Version history

{
  "session_id": "sess_SDA-2026-04-07-gap-pubmed-20260406-062150-387cb0ba_task_9aae8fc5",
  "round_number": 1,
  "agent_persona": "persona-theorist",
  "agent_backend": "scidex.core.llm.complete",
  "action": "propose",
  "content": "# Therapeutic/Mechanistic Hypotheses: Specificity of Trehalose-Induced Calcineurin Activation\n\n---\n\n## Hypothesis 1: TRPML1-Associated Calcium Microdomains Bias Activation Toward Calcineurin\n\n**Title:** Spatiotemporal coupling between TRPML1-mediated lysosomal calcium release and calcineurin nanodomain activation\n\n**Mechanism:** Trehalose-induced LMP may preferentially release lysosomal Ca²⁺ through mucolipin-1 (TRPML1) channels, creating localized Ca²⁺ microdomains with specific amplitude/duration kinetics that selectively activate calcineurin over CaMK family members. The slow, sustained Ca²⁺ rise from lysosomes favors calcineurin activation (low-Kd calmodulin binding) versus transient Ca²⁺ spikes that activate CaMKs. Calcineurin may be spatially enriched near lysosomal membranes via interactions with AKAP proteins or directly with TRPML1.\n\n**Target gene/protein/pathway:** TRPML1 (MCOLN1), PPP3CA/B/C (calcineurin A subunits), calmodulin-dependent kinase cascade\n\n**Supporting evidence:**\n- TRPML1 mutations cause lysosomal storage disorders with impaired autophagy (PMID: 29155873)\n- Calcineurin exhibits high affinity for sustained Ca²⁺/calmodulin signals versus transient high-frequency signals (PMID: 24613340)\n- AKAP proteins scaffold calcineurin to specific subcellular compartments (PMID: 28701342)\n- Lysosomal Ca²⁺ release via TPC/TRPML channels activates calcineurin-NFAT signaling (PMID: 28481357)\n\n**Predicted experiment:** Co-immunoprecipitation of PPP3CA with TRPML1 from trehalose-treated cells; TIRF microscopy measuring Ca²⁺ microdomains with simultaneous calcineurin activity biosensor (calcineurin activity reporter) imaging; TRPML1 knockout or ML-SI3 inhibition attenuates trehalose-induced TFEB nuclear translocation\n\n**Confidence:** 0.72\n\n---\n\n## Hypothesis 2: Calmodulin-Dependent Reticulocalbin-2/ERC55-Mediated Calcineurin Lysosomal Recruitment\n\n**Title:** Reticulocalbin-2 bridges calcineurin to lysosomal membranes for Ca²⁺-dependent activation\n\n**Mechanism:** The calcium-binding protein reticulocalbin-2 (RCN2/ERC55), an endoplasmic reticulum-resident protein, may translocate to lysosomes during trehalose-induced permeabilization, bringing calcineurin into proximity with lysosomal Ca²⁺ stores. Trehalose may cause RCN2 mislocalization or lysosomal association, enabling Ca²⁺ release from permeabilized lysosomes to directly activate membrane-associated calcineurin. RCN2 contains multiple EF-hand motifs with appropriate Ca²⁺ affinity to sense lysosomal calcium.\n\n**Target gene/protein/pathway:** RCN2 (reticulocalbin-2), PPP3R1 (calcineurin B), lysosomal membrane integrity complex\n\n**Supporting evidence:**\n- RCN2 is a EF-hand calcium-binding protein with ER retention (PMID: 7527111)\n- Trehalose induces ER stress and alters calcium homeostasis (PMID: 30335591)\n- Lysosome-associated calcium-binding proteins coordinate calcium release (PMID: 31722219)\n- Calcineurin B subunit directs localization through myristoylation signals (PMID: 25446908)\n\n**Predicted experiment:** Subcellular fractionation + immunoblot for RCN2/calcineurin association with lysosomal fractions after trehalose treatment; proximity ligation assay (PLA) for RCN2-calcineurin interaction; CRISPR knockout of RCN2 prevents trehalose-induced TFEB activation\n\n**Confidence:** 0.58\n\n---\n\n## Hypothesis 3: Differential Calmodulin Isoform Availability Determines Calcineurin Specificity\n\n**Title:** Calmodulin isoform switching from CaMK to calcineurin activation upon lysosomal permeabilization\n\n**Mechanism:** Global cytosolic Ca²⁺ elevation from LMP exceeds threshold that depletes calmodulin availability for high-affinity CaMKs, leaving residual calmodulin to bind and activate lower-affinity calcineurin. Alternatively, lysosomal permeabilization releases calmodulin-bound Ca²⁺ pools that preferentially activate calcineurin. The unique calmodulin isoform composition near lysosomes determines the signaling outcome toward TFEB rather than general autophagy inhibition.\n\n**Target gene/protein/pathway:** CALM1/CALM2/CALM3 (calmodulin isoforms), PPP3CB, CaMK2A/B\n\n**Supporting evidence:**\n- Calmodulin has distinct affinities for different targets based on isoform and localization (PMID: 25454361)\n- Lysosomal calcium release specifically activates calcineurin-NFAT over CaMK pathways (PMID: 28481357)\n- Calmodulin availability limits kinase vs. phosphatase activation in different Ca²⁺ regimes (PMID: 29800551)\n\n**Predicted experiment:** Measure Ca²⁺/calmodulin availability using FRET-based calmodulin biosensors during trehalose treatment; siRNA knockdown of specific CALM isoforms shifts activation toward CaMK or calcineurin; recombinant calmodulin addition rescues phenotype in low-calmodulin conditions\n\n**Confidence:** 0.65\n\n---\n\n## Hypothesis 4: mTORC1 Dissociation from Lysosomes Primes Calcineurin-TFEB Axis\n\n**Title:** mTORC1 displacement from lysosomal surface enables calcineurin access to TFEB\n\n**Mechanism:** Trehalose-induced LMP disrupts the lysosomal mTORC1 complex (possibly through v-ATPase inhibition), causing TFEB release from lysosomal membranes into the cytosol where it becomes accessible to calcineurin-mediated dephosphorylation. mTORC1 normally phosphorylates TFEB at S211, preventing nuclear translocation. Calcineurin specifically dephosphorylates this site upon mTORC1 dissociation. The specificity arises from coincident detection: calcineurin is activated by Ca²⁺ while TFEB is simultaneously available as a substrate after mTORC1 displacement.\n\n**Target gene/protein/pathway:** mTOR (FRAP1), TFEB (TFE3), v-ATPase complex, PPP3CA\n\n**Supporting evidence:**\n- Trehalose inhibits mTORC1 signaling (PMID",
  "tokens_used": "1414",
  "persona_id": "persona-theorist"
}