Cholesterol Metabolism Decoded: From Cell Biology to Next-Gen Therapies
A sweeping 2025 review maps cholesterol's molecular machinery, disease links, and emerging treatments—from CRISPR gene editing to microbiome interventions.
Summary
This comprehensive 2025 review from West China Hospital dissects how cholesterol is synthesized, absorbed, converted, and cleared, and how dysregulation drives atherosclerosis, fatty liver disease, neurodegeneration, and cancer. It traces the full biosynthetic cascade—from acetyl-CoA through the Bloch and Kandutsch-Russell pathways—alongside intestinal absorption via NPC1L1, bile acid production, steroid hormone synthesis, and lipoprotein-mediated clearance via LDLR and HDL. The authors catalog how disruptions in these pathways cause disease, then survey therapeutic advances: statins, PCSK9 inhibitors, siRNA therapies like inclisiran, CRISPR-based editing (VERVE-101), and novel targets including ANGPTL3 and Lp(a). Natural agents such as berberine and probiotics are also assessed. The review frames a shift toward personalized, multi-target lipid management in the genomic medicine era.
Detailed Summary
Cholesterol is far more than a dietary villain—it is an essential structural lipid, signaling molecule, and biosynthetic precursor. This 2025 narrative review from Sichuan University provides one of the most thorough integrations of cholesterol biology and therapeutics published to date, synthesizing decades of biochemistry with cutting-edge clinical developments.
The review opens by mapping the two de novo synthesis pathways. The Bloch pathway (>90% of output) and the Kandutsch-Russell pathway share early steps converting acetyl-CoA to lanosterol via the rate-limiting enzymes HMGCR and SQLE, then diverge. The K-R pathway, dominant under hypoxia or UV stress in skin and gonads, bypasses oxygen-dependent steps via 7-dehydrocholesterol reductase (DHCR7). Intestinal absorption centers on NPC1L1, which uses both clathrin-mediated endocytosis and a direct transmembrane tunnel mechanism revealed by cryo-EM. ABCG5/G8 heterodimers counter-regulate absorption by pumping excess cholesterol back into the intestinal lumen.
Cholesterol's metabolic fates are diverse: CYP7A1 drives the classic bile acid synthesis pathway (>90% of hepatic output), while CYP27A1/CYP7B1 support an alternative route during metabolic stress. Sequential UV-driven and enzymatic hydroxylation steps produce active vitamin D3. Tissue-specific steroidogenesis in the adrenal cortex generates mineralocorticoids, glucocorticoids, and sex hormones. Cholesterol also forms cholesteryl glucosides that modulate membrane fluidity and may participate in innate immune signaling. Clearance occurs via HDL-mediated reverse cholesterol transport (ABCA1/ABCG1 efflux → LCAT esterification → SR-BI or CETP-mediated hepatic delivery) and LDL-LDLR endocytosis regulated by PCSK9-driven receptor degradation.
Dysregulation of these modules underlies a spectrum of diseases. In atherosclerosis, LDL oxidation and macrophage foam cell formation drive plaque development; in MAFLD, impaired hepatic cholesterol efflux and de novo lipogenesis promote steatosis and fibrosis. Neurodegenerative diseases including Alzheimer's involve disrupted brain cholesterol homeostasis and ApoE4-mediated transport defects. In cancer, cholesterol supports membrane raft assembly for oncogenic signaling and tumor cell proliferation, making HMGCR and SQLE emerging oncology targets.
Therapeutically, the review charts a clear evolution. Statins (HMGCR inhibitors) and ezetimibe (NPC1L1 blocker) remain first-line, complemented by PCSK9 inhibitors (evolocumab, alirocumab). RNA-based therapies mark a paradigm shift: inclisiran, a siRNA targeting hepatic PCSK9 mRNA, achieves durable LDL-C reduction with twice-yearly dosing. VERVE-101 applies adenine base editing via CRISPR to permanently silence PCSK9 in vivo. ANGPTL3 inhibitors (evinacumab) and antisense oligonucleotides targeting Lp(a) address residual cardiovascular risk. The authors also highlight berberine's pleiotropic lipid-lowering effects and gut microbiome interventions as accessible adjuncts. The conclusion advocates a precision medicine framework combining genomic profiling, multi-target regimens, and lifestyle-directed approaches.
Key Findings
- HMGCR and SQLE are dual rate-limiting enzymes in cholesterol synthesis, both validated as therapeutic targets.
- NPC1L1 uses two distinct uptake mechanisms: clathrin endocytosis and a cryo-EM-confirmed transmembrane tunnel.
- PCSK9 enhances LDLR degradation 150-fold at endosomal pH, explaining its potency as a therapeutic target.
- CRISPR base-editing therapy VERVE-101 permanently silences PCSK9 in vivo, representing a one-time treatment approach.
- Cholesterol dysregulation links atherosclerosis, MAFLD, Alzheimer's disease, and oncogenesis via shared metabolic nodes.
Methodology
This is a comprehensive narrative review drawing on published molecular biology, genetics, clinical trials, and emerging therapeutic data. The authors synthesize mechanistic pathways alongside disease models and therapeutic evidence but do not conduct primary experimental or meta-analytic research. Coverage spans foundational biochemistry through 2024-era clinical developments.
Study Limitations
As a narrative review, the paper does not apply systematic search criteria or meta-analytic weighting, introducing potential selection bias in cited evidence. Many highlighted emerging therapies (VERVE-101, ANGPTL3 inhibitors) have limited long-term safety data, and the microbiome and natural agent sections rely on largely preclinical or small-scale evidence. The review's breadth may sacrifice depth on individual disease mechanisms.
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