Oxidative stress disassembles the p38/NPM/PP2A complex, which leads to modulation of nucleophosmin-mediated signaling...

Area of Science:

• Cellular biology
• Molecular mechanisms of stress response
• Endothelial cell function

Background:

• Oxidative stress is a key factor in endothelial dysfunction.
• The p38 MAPK pathway is crucial for cellular stress response and is regulated by protein interactions.
• Understanding these interactions is vital for comprehending endothelial cell behavior under stress.

Purpose of the Study:

• To identify novel interacting partners of p38 in human umbilical vein endothelial cells (HUVECs).
• To elucidate the role of the p38/nucleophosmin (NPM) complex in endothelial cells during oxidative stress.
• To investigate how oxidative stress modulates the p38/NPM/PP2A complex and subsequent DNA damage signaling.

Main Methods:

• Proteomic analysis to identify p38 interacting partners.
• Coimmunoprecipitation and microscopic analyses to confirm protein interactions.
• Experimental induction of oxidative stress using hydrogen peroxide (H2O2) and phosphatase inhibition.

Main Results:

• Nucleophosmin (NPM) was identified as a novel cytosolic binding partner of p38 in HUVECs.
• Oxidative stress induced dephosphorylation of NPM at T199, dependent on PP2A phosphatase activity.
• Dephosphorylation of NPM led to its nuclear translocation and impaired signaling of DNA damage response pathways.

Conclusions:

• The p38/NPM/PP2A complex functions as a dynamic sensor for acute oxidative stress in endothelial cells.
• Oxidative stress causes the disassembly of this complex, modulating NPM's role in DNA damage response.
• Findings reveal a novel mechanism by which endothelial cells respond to oxidative insults.