Acrolein modifies apolipoprotein A-I in the human artery wall

Area of Science:

• Biochemistry
• Cardiovascular Biology
• Molecular Medicine

Background:

• Carbonyl stress accelerates vascular disease, but protein modification mechanisms are unclear.
• Acrolein, a reactive carbonyl from lipid oxidation and smoking, is a potential protein-damaging agent.
• Apolipoprotein A-I (apoA-I) is crucial for cholesterol efflux in high-density lipoprotein (HDL) mediated reverse cholesterol transport.

Purpose of the Study:

• To investigate acrolein's reaction with apolipoprotein A-I (apoA-I).
• To determine if acrolein modification of apoA-I impacts its function in cholesterol transport.
• To assess the role of acrolein-apoA-I adducts in human atherosclerotic lesions.

Main Methods:

• Tandem mass spectrometry to identify amino acids modified by acrolein in apoA-I.
• Immunohistochemistry using a monoclonal antibody to detect acrolein adducts in atherosclerotic lesions.
• Cell-based assays to measure apoA-I's cholesterol efflux capacity after acrolein exposure.

Main Results:

• Lysine residues were identified as the sole sites of acrolein modification on apoA-I.
• Acrolein-apoA-I adducts were found to colocalize with apoA-I in human atherosclerotic plaques.
• Acrolein exposure significantly impaired apoA-I's ability to promote cholesterol efflux from cultured cells.

Conclusions:

• Acrolein reacts with apoA-I, primarily at lysine residues.
• Acrolein modification of apoA-I may hinder HDL's role in reverse cholesterol transport.
• This mechanism suggests a novel pathway by which acrolein contributes to atherogenesis.