Related Experiment Video
Updated: Aug 8, 2026
Isolation and Analysis of Plasma Lipoproteins by Ultracentrifugation
Published on: January 28, 2021
Isolation and characterization of human apolipoprotein M-containing lipoproteins
Christina Christoffersen1, Lars Bo Nielsen, Olof Axler
1Department of Clinical Biochemistry, Rigshospital, University of Copenhagen, Copenhagen DK-2100, Denmark.
Abstract:
Apolipoprotein M (apoM) is a novel apolipoprotein with unknown function. In this study, we established a method for isolating apoM-containing lipoproteins and studied their composition and the effect of apoM on HDL function. ApoM-containing lipoproteins were isolated from human plasma with immunoaffinity chromatography and compared with lipoproteins lacking apoM. The apoM-containing lipoproteins were predominantly of HDL size; approximately 5% of the total HDL population contained apoM. Mass spectrometry showed that the apoM-containing lipoproteins also contained apoJ, apoA-I, apoA-II, apoC-I, apoC-II, apoC-III, paraoxonase 1, and apoB. ApoM-containing HDL (HDL(apoM+)) contained significantly more free cholesterol than HDL lacking apoM (HDL(apoM-)) (5.9 +/- 0.7% vs. 3.2 +/- 0.5%; P < 0.005) and was heterogeneous in size with both small and large particles. HDL(apoM+) inhibited Cu(2+)-induced oxidation of LDL and stimulated cholesterol efflux from THP-1 foam cells more efficiently than HDL(apoM-). In conclusion, our results suggest that apoM is associated with a small heterogeneous subpopulation of HDL particles. Nevertheless, apoM designates a subpopulation of HDL that protects LDL against oxidation and stimulates cholesterol efflux more efficiently than HDL lacking apoM.
Insights
Apolipoprotein M (apoM) is linked to a small HDL subpopulation. This HDL subset protects LDL from oxidation and enhances cholesterol removal, suggesting a key role for apoM in cardiovascular health.
Area of Science:
- Lipid metabolism
- Cardiovascular research
- Proteomics
Background:
- Apolipoprotein M (apoM) is a novel apolipoprotein with a largely unknown function.
- Understanding apoM's role in lipoprotein metabolism and function is crucial for cardiovascular research.
Purpose of the Study:
- To establish a method for isolating apoM-containing lipoproteins.
- To characterize the composition of apoM-associated lipoproteins.
- To investigate the functional impact of apoM on High-Density Lipoprotein (HDL) function.
Main Methods:
- Immunoaffinity chromatography was used to isolate apoM-containing lipoproteins from human plasma.
- Mass spectrometry was employed to determine the protein composition of isolated lipoproteins.
- Functional assays assessed the effects of apoM-containing HDL on LDL oxidation and cholesterol efflux.
Main Results:
- ApoM was found on a small subpopulation (approx. 5%) of HDL particles, which were heterogeneous in size.
- ApoM-containing HDL (HDL(apoM+)) exhibited higher free cholesterol content compared to HDL lacking apoM (HDL(apoM-)).
- HDL(apoM+) demonstrated enhanced inhibition of LDL oxidation and more efficient cholesterol efflux from foam cells than HDL(apoM-).
Conclusions:
- Apolipoprotein M is associated with a distinct, heterogeneous subpopulation of HDL particles.
- This apoM-designated HDL subpopulation possesses enhanced atheroprotective properties, including protection against LDL oxidation and improved cholesterol efflux.
- These findings highlight apoM as a significant marker and potential mediator in HDL-related cardiovascular protection.
More Related Videos
09:48Fast and Simplified Method for High Through-put Isolation of miRNA from Highly Purified High Density Lipoprotein
Published on: July 27, 2016
11:13Enrichment of Native Lipoprotein Particles with microRNA and Subsequent Determination of Their Absolute/Relative microRNA Content and Their Cellular Transfer Rate
Published on: May 9, 2019