LDL Cholesterol Metabolism Pathway

Canonical source: hsa04979

Pathway Overview

The LDL cholesterol pathway governs uptake and clearance of low-density lipoprotein particles from circulation. Hepatocytes synthesize LDL receptors (LDLR) that bind apolipoprotein B (APOB) on LDL particles; internalization delivers cholesterol for regulatory feedback. PCSK9 binds LDLR at the cell surface and targets it for lysosomal degradation, reducing LDL clearance. APOE mediates remnant lipoprotein clearance. Gain-of-function PCSK9 or loss-of-function LDLR variants elevate LDL-C and coronary artery disease risk. Statins upregulate LDLR; PCSK9 inhibitors are therapeutic. Environmental factors including diet quality (saturated fat), smoking, and obesity amplify genetic susceptibility by promoting inflammation and endothelial dysfunction.

Environmental Triggers

Exposure	Trigger type
diet-quality	Saturated fat elevates LDL-C; fiber and phytosterols reduce absorption
tobacco	Oxidative stress and endothelial dysfunction amplify atherogenic effects
obesity-exposure	Dyslipidemia and insulin resistance perturb cholesterol homeostasis

Genetic Modulation Points

Key genes

ldlr— Cell surface receptor; binds and internalizes LDL particles; central to cholesterol homeostasis
pcsk9— Proprotein convertase; degrades LDLR; gain-of-function increases LDL-C
apoe— Mediates remnant lipoprotein clearance; isoforms influence LDL levels and CAD risk

Regulatory checkpoints

LDLR synthesis— ldlrTherapeutic target
PCSK9-LDLR binding— pcsk9Therapeutic target

Tissue Specificity

liver— Primary site of LDLR and PCSK9 expression; hepatic clearance

adrenal gland— Cholesterol for steroid synthesis

Disease Relevance

Linked diseases

coronary-artery-disease— Core pathogenic pathway; elevated LDL-C drives atherosclerosis
hypertension— Shared risk factors; dyslipidemia accompanies metabolic syndrome

Linked exposures

diet-quality— Dietary lipids directly affect LDL levels; Mediterranean diet buffers risk
obesity-exposure— Obesity drives dyslipidemia and amplifies genetic susceptibility

Pathway Diagram

Pathway diagram placeholder. A visual representation of this pathway will be integrated when available.

Evidence Nodes

Evidence for this pathway is derived from:

3 environmental trigger(s)
3 key gene(s)
2 linked disease(s)
2 linked exposure(s)

References

1.Horton JD, et al. (2009). LDL cholesterol metabolism and coronary artery disease. Journal of Clinical Investigation. doi:10.1172/JCI38630
2.Cohen JC, et al. (2006). PCSK9 and LDL cholesterol: therapeutic targeting. Nature Genetics. doi:10.1038/ng1836
3.Ordovas JM, et al. (2018). Gene-environment interaction in dyslipidemia. Circulation Research. doi:10.1161/CIRCRESAHA.118.311366
4.Mahley RW, Rall SC Jr (2000). APOE and cardiovascular disease. Annual Review of Genomics and Human Genetics. doi:10.1146/annurev.genom.1.1.507