GO:0090122 cholesterol ester hydrolysis involved in cholesterol transport: Lysosomal Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0090122 describes the lysosomal hydrolysis of cholesterol esters into free fatty acids and cholesterol, a step that contributes to intracellular cholesterol transport.
• The process is essential for mobilizing stored cholesterol from lipid droplets and lipoprotein-derived cholesteryl esters, enabling cells to redistribute cholesterol to membranes, mitochondria, and other organelles.
• Key enzymes include lysosomal acid lipase (LIPA), neutral cholesteryl ester hydrolase 1 (CES1), and hormone-sensitive lipase (LIPE), each acting in distinct cellular compartments.
• Defective cholesterol ester hydrolysis causes cholesteryl ester storage disease (CESD) and Wolman disease, and contributes to macrophage foam cell formation in atherosclerosis.
• Cholesterol released by hydrolysis can be directed to steroidogenic mitochondria for hormone synthesis or to the plasma membrane for efflux, linking the term to endocrine and cardiovascular biology.
• CRISPR knockout, point-mutation, knock-in, and overexpression models are powerful tools to dissect the causal roles of LIPA, CES1, LIPE, and related genes in this pathway.
Description
GO:0090122, cholesterol ester hydrolysis involved in cholesterol transport, is a biological process that specifically refers to the lysosomal hydrolysis of cholesterol esters into free fatty acids and cholesterol, a reaction that contributes to intracellular cholesterol transport. Cholesterol esters are the storage form of cholesterol and must be hydrolyzed to release free cholesterol for use in membrane synthesis, steroid hormone production, and bile acid formation. This process is therefore central to cellular cholesterol homeostasis and is particularly important in cells that handle large amounts of lipoprotein-derived cholesterol, such as macrophages, hepatocytes, and steroidogenic cells. Research on GO:0090122 has revealed that the lysosomal enzyme lysosomal acid lipase (LIPA) is the primary hydrolase responsible for this activity, and its deficiency leads to cholesteryl ester storage disease (CESD) and Wolman disease. In addition, neutral cholesteryl ester hydrolase 1 (CES1) and hormone-sensitive lipase (LIPE) contribute to cholesteryl ester hydrolysis in other compartments, highlighting the existence of multiple enzymatic routes for this process. The free cholesterol generated by hydrolysis is subsequently transported out of the lysosome and distributed to the plasma membrane, endoplasmic reticulum, and mitochondria, where it regulates key signaling and metabolic pathways. Understanding GO:0090122 is therefore critical for researchers studying atherosclerosis, lysosomal storage disorders, and steroid hormone synthesis, as well as for those developing therapies that target cholesterol trafficking. This article provides a comprehensive overview of the definition, mechanism, key genes, disease links, and experimental models relevant to this GO term.
cholesterol ester hydrolysis involved in cholesterol transport At A Glance
| GO ID | GO:0090122 |
|---|---|
| GO term | cholesterol ester hydrolysis involved in cholesterol transport |
| Ontology | biological_process |
| Synonym | None |
| Major function | Lysosomal hydrolysis of cholesterol esters into free fatty acids and cholesterol, contributing to intracellular cholesterol transport |
| Cellular location | Lysosome |
| Key enzymes | LIPA, CES1, LIPE |
| Related diseases | Cholesteryl ester storage disease, Wolman disease, atherosclerosis |
| Research relevance | Target for cardiovascular, metabolic, and lysosomal storage disease studies |
What Is GO:0090122?
GO:0090122 is defined as the cholesterol metabolic process in which cholesterol esters are hydrolyzed into free fatty acids and cholesterol in the lysosome, and this hydrolysis contributes to intracellular cholesterol transport. In other words, it is the lysosomal step that converts stored or lipoprotein-derived cholesteryl esters into free cholesterol, which can then be moved to other cellular destinations.
Why Is cholesterol ester hydrolysis involved in cholesterol transport Important in Cell Biology?
GO:0090122 is important because it represents the committed step that mobilizes cholesterol from its esterified storage form, thereby supplying free cholesterol for essential cellular functions such as membrane biogenesis, steroid hormone synthesis, and bile acid production. Dysregulation of this process leads to cholesterol accumulation in macrophages, a hallmark of atherosclerosis, and to lysosomal storage disorders such as CESD and Wolman disease. Moreover, the free cholesterol released by this hydrolysis can influence signaling pathways and mitochondrial steroidogenesis, making it a focal point for research in cardiovascular disease, endocrinology, and rare genetic disorders.
• Provides free cholesterol for membrane synthesis and repair.
• Supplies substrate for steroid hormone production in adrenal and gonadal cells.
• Prevents excessive cholesteryl ester accumulation in macrophages, reducing foam cell formation.
• Defects cause cholesteryl ester storage disease and Wolman disease.
• Contributes to reverse cholesterol transport and plasma lipoprotein function.
• Links lysosomal function to whole-body cholesterol homeostasis.
• Modulates intestinal cholesterol absorption via hormone-sensitive lipase.
• Involved in SREBP2-STARD4-mediated cholesteryl ester synthesis and transport.
• Target for anti-atherosclerotic therapies, including calcium channel blockers.
• Essential for normal macrophage cholesterol handling in atherosclerosis.
What Happens During cholesterol ester hydrolysis involved in cholesterol transport?
Delivery of Cholesteryl Esters to the Lysosome
In simple terms: Cholesteryl esters from lipoproteins are brought into the lysosome to be broken down.
Cholesteryl esters are delivered to the lysosome primarily through the endocytic uptake of lipoproteins, such as LDL, and through autophagy of lipid droplets. Once inside the lysosome, these esters become accessible to lysosomal acid lipase (LIPA), which initiates hydrolysis. This step is critical for mobilizing stored cholesterol and is conserved across cell types, including macrophages and hepatocytes.
Enzymatic Hydrolysis by Lysosomal Acid Lipase
In simple terms: An enzyme called LIPA cuts cholesteryl esters into free cholesterol and fatty acids.
LIPA catalyzes the hydrolysis of cholesteryl esters and triglycerides at acidic pH within the lysosome. Deficiency of LIPA leads to massive accumulation of cholesteryl esters in lysosomes, as seen in CESD and Wolman disease. This enzyme is considered the primary hydrolase for GO:0090122, and its activity is essential for the subsequent transport of free cholesterol out of the lysosome.
Release and Transport of Free Cholesterol
In simple terms: The free cholesterol produced is moved out of the lysosome to other parts of the cell.
After hydrolysis, free cholesterol is transported out of the lysosome by proteins such as NPC1 and NPC2, although the exact mechanisms remain under investigation. This transport is a key part of GO:0090122, as it delivers cholesterol to the plasma membrane, endoplasmic reticulum, and mitochondria. In steroidogenic cells, cholesterol is directed to the inner mitochondrial membrane for conversion to pregnenolone by cytochrome P450scc.
Integration with Cellular Cholesterol Homeostasis
In simple terms: The released cholesterol helps the cell maintain proper cholesterol levels.
The free cholesterol generated by GO:0090122 participates in feedback regulation of cholesterol synthesis and uptake, including SREBP2-mediated pathways. It can also be esterified again by ACAT enzymes for storage or effluxed to extracellular acceptors. This integration ensures that cells balance cholesterol storage, utilization, and export, and defects in this process contribute to atherosclerosis and lysosomal storage diseases.
Key Genes Involved in GO:0090122 cholesterol ester hydrolysis involved in cholesterol transport
The following genes and proteins are directly implicated in cholesterol ester hydrolysis involved in cholesterol transport (GO:0090122) and its regulatory network.
| Gene | Major Role | Research Relevance |
|---|---|---|
| LIPA | Lysosomal acid lipase that hydrolyzes cholesteryl esters in the lysosome | Primary enzyme for GO:0090122; mutations cause CESD and Wolman disease |
| CES1 | Neutral cholesteryl ester hydrolase 1 that hydrolyzes cholesteryl esters in macrophages | Critical for cholesteryl ester hydrolysis in murine macrophages |
| LIPE | Hormone-sensitive lipase with cholesteryl ester hydrolase activity | Intestine-specific knockout leads to cholesteryl ester accumulation and accelerated cholesterol absorption |
| NPC1 | Mediates egress of free cholesterol from the lysosome | Mutations cause Niemann-Pick type C disease; linked to cholesterol trafficking |
| NPC2 | Soluble lysosomal protein that transfers cholesterol to NPC1 | Essential for lysosomal cholesterol export |
| STARD4 | Steroidogenic acute regulatory protein-related lipid transfer domain protein | Involved in SREBP2-STARD4 pathway for cholesteryl ester synthesis and transport |
| SREBP2 | Transcription factor regulating cholesterol synthesis and uptake | Regulates genes involved in cholesteryl ester metabolism |
| CYP11A1 | Cytochrome P450scc that converts cholesterol to pregnenolone | Uses free cholesterol released by hydrolysis for steroidogenesis |
| ABCA1 | Mediates efflux of free cholesterol to apolipoproteins | Links hydrolysis to reverse cholesterol transport |
| ABCG1 | Mediates efflux of cholesterol to HDL | Contributes to cholesterol removal after hydrolysis |
| ACAT1 | Acyl-CoA:cholesterol acyltransferase that re-esterifies cholesterol | Balances free cholesterol and cholesteryl ester pools |
| ACAT2 | Acyl-CoA:cholesterol acyltransferase involved in lipoprotein assembly | Influences cholesteryl ester formation in intestine and liver |
| SR-BI | Scavenger receptor BI that mediates selective cholesteryl ester uptake | Delivers cholesteryl esters to cells for hydrolysis |
| LDLR | LDL receptor that mediates endocytosis of LDL | Provides cholesteryl esters to lysosomes for hydrolysis |
| ApoA-I | Major apolipoprotein of HDL | Accepts free cholesterol after hydrolysis for reverse transport |
| LCAT | Lecithin:cholesterol acyltransferase that esterifies free cholesterol in plasma | Opposes hydrolysis by re-esterifying cholesterol |
| CETP | Cholesteryl ester transfer protein | Transfers cholesteryl esters between lipoproteins, affecting substrate availability |
How Is cholesterol ester hydrolysis involved in cholesterol transport Regulated?
The process of cholesterol ester hydrolysis involved in cholesterol transport is regulated at multiple levels. Transcription of LIPA and other lysosomal genes is controlled by the transcription factor TFEB, which responds to lysosomal stress and nutrient status. In macrophages, inflammatory signals and cholesterol loading modulate the expression and activity of CES1 and LIPE, thereby affecting the balance between esterification and hydrolysis. Hormone-sensitive lipase (LIPE) is regulated by phosphorylation in response to hormonal signals, which can acutely increase cholesteryl ester hydrolysis. Additionally, the SREBP2-STARD4 axis regulates cholesteryl ester synthesis and transport, indirectly influencing the availability of substrates for hydrolysis. These regulatory mechanisms ensure that free cholesterol is produced according to cellular demand and that excess cholesterol is either re-esterified or effluxed.
cholesterol ester hydrolysis involved in cholesterol transport and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| LIPA | Cholesteryl ester storage disease, Wolman disease | LIPA knockout mice, patient-derived fibroblasts |
| CES1 | Atherosclerosis, macrophage foam cell formation | CES1 knockout macrophages, ApoE-/- mice |
| LIPE | Intestinal cholesterol absorption, dyslipidemia | Intestine-specific LIPE knockout mice |
| NPC1 | Niemann-Pick type C disease | NPC1 mutant cell lines, knockout mice |
| STARD4 | Steroidogenesis, cholesteryl ester synthesis | STARD4 overexpression in MLTC-1 cells |
Cholesteryl Ester Storage Disease and Wolman Disease
Mutations in LIPA cause cholesteryl ester storage disease (CESD) and the more severe Wolman disease, both characterized by lysosomal accumulation of cholesteryl esters and triglycerides. Patients with CESD exhibit altered cholesterol trafficking-related serum lipoprotein functions, including reduced cholesterol efflux capacity. These disorders directly result from defective GO:0090122 and highlight the importance of lysosomal acid lipase in cholesterol homeostasis.
Atherosclerosis and Macrophage Foam Cell Formation
In atherosclerosis, macrophages accumulate cholesteryl esters derived from modified lipoproteins, leading to foam cell formation. Efficient hydrolysis of these esters by CES1 and LIPA is required to prevent excessive lipid accumulation and to promote cholesterol efflux. Deficiency or dysregulation of these enzymes exacerbates foam cell formation and plaque development, making GO:0090122 a protective process in cardiovascular disease.
Steroid Hormone Synthesis and Endocrine Disorders
The free cholesterol released by GO:0090122 is a substrate for steroid hormone synthesis in adrenal, ovarian, and testicular cells. Cholesterol must be transported to mitochondria and converted to pregnenolone by CYP11A1, a step regulated by STARD4 and other proteins. Impaired hydrolysis can therefore affect steroidogenesis and contribute to endocrine dysfunction.
Intestinal Cholesterol Absorption
Hormone-sensitive lipase (LIPE) in the intestine contributes to cholesteryl ester hydrolysis, and its deficiency leads to cholesteryl ester accumulation and accelerated cholesterol absorption in mice. This suggests that GO:0090122 also plays a role in dietary cholesterol handling and may influence plasma cholesterol levels.
From cholesterol ester hydrolysis involved in cholesterol transport-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does LIPA loss impair lysosomal cholesterol hydrolysis? | LIPA knockout cell line (e.g., HepG2, macrophages) |
| Does CES1 deficiency increase foam cell formation? | CES1 knockout macrophages treated with oxidized LDL |
| Does LIPE regulate intestinal cholesterol absorption? | Intestine-specific LIPE knockout mice |
| Does STARD4 overexpression alter cholesteryl ester synthesis? | STARD4 overexpression in MLTC-1 cells |
| Does a point mutation in LIPA affect enzymatic activity? | CRISPR point-mutation knock-in of LIPA in cell lines |
| Can a tagged LIPA knock-in reveal lysosomal localization? | LIPA-GFP knock-in via CRISPR |
How to Study the cholesterol ester hydrolysis involved in cholesterol transport Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Lipidomics (LC-MS) | Free cholesterol and cholesteryl ester species | Quantify hydrolysis in knockout vs. wild-type cells |
| Filipin staining | Free cholesterol distribution | Detect lysosomal cholesterol accumulation |
| LAL activity assay | Lysosomal acid lipase enzymatic activity | Diagnose CESD and assess LIPA function |
| NCEH activity assay | Neutral cholesteryl ester hydrolase activity | Measure CES1 function in macrophages |
| RNA-seq | Transcriptional changes | Identify SREBP2 target genes after hydrolysis |
| Proteomics | Protein abundance and modifications | Discover regulators of cholesterol trafficking |
| Live-cell imaging | Cholesterol movement | Track lysosome-to-membrane transport |
| CRISPR screening | Gene essentiality in cholesterol handling | Identify novel genes in GO:0090122 |
Lipidomics and Cholesterol Quantification
Mass spectrometry-based lipidomics and enzymatic assays can quantify free cholesterol and cholesteryl esters in cells and tissues, providing direct readouts of GO:0090122 activity. These methods are essential for assessing the impact of genetic perturbations on cholesterol ester hydrolysis.
Fluorescence Microscopy and Cholesterol Trafficking
Filipin staining and fluorescent cholesterol analogs (e.g., BODIPY-cholesterol) allow visualization of cholesterol distribution and lysosomal accumulation, revealing defects in hydrolysis and transport. Live-cell imaging can track the movement of free cholesterol after hydrolysis.
Enzyme Activity Assays
Lysosomal acid lipase and neutral cholesteryl ester hydrolase activities can be measured using fluorogenic or radiolabeled cholesteryl ester substrates in cell lysates or purified fractions. These assays directly assess the catalytic function of LIPA and CES1.
Transcriptomics and Proteomics
RNA-seq and quantitative proteomics can identify changes in gene expression and protein abundance in response to altered cholesterol ester hydrolysis, uncovering regulatory networks involving SREBP2 and STARD4. These approaches help define the broader impact of GO:0090122 on cellular metabolism.
How CRISPR Can Be Used to Study GO:0090122 cholesterol ester hydrolysis involved in cholesterol transport
Knockout
CRISPR knockout of LIPA, CES1, or LIPE in cell lines such as HepG2, THP-1 macrophages, or MLTC-1 cells can abolish specific hydrolysis activities, leading to cholesteryl ester accumulation. These models are valuable for studying the contribution of each enzyme to GO:0090122 and for testing compensatory pathways.
Point Mutation
Introducing disease-associated point mutations (e.g., in LIPA) via CRISPR base editing or homology-directed repair allows researchers to dissect the functional consequences of specific amino acid changes on enzyme activity and cholesterol transport. Such models mimic human CESD mutations and can reveal genotype-phenotype relationships.
Knock-in
Knock-in of epitope tags (e.g., GFP, HA) into endogenous LIPA or CES1 loci enables real-time tracking of protein localization and interactions within the lysosome. Tagged knock-in models are also useful for isolating protein complexes involved in cholesterol hydrolysis and transport.
Overexpression
Overexpression of LIPA, CES1, or STARD4 using CRISPR activation or lentiviral vectors can enhance cholesteryl ester hydrolysis and alter cholesterol trafficking. These models help determine whether increased hydrolysis is sufficient to reduce foam cell formation or boost steroidogenesis.
How EDITGENE Supports cholesterol ester hydrolysis involved in cholesterol transport Research
Researchers studying cholesterol ester hydrolysis involved in cholesterol transport-related genes often need to determine whether a candidate gene is causally involved in lysosomal cholesterol mobilization, foam cell formation, or steroidogenesis. EDITGENE provides a comprehensive suite of CRISPR-based services to generate precisely engineered cell models that answer these questions.
Contact EDITGENE today to design your custom CRISPR model for cholesterol ester hydrolysis involved in cholesterol transport research.
Frequently Asked Questions About cholesterol ester hydrolysis involved in cholesterol transport
What is GO:0090122?
GO:0090122 is the biological process of cholesterol ester hydrolysis involved in cholesterol transport, where cholesterol esters are broken down into free fatty acids and cholesterol in the lysosome to facilitate intracellular cholesterol movement.
What genes are involved in cholesterol ester hydrolysis involved in cholesterol transport?
Key genes include LIPA, CES1, LIPE, NPC1, NPC2, STARD4, and SREBP2, among others.
Which enzyme hydrolyzes cholesteryl esters in the lysosome?
Lysosomal acid lipase (LIPA) is the primary enzyme that hydrolyzes cholesteryl esters in the lysosome.
What diseases are linked to defective cholesterol ester hydrolysis?
Defective hydrolysis causes cholesteryl ester storage disease, Wolman disease, and contributes to atherosclerosis.
How is cholesterol ester hydrolysis involved in cholesterol transport studied?
It is studied using lipidomics, enzyme activity assays, fluorescence microscopy, and CRISPR knockout models.
What is the role of CES1 in cholesterol ester hydrolysis?
CES1 (neutral cholesteryl ester hydrolase 1) hydrolyzes cholesteryl esters in macrophages and helps prevent foam cell formation.
Does hormone-sensitive lipase (LIPE) contribute to cholesterol ester hydrolysis?
Yes, LIPE has cholesteryl ester hydrolase activity, and its deficiency in the intestine leads to cholesteryl ester accumulation and accelerated cholesterol absorption.
How does STARD4 relate to cholesterol ester hydrolysis?
STARD4 is involved in SREBP2-mediated cholesteryl ester synthesis and transport, indirectly affecting substrate availability for hydrolysis.
What are the symptoms of cholesteryl ester storage disease?
CESD is characterized by lysosomal cholesteryl ester accumulation, hepatomegaly, and altered serum lipoprotein functions.
Can CRISPR be used to model cholesterol ester hydrolysis disorders?
Yes, CRISPR knockout and point-mutation models of LIPA and other genes can replicate key features of CESD and atherosclerosis.
Conclusion
GO:0090122, cholesterol ester hydrolysis involved in cholesterol transport, is a fundamental lysosomal process that mobilizes cholesterol for cellular use and maintains cholesterol homeostasis. Its dysregulation is directly linked to lysosomal storage disorders and atherosclerosis, making it a critical area of biomedical research. Advances in CRISPR-based models and lipidomics continue to unravel the molecular players and regulatory mechanisms of this pathway. Understanding GO:0090122 offers promising avenues for therapeutic intervention in cardiovascular and metabolic diseases.
References
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- 3. Obrowsky S et al.. 2012. Cholesteryl ester accumulation and accelerated cholesterol absorption in intestine-specific hormone sensitive lipase-null mice.. Biochim Biophys Acta 1821(11):1406-14 PMID: 22842588
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