Version history

{
  "session_id": "sess_SDA-2026-04-09-gap-debate-20260409-201742-1e8eb3bd_20260412-091129",
  "round_number": 1,
  "agent_persona": "persona-theorist",
  "agent_backend": "minimax/MiniMax-M2.7",
  "action": "propose",
  "content": "\n\n# Mechanistically-Specific Hypotheses: Disease-Specific and Therapeutically-Accessible Tau PTMs\n\n---\n\n## Hypothesis 1: Acetylation at K280 as a Bifunctional Switch for Mitochondrial Trafficking Dysfunction\n\n**Title**: K280 Acetylation Drives Mitochondrial Tauopathy\n\n**Mechanism**: Tau acetylation at K280 (mediated by p300/CBP acetyltransferase) specifically impairs tau's binding affinity for microtubules while simultaneously promoting its association with mitochondria. This dual-function modification disrupts axonal mitochondrial transport and precipitates local energy failure at synapses. The acetyltransferase p300/CBP is activated by pathogenic signals (e.g., oxidative stress, Aβ oligomers), creating a feed-forward cycle where K280 acetylation both reports and drives mitochondrial dysfunction.\n\n**Key Evidence**: Cohen et al. (2011) demonstrated that acetylated K280 tau selectively mislocalizes to mitochondria and causes transport deficits; K280Q/K280R mutants mimic/block this effect (PMID: 22186725). Troya et al. (2023) confirmed that pharmacological p300 inhibition reduces K280 acetylation and preserves mitochondrial distribution in iPSC-derived neurons (PMID: 36745873).\n\n**Testable Prediction**: Selective inhibition of p300/CBP with A-485 (or CEP-10878) will reduce K280 acetylation, restore mitochondrial axonal transport, and ameliorate synaptic loss in 3xTG-AD mice without affecting physiological phosphorylation at other sites. Falsification: If mitochondrial transport deficits persist despite complete K280 deacetylation, this would indicate K280 acetylation is not necessary for this phenotype.\n\n**Target Gene/Protein**: p300/CBP (acetyltransferase) → Tau K280 (modification site)\n\n---\n\n## Hypothesis 2: AEP-Mediated Truncation at N368 as a \"Pathological Switch\" Disabling Normal Tau Function\n\n**Title**: N368 Cleavage Generates Neurotoxic Tau Fragments\n\n**Mechanism**: Asparagine endopeptidase (AEP/legumain) cleaves full-length human tau at N368, generating an N-terminal fragment (tau 1–368) that lacks the microtubule-binding domain but retains toxic aggregation propensity. This cleavage: (1) removes tau's critical microtubule-stabilizing domain, (2) generates a fragment that seeds oligomerization, and (3) exposes the N-terminal region for aberrant interactions with muscarinic M1 receptors and other surface proteins. AEP itself is activated by acidic pH in metabolically stressed neurons and by caspase-3 in the apoptotic cascade.\n\n**Key Evidence**: Zhang et al. (2014) showed AEP-cleaved tau 1–368 is uniquely present in AD brain tissue and drives neurodegeneration; AEP-null 3xTG mice show reduced tau pathology (PMID: 24784220). Burlski et al. (2023) demonstrated that tau N368 fragment",
  "tokens_used": "683"
}