GO:0034374 low-density lipoprotein particle remodeling: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0034374 low-density lipoprotein particle remodeling describes the acquisition, loss, or modification of proteins and lipids within LDL particles, including triglyceride hydrolysis by hepatic lipase and cholesteryl ester transfer protein (CETP)-mediated lipid exchange.
• The process generates small dense LDL (sdLDL), a highly atherogenic subfraction that penetrates the arterial intima more readily than buoyant LDL.
• CETP transfers cholesteryl esters from LDL to triglyceride-rich lipoproteins while simultaneously transferring triglyceride to LDL, creating a triglyceride-enriched LDL that is subsequently lipolyzed.
• Hepatic lipase (LIPC) hydrolyzes LDL triglycerides and phospholipids, a step that is central to the remodeling cascade and sdLDL formation.
• LDL remodeling is mechanistically linked to atherosclerosis, foam cell formation, and cardiovascular disease through pathways involving Gsα, SRB1, USP9X, and PCSK9.
• CRISPR-based knockout, point-mutation, knock-in, and overexpression models enable causal interrogation of remodeling genes in macrophages, hepatocytes, and endothelial cells.
Description
Low-density lipoprotein (LDL) particles are not static carriers of cholesterol; they undergo continuous structural and compositional modification in the circulation, a process formally annotated as GO:0034374 low-density lipoprotein particle remodeling. This biological process encompasses the acquisition, loss, or modification of proteins and lipids within an LDL particle, including the hydrolysis of triglyceride by hepatic lipase with subsequent loss of free fatty acid, and the transfer of cholesteryl esters from LDL to triglyceride-rich lipoprotein particles by cholesteryl ester transfer protein (CETP), with simultaneous transfer of triglyceride to LDL. The remodeling cascade is a central determinant of circulating LDL heterogeneity and is directly implicated in the generation of small dense LDL (sdLDL), a subfraction with enhanced atherogenic potential. For researchers, GO:0034374 provides a structured framework for investigating how lipid transfer proteins, lipases, and lipoprotein receptors cooperate to alter LDL composition and function. The term is particularly relevant to cardiovascular biology because remodeling products accumulate in the arterial wall and drive foam cell formation, endothelial dysfunction, and plaque progression. Recent work has identified macrophage-intrinsic regulators such as Gsα and USP9X that modulate foam cell formation and atherosclerosis, providing mechanistic entry points for studying LDL remodeling in disease. Similarly, SRB1 ubiquitination by RNF128 and PCSK9 inhibitor-mediated anti-inflammatory effects within atherosclerotic plaques highlight the therapeutic tractability of this pathway. Understanding GO:0034374 therefore requires integrating enzymology (hepatic lipase, CETP), lipoprotein receptor biology (SRB1, LDLR), and cellular lipid handling (macrophage foam cells) into a coherent model. This article synthesizes the QuickGO definition with verified PubMed literature to provide a research-grade overview of the mechanisms, genes, disease links, and experimental methods relevant to LDL particle remodeling.
low-density lipoprotein particle remodeling At A Glance
| GO ID | GO:0034374 |
|---|---|
| GO term | low-density lipoprotein particle remodeling |
| Ontology | biological_process |
| Synonym | LDL remodeling; LDL remodelling; low-density lipoprotein particle remodelling; small dense LDL formation; small dense low-density lipoprotein particle formation |
| Major function | Modification of LDL lipid and protein composition, including triglyceride hydrolysis and CETP-mediated lipid exchange |
| Key enzymes | Hepatic lipase (LIPC), cholesteryl ester transfer protein (CETP) |
| Key lipid species | Triglycerides, cholesteryl esters, free fatty acids, phospholipids |
| Cellular context | Plasma lipoprotein metabolism; macrophage foam cell formation; arterial wall lipid deposition |
| Disease relevance | Atherosclerosis, cardiovascular disease, dyslipidemia |
What Is GO:0034374?
GO:0034374 low-density lipoprotein particle remodeling is a biological process defined as the acquisition, loss, or modification of a protein or lipid within a low-density lipoprotein particle. This includes the hydrolysis of triglyceride by hepatic lipase with the subsequent loss of free fatty acid, and the transfer of cholesteryl esters from LDL to a triglyceride-rich lipoprotein particle by cholesteryl ester transfer protein (CETP), with the simultaneous transfer of triglyceride to LDL. In essence, it captures all post-secretory compositional changes that convert buoyant LDL into modified LDL subspecies, including small dense LDL.
Why Is low-density lipoprotein particle remodeling Important in Cell Biology?
GO:0034374 is important because LDL remodeling directly determines the atherogenicity of circulating cholesterol. The generation of small dense LDL through CETP-mediated lipid exchange and hepatic lipase activity increases arterial wall retention and foam cell formation, which are initiating events in atherosclerosis. Macrophage foam cell formation is regulated by Gsα, and its disruption alters atherosclerotic lesion development in mice. Similarly, USP9X deficiency in macrophages promotes foam cell formation and atherosclerosis, linking LDL handling to ubiquitin-dependent pathways. SRB1, a key HDL receptor, is also regulated by RNF128-mediated Lys63-linked polyubiquitination in macrophages, aggravating atherosclerosis and highlighting the intersection of lipoprotein remodeling with receptor trafficking. PCSK9 inhibitors exert anti-inflammatory effects within human atherosclerotic plaques, further underscoring the clinical relevance of LDL-related pathways. Thus, GO:0034374 sits at the nexus of lipid metabolism, inflammation, and cardiovascular disease.
• Generates small dense LDL, a subfraction with enhanced arterial wall penetration and atherogenic potential.
• CETP-mediated exchange of cholesteryl esters and triglycerides is a core driver of LDL compositional change.
• Hepatic lipase hydrolyzes LDL triglycerides, producing free fatty acids and remodeling the particle surface.
• Macrophage foam cell formation, a hallmark of early atherosclerosis, is regulated by Gsα and USP9X.
• SRB1 ubiquitination by RNF128 aggravates atherosclerosis, linking receptor turnover to lipoprotein metabolism.
• PCSK9 inhibitors reduce inflammation within human atherosclerotic plaques, connecting LDL pathways to clinical therapy.
• Smoking-induced endothelial dysfunction accelerates early atherogenesis, a process in which remodeled LDL plays a central role.
• Red yeast rice improves lipid profiles in mild-to-moderate hypercholesterolemia, illustrating dietary modulation of LDL metabolism.
• Circulating LDL composition is a dynamic readout of remodeling enzyme activity and lipid transfer protein function.
• CRISPR models enable causal testing of remodeling genes in macrophages, hepatocytes, and endothelial cells.
What Happens During low-density lipoprotein particle remodeling?
CETP-Mediated Cholesteryl Ester and Triglyceride Exchange
In simple terms: CETP acts like a molecular swap meet, trading cholesterol packets from LDL for triglyceride packets from other lipoproteins.
Cholesteryl ester transfer protein (CETP) transfers cholesteryl esters from LDL to triglyceride-rich lipoprotein particles while simultaneously transferring triglyceride to LDL. This exchange enriches LDL with triglyceride and depletes it of cholesteryl esters, altering the particle's core lipid composition and setting the stage for subsequent lipolysis. The reaction is a defining step of GO:0034374 and is central to the generation of small dense LDL.
Hepatic Lipase-Mediated Triglyceride Hydrolysis
In simple terms: Hepatic lipase acts like a pair of molecular scissors that cuts triglycerides inside LDL, releasing free fatty acids.
Hepatic lipase hydrolyzes triglyceride within LDL particles, with the subsequent loss of free fatty acid. This hydrolysis reduces the triglyceride content of the LDL core and contributes to particle shrinkage, a key event in the remodeling cascade. The activity of hepatic lipase is therefore a major determinant of LDL size and density.
Formation of Small Dense LDL
In simple terms: After losing triglycerides and gaining cholesterol esters in exchange, LDL particles shrink into a smaller, denser form that is more dangerous for arteries.
The combined actions of CETP and hepatic lipase convert buoyant LDL into small dense LDL (sdLDL), a subfraction with increased atherogenic potential. Small dense LDL particles penetrate the arterial intima more readily and are more susceptible to oxidative modification, promoting foam cell formation. This step is explicitly captured by the synonym small dense LDL formation within GO:0034374.
Macrophage Foam Cell Formation and LDL Uptake
In simple terms: Macrophages engulf modified LDL and become foam cells, the hallmark of early atherosclerotic plaques.
Remodeled LDL particles are taken up by macrophages, leading to foam cell formation. Gsα regulates macrophage foam cell formation during atherosclerosis, and its disruption alters lesion development in mice. USP9X deficiency in macrophages also promotes foam cell formation and atherosclerosis, demonstrating that ubiquitin-dependent pathways modulate LDL handling. These findings link GO:0034374 to cellular lipid accumulation and plaque initiation.
Receptor-Mediated Clearance and SRB1 Regulation
In simple terms: Receptors like SRB1 and LDLR control how much remodeled LDL is cleared from the blood, and their regulation affects plaque buildup.
SRB1 (scavenger receptor class B type 1) is a key receptor in lipoprotein metabolism, and its ubiquitination by the E3 ligase RNF128 promotes Lys63-linked polyubiquitination in macrophages, aggravating atherosclerosis. This regulation influences the balance between lipid uptake and efflux, indirectly affecting LDL remodeling outcomes. PCSK9 inhibitors also modulate atherosclerotic plaque inflammation, further connecting receptor biology to LDL-related pathways.
Key Genes Involved in GO:0034374 low-density lipoprotein particle remodeling
The following genes and proteins are experimentally implicated in LDL particle remodeling, lipid transfer, receptor regulation, and atherosclerosis biology.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CETP | Transfers cholesteryl esters from LDL to triglyceride-rich lipoproteins and triglyceride to LDL | Core enzyme of GO:0034374; target for lipid-modifying therapies |
| LIPC | Hepatic lipase; hydrolyzes LDL triglycerides and phospholipids | Directly executes triglyceride hydrolysis in LDL remodeling |
| LDLR | LDL receptor; mediates clearance of LDL particles | Determines circulating LDL levels and remodeling substrate availability |
| SRB1 | Scavenger receptor class B type 1; mediates selective cholesterol uptake | Regulated by RNF128 ubiquitination in macrophages; linked to atherosclerosis |
| RNF128 | E3 ubiquitin ligase; promotes Lys63-linked polyubiquitination of SRB1 | Aggravates atherosclerosis via macrophage SRB1 regulation |
| GNA S | Gsα; regulates macrophage foam cell formation | Disruption alters foam cell formation and atherosclerosis in mice |
| USP9X | Deubiquitinase; regulates macrophage lipid handling | Deficiency promotes foam cell formation and atherosclerosis |
| PCSK9 | Proprotein convertase; regulates LDLR degradation | Inhibitors reduce inflammation in human atherosclerotic plaques |
| PIM1 | Serine/threonine kinase; instigates endothelial-to-mesenchymal transition | Aggravates atherosclerosis via endothelial remodeling |
| APOB | Apolipoprotein B-100; structural protein of LDL | Provides the protein scaffold for LDL particle remodeling |
| APOE | Apolipoprotein E; mediates lipoprotein clearance | Modulates LDL and remnant lipoprotein metabolism |
| LPL | Lipoprotein lipase; hydrolyzes triglycerides in triglyceride-rich lipoproteins | Indirectly influences LDL remodeling by altering substrate availability |
| CETP | Cholesteryl ester transfer protein | Central to cholesteryl ester and triglyceride exchange in LDL |
| SCARB1 | Alternative symbol for SRB1 | Macrophage cholesterol uptake and atherosclerosis |
| ABCA1 | Cholesterol efflux transporter | Modulates macrophage cholesterol balance and foam cell formation |
| ABCG1 | Cholesterol efflux transporter | Contributes to macrophage lipid homeostasis |
| NR1H3 | Liver X receptor alpha; regulates cholesterol efflux genes | Transcriptionally controls lipid handling pathways relevant to remodeling |
| PPARG | Peroxisome proliferator-activated receptor gamma | Regulates macrophage lipid metabolism and inflammation |
How Is low-density lipoprotein particle remodeling Regulated?
LDL particle remodeling is regulated at multiple levels, including enzyme activity, receptor availability, and cellular lipid handling. CETP and hepatic lipase activities determine the rate of lipid exchange and triglyceride hydrolysis, respectively. Receptor-mediated clearance via LDLR and SRB1 modulates the residence time of LDL in circulation, thereby influencing remodeling extent. In macrophages, Gsα signaling regulates foam cell formation, and its disruption alters atherosclerotic lesion development. USP9X deficiency promotes foam cell formation, indicating that deubiquitination pathways control lipid handling. RNF128-mediated Lys63-linked polyubiquitination of SRB1 aggravates atherosclerosis, linking ubiquitin signaling to lipoprotein receptor regulation. PCSK9 inhibitors reduce inflammation within human atherosclerotic plaques, demonstrating pharmacological modulation of LDL-related pathways. Endothelial-to-mesenchymal transition driven by PIM1 also contributes to atherosclerosis progression, indirectly affecting the vascular environment in which LDL remodeling occurs.
low-density lipoprotein particle remodeling and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| GNA S | Atherosclerosis; macrophage foam cell formation | Macrophage-specific knockout mouse |
| USP9X | Atherosclerosis; foam cell formation | Macrophage conditional knockout |
| RNF128 | Atherosclerosis; SRB1 ubiquitination | Knockout and point-mutation models |
| PCSK9 | Atherosclerotic plaque inflammation | Overexpression and inhibitor-treated models |
| PIM1 | Endothelial-to-mesenchymal transition; atherosclerosis | Endothelial-specific knockout |
Atherosclerosis and Cardiovascular Disease
LDL particle remodeling generates small dense LDL, which penetrates the arterial intima and promotes foam cell formation, a hallmark of atherosclerosis. Gsα regulates macrophage foam cell formation, and its disruption alters atherosclerotic lesion development in mice. USP9X deficiency in macrophages promotes foam cell formation and atherosclerosis, linking deubiquitination to plaque progression. SRB1 ubiquitination by RNF128 aggravates atherosclerosis, further connecting receptor regulation to disease. Smoking-induced endothelial dysfunction accelerates early atherogenesis, a process in which remodeled LDL plays a central role.
Dyslipidemia and Hypercholesterolemia
Red yeast rice improves lipid profiles in mild-to-moderate hypercholesterolemia, illustrating that dietary and pharmacological interventions can modulate LDL metabolism. Circulating LDL composition is a dynamic readout of remodeling enzyme activity, and dysregulation of CETP or hepatic lipase contributes to atherogenic lipid profiles. PCSK9 inhibitors reduce inflammation within human atherosclerotic plaques, providing clinical evidence that LDL-lowering therapies affect vascular inflammation.
Endothelial Dysfunction and Vascular Remodeling
PIM1 instigates endothelial-to-mesenchymal transition to aggravate atherosclerosis, demonstrating that endothelial plasticity contributes to vascular disease. Smoking and cardiovascular disease mechanisms include endothelial dysfunction and early atherogenesis, processes in which remodeled LDL participates. These findings highlight the interplay between LDL remodeling and vascular cell biology.
From low-density lipoprotein particle remodeling-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of CETP alter LDL remodeling in vivo? | CETP knockout mouse or hepatocyte-specific knockout |
| Does hepatic lipase activity determine small dense LDL formation? | LIPC knockout and overexpression models |
| Does Gsα regulate macrophage foam cell formation? | Macrophage-specific Gsα knockout |
| Does USP9X deficiency promote atherosclerosis? | Macrophage conditional USP9X knockout |
| Does RNF128-mediated SRB1 ubiquitination affect plaque burden? | RNF128 knockout and SRB1 point-mutation knock-in |
| Does PIM1 drive endothelial-to-mesenchymal transition? | Endothelial-specific PIM1 knockout |
How to Study the low-density lipoprotein particle remodeling Process
| Method | What It Measures | Typical Application |
|---|---|---|
| NMR lipoprotein profiling | LDL subfraction distribution and small dense LDL | Clinical and preclinical lipid phenotyping |
| Lipidomics | Cholesteryl ester and triglyceride content in LDL | Compositional analysis of remodeling |
| CRISPR knockout screen | Genes regulating foam cell formation | Functional genomics in macrophages |
| Ubiquitination assay | Lys63-linked polyubiquitination of SRB1 | Receptor regulation studies |
| Oil Red O staining | Lipid deposition in plaques | Atherosclerosis histology |
| Immunofluorescence | Protein localization in plaque macrophages | Validation of gene function in situ |
| Endothelial marker profiling | Endothelial-to-mesenchymal transition | PIM1 atherosclerosis studies |
| PCSK9 inhibitor treatment assay | Plaque inflammation markers | Clinical translation studies |
Lipoprotein Profiling and Lipidomics
Lipoprotein profiling by NMR or ultracentrifugation separates LDL subfractions and quantifies small dense LDL, a direct readout of GO:0034374 activity. Lipidomics can measure cholesteryl ester and triglyceride content within LDL particles, providing compositional evidence of CETP and hepatic lipase activity.
CRISPR Screens and Functional Genomics
CRISPR knockout screens in macrophage cell lines can identify genes that regulate foam cell formation and LDL uptake. Candidate genes such as Gsα, USP9X, and RNF128 can be validated in primary macrophages using pooled or arrayed screens. These approaches link genotype to lipid-handling phenotypes relevant to LDL remodeling.
Proteomics and Ubiquitination Assays
Proteomic analysis of LDL-associated proteins can detect changes in apolipoprotein composition during remodeling. Ubiquitination assays, including Lys63-linked polyubiquitination detection, are used to study SRB1 regulation by RNF128. These methods reveal post-translational mechanisms that control receptor availability and lipid uptake.
Imaging and Histology
Histological analysis of atherosclerotic plaques, including Oil Red O staining for lipid deposition, quantifies foam cell formation and lesion size in mouse models. Immunofluorescence can localize SRB1, Gsα, and USP9X within plaque macrophages. Endothelial-to-mesenchymal transition can be assessed by marker expression in PIM1 models.
How CRISPR Can Be Used to Study GO:0034374 low-density lipoprotein particle remodeling
Knockout
CRISPR knockout of genes such as Gsα, USP9X, and RNF128 in macrophages or hepatocytes enables loss-of-function studies of LDL remodeling and foam cell formation. Macrophage-specific knockout models have demonstrated altered atherosclerotic lesion development, providing causal evidence for gene function.
Point Mutation
Point-mutation knock-in can be used to dissect specific residues required for SRB1 ubiquitination by RNF128, distinguishing Lys63-linked polyubiquitination from other linkage types. Such models help determine whether a specific post-translational modification is required for receptor regulation and atherosclerosis progression.
Knock-in
Knock-in of tagged alleles, such as fluorescently tagged SRB1 or Gsα, allows real-time tracking of receptor trafficking and signaling in macrophages. Tagged knock-in models can also be used to isolate protein complexes and identify interacting partners involved in LDL remodeling.
Overexpression
Overexpression of CETP, hepatic lipase, or PCSK9 in cell or animal models can drive LDL remodeling and generate small dense LDL, enabling gain-of-function studies. Overexpression models are useful for testing whether increased remodeling enzyme activity is sufficient to accelerate atherosclerosis.
How EDITGENE Supports low-density lipoprotein particle remodeling Research
Researchers studying low-density lipoprotein particle remodeling-related genes often need to determine whether a candidate gene is causally involved in lipid handling, foam cell formation, or atherosclerosis progression. EDITGENE provides CRISPR-based cell model services that enable precise genetic manipulation of these pathways in relevant cell types.
Contact EDITGENE today to design your custom CRISPR model for low-density lipoprotein particle remodeling research.
Frequently Asked Questions About low-density lipoprotein particle remodeling
What is GO:0034374 low-density lipoprotein particle remodeling?
GO:0034374 is a biological process describing the acquisition, loss, or modification of proteins and lipids within LDL particles, including triglyceride hydrolysis by hepatic lipase and CETP-mediated lipid exchange.
What genes are involved in low-density lipoprotein particle remodeling?
Key genes include CETP, LIPC (hepatic lipase), LDLR, SRB1, RNF128, Gsα, USP9X, and PCSK9, all of which regulate lipid transfer, receptor function, or foam cell formation.
How does CETP contribute to LDL remodeling?
CETP transfers cholesteryl esters from LDL to triglyceride-rich lipoproteins while simultaneously transferring triglyceride to LDL, altering core lipid composition and promoting small dense LDL formation.
What is small dense LDL and why is it important?
Small dense LDL is a subfraction generated during LDL remodeling that penetrates the arterial intima more readily and is more atherogenic than buoyant LDL.
How is hepatic lipase involved in LDL remodeling?
Hepatic lipase hydrolyzes triglyceride within LDL particles, releasing free fatty acids and contributing to particle shrinkage and small dense LDL formation.
What diseases are linked to LDL particle remodeling?
LDL remodeling is linked to atherosclerosis, cardiovascular disease, dyslipidemia, and hypercholesterolemia, with contributions from macrophage foam cell formation and endothelial dysfunction.
How can CRISPR be used to study LDL remodeling genes?
CRISPR knockout, point-mutation, knock-in, and overexpression models enable causal testing of genes such as Gsα, USP9X, RNF128, and SRB1 in macrophages and hepatocytes.
What role does SRB1 play in atherosclerosis?
SRB1 mediates selective cholesterol uptake, and its Lys63-linked polyubiquitination by RNF128 in macrophages aggravates atherosclerosis.
Do PCSK9 inhibitors affect LDL remodeling?
PCSK9 inhibitors reduce inflammation within human atherosclerotic plaques, indicating that LDL-lowering therapies modulate vascular inflammation.
What experimental models are used to study LDL remodeling?
Common models include macrophage-specific knockout mice, hepatocyte cell lines, lipoprotein profiling by NMR, lipidomics, and CRISPR screens.
Conclusion
GO:0034374 low-density lipoprotein particle remodeling is a central biological process that governs LDL composition, size, and atherogenicity through CETP-mediated lipid exchange and hepatic lipase-mediated triglyceride hydrolysis. Its products, particularly small dense LDL, drive macrophage foam cell formation and atherosclerosis, with genetic regulators such as Gsα, USP9X, RNF128, and SRB1 playing causal roles in disease models. Understanding this process requires integrating enzymology, receptor biology, and cellular lipid handling. CRISPR-based cell models provide a powerful toolkit for dissecting the genes and mechanisms underlying LDL remodeling. By combining knockout, point-mutation, knock-in, and overexpression strategies with lipidomics and functional assays, researchers can accelerate the translation of mechanistic insights into therapeutic targets for cardiovascular disease.
References
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