxygenated cardiac myocytes.
• Demonstrated that eIF5A undergoes tyrosine sulfation and acts as a pro-apoptotic ligand.
• Showed that anti-eIF5A mAbs suppressed apoptosis induced by hypoxia/reoxygenation and UV irradiation.
• Observed increased plasma eIF5A levels in myocardial ischemia/reperfusion and reduced injury with anti-eIF5A mAb treatment.

Conclusions:

• eIF5A is a novel, secreted, pro-apoptotic factor mediating cardiac myocyte apoptosis.
• eIF5A is a potential biomarker for oxidative stress-induced cell injury.
• Targeting eIF5A with neutralizing antibodies offers a therapeutic strategy for myocardial injury.