This hypothesis proposes that NAD+ precursor supplementation can restore neuronal ketone body utilization by activating SIRT1-mediated transcriptional upregulation of MCT1 (monocarboxylate transporter 1). In neurodegenerative conditions, chronic PARP1 activation depletes cellular NAD+ pools, leading to reduced SIRT1 activity and subsequent downregulation of MCT1 expression. This creates a metabolic bottleneck where neurons cannot efficiently import ketone bodies as an alternative fuel source, exacerbating energy deficits. By supplementing with NAD+ precursors (such as nicotinamide riboside or nicotinamide mononucleotide), cellular NAD+ levels are restored, reactivating SIRT1 deacetylase activity. Active SIRT1 then deacetylates key transcription factors and chromatin proteins at the SLC16A1 promoter region, enhancing MCT1 gene expression. Increased MCT1 protein levels restore the neuron's capacity to import β-hydroxybutyrate and acetoacetate, providing crucial ketone-derived acetyl-CoA for mitochondrial ATP production. This mechanism bypasses glucose-dependent energy pathways that may be compromised in neurodegeneration.
...Curated pathway from expert analysis
flowchart TD
A["DNA Single-Strand Breaks<br/>Oxidative Stress in AD"]
B["PARP1 Hyperactivation<br/>PAR Polymer Synthesis"]
C["NAD+ Depletion<br/>40-60% Loss in AD"]
D["SIRT1 Inactivation<br/>Deacetylase Impaired"]
E["PGC1alpha Inactivation<br/>Mitochondrial Biogenesis Loss"]
F["Energy Failure<br/>Neuronal Death"]
G["PARP1 Inhibitor<br/>Olaparib/Veliparib"]
A --> B
B --> C
C --> D
D --> E
E --> F
G -.->|"blocks"| B
style A fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9a
style F fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9a
style G fill:#1a237e,stroke:#4fc3f7,color:#4fc3f7No linked papers recorded for this hypothesis yet.
No curated PDB or AlphaFold mapping for SLC16A1 yet. Search RCSB →
Median TPM across 13 brain regions for SLC16A1 (MCT1) from GTEx v10.
No clinical trials data linked to this hypothesis yet.
No curated ClinVar variants loaded for this hypothesis.
Run scripts/backfill_clinvar_variants.py to fetch P/LP/VUS variants.
No DepMap CRISPR Chronos data found for SLC16A1 (MCT1).
Run python3 scripts/backfill_hypothesis_depmap.py to populate.
| Prediction | Predicted | Observed | Status | Conf |
|---|---|---|---|---|
| IF human iPSC-derived cortical neurons are pretreated with nicotinamide mononucleotide (NMN, 100 μM) for 24 hours under metabolic stress (2 μM oligomycin to impair oxidative phosphorylation) AND then | Increased initial uptake rate of 14C-β-hydroxybutyrate (≥40% increase in disintegrations per minute per mg protein at 5-minute timepoint); correlated with eleva | — no observation — | pending | 0.58 |
| IF primary mouse cortical neurons are cultured under chronic PARP1 activation (using 10 μM 3-aminobenzamide as a sub-lethal pharmacological PARP1 stimulus) for 72 hours AND then treated with nicotinam | MCT1 mRNA fold change ≥1.5 (ΔΔCt method) and corresponding MCT1 protein increase by ≥40% (Western blot densitometry) compared to vehicle control; cellular NAD+/ | — no observation — | pending | 0.65 |