APC/Cdh1 targets PECAM-1 for ubiquitination and degradation in endothelial cells

Area of Science:

• Endothelial cell biology
• Molecular mechanisms of inflammation
• Protein regulation and degradation

Background:

• Platelet endothelial cell adhesion molecule-1 (PECAM-1) is crucial for endothelial cell (EC) inflammatory responses under disturbed flow.
• The precise mechanisms governing PECAM-1 protein stability are not well understood.

Purpose of the Study:

• To elucidate the regulatory pathways controlling PECAM-1 protein stability.
• To investigate the role of the APC/Cdh1 E3 ubiquitin ligase in PECAM-1 degradation.
• To determine how fluid shear stress affects PECAM-1 stability via Cdh1.

Main Methods:

• Identified PECAM-1 as a substrate of APC/Cdh1.
• Utilized lentivirus-mediated Cdh1 depletion and overexpression in ECs.
• Employed the proteasome inhibitor MG132.
• Assessed K48-linked polyubiquitination of PECAM-1.
• Compared the effects of pulsatile (PS) and oscillatory shear stress (OSS) on Cdh1 expression and PECAM-1 ubiquitination.

Main Results:

• Cdh1 depletion stabilized PECAM-1; Cdh1 overexpression destabilized PECAM-1.
• MG132 inhibited Cdh1-mediated PECAM-1 degradation.
• Cdh1 induced K48-linked polyubiquitination of PECAM-1 dependent on its destruction box.
• Oscillatory shear stress reduced Cdh1 expression and PECAM-1 ubiquitination, leading to PECAM-1 stabilization and promoting EC inflammation.

Conclusions:

• PECAM-1 is a novel substrate of the APC/Cdh1 E3 ubiquitin ligase.
• Fluid flow patterns, specifically oscillatory shear stress, regulate EC homeostasis by modulating Cdh1-dependent PECAM-1 ubiquitination and degradation.
• This pathway represents a new mechanism linking mechanical forces to inflammatory responses in endothelial cells.