Unanchored tri-NEDD8 inhibits PARP-1 to protect from oxidative stress-induced cell death

Area of Science:

• Molecular Biology
• Cellular Stress Response
• Ubiquitin-like Modifications

Background:

• NEDD8 (Neural precursor cell expressed developmentally down-regulated 8) is a ubiquitin-like protein crucial for activating cullin-RING E3 ubiquitin ligases (CRLs).
• Poly(ADP-ribose) polymerase 1 (PARP-1) is a key enzyme involved in DNA repair and cell death pathways.

Purpose of the Study:

• To investigate the novel role of NEDD8 in modulating PARP-1 activity under oxidative stress conditions.
• To elucidate the specific mechanisms by which NEDD8 influences PARP-1 function and cellular responses to oxidative damage.

Main Methods:

• Cellular treatment with hydrogen peroxide (H2O2) to induce oxidative stress.
• Analysis of NEDD8 chain formation and interaction with PARP-1 using biochemical and mass spectrometry techniques.
• Gene deletion studies (Nedp1 knockout) to assess the impact on NEDD8-PARP-1 regulation.

Main Results:

• Oxidative stress leads to the accumulation of NEDD8 chains, potentially via inhibition of the deneddylase NEDP1.
• Unanchored NEDD8 trimers bind to PARP-1's zinc finger domain, attenuating its activation.
• NEDP1 deletion results in constitutive formation of tri-NEDD8, inhibiting PARP-1 and conferring protection against PARP-1-dependent cell death.
• NEDD8 trimers are acetylated, and their interaction with PARP-1 is modulated by histone deacetylases.

Conclusions:

• Trimeric, acetylated NEDD8 acts as a negative regulator of PARP-1 activation following oxidative stress.
• This mechanism likely serves to delay the onset of PARP-1-mediated cell death, providing a protective cellular response.
• The findings uncover a new regulatory pathway involving NEDD8 and PARP-1 in the context of oxidative stress and cell survival.