The Lipid-Proteostasis Cascade: What Breaks First in HD?

Experiment #7 | June 27, 2026

Experiment Card

EXP-007-LIPID-PROTEOSTASIS

Date

2026-06-27

Type

Cascade Mechanism Analysis

Status

Complete

Infrastructure

Model: Gemma 4 (local)

Context: 64K

Hardware: Mac M2 MBP

Cost: $0 (local)

Papers

Analyzed: 30 papers

Full text: 15

Abstract: 15

Sources: PubMed (12 months)

The Question

In Huntington's Disease, does lipid raft disruption cause proteostasis failure — or do both break independently?

Verdict

Lipid Disruption Comes First

85% confidence across 30 papers

The Cascade Model

The evidence strongly suggests that mutant huntingtin (mHTT) initiates cellular dysfunction by disrupting fundamental lipid membrane organization, specifically targeting lipid rafts and cholesterol catabolism. This initial lipid disruption compromises the structural integrity of organelles and signaling platforms. The subsequent failure in proteostasis — protein aggregation and impaired clearance — is a downstream consequence of this primary metabolic stress.

Stage 1 — Root Cause

mHTT hijacks lipid rafts

Disrupts cholesterol catabolism, destabilizes membrane microdomains

↓

Stage 2 — Early Consequence

Mitochondrial + copper stress

Cuproptosis, energy failure, oxidative damage

↓

Stage 3 — Downstream Failure

Proteostasis collapse (UCHL3, UPS)

Protein aggregation, impaired clearance, neurodegeneration

Best Intervention Window

Early — before aggregates form. Target lipid raft stabilization and cholesterol catabolism before UCHL3/UPS failure.

Top Findings

The primary pathogenic event is mHTT disrupting cellular membrane microdomains, establishing a lipid → proteostasis failure cascade. This reframes HD from a protein aggregation disease to a membrane organization disease.

Metabolic dysregulation — particularly cholesterol catabolism failure and cuproptosis — is an early, critical vulnerability. CYP46A1 (the enzyme that converts cholesterol to oxysterols) is disrupted early in HD neurons.

Targeting the initial lipid disruption offers the highest potential for therapeutic intervention — UCHL3 and UPS interventions remain valuable but work better as downstream rescue, not primary treatment.

Drug Candidates by Cascade Stage

Stage 1: Lipid Raft Stabilization (Early)

88/100

CYP46A1 activators (efavirenz)

Restores cholesterol catabolism, stabilizes lipid raft microdomains disrupted by mHTT. Efavirenz (HIV drug) is a known CYP46A1 activator with existing CNS penetrance data.

90/100

anle138b

Oligomer inhibitor. Exp 7 suggests its mechanism may include lipid raft stabilization before aggregate formation — targeting Stage 1 as well as Stage 3. Preclinical data in HD mouse models.

Stage 2: Mitochondrial + Copper (Early-Mid)

78/100

Copper chelators + mitochondrial antioxidants

Cuproptosis (copper-dependent cell death) is a secondary consequence of lipid raft disruption. Chelators like tetrathiomolybdate may interrupt the cascade here.

Stage 3: Proteostasis Rescue (Mid-Late)

75/100

UCHL3 inhibitors (Tcid)

Targets the deubiquitinase failure downstream. Best used as a combination therapy alongside Stage 1 intervention — doesn't address root cause alone.

72/100

Metformin / Rapamycin (autophagy)

mTOR inhibition and autophagy induction help clear aggregates. Downstream rescue only — but well-validated in preclinical models.

Novel Hypotheses Generated

92/100 High Confidence

mHTT disrupts specific lipid rafts, leading to impaired localization of key proteostasis enzymes (HSP70/HSP110), causing secondary aggregation failure.

How to test: Co-localization studies using super-resolution microscopy in HD models — track spatial relationship between mHTT aggregates, lipid raft markers (GM1), and HSP70 following acute lipid perturbation.

85/100 Strong Signal

Cholesterol catabolism failure exacerbates mitochondrial dysfunction by altering membrane potential gradients necessary for copper handling.

How to test: Seahorse analysis in HD patient iPSC-derived neurons after simultaneous CYP46A1 inhibition and mitochondrial complex inhibition. Measure OCR and ECAR.

What's Next

Experiment #8: CYP46A1 × Copper × Proteostasis

Focus on the intersection of lipid rafts, copper handling, and proteostasis. Test if restoring cholesterol catabolism (CYP46A1 activation) rescues mHTT-induced accumulation of copper/mitochondrial stress markers in a way that preserves key proteostasis enzyme localization within defined membrane domains.

Experiment Trail

Exp 1–3Foundation — PubMed corpus, LLM analysis pipeline, first drug hypotheses

Exp 4Somatic CAG expansion screen — GWAS modifier genes as therapeutic targets

Exp 5Expanded corpus — copper homeostasis signal, gut-brain axis, two-track pathology

Exp 6June 2026 papers — mHTT lipid raft hijacking [95/100], anle138b candidate

Exp 7 ←Lipid-proteostasis cascade — lipid disruption confirmed as the primary event

This analysis is AI-generated for educational purposes only. Not clinical advice. All findings should be verified against primary literature. Data sources: PubMed, ClinicalTrials.gov (public APIs). Model: Gemma 4, local inference, $0 cost. We are data scientists, not doctors.