GO:0034360 chylomicron remnant: Components, Assembly and Research Methods, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0034360 chylomicron remnant is a lipoprotein particle derived from mature chylomicrons after triglyceride removal by lipoprotein lipase, characteristically containing apolipoprotein E (APOE).
• Chylomicron remnants are cleared from the blood primarily by the liver via receptor-mediated uptake involving APOE and hepatic receptors.
• Impaired clearance of chylomicron remnants leads to postprandial hyperlipidemia and is associated with atherosclerotic cardiovascular disease [5, 7].
• Chylomicron remnants can be taken up by macrophages, contributing to foam cell formation and atherosclerosis.
• Chylomicron-remnant-like particles inhibit endothelium-dependent vasorelaxation, linking them to endothelial dysfunction.
• Key genes involved include APOE, APOB, LPL, LDLR, LRP1, and APOC3, which regulate remnant formation and clearance [1, 3, 6].
Description
Chylomicron remnants (GO:0034360) are lipoprotein particles that originate from mature chylomicrons after the removal of triglycerides from the chylomicron core by lipoprotein lipase (LPL) and the subsequent loss of surface components. They are characterized by the presence of apolipoprotein E (APOE) and are primarily cleared from the blood by the liver. This process is essential for the efficient delivery of dietary lipids to tissues and for maintaining lipid homeostasis. Dysregulation of chylomicron remnant metabolism leads to the accumulation of remnant lipoproteins in the circulation, a condition known as postprandial hyperlipidemia, which is increasingly recognized as a risk factor for atherosclerotic cardiovascular disease [5, 7]. Chylomicron remnants can also be taken up by macrophages, promoting foam cell formation and contributing to atherogenesis. Furthermore, chylomicron-remnant-like particles have been shown to inhibit receptor-mediated endothelium-dependent vasorelaxation, suggesting a direct role in endothelial dysfunction. Given their central role in lipid transport and their implication in cardiovascular pathology, chylomicron remnants are a critical subject of study in lipidology, metabolism, and cardiovascular research [1, 2, 3].
chylomicron remnant At A Glance
| GO ID | GO:0034360 |
|---|---|
| GO term | chylomicron remnant |
| Ontology | cellular_component |
| Synonym | none |
| Major function | Transport and delivery of dietary lipids to the liver and peripheral tissues; clearance from blood by liver |
| Characteristic component | Apolipoprotein E (APOE) |
| Derivation | Formed from mature chylomicrons by lipoprotein lipase-mediated triglyceride hydrolysis and loss of surface components |
| Clearance mechanism | Receptor-mediated uptake by the liver |
| Associated disease | Atherosclerotic cardiovascular disease, postprandial hyperlipidemia [5, 7] |
What Is GO:0034360?
According to the Gene Ontology, chylomicron remnant (GO:0034360) is a cellular component defined as a lipoprotein particle that is derived from a mature chylomicron particle by the removal of triglycerides from the chylomicron core by lipoprotein lipase and the subsequent loss of surface components. It characteristically contains apolipoprotein E (APOE) and is cleared from the blood by the liver.
Why Is chylomicron remnant Important in Cell Biology?
Chylomicron remnants are critical for the transport and delivery of dietary lipids, and their efficient clearance prevents the accumulation of atherogenic remnant particles in the circulation [1, 6]. Impaired remnant clearance is a hallmark of postprandial hyperlipidemia and is strongly associated with an increased risk of atherosclerotic cardiovascular disease [5, 7]. Remnants can penetrate the arterial wall, be taken up by macrophages, and contribute to foam cell formation and plaque development. Additionally, chylomicron-remnant-like particles impair endothelial function, further linking them to vascular pathology. Therefore, understanding the biology of chylomicron remnants is essential for developing therapeutic strategies to manage dyslipidemia and reduce cardiovascular risk [2, 3].
• Chylomicron remnants are key mediators of dietary lipid transport and delivery to the liver and peripheral tissues.
• Impaired clearance of chylomicron remnants leads to postprandial hyperlipidemia, a risk factor for cardiovascular disease [5, 7].
• Remnant lipoproteins can be taken up by macrophages, promoting foam cell formation and atherosclerosis.
• Chylomicron-remnant-like particles inhibit endothelium-dependent vasorelaxation, contributing to endothelial dysfunction.
• APOE is a critical ligand for hepatic clearance of chylomicron remnants, and its isoforms affect remnant clearance efficiency.
• Dietary interventions can modulate chylomicron and chylomicron remnant clearance, highlighting their responsiveness to lifestyle factors.
• Apolipoprotein B (APOB) is a marker of cardiovascular risk and is integral to the structure of chylomicrons and their remnants.
• Chylomicron remnant metabolism is a target for therapeutic strategies aimed at reducing remnant cholesterol and cardiovascular risk [5, 7].
• Research on chylomicron remnants informs our understanding of lipid metabolism disorders such as familial dysbetalipoproteinemia.
• Studying chylomicron remnants requires integrated approaches from biochemistry, cell biology, and genetics.
Structure and Composition of chylomicron remnant
Formation from mature chylomicrons
In simple terms: Chylomicron remnants are what is left of chylomicrons after most of their fat has been removed.
Chylomicron remnants are derived from mature chylomicrons through the action of lipoprotein lipase (LPL), which hydrolyzes triglycerides in the chylomicron core. This process leads to the loss of surface components and a reduction in particle size, resulting in a remnant particle that is enriched in cholesteryl esters and apolipoprotein E (APOE) [1, 6].
Characteristic apolipoprotein E (APOE) content
In simple terms: APOE is a protein that acts like a ticket for the remnant to be recognized and taken up by the liver.
Chylomicron remnants characteristically contain apolipoprotein E (APOE), which serves as a ligand for hepatic receptors. APOE is acquired from HDL particles in the circulation and is essential for the efficient clearance of remnants by the liver.
Lipid core and surface components
In simple terms: The remnant has a core of fats and a surface made of proteins and phospholipids.
The remnant particle retains a core of triglycerides and cholesteryl esters, surrounded by a surface monolayer of phospholipids, free cholesterol, and apolipoproteins including APOB-48 and APOE [3, 6]. The loss of surface components during lipolysis contributes to the remodeling of the particle.
Hepatic clearance receptors
In simple terms: The liver has receptors that grab remnants and pull them out of the blood.
Chylomicron remnants are cleared from the blood by the liver via receptor-mediated uptake. Receptors such as the LDL receptor (LDLR) and LDL receptor-related protein 1 (LRP1) recognize APOE on the remnant surface, facilitating endocytosis. Other hepatic receptors may also participate in this process.
Key Genes Involved in GO:0034360 chylomicron remnant
The following genes encode proteins that are critical for the formation, remodeling, and clearance of chylomicron remnants.
| Gene | Major Role | Research Relevance |
|---|---|---|
| APOE | Ligand for hepatic receptors; mediates clearance of chylomicron remnants | Central to remnant clearance; isoforms affect cardiovascular risk |
| APOB | Structural apolipoprotein of chylomicrons and remnants; marker of cardiovascular risk | Target for lipid-lowering therapies; marker of atherogenic particles |
| LPL | Hydrolyzes triglycerides in chylomicrons to form remnants | Key enzyme in remnant generation; mutations cause dyslipidemia [1, 6] |
| LDLR | Hepatic receptor that binds APOE and mediates remnant uptake | Defects cause familial hypercholesterolemia; target for statins |
| LRP1 | Hepatic receptor involved in remnant clearance | Alternative clearance pathway; studied in liver metabolism |
| APOC3 | Inhibits LPL and hepatic remnant uptake | Therapeutic target; loss-of-function mutations reduce cardiovascular risk |
| APOC2 | Activates LPL | Deficiency causes hypertriglyceridemia |
| APOA5 | Modulates LPL activity and remnant clearance | Genetic variants affect triglyceride levels |
| LMF1 | Lipase maturation factor; required for LPL activity | Mutations cause combined lipase deficiency |
| GPIHBP1 | Endothelial protein that transports LPL | Deficiency causes hypertriglyceridemia |
| ANGPTL4 | Inhibits LPL activity | Regulates plasma triglyceride levels |
| ANGPTL3 | Inhibits LPL and endothelial lipase | Therapeutic target for hyperlipidemia |
| CREBH | Transcription factor regulating APOC2 and APOA5 | Links ER stress to lipid metabolism |
| SORT1 | Sortilin; modulates hepatic lipoprotein secretion | GWAS locus for LDL-C and cardiovascular risk |
| PCSK9 | Promotes LDLR degradation | Target for lipid-lowering antibodies and siRNA |
| ABCA1 | Cholesterol efflux; influences HDL and APOE lipidation | Mutations cause Tangier disease |
| ABCG1 | Cholesterol efflux to HDL | Affects remnant remodeling |
| CETP | Transfers cholesteryl esters between lipoproteins | Modulates remnant composition |
How Is chylomicron remnant Regulated?
Chylomicron remnant metabolism is regulated at multiple levels. Lipoprotein lipase (LPL) activity is controlled by apolipoproteins such as APOC2 (activator) and APOC3, ANGPTL3, and ANGPTL4 (inhibitors) [5, 6, 7]. Hepatic clearance of remnants is regulated by the expression of receptors such as LDLR and LRP1, which can be modulated by intracellular cholesterol levels and hormones. Additionally, transcription factors like CREBH regulate the expression of APOC2 and APOA5 in response to metabolic stress. Dietary interventions, including fat intake and composition, can acutely affect chylomicron and remnant clearance.
chylomicron remnant and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| APOE | Familial dysbetalipoproteinemia; impaired remnant clearance | Apoe knockout mouse; APOE isoform knock-in |
| LPL | Hypertriglyceridemia; impaired remnant formation | Lpl knockout mouse; tissue-specific KO |
| APOC3 | Hypertriglyceridemia; increased remnant levels | Apoc3 knockout mouse; overexpression models |
| LDLR | Familial hypercholesterolemia; reduced remnant uptake | Ldlr knockout mouse; point mutation knock-in |
| LRP1 | Impaired hepatic remnant clearance | Liver-specific Lrp1 knockout mouse |
Atherosclerotic cardiovascular disease
Elevated levels of chylomicron remnants are independently associated with an increased risk of atherosclerotic cardiovascular disease [5, 7]. Remnants can penetrate the arterial intima, where they are taken up by macrophages, leading to foam cell formation and plaque development. Chylomicron-remnant-like particles also impair endothelial function, contributing to vascular dysfunction.
Postprandial hyperlipidemia
Impaired clearance of chylomicron remnants results in postprandial hyperlipidemia, characterized by prolonged elevation of triglyceride-rich lipoproteins after meals. This condition is linked to insulin resistance, obesity, and type 2 diabetes, and is a risk factor for cardiovascular disease [5, 7].
Familial dysbetalipoproteinemia
Familial dysbetalipoproteinemia (type III hyperlipoproteinemia) is caused by defective APOE, leading to impaired clearance of chylomicron remnants and accumulation of remnant lipoproteins. This disorder is associated with premature atherosclerosis and requires accurate diagnosis and management.
From chylomicron remnant-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does APOE isoform affect chylomicron remnant clearance? | APOE2, APOE3, APOE4 knock-in mice |
| What is the role of hepatic LRP1 in remnant uptake? | Liver-specific LRP1 knockout mouse |
| How does APOC3 inhibition affect remnant metabolism? | APOC3 knockout or antisense oligonucleotide-treated mice |
| Does LPL deficiency alter remnant formation? | Inducible LPL knockout mouse |
| Can overexpression of APOA5 reduce remnant cholesterol? | Transgenic APOA5 overexpression mouse |
| What is the effect of a point mutation in APOE on receptor binding? | CRISPR knock-in of APOE mutation in cell lines |
How to Study the chylomicron remnant Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Ultracentrifugation | Isolation of remnant particles | Preparation of remnants for biochemical assays |
| Fluorescent labeling and flow cytometry | Cellular uptake of remnants | Macrophage and hepatocyte uptake studies |
| Surface plasmon resonance | Binding affinity of APOE to receptors | Receptor-ligand interaction studies |
| Stable isotope kinetics | Production and clearance rates of remnants | In vivo metabolic studies |
| Genotyping and sequencing | Genetic variants associated with remnant levels | Population studies and clinical diagnostics |
| CRISPR-Cas9 gene editing | Functional validation of candidate genes | Knockout and knock-in models |
| RNA-seq | Gene expression changes in response to remnants | Transcriptomic profiling of cells |
| Proteomics | Apolipoprotein composition of remnants | Characterization of remnant particles |
Lipoprotein isolation and characterization
Chylomicron remnants can be isolated from plasma by ultracentrifugation or gel filtration and characterized by lipid and apolipoprotein composition. These methods are fundamental for studying remnant metabolism.
Receptor binding and uptake assays
Cellular uptake of chylomicron remnants can be measured using fluorescently labeled remnants and flow cytometry or confocal microscopy. Receptor binding assays using recombinant receptors or cell membranes help identify clearance mechanisms.
Genetic and genomic approaches
Genome-wide association studies and candidate gene approaches have identified variants in APOE, APOC3, LPL, and other genes that influence remnant levels [5, 7]. CRISPR-based gene editing enables functional validation of these variants.
In vivo kinetic studies
Stable isotope or radiolabeled tracer studies in animal models or humans can measure the production and clearance rates of chylomicron remnants. These studies are essential for understanding the dynamics of remnant metabolism.
How CRISPR Can Be Used to Study GO:0034360 chylomicron remnant
Knockout
CRISPR knockout of genes such as APOE, LPL, or LDLR in cell lines or animal models can elucidate their roles in chylomicron remnant formation and clearance. For example, APOE knockout mice exhibit impaired remnant clearance and develop hyperlipidemia.
Point Mutation
Introducing point mutations via CRISPR, such as the APOE2 or APOE4 isoforms, allows researchers to study how specific amino acid changes affect remnant clearance and cardiovascular risk. Point mutations in LPL can also reveal structure-function relationships.
Knock-in
Knock-in of human APOE isoforms or other humanized genes into mouse models enables the study of human-specific aspects of remnant metabolism. This approach is valuable for preclinical testing of therapeutics targeting remnant clearance.
Overexpression
CRISPR-mediated overexpression of genes like APOA5 or APOC3 can be achieved by inserting strong promoters or using CRISPR activation (CRISPRa). Overexpression models help determine the effects of increased gene dosage on remnant levels and atherosclerosis.
How EDITGENE Supports chylomicron remnant Research
Researchers studying chylomicron remnant-related genes often need to determine whether a candidate gene is causally involved in remnant formation, clearance, or associated diseases. EDITGENE provides a comprehensive suite of CRISPR-based services to accelerate this research, from gene knockout to precise point mutations and knock-in models.
Contact EDITGENE today to design your custom CRISPR model for chylomicron remnant research.
Frequently Asked Questions About chylomicron remnant
What is a chylomicron remnant?
A chylomicron remnant is a lipoprotein particle derived from a mature chylomicron after triglyceride removal by lipoprotein lipase. It contains apolipoprotein E and is cleared by the liver.
What genes are involved in chylomicron remnant clearance?
Key genes include APOE, APOB, LPL, LDLR, LRP1, and APOC3, among others [1, 3, 6].
How are chylomicron remnants cleared from the blood?
They are cleared primarily by the liver via receptor-mediated uptake involving APOE as a ligand.
What diseases are associated with chylomicron remnants?
Elevated remnants are linked to atherosclerotic cardiovascular disease, postprandial hyperlipidemia, and familial dysbetalipoproteinemia [5, 7].
What is the role of APOE in chylomicron remnants?
APOE on the remnant surface mediates binding to hepatic receptors, facilitating clearance.
Can diet affect chylomicron remnant clearance?
Yes, dietary interventions, particularly fat intake, can modulate chylomicron and remnant clearance.
How can I study chylomicron remnants in the lab?
Methods include ultracentrifugation, fluorescent labeling, receptor binding assays, and CRISPR gene editing [1, 6].
What CRISPR models are available for chylomicron remnant research?
Knockout, point mutation, knock-in, and overexpression models for genes like APOE, LPL, and LDLR.
What is postprandial hyperlipidemia?
It is a condition of prolonged elevation of triglyceride-rich lipoproteins, including chylomicron remnants, after meals.
Why are chylomicron remnants atherogenic?
They can penetrate the arterial wall, be taken up by macrophages, and promote foam cell formation and endothelial dysfunction [4, 8].
Conclusion
Chylomicron remnants (GO:0034360) are essential lipoprotein particles in dietary lipid transport, and their efficient clearance is critical for cardiovascular health. Dysregulation of remnant metabolism contributes to postprandial hyperlipidemia and atherosclerosis, making remnants an important therapeutic target. Advances in CRISPR gene editing and related technologies are enabling deeper insights into the genetic and molecular mechanisms governing remnant biology, offering new avenues for disease prevention and treatment.
References
- 1. Willnow TE. 1997. Mechanisms of hepatic chylomicron remnant clearance.. Diabet Med 14 Suppl 3:S75-80 PMID: 9272618
- 2. Williams CM. 1998. Dietary interventions affecting chylomicron and chylomicron remnant clearance.. Atherosclerosis 141 Suppl 1:S87-92 PMID: 9888649
- 3. Glavinovic T et al.. 2022. Physiological Bases for the Superiority of Apolipoprotein B Over Low-Density Lipoprotein Cholesterol and Non-High-Density Lipoprotein Cholesterol as a Marker of Cardiovascular Risk.. J Am Heart Assoc 11(20):e025858 PMID: 36216435
- 4. Bravo E et al.. 2007. Mechanisms involved in chylomicron remnant lipid uptake by macrophages.. Biochem Soc Trans 35(Pt 3):459-63 PMID: 17511627
- 5. Tada H et al.. 2019. Remnant lipoproteins and atherosclerotic cardiovascular disease.. Clin Chim Acta 490:1-5 PMID: 30553862
- 6. Redgrave TG. 2004. Chylomicron metabolism.. Biochem Soc Trans 32(Pt 1):79-82 PMID: 14748717
- 7. Masuda D et al.. 2017. Postprandial Hyperlipidemia and Remnant Lipoproteins.. J Atheroscler Thromb 24(2):95-109 PMID: 27829582
- 8. Goulter AB et al.. 2002. Chylomicron-remnant-like particles inhibit receptor-mediated endothelium-dependent vasorelaxation in pig coronary arteries.. Clin Sci (Lond) 103(5):451-60 PMID: 12401117
