Does SORT1 variation affect hepatic lipoprotein handling and raise atherogenic lipids?

The 1p13 locus is one of the most strongly associated genetic regions with coronary artery disease and lipid metabolism. Genetic variations in this locus, specifically within the SORT1 gene, directly dictate hepatic lipoprotein trafficking and influence circulating atherogenic lipid levels.

Mechanistic pathways of hepatic sortilin

• Transcriptional upregulation: The noncoding variant rs12740374 acts as a liver-specific expression quantitative trait locus (eQTL). The minor allele of this variant creates a novel CCAAT/enhancer-binding protein (C/EBP) transcription factor binding site, which drives elevated transcriptional expression of sortilin (SORT1) in hepatocytes.
• Intracellular routing: Sortilin functions as a sorting receptor primarily localized within the Golgi apparatus and the endolysosomal system. It binds directly to intracellular apolipoprotein B-100 (ApoB)—the essential structural protein for very-low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) particles.
• Lysosomal degradation and clearance: Elevated hepatic sortilin redirects apoB-containing VLDL precursors away from the secretory pathway in the Golgi, targeting them for autophagic and presecretory lysosomal degradation. Furthermore, sortilin expressed at the plasma membrane binds extracellular LDL, facilitating its internalization and clearance.

Impact on atherogenic lipid profiles

• Secretory dynamics: Alterations in these trafficking pathways directly govern circulating lipid concentrations. When hepatic sortilin expression or activity is reduced, presecretory lysosomal degradation decreases, which enhances VLDL secretion and elevates circulating levels of LDL cholesterol (LDL-C), ApoB, LDL particle count (LDL-P), and non-HDL-C.
• Clinical associations: Population-based genetic cohort studies consistently show that functional variations in this sorting pathway modify circulating concentrations of these atherogenic lipoproteins, directly influencing systemic lipid profiles and cardiovascular risk.

Bottom line

• Genetically driven changes in hepatic SORT1 expression alter the intracellular routing and lysosomal degradation of ApoB, directly regulating circulating levels of LDL-C, ApoB, LDL-P, and non-HDL-C.