Microparticle-Induced Activation of the Vascular Endothelium Requires Caveolin-1/Caveolae

Area of Science:

• Cell Biology
• Vascular Biology
• Biochemistry

Background:

• Microparticles (MPs) are cell fragments influencing vascular cells via signaling.
• Caveolae are membrane microdomains involved in signal transduction and endocytosis.
• The precise mechanism of MP-induced endothelial cell (EC) activation remains unclear.

Purpose of the Study:

• To investigate the role of caveolae in mediating MP-induced pro-inflammatory responses in ECs.
• To determine if caveolae are essential for MP-induced EC activation and associated signaling.

Main Methods:

• ECs were challenged with MPs, and intracellular adhesion molecule-1 (ICAM-1) expression was measured.
• Key signaling molecules including NF-κB, Poly [ADP-ribose] polymerase 1 (PARP-1), and epidermal growth factor receptor (EGFR) were assessed.
• Experiments were conducted in ECs with and without caveolin-1 (lacking caveolae) and using a dynamin-2 inhibitor (dynasore) to block endocytosis.

Main Results:

• MP challenge upregulated ICAM-1 expression in ECs, mediated by NF-κB, PARP-1, and EGFR activation.
• This pro-inflammatory response was abolished in ECs lacking caveolin-1/caveolae.
• Inhibition of dynamin-2-dependent endocytosis using dynasore significantly attenuated MP-induced EGFR phosphorylation, NF-κB activation, and ICAM-1 upregulation.

Conclusions:

• Caveolae are critical mediators of the pro-inflammatory signaling pathways induced by MPs in ECs.
• MP-induced EC activation depends on caveolae-mediated endocytosis and downstream signaling cascades.
• Targeting caveolae or endocytosis may offer therapeutic strategies for MP-related vascular dysfunction.