ID: h-bc161bb779
Hypothesis
OPTN/TBK1 mutations create selective vulnerability by blocking PINK1-Parkin-independent mitophagy in lower motor neurons
OPTN/TBK1 mutations create selective vulnerability by blocking PINK1-Parkin-independent mitophagy in lower motor neurons starts from the claim that modulating OPTN within the disease context of neurodegeneration can redirect a disease-re.
EvidencePending (0%)📖 0 cit🗣 1 debates✓ 3 support✗ 3 oppose
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🧪 Overview
Mechanistic Overview
OPTN/TBK1 mutations create selective vulnerability by blocking PINK1-Parkin-independent mitophagy in lower motor neurons starts from the claim that modulating OPTN within the disease context of neurodegeneration can redirect a disease-relevant process. The original description reads: "## Mechanistic Overview OPTN/TBK1 mutations create selective vulnerability by blocking PINK1-Parkin-independent mitophagy in lower motor neurons starts from the claim that modulating OPTN within the disease context of neurodegeneration can redirect a disease-relevant process. The original description reads: "## Mechanistic Overview OPTN/TBK1 mutations create selective vulnerability by blocking PINK1-Parkin-independent mitophagy in lower motor neurons starts from the claim that OPTN serves as the primary autophagy receptor for damaged mitochondria in neurons via its LC3-interacting region. TBK1 phosphorylates OPTN at S177, enhancing its affinity for ubiquitinated mitochondrial proteins. ALS-causing mutations impair this phospho-regulation, causing accumulation of dysfunctional mitochondria specifically in motor neurons with high energy demands....
🧬 Mechanism
🧬 Curated Mechanism Pathway
Curated pathway from expert analysis
flowchart TD
A["OPTN<br/>Hypothesis Target"]
B["Autophagy<br/>Cited Mechanism"]
C["Cellular Response<br/>Stress or Clearance Change"]
D["Neural Circuit Effect<br/>Synapse/Glia Vulnerability"]
E["ALS<br/>Disease-Relevant Outcome"]
A --> B
B --> C
C --> D
D --> E
style A fill:#1a237e,stroke:#4fc3f7,color:#4fc3f7
style B fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9a
style E fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9a⚖️ Evidence
⚖️ Evidence Matrix3 supports3 contradicts
📖 Linked Papers
No linked papers recorded for this hypothesis yet.
🏥 Translation
🧬 3D Protein Structure — OPTN
No curated PDB or AlphaFold mapping for OPTN yet. Search RCSB →
🧠 GTEx v10 Brain ExpressionJSON
Median TPM across 13 brain regions for OPTN from GTEx v10.
💉 Clinical Trials
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 OPTN.
Run python3 scripts/backfill_hypothesis_depmap.py to populate.
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🔮 Predictions
🔎 Predictions vs Observations12 predictions · 0 with recorded observations
| Prediction | Predicted | Observed | Status | Conf |
|---|---|---|---|---|
| IF ALS-associated OPTN mutations (S177A phospho-deficient) are introduced into motor neurons, THEN mitochondria will accumulate morphological and functional defects (enlarged size, loss of membrane po | Phospho-deficient OPTN motor neurons will show ≥40% increase in mitochondrial area, ≥30% reduction in TMRE fluorescence, and ≥25% decrease in spare respiratory | — no observation — | pending | 0.78 |
| IF TBK1 activity is pharmacologically enhanced (TBK1 agonist) in motor neurons harboring OPTN ALS mutations, THEN OPTN S177 phosphorylation levels and mitophagic flux will increase proportionally with | TBK1 agonist treatment will produce dose-dependent increase in p-OPTN S177 (≥3-fold at 10μM), ≥50% reduction in mitochondrial:cytosolic ratio of oxidatively dam | — no observation — | pending | 0.69 |
| IF phospho-mimetic OPTN (S177D) is expressed in motor neurons carrying ALS-linked OPTN mutations, THEN mitochondrial protein turnover rates and cellular respiration will normalize to wild-type levels | Motor neurons expressing S177D-OPTN will show ≥70% rescue of mitochondrial membrane potential and ≥60% reduction in mt-Keima signal in acidic compartments, whil | — no observation — | pending | 0.72 |
| IF motor neurons derived from OPTN-ALS patient iPSCs are treated with mitochondrial stressors (CCCP), THEN time-dependent accumulation of dysfunctional mitochondria (measured by mt-Keima red/green rat | Patient motor neurons will show significantly impaired clearance of damaged mitochondria (>50% reduction in mitophagy flux) and increased mitochondrial ROS prod | — no observation — | pending | 0.78 |
| IF phospho-deficient OPTN (S177A) is expressed in OPTN knockout motor neurons, THEN mitochondrial dysfunction will be observed similar to OPTN-ALS mutants, using rescue experiments in mouse ESC-derive | OPTN-S177A rescue will fail to restore normal mitochondrial morphology (reduced aspect ratio, increased fragmentation) and function (reduced ATP production, inc | — no observation — | pending | 0.72 |
| IF TBK1 activity is pharmacologically inhibited in wildtype motor neurons, THEN mitochondrial dysfunction will phenocopy OPTN-ALS mutations, using pharmacological TBK1 inhibition in primary mouse moto | TBK1 inhibition (BX-795 or MRT67307 at 1 μM) will reduce OPTN S177 phosphorylation by >60% and cause accumulation of ubiquitinated mitochondrial proteins, impai | — no observation — | pending | 0.75 |
| IF OPTN phospho-deficient mutants (S177A) are expressed in iPSC-derived motor neurons, THEN mitochondrial clearance rates will decrease by >40% following CCCP-induced depolarization compared to wild-t | Reduced colocalization of mitochondria with autophagosomes (mito-QC signal loss), increased mitochondrial mass (TOMM20+ area), and elevated mtDNA damage markers | — no observation — | pending | 0.82 |
| IF PINK1/Parkin are genetically ablated in OPTN-mutant motor neurons, THEN mitochondrial dysfunction severity will increase significantly beyond OPTN mutation alone, demonstrating non-redundant pathwa | Synergistic reduction in ATP production (>60% decrease vs ~30% for OPTN alone), OCR Reserve Capacity <15% of baseline, and mtROS accumulation (MitoSOX mean fluo | — no observation — | pending | 0.78 |
| IF motor neurons are subjected to repetitive calcium influx stimulation (40 Hz, 2h), THEN OPTN/TBK1 mutant motor neurons will exhibit accelerated mitochondrial calcium overload, membrane potential los | Earlier onset of mitochondrial depolarization (JC-1 ratio shift), increased cytosolic calcium (GCaMP6f), fragmented mitochondrial networks (Mito-DsRed), and cel | — no observation — | pending | 0.74 |
| IF ALS-associated OPTN mutations (E478G or Q398X) that disrupt TBK1 phosphorylation at S177 are expressed in iPSC-derived motor neurons, THEN the clearance of damaged mitochondria following CCCP-induc | Mutant OPTN motor neurons will retain 50% more mitochondrial signal at 24h post-damage, accumulate Tom20+ puncta, and show decreased colocalization of OPTN with | — no observation — | pending | 0.75 |
| IF mitochondrial stress is induced via complex I inhibition (rotenone, 100 nM for 6h) in motor neurons versus cortical neurons derived from the same OPTN E478G patient iPSC line, THEN motor neurons wi | Motor neurons will exhibit significantly greater mtDNA copy number increase, reduced mitochondrial fission protein Drp1 activation, and accumulate dysfunctional | — no observation — | pending | 0.65 |
| IF PINK1/Parkin pathway is genetically ablated (PRKN knockout) in motor neurons with OPTN E478G mutation, THEN mitochondrial dysfunction markers (mtDNA depletion, ROS accumulation, ATP decline) will r | Double knockout (OPTNmut + PRKN-/-) will show additive accumulation of damaged mitochondria, with no statistically significant rescue compared to OPTNmut alone, | — no observation — | pending | 0.70 |
🔮 Falsifiable Predictions (10)
pendingconf 82%
IF OPTN phospho-deficient mutants (S177A) are expressed in iPSC-derived motor neurons, THEN mitochondrial clearance rates will decrease by >40% following CCCP-induced depolarization compared to wild-type OPTN, while PINK1/Parkin pathway components remain functionally intact within 72 hours using liv
Predicted outcome: Reduced colocalization of mitochondria with autophagosomes (mito-QC signal loss), increased mitochondrial mass (TOMM20+ area), and elevated mtDNA dama
Falsification: If OPTN-S177A motor neurons show normal mitochondrial clearance rates equivalent to wild-type controls, OR if PINK1/Parkin components show compensatory activation (p-S65 ubiquitin accumulation), the h
pendingconf 78%
IF ALS-associated OPTN mutations (S177A phospho-deficient) are introduced into motor neurons, THEN mitochondria will accumulate morphological and functional defects (enlarged size, loss of membrane potential, reduced oxygen consumption) compared to wild-type OPTN-expressing controls within 14-21 day
Predicted outcome: Phospho-deficient OPTN motor neurons will show ≥40% increase in mitochondrial area, ≥30% reduction in TMRE fluorescence, and ≥25% decrease in spare re
Falsification: If phospho-deficient OPTN motor neurons exhibit normal mitochondrial morphology, function, and clearance rates identical to wild-type controls (within statistical noise), the hypothesis is falsified
pendingconf 78%
IF motor neurons derived from OPTN-ALS patient iPSCs are treated with mitochondrial stressors (CCCP), THEN time-dependent accumulation of dysfunctional mitochondria (measured by mt-Keima red/green ratio, mitochondrial membrane potential decline) will occur within 7 days compared to isogenic controls
Predicted outcome: Patient motor neurons will show significantly impaired clearance of damaged mitochondria (>50% reduction in mitophagy flux) and increased mitochondria
Falsification: If PINK1/Parkin-dependent mitophagy compensates and mitochondrial clearance rates are equivalent between patient and control motor neurons, or if mitochondrial dysfunction is equally severe in non-mot
pendingconf 78%
IF PINK1/Parkin are genetically ablated in OPTN-mutant motor neurons, THEN mitochondrial dysfunction severity will increase significantly beyond OPTN mutation alone, demonstrating non-redundant pathways within 14 days using XF96 extracellular flux analysis.
Predicted outcome: Synergistic reduction in ATP production (>60% decrease vs ~30% for OPTN alone), OCR Reserve Capacity <15% of baseline, and mtROS accumulation (MitoSOX
Falsification: If OPTN-mutant;PINK1/Parkin-null neurons show identical mitochondrial function to OPTN-mutant neurons with intact PINK1/Parkin, this would indicate OPTN mutations fully activate compensatory PINK1/Par
pendingconf 75%
IF TBK1 activity is pharmacologically inhibited in wildtype motor neurons, THEN mitochondrial dysfunction will phenocopy OPTN-ALS mutations, using pharmacological TBK1 inhibition in primary mouse motor neurons.
Predicted outcome: TBK1 inhibition (BX-795 or MRT67307 at 1 μM) will reduce OPTN S177 phosphorylation by >60% and cause accumulation of ubiquitinated mitochondrial prote
Falsification: If TBK1 inhibition does not impair mitophagy or mitochondrial function in motor neurons, or if other TBK1 substrates compensate (e.g., p62/SQSTM1), this would indicate redundant pathways and challenge
pendingconf 75%
IF ALS-associated OPTN mutations (E478G or Q398X) that disrupt TBK1 phosphorylation at S177 are expressed in iPSC-derived motor neurons, THEN the clearance of damaged mitochondria following CCCP-induced depolarization will be significantly impaired (≥50% reduction in mitochondrial turnover rate) com
Predicted outcome: Mutant OPTN motor neurons will retain 50% more mitochondrial signal at 24h post-damage, accumulate Tom20+ puncta, and show decreased colocalization of
Falsification: If OPTN mutant lines clear damaged mitochondria at rates statistically indistinguishable from wild-type controls (p>0.05), or if PINK1/Parkin pathway components compensate by increasing recruitment to
pendingconf 74%
IF motor neurons are subjected to repetitive calcium influx stimulation (40 Hz, 2h), THEN OPTN/TBK1 mutant motor neurons will exhibit accelerated mitochondrial calcium overload, membrane potential loss, and fragmented morphology at significantly earlier timepoints (6h vs 24h) compared to cortical ne
Predicted outcome: Earlier onset of mitochondrial depolarization (JC-1 ratio shift), increased cytosolic calcium (GCaMP6f), fragmented mitochondrial networks (Mito-DsRed
Falsification: If cortical neurons show equal or greater mitochondrial dysfunction compared to motor neurons under identical stimulation conditions, or if OPTN-mutant motor neurons maintain normal mitochondrial func
pendingconf 72%
IF phospho-mimetic OPTN (S177D) is expressed in motor neurons carrying ALS-linked OPTN mutations, THEN mitochondrial protein turnover rates and cellular respiration will normalize to wild-type levels specifically in motor neurons but NOT in cortical neurons using isogenic iPSC-derived neuronal cultu
Predicted outcome: Motor neurons expressing S177D-OPTN will show ≥70% rescue of mitochondrial membrane potential and ≥60% reduction in mt-Keima signal in acidic compartm
Falsification: If phospho-mimetic OPTN rescues mitochondrial function equally in motor neurons AND cortical/sensory neurons, motor neuron specificity is disproven. If rescue is partial or absent in motor neurons, th
pendingconf 72%
IF phospho-deficient OPTN (S177A) is expressed in OPTN knockout motor neurons, THEN mitochondrial dysfunction will be observed similar to OPTN-ALS mutants, using rescue experiments in mouse ESC-derived motor neurons.
Predicted outcome: OPTN-S177A rescue will fail to restore normal mitochondrial morphology (reduced aspect ratio, increased fragmentation) and function (reduced ATP produ
Falsification: If OPTN-S177A fully rescues mitochondrial function or if phospho-mimetic S177D fails to improve the phenotype, the hypothesis that S177 phosphorylation is critical for OPTN function in motor neuron mi
pendingconf 70%
IF PINK1/Parkin pathway is genetically ablated (PRKN knockout) in motor neurons with OPTN E478G mutation, THEN mitochondrial dysfunction markers (mtDNA depletion, ROS accumulation, ATP decline) will remain significantly elevated compared to either single mutant alone, demonstrating OPTN/TBK1 operate
Predicted outcome: Double knockout (OPTNmut + PRKN-/-) will show additive accumulation of damaged mitochondria, with no statistically significant rescue compared to OPTN
Falsification: If PRKN knockout completely rescues the mitochondrial dysfunction phenotype in OPTN mutant motor neurons, or if OPTN mutants fail to show any mitochondrial phenotypes in PRKN-/- background, then OPTN/
📖 References (4)
- Whole-exome-sequencing-based discovery of human FADD deficiency.["Bolze et al.. American journal of human genetics (2010)
- GATA2 mutations in patients with acute myeloid leukemia-paired samples analyses show that the mutation is unstable during disease evolution.["Hou et al.. Annals of hematology (2015)
- Pb(II) Induces Scramblase Activation and Ceramide-Domain Generation in Red Blood Cells.["Ahyayauch et al.. Scientific reports (2018)
- Significance of prolonged PR interval in infections.["Mishra et al.. QJM : monthly journal of the Association of Physicians (2020)
▸Metadatasource: v1_phase_c_backfill · origin_type: debate_synthesizer
| source | v1_phase_c_backfill |
| origin_type | debate_synthesizer |
| _schema_version | 1 |
📊 Evidence Profile
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