LXR-Mediated ABCA1 Expression and Function Are Modulated by High Glucose and PRMT2

Area of Science:

• Biochemistry
• Molecular Biology
• Cardiovascular Science

Background:

• Atherosclerosis, a major risk factor for cardiovascular disease, is exacerbated by high cholesterol and diabetes.
• Liver X Receptor (LXR) activation promotes cholesterol efflux, crucial for atherosclerosis regression.
• Diabetes impairs atherosclerosis regression, suggesting glucose dysregulation affects LXR-mediated processes.

Purpose of the Study:

• To investigate how glucose levels modulate Liver X Receptor (LXR)-dependent gene expression in macrophages.
• To identify molecular mechanisms underlying impaired atherosclerosis regression in diabetes.

Main Methods:

• Utilized mouse macrophage cell lines (RAW 264.7) and primary bone marrow-derived macrophages (BMDMs).
• Cultured cells in normal and high glucose conditions mimicking diabetes.
• Assessed LXR-dependent gene expression, including ATP-binding cassette transporter A1 (ABCA1) and ABCG1.
• Examined the expression of chromatin-modifying enzymes, focusing on Protein Arginine Methyltransferase 2 (PRMT2).
• Compared ABCA1 expression and cholesterol efflux in wild-type and Prmt2 knockout (Prmt2-/-) macrophages.
• Analyzed monocyte PRMT2 expression in diabetic and non-diabetic mice.

Main Results:

• High glucose significantly inhibited LXR-dependent ATP-binding cassette transporter A1 (ABCA1) expression, but not ABCG1.
• Protein Arginine Methyltransferase 2 (PRMT2) expression was reduced under high glucose conditions.
• Macrophages lacking PRMT2 (Prmt2-/-) exhibited reduced ABCA1 expression and impaired ABCA1-mediated cholesterol efflux.
• Diabetic mouse monocytes displayed decreased PRMT2 expression compared to non-diabetic controls.

Conclusions:

• Protein Arginine Methyltransferase 2 (PRMT2) is a glucose-sensitive factor involved in regulating ABCA1 expression and cholesterol efflux.
• Reduced PRMT2 under high glucose conditions contributes to impaired LXR-mediated cholesterol transport.
• These findings provide a molecular link between diabetes, PRMT2 deficiency, and increased atherosclerosis risk.