LDLR Gene

LDLR Gene

Introduction

Ldlr Gene is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

<div class="infobox infobox-gene"> [@supsup2009a]
<table> [@supsup2012]
<tr><th>Gene Symbol</th><td>LDLR</td></tr> [@supsup2014]
<tr><th>Full Name</th><td>Low-Density Lipoprotein Receptor</td></tr> [@supsup2016]
<tr><th>Chromosomal Location</th><td>19p13.2</td></tr> [@supsup2008]
<tr><th>NCBI Gene ID</th><td>3955</td></tr>
<tr><th>OMIM</th><td>143890</td></tr>
<tr><th>Ensembl ID</th><td>ENSG00000130164</td></tr>
<tr><th>UniProt ID</th><td>P01130</td></tr>
<tr><th>Protein Length</th><td>860 amino acids</td></tr>
<tr><th>Protein Class</th><td>LDL Receptor Family</td></tr>
<tr><th>Associated Diseases</th><td>Familial Hypercholesterolemia, Alzheimer's Disease, Cerebral Amyloid Angiopathy, Atherosclerosis, Stroke</td></tr>
</table>
</div>

Pathway Diagram

LDLR Gene

Introduction

Ldlr Gene is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

<div class="infobox infobox-gene"> [@supsup2009a]
<table> [@supsup2012]
<tr><th>Gene Symbol</th><td>LDLR</td></tr> [@supsup2014]
<tr><th>Full Name</th><td>Low-Density Lipoprotein Receptor</td></tr> [@supsup2016]
<tr><th>Chromosomal Location</th><td>19p13.2</td></tr> [@supsup2008]
<tr><th>NCBI Gene ID</th><td>3955</td></tr>
<tr><th>OMIM</th><td>143890</td></tr>
<tr><th>Ensembl ID</th><td>ENSG00000130164</td></tr>
<tr><th>UniProt ID</th><td>P01130</td></tr>
<tr><th>Protein Length</th><td>860 amino acids</td></tr>
<tr><th>Protein Class</th><td>LDL Receptor Family</td></tr>
<tr><th>Associated Diseases</th><td>Familial Hypercholesterolemia, Alzheimer's Disease, Cerebral Amyloid Angiopathy, Atherosclerosis, Stroke</td></tr>
</table>
</div>

Pathway Diagram

Overview

The LDLR (Low-Density Lipoprotein Receptor) is a cell surface receptor responsible for the uptake of LDL cholesterol into cells via receptor-mediated endocytosis. It plays a crucial role in maintaining plasma cholesterol homeostasis, and LDLR dysfunction leads to familial hypercholesterolemia (FH), characterized by elevated LDL levels and premature cardiovascular disease. Beyond its well-established role in peripheral cholesterol metabolism, LDLR has emerged as an important player in Alzheimer's disease and cerebrovascular pathology, influencing [amyloid-beta](/proteins/amyloid-beta) (Aβ) clearance and cerebral amyloid angiopathy (CAA).[@supsup2009]

Gene Structure

The LDLR gene consists of:

• 18 exons spanning approximately 45 kb on chromosome 19p13.2
• Alternative splicing produces multiple isoforms
• Strong transcriptional regulation by sterol regulatory element-binding proteins (SREBPs)

Promoter Structure

• Contains SRE (sterol regulatory element) for cholesterol-responsive regulation
• Multiple transcription factor binding sites
• Responsive to statins via SREBP activation

Protein Structure

The LDLR is a modular transmembrane protein with distinct domains:

Extracellular Domain (1-699)

Transmembrane Domain (700-722)

• Single-pass transmembrane helix
• Anchors receptor in plasma membrane

Cytoplasmic Tail (723-860)

• NPxY motif: Essential for clathrin-mediated endocytosis
• FDNPVY motif: Required for internalization
• Ser/Thr phosphorylation sites: Regulate trafficking

Normal Function

Cholesterol Homeostasis

LDLR mediates cellular uptake of LDL particles:[@supsup2009a]

Regulatory Mechanisms

• Negative feedback: High intracellular cholesterol reduces LDLR expression
• Statin effect: Statins upregulate LDLR via SREBP activation
• PCSK9 regulation: PCSK9 binding targets LDLR for degradation

Expression Pattern

Peripheral Tissues

• Liver: Highest expression - primary LDL clearance organ
• Adrenal glands: Cholesterol for steroid synthesis
• Ovaries: Cholesterol for steroid hormone production
• Intestine: Minor contribution to cholesterol absorption

Brain Expression

In the central nervous system, LDLR is expressed in:[@supsup2012]

• [Neurons](/entities/neurons): Pyramidal neurons in [cortex](/brain-regions/cortex) and [hippocampus](/brain-regions/hippocampus)
• [Astrocytes](/entities/astrocytes): Regulate brain cholesterol homeostasis
• [Microglia](/entities/microglia): Cholesterol clearance in inflammatory states
• Brain vasculature: Endothelial cells of the [BBB](/entities/blood-brain-barrier)

Disease Associations

Familial Hypercholesterolemia (FH)

Heterozygous FH (1 in 500) and homozygous FH (1 in 1 million):[@supsup2014]

• Caused by LDLR mutations (over 2000 identified)
• Types:
• FH type I: Receptor absent (null)
• FH type II: Receptor defective binding
• FH type III: Recycling defect
• FH type IV: Internalization defect
• FH type V: Transport defect

• Elevated LDL-C ( > 330 mg/dL heterozygous)
• Tendon xanthomas
• Premature coronary artery disease
• Arcus corneae

Alzheimer's Disease

LDLR plays complex roles in AD:[@supsup2016]

• Aβ clearance: LDLR mediates neuronal Aβ uptake and clearance
• Cholesterol-Aβ link: LDLR dysfunction affects brain cholesterol and Aβ metabolism
• Genetic association: LDLR polymorphisms modify AD risk
• Therapeutic target: LDLR modulators may enhance Aβ clearance
• APOE interaction: LDLR regulates APOE lipidation status

Cerebral Amyloid Angiopathy (CAA)

• LDLR dysfunction impairs Aβ clearance from cerebral vessels
• Contributes to CAA development
• Increases hemorrhagic stroke risk

Stroke

• LDLR variants associated with stroke risk
• Atherosclerosis of cerebral vessels
• Interaction with other vascular risk factors

Molecular Mechanisms

LDLR in Aβ Metabolism

| Process | Role | Relevance |
|---------|------|-----------|
| Cellular uptake | LDLR binds and internalizes Aβ | Clearance |
| Lysosomal degradation | Aβ delivered to lysosomes | Processing |
| ApoE interaction | LDLR binds ApoE-Aβ complexes | AD pathology |
| Perivascular drainage | LDLR in perivascular Aβ clearance | CAA |

Signaling Pathways

• SREBP2: Master regulator of LDLR transcription
• PCSK9: Induces LDLR degradation
• IDOL: Induces LDLR degradation
• ERK/MAPK: Regulates LDLR function

Therapeutic Implications

Current Therapies

| Treatment | Mechanism | Effect |
|-----------|-----------|--------|
| Statins | Inhibit HMG-CoA, activate SREBP | ↑ LDLR expression |
| Ezetimibe | Block intestinal cholesterol absorption | ↑ LDLR indirectly |
| PCSK9 inhibitors | Prevent LDLR degradation | ↑ LDLR on surface |
| Bile acid sequestrants | Bind bile acids | ↑ LDLR expression |
| LDL apheresis | Mechanical LDL removal | Direct clearance |

AD Therapeutic Strategies

• LDLR agonists: Enhance Aβ clearance
• Gene therapy: AAV-LDLR delivery to brain
• Small molecule modulators: Target LDLR trafficking
• Combination approaches: With anti-amyloid antibodies

Emerging Approaches

• CRISPR-Cas9: Correct LDLR mutations in hepatocytes
• mRNA therapeutics: Deliver functional LDLR mRNA
• Brain-penetrant modulators: Target CNS LDLR

Animal Models

• LDLR knockout mice: Hypercholesterolemia, atherosclerosis
• Humanized LDLR: Expressing human LDLR in mice
• Transgenic AD models: LDLR manipulation in amyloid models

See Also

• [LDLR Protein](/proteins/ldlr-protein)
• [APOE Gene](/proteins/apoe) - Major AD risk gene, interacts with LDLR
• [PCSK9 Gene](/proteins/pcsk9-protein) - LDLR regulator
• [Familial Hypercholesterolemia](/diseases/familial-hypercholesterolemia)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Lipid Metabolism in Neurodegeneration](/mechanisms/lipid-metabolism)mechanisms/sphingolipid-metabolism)
• [Cerebral Amyloid Angiopathy](/diseases/cerebral-amyloid-angiopathy)
• [Atherosclerosis](/diseases/atherosclerosis)

External Links

• [NCBI Gene: LDLR](https://www.ncbi.nlm.nih.gov/gene/3955)
• [UniProt: LDLR](https://www.uniprot.org/uniprot/P01130)
• [OMIM: LDLR](https://www.omim.org/entry/143890)
• [GeneCards: LDLR](https://www.genecards.org/cgi-bin/carddisp.pl?gene=LDLR)
• [LDLR Database](http://www.ucl.ac.uk/ldlr/)

Background

The study of Ldlr Gene has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

References

PMID: 19240241(https://pubmed.ncbi.nlm.nih.gov/19240241/) PMID: 19141427(https://pubmed.ncbi.nlm.nih.gov/19141427/) PMID: 22903161(https://pubmed.ncbi.nlm.nih.gov/22903161/) PMID: 25099581(https://pubmed.ncbi.nlm.nih.gov/25099581/) PMID: 27589516(https://pubmed.ncbi.nlm.nih.gov/27589516/) PMID: 17416464(https://pubmed.ncbi.nlm.nih.gov/17416464/)

Related Hypotheses

From the [SciDEX Exchange](/exchange) — scored by multi-agent debate

• [Membrane Cholesterol Gradient Modulators](/hypothesis/h-9d29bfe5) — <span style="color:#ffd54f;font-weight:600">0.57</span> · Target: ABCA1/LDLR/SREBF2
• [Engineered Apolipoprotein E4-Neutralizing Shuttle Peptides](/hypothesis/h-b948c32c) — <span style="color:#ffd54f;font-weight:600">0.49</span> · Target: APOE, LRP1, LDLR

Pathway Diagram

The following diagram shows the key molecular relationships involving LDLR Gene discovered through SciDEX knowledge graph analysis: