N-acetyl-cysteine abolishes hydrogen peroxide-induced modification of eukaryotic initiation factor 4F activity via...

Area of Science:

• Cellular Biology
• Neuroscience
• Molecular Biology

Background:

• Oxidative stress, induced by hydrogen peroxide (H2O2), impacts protein synthesis initiation.
• Key regulatory proteins, eukaryotic initiation factor 4E (eIF4E) and eIF4E binding protein (4E-BP1), are affected during oxidative stress.

Purpose of the Study:

• To investigate the molecular mechanisms underlying oxidative stress-induced alterations in protein synthesis initiation factors.
• To elucidate the roles of N-acetyl-cysteine (NAC) and rapamycin in modulating these stress responses.

Main Methods:

• Utilized nerve growth factor (NGF)-differentiated PC12 cells.
• Applied hydrogen peroxide (H2O2) to induce oxidative stress.
• Administered N-acetyl-cysteine (NAC) and rapamycin (mTOR inhibitor) for treatment.
• Assessed phosphorylation levels of 4E-BP1 and eIF4E, and eIF4F complex formation.

Main Results:

• H2O2 decreased phosphorylation of 4E-BP1 and eIF4E, increasing 4E-BP1/eIF4E association and inhibiting eIF4F formation.
• NAC treatment reversed H2O2-induced eIF4E dephosphorylation but only partially restored 4E-BP1 phosphorylation and eIF4F activity.
• Rapamycin blocked NAC's effect on eIF4F formation and mimicked H2O2's effect on 4E-BP1 phosphorylation.
• MAP kinase inhibitors (PD98056, SB203580) and okadaic acid did not replicate NAC's protective effects on eIF4E.

Conclusions:

• Oxidative stress affects eIF4 factors via at least two MAP kinase-independent signaling pathways.
• One of these pathways is sensitive to rapamycin (mTOR signaling).
• NAC partially mitigates oxidative stress effects through distinct, rapamycin-dependent and independent mechanisms.