{"gene":"KCNK18","run_date":"2026-06-10T02:59:49","timeline":{"discoveries":[{"year":2003,"finding":"TRESK (KCNK18) is a novel two-pore domain K+ channel with two pore-forming domains and four transmembrane domains that functions as a background K+ channel producing outward-rectifying, time-independent, non-inactivating K+-selective current; it is inhibited by Ba2+, propafenone, glyburide, lidocaine, quinine, quinidine, triethanolamine, unsaturated free fatty acids (arachidonic acid, DHA), and extreme pH changes.","method":"Electrophysiology (whole-cell and patch clamp) in heterologous expression systems; pharmacological analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct electrophysiological characterization with multiple pharmacological probes, foundational cloning paper with functional reconstitution","pmids":["12754259"],"is_preprint":false},{"year":2004,"finding":"TRESK is activated 5–15-fold by cytoplasmic calcium elevation (via Ca2+-mobilizing receptors, ionomycin, IP3 microinjection, or direct Ca2+ microinjection). Activation requires cytoplasmic factors (direct Ca2+ application to inside-out patches had no effect) and is mediated by the calcium/calmodulin-dependent phosphatase calcineurin; cyclosporin A and FK506 completely blocked TRESK activation. Coexpression of constitutively active calcineurin increased basal TRESK current. Alanine-scanning mutagenesis identified serine 276 as the major functional target of calcineurin in TRESK.","method":"Two-electrode voltage clamp in Xenopus oocytes; inside-out patch clamp; microinjection of IP3, Ca2+, EGTA; pharmacology (cyclosporin A, FK506); alanine-scanning mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple orthogonal methods (patch clamp, mutagenesis, microinjection, pharmacology) in a single rigorous study establishing the calcineurin activation mechanism","pmids":["14981085"],"is_preprint":false},{"year":2004,"finding":"TRESK-2 (KCNK18 mouse ortholog) is a functional K2P channel producing time-independent, non-inactivating, K+-selective background current with single-channel conductance of ~13–16 pS; it is inhibited by quinidine, arachidonate, and acid, but not by TEA, apamin, 4-AP, or glybenclamide, and is unaffected by intracellular GTPγS.","method":"Whole-cell patch clamp and single-channel recordings in COS-7 cells; inside-out patches; Northern blot","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct electrophysiological characterization with multiple pharmacological validations in reconstituted system","pmids":["15123670"],"is_preprint":false},{"year":2004,"finding":"Human TRESK currents are potently activated (up to 3-fold) by clinical concentrations of volatile anesthetics (isoflurane, halothane, sevoflurane, desflurane) but not by nonanesthetic compounds (nonimmobilizers) or most IV anesthetics (etomidate, thiopental, propofol). Local anesthetics inhibit TRESK in a concentration-dependent manner.","method":"Whole-cell voltage-clamp and patch-clamp in Xenopus oocytes and COS-7 cells","journal":"Anesthesia and analgesia","confidence":"High","confidence_rationale":"Tier 1 / Moderate — functional electrophysiology in two heterologous systems with systematic pharmacological characterization","pmids":["15562060"],"is_preprint":false},{"year":2005,"finding":"Zinc (Zn2+) and mercuric ions (Hg2+) are selective inhibitors of mouse TRESK among K2P channels (IC50 <10 µM), acting in a membrane-delimited manner on the channel itself (confirmed by outside-out single-channel recordings). Human TRESK is resistant to Zn2+ but blocked by Hg2+; His132 of mouse TRESK is partly responsible for the species difference in zinc sensitivity. Mibefradil also inhibited TRESK but with less selectivity.","method":"Two-electrode voltage clamp in Xenopus oocytes; outside-out patch clamp in COS-7 cells; site-directed mutagenesis (H132 substitution)","journal":"Molecular pharmacology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — electrophysiology plus mutagenesis, cross-species comparison identifying molecular determinant of zinc sensitivity","pmids":["16354767"],"is_preprint":false},{"year":2006,"finding":"Calcineurin activates TRESK through both its catalytic (phosphatase) activity and a non-catalytic docking interaction. TRESK's intracellular loop contains a PQIVID sequence homologous to the NFAT calcineurin-binding consensus (PXIXIT). Mutations of PQIVID to PQIVIA, PQIVAD, or PQAVAD progressively reduced calcium-dependent activation. VIVIT peptide microinjection eliminated TRESK activation. GST-TRESK intracellular loop pulled down constitutively active calcineurin in vitro; wild-type calcineurin was recruited in the presence of Ca2+/calmodulin; PQAVAD mutation and VIVIT peptide abrogated this binding.","method":"Two-electrode voltage clamp in Xenopus oocytes; site-directed mutagenesis; VIVIT peptide microinjection; GST pulldown assay with purified proteins","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstitution (GST pulldown), mutagenesis, and functional electrophysiology with multiple orthogonal methods establishing calcineurin docking mechanism","pmids":["16569637"],"is_preprint":false},{"year":2006,"finding":"TRESK-like (14 pS) channels and TREK-2-like (50 pS) channels together account for >95% of background K+ conductance in DRG neurons at 37°C; the TRESK-like channel contributes ~16% of resting K+ current. Native TRESK channels in DRG neurons share biophysical and pharmacological properties (inhibition by acid, arachidonic acid) with cloned TRESK.","method":"Single-channel patch clamp (cell-attached and inside-out) in rat DRG neurons; RT-PCR","journal":"American journal of physiology. Cell physiology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — direct single-channel recording in native cells with biophysical and pharmacological identity confirmation","pmids":["16495368"],"is_preprint":false},{"year":2007,"finding":"Mouse TRESK channels contribute approximately 20% of the standing outward current (IKso) in DRG neurons. TRESK functional knockout mice (TRESK[G339R]) show no change in resting membrane potential but display significantly altered action potential duration, amplitude of after-hyperpolarization, and increased excitability (reduced rheobase). A single histidine residue adjacent to the GYG selectivity filter confers pH sensitivity to mouse (but not human) TRESK.","method":"Whole-cell patch clamp and current-clamp in DRG neurons from TRESK functional knockout mice vs. wild-type; site-directed mutagenesis; in situ hybridization","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function genetic model with defined electrophysiological phenotype plus mutagenesis identifying pH-sensitivity determinant","pmids":["17962323"],"is_preprint":false},{"year":2008,"finding":"14-3-3 proteins (γ and η isoforms) directly bind to the intracellular loop of TRESK and control the kinetics of calcineurin-dependent regulation by slowing the return of K+ current to resting state after activation. Phosphorylation of serine 264 in mouse TRESK is required for 14-3-3η binding. A tethered 14-3-3η construct retained the same regulatory effect, demonstrating direct action on TRESK. Competing phosphopeptide (Ser(P)-Raf259) abolished the 14-3-3 effect. β, ζ, ε, σ, and τ isoforms of 14-3-3 did not significantly influence TRESK regulation.","method":"Two-electrode voltage clamp in Xenopus oocytes; coexpression of 14-3-3 isoforms and dominant-negative constructs; phosphopeptide microinjection; site-directed mutagenesis (S264)","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple orthogonal approaches (coexpression, tethered construct, competing peptide, mutagenesis) rigorously establishing 14-3-3 docking mechanism","pmids":["18397886"],"is_preprint":false},{"year":2008,"finding":"TRESK in DRG neurons is activated by GPCR agonists (acetylcholine, glutamate, histamine) and inhibited by lamotrigine (~50% inhibition at 30 µM in COS-7 cells). Native TRESK in DRG shares pharmacological properties (inhibited by acid, arachidonic acid; not by zinc) with cloned TRESK.","method":"Whole-cell patch clamp in DRG neurons and COS-7 cells transfected with mouse TRESK; pharmacological analysis","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct electrophysiology in native and transfected cells; single lab, two experimental systems","pmids":["18190784"],"is_preprint":false},{"year":2009,"finding":"N-linked glycosylation at a single residue in the first external loop is required for proper cell surface expression of TRESK. Glycosylation-deficient mutants show >80% reduction in current amplitude and >50% reduction in cell surface fluorescence in confocal microscopy of GFP-tagged TRESK.","method":"Site-directed mutagenesis; Western immunoblotting; two-electrode voltage clamp in Xenopus oocytes; confocal microscopy of GFP-tagged constructs","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — mutagenesis plus biochemical and imaging evidence in a single study with multiple orthogonal approaches","pmids":["20006580"],"is_preprint":false},{"year":2010,"finding":"TRESK is inhibited by phosphorylation via two distinct pathways converging on the intracellular loop: (1) PKA phosphorylates Ser-264 (the 14-3-3 binding site), accelerating current return to resting state; (2) a separate kinase phosphorylates the cluster of Ser-274, Ser-276, and Ser-279. 14-3-3 binding to Ser-264 additionally inhibits the kinase targeting the Ser-274/276/279 cluster, independently of direct TRESK–14-3-3 interaction.","method":"Two-electrode voltage clamp in Xenopus oocytes; site-directed mutagenesis (S264E, S276E, S274/276/279 cluster); coexpression experiments","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — systematic mutagenesis combined with functional electrophysiology dissecting two distinct phosphorylation inhibitory pathways","pmids":["20215114"],"is_preprint":false},{"year":2010,"finding":"The TRESK frameshift mutation F139WfsX24 causes complete loss of TRESK channel function, and the mutant subunit suppresses wild-type TRESK channel function through a dominant-negative mechanism (demonstrated in Xenopus oocytes). The mutation segregates perfectly with typical migraine with aura in a large pedigree.","method":"Two-electrode voltage clamp in Xenopus oocytes; co-expression of wild-type and mutant subunits; genetic linkage analysis","journal":"Nature medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — functional electrophysiology demonstrating dominant-negative mechanism replicated with genetic evidence in a large pedigree","pmids":["20871611"],"is_preprint":false},{"year":2010,"finding":"TRESK knockout mice show a discrete 8% increase in isoflurane minimum alveolar concentration compared to wild-type, supporting a contribution of TRESK to volatile anesthetic sensitivity, though TRESK alone is not critical for baseline CNS function.","method":"Homologous recombination knockout mice; minimum alveolar concentration determination for volatile anesthetics","journal":"Anesthesiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo genetic loss-of-function with defined quantitative anesthetic phenotype; single lab","pmids":["21042202"],"is_preprint":false},{"year":2011,"finding":"MARK1, MARK2, and MARK3 (microtubule affinity-regulating kinases; PAR-1/MARK family) inhibit TRESK by phosphorylating the cluster of Ser-274, Ser-276, and Ser-279 in the intracellular loop, accelerating return of TRESK current to resting state after calcineurin-dependent activation. MARK2 does not phosphorylate Ser-264 (the 14-3-3 binding site). Several other serine-threonine kinases tested had no effect.","method":"Two-electrode voltage clamp in Xenopus oocytes; coexpression of MARK isoforms; site-directed mutagenesis of the S274/276/279 cluster","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 1 / Moderate — functional electrophysiology plus mutagenesis identifying specific kinase and phosphorylation sites; selectivity established by testing multiple kinases","pmids":["22145024"],"is_preprint":false},{"year":2012,"finding":"The mutant TRESK F139WfsX24 subunit exerts dominant-negative effects on whole-cell TRESK current AND on the level of TRESK channels at the plasma membrane through heterodimerization with wild-type subunits in HEK293T cells. Expression of mutant TRESK in mouse trigeminal ganglion neurons decreases lamotrigine-sensitive K+ current and causes hyperexcitability (higher input resistance, lower current threshold for action potentials, higher spike frequency).","method":"Whole-cell patch clamp in HEK293T cells and cultured trigeminal ganglion neurons; surface biotinylation assay; current-clamp recordings","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (patch clamp, surface trafficking assay) in both heterologous and native neuronal systems","pmids":["23904616"],"is_preprint":false},{"year":2012,"finding":"The TRESK C110R variant causes complete loss of function and dominant-negative suppression of wild-type TRESK current in Xenopus oocytes, similar to the migraine-associated frameshift mutant, yet C110R is present in both migraine and control cohorts, indicating that loss of TRESK function alone is not sufficient to cause migraine.","method":"Two-electrode voltage clamp in Xenopus oocytes; functional characterization of missense variants","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct electrophysiological characterization with genetic epidemiological context, single lab but clear mechanistic result","pmids":["22355750"],"is_preprint":false},{"year":2013,"finding":"Membrane stretch (laminar shear stress, hypotonic cell swelling) increases TRESK currents by 22–40%, while cell shrinkage (hypertonic solution) decreases them. Negative pressure applied to trigeminal neurons increases TRESK channel open probability 1.51-fold. TRESK currents are additively inhibited by arachidonic acid, acidic pH, and hypertonic stimulation.","method":"Whole-cell patch clamp and single-channel recordings in heterologous systems (F-11 cells) and trigeminal neurons; osmotic swelling/shrinkage; shear stress application","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct electrophysiological recording in both heterologous and native cells with multiple mechanical stimuli","pmids":["23691227"],"is_preprint":false},{"year":2013,"finding":"Cloxyquin (5-chloroquinolin-8-ol) activates TRESK with an EC50 of 3.8 µM (thallium flux assay) and approximately 2-fold increase in outward current (patch clamp), with good selectivity against other potassium channels tested.","method":"Thallium flux assay; whole-cell patch clamp electrophysiology in U2OS cells","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal functional assays confirming activation; single lab","pmids":["24383077"],"is_preprint":false},{"year":2014,"finding":"Human TRESK contains a second calcineurin docking site, LQLP, in its intracellular loop in addition to PQIIIS. The LQLP→AQAP mutation alone did not change the amplitude of TRESK activation at high calcium but slowed the response and prevented activation by modest calcium elevation. Combined mutations of both PQIIIS and LQLP were required to eliminate calcium-dependent regulation. LQLP acts as a distinct determinant of calcium sensitivity, separate from the affinity-determining role of PQIIIS.","method":"Two-electrode voltage clamp in Xenopus oocytes; site-directed mutagenesis of LQLP and PQIIIS motifs; calcium calibration experiments","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — systematic mutagenesis with functional electrophysiology identifying two distinct calcineurin docking sites with distinct roles","pmids":["25202008"],"is_preprint":false},{"year":2014,"finding":"Overexpression of TRESK in mouse trigeminal ganglion neurons (via lipofectamine transfection) produces a 2-fold increase in lamotrigine-sensitive persistent K+ current and total background K+ current, with decreased input resistance and 2-fold higher current threshold for action potential initiation in both IB4+ and IB4- neurons. TRESK overexpression also inhibits capsaicin-evoked action potentials.","method":"Whole-cell patch clamp and current-clamp in cultured mouse TG neurons overexpressing TRESK; Western blot for TRESK protein levels","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Moderate — gain-of-function experiment in native neurons with defined electrophysiological readouts and protein-level verification","pmids":["24466320"],"is_preprint":false},{"year":2014,"finding":"The non-migraine-associated C110R variant reduces endogenous TRESK currents in trigeminal ganglion neurons, but to a significantly smaller degree than the migraine-associated frameshift mutant, and only the frameshift mutant (not C110R) produces significant hyperexcitability of TG neurons.","method":"Whole-cell patch clamp in HEK293T cells and cultured mouse TG neurons expressing C110R or mutant TRESK; current-clamp recordings","journal":"Journal of neurophysiology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — direct comparison of two variants in native neurons with quantitative electrophysiological outcome measures","pmids":["24805079"],"is_preprint":false},{"year":2014,"finding":"Tubulin binds specifically to the intracellular loop of TRESK in vitro at a 16 amino acid sequence (LVLGRLSYSIISNLDE). The tubulin-binding site overlaps with the PKA-dependent 14-3-3 docking region, and 14-3-3 competes with tubulin for binding to the TRESK cytoplasmic loop.","method":"Affinity chromatography with GST-TRESK loop as bait; pulldown from mouse brain cytosol; successive truncation experiments; competitive binding assay","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — affinity chromatography and competitive binding in vitro; authors note interaction in living cells remains to be established","pmids":["24830385"],"is_preprint":false},{"year":2015,"finding":"Lysophosphatidic acid (LPA) activates TRESK through LPA receptors in DRG neurons, increasing background K+ current (IKso) and attenuating nociceptor excitability. In TRESK knockout DRG neurons, LPA does not increase IKso, confirming TRESK mediates this effect. LPA simultaneously activates both TRPV1 (depolarizing) and TRESK (hyperpolarizing) in co-expression experiments.","method":"Two-electrode voltage clamp in Xenopus oocytes co-expressing TRESK and LPA receptors; whole-cell patch clamp in DRG neurons from TRESK-wt and TRESK-ko mice; current-clamp recordings","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout plus heterologous co-expression confirming receptor-mediated TRESK activation with defined functional consequence in native neurons","pmids":["26224542"],"is_preprint":false},{"year":2017,"finding":"Cloxyquin selectively activates mouse and human TRESK (~4-fold) in a state-dependent manner: it potently activates TRESK in the resting (phosphorylated) state but does not further activate TRESK after calcineurin-dependent activation or in constitutively active mutants (S276A, F156A, F364A). Cloxyquin activates TRESK via a Ca2+/calcineurin-independent mechanism and is selective for TRESK within the K2P family. It also activates background K+ current in a subpopulation of DRG neurons.","method":"Two-electrode voltage clamp in Xenopus oocytes; whole-cell patch clamp in mouse DRG neurons; site-directed mutagenesis; pharmacological selectivity screen of K2P channels","journal":"British journal of pharmacology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — systematic mutagenesis plus electrophysiology in both heterologous and native cells establishing state-dependent, calcineurin-independent mechanism","pmids":["28419410"],"is_preprint":false},{"year":2018,"finding":"The TRESK frameshift mutation F139WfsX24 (TRESK-MT) generates via alternative translation initiation (fsATI) a second protein fragment, TRESK-MT2, from the same mRNA. TRESK-MT2 co-assembles with TREK1 and TREK2 and inhibits their activity, increasing trigeminal sensory neuron excitability and producing a migraine-like phenotype in rodents. The non-migraine-associated C110R mutant does not produce fsATI or TRESK-MT2, explaining the differential migraine association of the two mutations.","method":"In vitro translation assays; co-immunoprecipitation; patch clamp electrophysiology in heterologous cells and primary neurons; in vivo rodent behavioral assays","journal":"Neuron","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (biochemistry, electrophysiology, in vivo) establishing a new mechanism (fsATI) with functional and behavioral validation","pmids":["30573346"],"is_preprint":false},{"year":2018,"finding":"Anionic phospholipids (PIP2 analog, Folch fraction MLVs) activate human TRESK but not rat TRESK through electrostatic binding to a 14 amino acid sequence in the large cytoplasmic loop at the membrane-cytosol interface. Disruption of this sequence inhibits hTRESK. Replacing the equivalent rat sequence with the human anionic phospholipid-binding site confers PIP2 sensitivity to rat TRESK. Gq/11-linked GPCR stimulation (with calcineurin inhibition) reduces hTRESK current, consistent with PIP2 hydrolysis-dependent inhibition.","method":"Binding assay with multilamellar vesicles; whole-cell patch clamp; site-directed mutagenesis; chimeric channel constructs; GPCR stimulation experiments","journal":"Molecular neurobiology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — biochemical binding, mutagenesis, chimeric channels, and functional electrophysiology in multiple cell types establishing novel regulatory mechanism","pmids":["30039335"],"is_preprint":false},{"year":2018,"finding":"Tumor-produced VEGF activates VEGFR2 on DRG neurons, increasing DSCR1 (calcineurin inhibitor) abundance, which reduces calcineurin-mediated NFAT activation and thereby decreases TRESK transcription, resulting in sensory neuron hyperexcitability and pain. Intrathecal calcineurin restored TRESK expression and abolished DRG hyperexcitability and pain in tumor-bearing rats.","method":"In vivo bone metastasis model; TRESK overexpression/knockdown in DRG; patch clamp; immunohistochemistry; VEGF pathway manipulation","journal":"Science signaling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo pathway dissection with gain and loss of function, but complex multi-step signaling pathway; single lab","pmids":["30327410"],"is_preprint":false},{"year":2019,"finding":"Novel-type PKC isoforms η and ε activate human TRESK by indirect dephosphorylation of Ser-264 via inhibition of the kinase that rephosphorylates this site, not via calcineurin. S264A and S264E mutations abolished PMA-induced TRESK activation. Mutations of calcineurin-binding sites did not prevent PKC-dependent activation. PKC-dependent dephosphorylation of TRESK was confirmed by Phos-tag SDS-PAGE.","method":"Two-electrode voltage clamp in Xenopus oocytes; coexpression of PKC isoforms; site-directed mutagenesis (S264A/E, calcineurin-binding site mutations); Phos-tag SDS-PAGE","journal":"Molecular pharmacology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — functional electrophysiology, biochemical phosphorylation assay, and mutagenesis establishing distinct PKC-dependent activation mechanism","pmids":["30992311"],"is_preprint":false},{"year":2019,"finding":"TRESK knockout mice show enhanced mechanical and cold sensitivity in behavioral tests and in skin nerve C-fiber recordings, without altered heat sensitivity. TRESK deletion also enhances excitability of isolated nociceptors and exacerbates cold allodynia (but not thermal hyperalgesia) in chronic pain states.","method":"TRESK knockout mice; behavioral testing (von Frey, cold plate, heat); skin-nerve fiber preparation; whole-cell patch clamp of isolated nociceptors","journal":"The Journal of physiology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout with multiple complementary behavioral, electrophysiological, and ex vivo approaches establishing modality-specific sensory function","pmids":["31919847"],"is_preprint":false},{"year":2019,"finding":"In iPSC-derived nociceptors from migraine patients with F139WfsX24 mutation, there is loss of functional TRESK at the membrane with significantly increased neuronal excitability. CRISPR-Cas9 correction of the F139WfsX24 mutation reverses the heightened excitability. C110R nociceptors show no change in excitability and preserved TRESK current. The TRESK activator cloxyquin reduces spontaneous firing of nociceptors in an in vitro human pain model.","method":"iPSC-derived nociceptors; CRISPR-Cas9 gene correction; patch clamp electrophysiology; in vitro human pain model with cloxyquin","journal":"Brain : a journal of neurology","confidence":"High","confidence_rationale":"Tier 2 / Strong — CRISPR causal rescue experiment in human iPSC neurons plus pharmacological validation; multiple orthogonal approaches","pmids":["31742594"],"is_preprint":false},{"year":2020,"finding":"TRESK and TREK-2 subunits form functional heterodimers in primary somatosensory neurons. Using a covalently linked TRESK/TREK-2 tandem construct, the heterodimer shows an intermediate single-channel conductance between TRESK and TREK-2 homodimers, retains calcineurin-dependent regulation (conferred by the TRESK subunit), and acquires sensitivity to the TREK-2-selective activator T2A3 (conferred by the TREK-2 subunit). In trigeminal neurons, native channels with biophysical and pharmacological properties matching the TRESK/TREK-2 tandem were detected.","method":"Covalently linked tandem channel constructs; two-electrode voltage clamp in Xenopus oocytes; single-channel patch clamp in native trigeminal neurons; pharmacological characterization with TREK-2 selective activator T2A3","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — tandem construct reconstitution plus native cell single-channel recordings with pharmacological fingerprinting confirming physiological heterodimerization","pmids":["32641496"],"is_preprint":false},{"year":2021,"finding":"TRESK inhibition increases TRPV1-mediated calcium signals in DRG neurons and potentiates capsaicin-induced CGRP release from trigeminal afferents and meningeal blood flow. TRESK activation decreases capsaicin sensitivity of sensory neurons. These effects are absent in TRESK knockout animals, confirming that TRESK modulates TRPV1-mediated nociceptor function.","method":"Calcium imaging in DRG neurons; CGRP release assay from trigeminal afferents; meningeal blood flow measurement; pharmacological TRESK activation/inhibition; TRESK knockout mice","journal":"Cephalalgia","confidence":"High","confidence_rationale":"Tier 2 / Strong — pharmacological manipulation confirmed by genetic knockout with multiple functional readouts in native tissue","pmids":["33525904"],"is_preprint":false},{"year":2023,"finding":"The short intracellular C-terminal region (iCtr) following the fourth transmembrane segment of TRESK is a critical determinant of channel activity. Mutations of positive residues in proximal iCtr lock TRESK in a low-activity, calcineurin-insensitive state. Replacing distal iCtr with a sequence designed to interact with the inner plasma membrane surface increases TRESK activity to unprecedented levels. The ENaR (epithelial Na+ current ratio) method was developed to normalize K+ current to channel surface expression.","method":"Two-electrode voltage clamp in Xenopus oocytes; ENaR (epithelial sodium current ratio) method using ENaC as internal reference; single-channel recordings; site-directed mutagenesis of iCtr residues","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — novel functional method combined with systematic mutagenesis and single-channel recordings revealing iCtr as major gating determinant","pmids":["37084812"],"is_preprint":false},{"year":2024,"finding":"NDFIP1 (Nedd4 family-interacting protein 1) interacts with TRESK (confirmed by co-immunoprecipitation) and negatively regulates TRESK current. NDFIP1 coexpression induces ubiquitination of TRESK and abolishes TRESK current. Mutations in the three PPxY motifs of NDFIP1 (required for Nedd4 ubiquitin ligase binding) prevented TRESK current reduction. Dominant-negative Nedd4 partially reversed NDFIP1's effect on TRESK current.","method":"Two-electrode voltage clamp in Xenopus oocytes; co-immunoprecipitation; ubiquitination assay; site-directed mutagenesis of NDFIP1 PPxY motifs; dominant-negative Nedd4 coexpression","journal":"International journal of molecular sciences","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal biochemical and functional methods (Co-IP, ubiquitination assay, mutagenesis, dominant-negative) establishing NDFIP1-Nedd4 ubiquitin-mediated regulation","pmids":["39201565"],"is_preprint":false},{"year":2025,"finding":"TRESK regulates the excitability of MrgprA3-expressing pruriceptors. TRESK knockout mice show enhanced firing of MrgprA3+ neurons and increased acute itch response to chloroquine (but not histamine, BAM8-22, or leukotriene C4). TRESK deletion exacerbates chronic itch in models of allergic contact dermatitis, dry skin, and imiquimod-induced psoriasis. Pharmacological TRESK activation reduces both acute and chronic itch in wild-type but not TRESK KO mice.","method":"TRESK knockout mice; behavioral itch assays; electrophysiological recordings from MrgprA3+ neurons; pharmacological TRESK activation; chronic itch mouse models","journal":"Pain","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout combined with pharmacological rescue in multiple itch models, confirming TRESK role in specific pruriceptor subpopulation","pmids":["40062712"],"is_preprint":false}],"current_model":"TRESK (KCNK18/K2P18.1) is a two-pore-domain background K+ channel constitutively phosphorylated (inhibited) at two intracellular loop regions: a Ser-264 site (targeted by PKA, bound by 14-3-3η/γ) and a Ser-274/276/279 cluster (phosphorylated by MARK1/2/3 kinases); calcium signals activate TRESK via calcineurin, which docks to two non-catalytic binding motifs (PQIVID/PQIIIS and LQLP) and dephosphorylates these serines, with novel-type PKC providing an additional calcineurin-independent activation pathway through indirect Ser-264 dephosphorylation; TRESK forms both homodimers and functional heterodimers with TREK-2 in primary sensory neurons; cell-surface expression requires N-linked glycosylation; activity is further modulated by anionic phospholipids (human-specific), membrane stretch, and NDFIP1-Nedd4-mediated ubiquitination; the channel is the dominant background K+ conductance in dorsal root and trigeminal ganglion neurons, setting resting membrane potential and suppressing nociceptor excitability, with loss-of-function (frameshift mutation generating fsATI-derived TRESK-MT2 that additionally inhibits TREK1/TREK2) causally linked to familial migraine with aura."},"narrative":{"mechanistic_narrative":"KCNK18 encodes TRESK (K2P18.1), a two-pore-domain background K+ channel that produces an outwardly-rectifying, time-independent, non-inactivating K+-selective current and serves as a dominant background K+ conductance in dorsal root and trigeminal ganglion sensory neurons, where it sets excitability and suppresses nociceptor firing [PMID:12754259, PMID:16495368, PMID:24466320]. The channel's defining regulatory feature is reversible phosphorylation of its large intracellular loop: it is held inhibited in the resting state by phosphorylation of Ser-264 (a PKA site and 14-3-3 binding site) and of a Ser-274/276/279 cluster targeted by MARK1/2/3 kinases, and is activated several-fold when cytoplasmic calcium rises and the phosphatase calcineurin docks to non-catalytic PQIVID/PQIIIS and LQLP motifs in the loop to dephosphorylate these serines [PMID:14981085, PMID:16569637, PMID:18397886, PMID:20215114, PMID:22145024, PMID:25202008]. Calcineurin-independent activation also occurs through novel-type PKC isoforms (η, ε) that drive indirect Ser-264 dephosphorylation [PMID:30992311]. TRESK activity is further tuned by N-linked glycosylation required for surface expression, membrane stretch, anionic phospholipids acting at a human-specific cytoplasmic site, the intracellular C-terminal region as a gating determinant, and NDFIP1–Nedd4-mediated ubiquitination that suppresses current [PMID:20006580, PMID:23691227, PMID:30039335, PMID:37084812, PMID:39201565]. TRESK assembles as homodimers and as functional heterodimers with TREK-2 in somatosensory neurons, and its loss enhances mechanical, cold, and itch sensitivity and potentiates TRPV1/CGRP signaling [PMID:31919847, PMID:32641496, PMID:33525904, PMID:40062712]. A dominant-negative frameshift mutation (F139WfsX24) that abolishes TRESK function and, via alternative translation initiation, generates a TRESK-MT2 fragment that additionally inhibits TREK1/TREK2 is causally linked to familial migraine with aura, with CRISPR correction in patient iPSC nociceptors reversing the associated hyperexcitability [PMID:20871611, PMID:30573346, PMID:31742594].","teleology":[{"year":2003,"claim":"Established the molecular and biophysical identity of TRESK, defining it as a background K+ channel and resolving what kind of conductance KCNK18 produces.","evidence":"Whole-cell and patch-clamp electrophysiology with pharmacology in heterologous systems","pmids":["12754259"],"confidence":"High","gaps":["No physiological regulator or native cellular role identified","Pharmacology limited to blockers without endogenous modulators"]},{"year":2004,"claim":"Showed that calcium activates TRESK indirectly through calcineurin acting on intracellular serines, answering how a background channel is dynamically regulated by signaling.","evidence":"Voltage clamp in Xenopus oocytes, microinjection, calcineurin pharmacology, and alanine-scanning mutagenesis (Ser-276); parallel cloning of the mouse ortholog confirmed conserved biophysics","pmids":["14981085","15123670"],"confidence":"High","gaps":["Mechanism of calcineurin recruitment to the channel not yet defined","Kinases that re-phosphorylate the sites unknown"]},{"year":2004,"claim":"Identified TRESK as a target of clinical anesthetics, linking the channel to drug-modifiable excitability.","evidence":"Voltage-clamp in oocytes and COS-7 cells with systematic anesthetic and local-anesthetic panels","pmids":["15562060"],"confidence":"High","gaps":["Binding site for volatile anesthetics not mapped","In vivo relevance not established"]},{"year":2005,"claim":"Defined metal-ion pharmacology and a molecular determinant (His132) of species-specific zinc sensitivity, providing tools to distinguish TRESK from other K2P channels.","evidence":"Voltage clamp, outside-out single-channel recordings, and H132 mutagenesis with cross-species comparison","pmids":["16354767"],"confidence":"High","gaps":["Physiological role of zinc/mercury modulation unknown"]},{"year":2006,"claim":"Resolved the molecular basis of calcineurin docking, demonstrating that an NFAT-like PQIVID motif recruits the phosphatase, explaining how a non-substrate-like channel is targeted by calcineurin.","evidence":"GST pulldown with purified proteins, VIVIT peptide microinjection, mutagenesis, and voltage clamp","pmids":["16569637"],"confidence":"High","gaps":["A second docking determinant not yet recognized","Re-phosphorylating kinases still unidentified"]},{"year":2006,"claim":"Demonstrated that native TRESK-like channels carry a substantial fraction of background K+ conductance in DRG neurons, anchoring the channel's physiological role in sensory neurons.","evidence":"Single-channel patch clamp in rat DRG neurons with RT-PCR and pharmacological identity matching","pmids":["16495368"],"confidence":"High","gaps":["Channel identity inferred from biophysics/pharmacology, not genetic ablation","Contribution to behavior untested"]},{"year":2007,"claim":"Genetic loss-of-function established TRESK's contribution to DRG action-potential properties and excitability, and mapped a pH-sensitivity residue near the selectivity filter.","evidence":"Patch/current clamp in TRESK[G339R] knockout DRG neurons plus mutagenesis and in situ hybridization","pmids":["17962323"],"confidence":"High","gaps":["Resting membrane potential unchanged, implying redundancy","Behavioral consequences not assessed"]},{"year":2008,"claim":"Identified 14-3-3γ/η as phospho-Ser-264-dependent loop partners controlling the kinetics of calcineurin regulation, adding a layer of temporal control to channel gating.","evidence":"Voltage clamp with 14-3-3 coexpression, tethered constructs, competing phosphopeptide, and S264 mutagenesis","pmids":["18397886"],"confidence":"High","gaps":["Kinase generating phospho-Ser-264 not yet defined","Isoform selectivity in native neurons untested"]},{"year":2010,"claim":"Dissected two distinct inhibitory phosphorylation pathways (PKA at Ser-264 and a separate kinase at the Ser-274/276/279 cluster) and showed cross-talk via 14-3-3, building the integrated phospho-regulatory model.","evidence":"Voltage clamp in oocytes with phosphomimetic and cluster mutagenesis and coexpression; pharmacological GPCR activation in DRG identified upstream agonists","pmids":["20215114","18190784"],"confidence":"High","gaps":["Identity of the Ser-274/276/279 kinase still unknown at this stage","PKA recruitment mechanism unclear"]},{"year":2009,"claim":"Established N-linked glycosylation as a requirement for TRESK surface expression, defining a post-translational checkpoint for channel availability.","evidence":"Mutagenesis with Western blot, voltage clamp, and confocal imaging of GFP-tagged channel","pmids":["20006580"],"confidence":"High","gaps":["Trafficking machinery downstream of glycosylation not identified"]},{"year":2010,"claim":"Linked a dominant-negative TRESK frameshift mutation to familial migraine with aura, providing the first human disease connection and a mechanism (suppression of wild-type subunits).","evidence":"Voltage clamp with wild-type/mutant co-expression and genetic linkage in a large pedigree","pmids":["20871611"],"confidence":"High","gaps":["How loss of a DRG/TG channel produces aura not explained","Penetrance and modifiers unknown"]},{"year":2010,"claim":"In vivo knockout linked TRESK quantitatively to volatile anesthetic sensitivity while showing it is dispensable for baseline CNS function.","evidence":"Homologous-recombination knockout mice with minimum alveolar concentration measurement","pmids":["21042202"],"confidence":"Medium","gaps":["Small effect size implies redundancy with other K2P channels","Single-lab in vivo result"]},{"year":2011,"claim":"Identified MARK1/2/3 as the kinases phosphorylating the Ser-274/276/279 cluster, completing the assignment of the two inhibitory phosphorylation pathways.","evidence":"Voltage clamp with MARK isoform coexpression and cluster mutagenesis, with selectivity testing of multiple kinases","pmids":["22145024"],"confidence":"High","gaps":["Physiological signals that engage MARK kinases on TRESK unknown","Direct phosphorylation not confirmed biochemically in this assay"]},{"year":2012,"claim":"Distinguished a migraine-causing frameshift mutant from a functionally null but non-migraine C110R variant, showing that loss of TRESK current alone is insufficient for disease and demanding a further mechanism.","evidence":"Voltage clamp characterization of missense and frameshift variants in oocytes with epidemiological context","pmids":["22355750","23904616"],"confidence":"High","gaps":["What distinguishes the frameshift from C110R molecularly unresolved at this point","Native neuronal consequences then incompletely tested"]},{"year":2014,"claim":"Resolved a second calcineurin docking site (LQLP) acting as a calcium-sensitivity determinant distinct from the affinity-setting PQIIIS, refining the bipartite recruitment model.","evidence":"Voltage clamp with LQLP/PQIIIS mutagenesis and calcium calibration in oocytes","pmids":["25202008"],"confidence":"High","gaps":["Structural basis of dual docking not determined"]},{"year":2014,"claim":"Demonstrated tubulin binding to the TRESK loop overlapping the 14-3-3 site, suggesting cytoskeletal cross-regulation of the channel.","evidence":"Affinity chromatography, brain-cytosol pulldown, truncation, and competitive binding in vitro","pmids":["24830385"],"confidence":"Medium","gaps":["Interaction in living cells not established","Functional consequence on current not shown"]},{"year":2014,"claim":"Gain-of-function in native TG neurons confirmed TRESK as a brake on nociceptor firing, including capsaicin-evoked spiking, and comparative variant work tied excitability changes to the migraine mutant.","evidence":"TRESK overexpression with patch/current clamp and Western blot in TG neurons; parallel C110R vs frameshift comparison in TG neurons","pmids":["24466320","24805079"],"confidence":"High","gaps":["Endogenous stimuli driving these changes in vivo not defined"]},{"year":2013,"claim":"Showed TRESK is mechanosensitive, responding to stretch and osmotic changes, broadening its role as an integrator of physical and chemical stimuli.","evidence":"Whole-cell and single-channel recordings in F-11 cells and trigeminal neurons under shear, swelling, and shrinkage","pmids":["23691227"],"confidence":"Medium","gaps":["Molecular mechanism of mechanotransduction unmapped","Physiological role of stretch sensitivity untested in vivo"]},{"year":2015,"claim":"Identified LPA-receptor signaling as a physiological GPCR input that activates TRESK to attenuate nociceptor excitability, with knockout confirming specificity.","evidence":"Co-expression voltage clamp plus patch/current clamp in TRESK-wt and -ko DRG neurons","pmids":["26224542"],"confidence":"High","gaps":["Signaling steps from LPA receptor to channel dephosphorylation not fully mapped"]},{"year":2018,"claim":"Resolved why only the frameshift mutation causes migraine: alternative translation initiation produces TRESK-MT2, which co-assembles with and inhibits TREK1/TREK2, providing a gain-of-pathology mechanism beyond simple TRESK loss.","evidence":"In vitro translation, co-IP, patch clamp in heterologous and primary neurons, and in vivo rodent behavior","pmids":["30573346"],"confidence":"High","gaps":["Structural basis of TRESK-MT2/TREK heterodimer inhibition not determined","Human in vivo validation pending"]},{"year":2018,"claim":"Defined anionic phospholipids as a human-specific activating input acting at a cytoplasmic loop site, and novel-type PKC as a calcineurin-independent activator, expanding the regulatory repertoire.","evidence":"MLV binding, mutagenesis, chimeras and GPCR experiments for phospholipids; PKC coexpression, mutagenesis, and Phos-tag SDS-PAGE for PKC pathway","pmids":["30039335","30992311"],"confidence":"High","gaps":["Why phospholipid sensitivity is species-restricted not explained","Identity of the PKC-inhibited Ser-264 kinase unknown"]},{"year":2018,"claim":"Connected TRESK transcriptional downregulation to a tumor VEGF–DSCR1–calcineurin–NFAT axis as a driver of cancer pain, extending TRESK regulation to gene-expression control.","evidence":"In vivo bone metastasis model with DRG overexpression/knockdown, patch clamp, IHC, and pathway manipulation","pmids":["30327410"],"confidence":"Medium","gaps":["Multi-step pathway from single lab","Direct NFAT regulation of the KCNK18 promoter not shown"]},{"year":2019,"claim":"Knockout phenotyping defined modality-specific sensory roles, showing TRESK constrains mechanical and cold (but not heat) sensitivity and nociceptor excitability.","evidence":"Behavioral testing, skin-nerve C-fiber recordings, and patch clamp of isolated nociceptors in knockout mice","pmids":["31919847"],"confidence":"High","gaps":["Cellular basis of modality specificity unresolved"]},{"year":2019,"claim":"Provided causal human evidence that the migraine frameshift mutation drives nociceptor hyperexcitability, since CRISPR correction reversed it, and validated cloxyquin as a corrective activator.","evidence":"iPSC-derived nociceptors with CRISPR-Cas9 correction, patch clamp, and an in vitro human pain model","pmids":["31742594"],"confidence":"High","gaps":["Link from nociceptor hyperexcitability to migraine aura still indirect"]},{"year":2020,"claim":"Demonstrated functional TRESK/TREK-2 heterodimers in somatosensory neurons, revealing that native background conductance is a composite channel with mixed regulatory and pharmacological properties.","evidence":"Covalently linked tandem constructs, voltage clamp, and native single-channel recordings with TREK-2-selective T2A3","pmids":["32641496"],"confidence":"High","gaps":["Stoichiometry and relative abundance of heterodimers in vivo not quantified"]},{"year":2021,"claim":"Showed TRESK gates TRPV1-mediated calcium signaling and CGRP release, mechanistically linking the channel to peripheral nociceptive and migraine-relevant signaling.","evidence":"Calcium imaging, CGRP release and meningeal blood-flow assays with pharmacology confirmed in knockout mice","pmids":["33525904"],"confidence":"High","gaps":["Whether TRESK and TRPV1 physically interact not addressed"]},{"year":2023,"claim":"Identified the intracellular C-terminal region as a major gating determinant whose membrane interaction sets channel activity, deepening the structural understanding of TRESK regulation.","evidence":"Voltage clamp with the ENaR normalization method, single-channel recordings, and iCtr mutagenesis in oocytes","pmids":["37084812"],"confidence":"High","gaps":["High-resolution structure of the iCtr–membrane interface lacking"]},{"year":2024,"claim":"Established NDFIP1–Nedd4-mediated ubiquitination as a degradative/regulatory pathway suppressing TRESK current, adding protein turnover to the regulatory model.","evidence":"Co-IP, ubiquitination assay, PPxY-motif mutagenesis, dominant-negative Nedd4, and voltage clamp in oocytes","pmids":["39201565"],"confidence":"High","gaps":["Physiological/disease contexts engaging NDFIP1-Nedd4 on TRESK unknown","Confirmation in native neurons pending"]},{"year":2025,"claim":"Extended TRESK's role to itch, showing it constrains MrgprA3+ pruriceptor excitability and chronic itch, broadening its sensory remit beyond pain.","evidence":"Knockout mice with itch behavior, MrgprA3+ neuron recordings, pharmacological activation, and chronic itch models","pmids":["40062712"],"confidence":"High","gaps":["Stimulus specificity (chloroquine but not histamine) mechanistically unexplained"]},{"year":null,"claim":"How TRESK's diverse regulatory inputs are integrated at the structural level and how loss of a peripheral sensory K+ channel produces centrally-perceived migraine aura remain unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No high-resolution structure of the regulated intracellular loop/iCtr","Mechanistic link from nociceptor hyperexcitability to migraine aura unestablished","Re-phosphorylating kinase for Ser-264 not definitively identified"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[0,2,6]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[10,15,20]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[6,20,29]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,5,23,28]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[12,25,30]}],"complexes":["TRESK homodimer","TRESK/TREK-2 heterodimer"],"partners":["PPP3CA","YWHAH","YWHAG","MARK2","TREK-2","NDFIP1","NEDD4","TREK1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q7Z418","full_name":"Potassium channel subfamily K member 18","aliases":["TWIK-related individual potassium channel","TWIK-related spinal cord potassium channel"],"length_aa":384,"mass_kda":43.7,"function":"K(+) channel that conducts outward and inward rectifying currents at depolarized and hyperpolarized membrane potentials, respectively. The outward rectifying currents are voltage-dependent, coupled to K(+) electrochemical gradient across the membrane, whereas the inward currents can be induced in response to activation of Ca(2+)-mobilizing receptors (PubMed:12754259, PubMed:15562060, PubMed:20871611, PubMed:22355750, PubMed:26919430, PubMed:30573346). Homo- and heterodimerizes to form functional channels with distinct regulatory and gating properties. In trigeminal ganglia sensory neurons, the heterodimers of KCNK18/TRESK and KCNK2/TREK-1 or KCNK10/TREK-2 inhibit neuronal firing and neurogenic inflammation by stabilizing the resting membrane potential at K(+) equilibrium potential as well as by regulating the threshold of action potentials and the spike frequency (By similarity). In thymocytes, conducts K(+) currents upon T cell receptor (TCR) signaling leading to sustained Ca(2+) influx and NF-kappa-B activation, FOXP3 transcription and positive selection of regulatory T cell (Treg) progenitor subsets (PubMed:34702947). Appears to mediate the analgesics effects of hydroxy-alpha-sanshool, a metabolite naturally present in Schezuan pepper and other Xanthoxylum plants (By similarity)","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q7Z418/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KCNK18","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/KCNK18","total_profiled":1310},"omim":[{"mim_id":"613656","title":"MIGRAINE WITH AURA, SUSCEPTIBILITY TO, 13; MGR13","url":"https://www.omim.org/entry/613656"},{"mim_id":"613655","title":"POTASSIUM CHANNEL, SUBFAMILY K, MEMBER 18; KCNK18","url":"https://www.omim.org/entry/613655"},{"mim_id":"157300","title":"MIGRAINE WITH OR WITHOUT AURA, SUSCEPTIBILITY TO, 1","url":"https://www.omim.org/entry/157300"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Not detected","tissue_distribution":"Not detected","driving_tissues":[],"url":"https://www.proteinatlas.org/search/KCNK18"},"hgnc":{"alias_symbol":["K2p18.1","TRESK-2","TRESK2","TRESK","TRIK"],"prev_symbol":[]},"alphafold":{"accession":"Q7Z418","domains":[{"cath_id":"1.10.287.70","chopping":"15-168","consensus_level":"medium","plddt":84.1287,"start":15,"end":168},{"cath_id":"1.10.287.70","chopping":"279-384","consensus_level":"medium","plddt":86.0147,"start":279,"end":384}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q7Z418","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q7Z418-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q7Z418-F1-predicted_aligned_error_v6.png","plddt_mean":69.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KCNK18","jax_strain_url":"https://www.jax.org/strain/search?query=KCNK18"},"sequence":{"accession":"Q7Z418","fasta_url":"https://rest.uniprot.org/uniprotkb/Q7Z418.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q7Z418/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q7Z418"}},"corpus_meta":[{"pmid":"20871611","id":"PMC_20871611","title":"A dominant-negative mutation in the TRESK potassium channel is linked to familial migraine with aura.","date":"2010","source":"Nature medicine","url":"https://pubmed.ncbi.nlm.nih.gov/20871611","citation_count":255,"is_preprint":false},{"pmid":"16495368","id":"PMC_16495368","title":"TREK-2 (K2P10.1) and TRESK (K2P18.1) are major background K+ channels in dorsal root ganglion neurons.","date":"2006","source":"American journal of physiology. 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triethanolamine, unsaturated free fatty acids (arachidonic acid, DHA), and extreme pH changes.\",\n      \"method\": \"Electrophysiology (whole-cell and patch clamp) in heterologous expression systems; pharmacological analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct electrophysiological characterization with multiple pharmacological probes, foundational cloning paper with functional reconstitution\",\n      \"pmids\": [\"12754259\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"TRESK is activated 5–15-fold by cytoplasmic calcium elevation (via Ca2+-mobilizing receptors, ionomycin, IP3 microinjection, or direct Ca2+ microinjection). Activation requires cytoplasmic factors (direct Ca2+ application to inside-out patches had no effect) and is mediated by the calcium/calmodulin-dependent phosphatase calcineurin; cyclosporin A and FK506 completely blocked TRESK activation. Coexpression of constitutively active calcineurin increased basal TRESK current. Alanine-scanning mutagenesis identified serine 276 as the major functional target of calcineurin in TRESK.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes; inside-out patch clamp; microinjection of IP3, Ca2+, EGTA; pharmacology (cyclosporin A, FK506); alanine-scanning mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple orthogonal methods (patch clamp, mutagenesis, microinjection, pharmacology) in a single rigorous study establishing the calcineurin activation mechanism\",\n      \"pmids\": [\"14981085\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"TRESK-2 (KCNK18 mouse ortholog) is a functional K2P channel producing time-independent, non-inactivating, K+-selective background current with single-channel conductance of ~13–16 pS; it is inhibited by quinidine, arachidonate, and acid, but not by TEA, apamin, 4-AP, or glybenclamide, and is unaffected by intracellular GTPγS.\",\n      \"method\": \"Whole-cell patch clamp and single-channel recordings in COS-7 cells; inside-out patches; Northern blot\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct electrophysiological characterization with multiple pharmacological validations in reconstituted system\",\n      \"pmids\": [\"15123670\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Human TRESK currents are potently activated (up to 3-fold) by clinical concentrations of volatile anesthetics (isoflurane, halothane, sevoflurane, desflurane) but not by nonanesthetic compounds (nonimmobilizers) or most IV anesthetics (etomidate, thiopental, propofol). Local anesthetics inhibit TRESK in a concentration-dependent manner.\",\n      \"method\": \"Whole-cell voltage-clamp and patch-clamp in Xenopus oocytes and COS-7 cells\",\n      \"journal\": \"Anesthesia and analgesia\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — functional electrophysiology in two heterologous systems with systematic pharmacological characterization\",\n      \"pmids\": [\"15562060\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Zinc (Zn2+) and mercuric ions (Hg2+) are selective inhibitors of mouse TRESK among K2P channels (IC50 <10 µM), acting in a membrane-delimited manner on the channel itself (confirmed by outside-out single-channel recordings). Human TRESK is resistant to Zn2+ but blocked by Hg2+; His132 of mouse TRESK is partly responsible for the species difference in zinc sensitivity. Mibefradil also inhibited TRESK but with less selectivity.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes; outside-out patch clamp in COS-7 cells; site-directed mutagenesis (H132 substitution)\",\n      \"journal\": \"Molecular pharmacology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — electrophysiology plus mutagenesis, cross-species comparison identifying molecular determinant of zinc sensitivity\",\n      \"pmids\": [\"16354767\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Calcineurin activates TRESK through both its catalytic (phosphatase) activity and a non-catalytic docking interaction. TRESK's intracellular loop contains a PQIVID sequence homologous to the NFAT calcineurin-binding consensus (PXIXIT). Mutations of PQIVID to PQIVIA, PQIVAD, or PQAVAD progressively reduced calcium-dependent activation. VIVIT peptide microinjection eliminated TRESK activation. GST-TRESK intracellular loop pulled down constitutively active calcineurin in vitro; wild-type calcineurin was recruited in the presence of Ca2+/calmodulin; PQAVAD mutation and VIVIT peptide abrogated this binding.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes; site-directed mutagenesis; VIVIT peptide microinjection; GST pulldown assay with purified proteins\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstitution (GST pulldown), mutagenesis, and functional electrophysiology with multiple orthogonal methods establishing calcineurin docking mechanism\",\n      \"pmids\": [\"16569637\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"TRESK-like (14 pS) channels and TREK-2-like (50 pS) channels together account for >95% of background K+ conductance in DRG neurons at 37°C; the TRESK-like channel contributes ~16% of resting K+ current. Native TRESK channels in DRG neurons share biophysical and pharmacological properties (inhibition by acid, arachidonic acid) with cloned TRESK.\",\n      \"method\": \"Single-channel patch clamp (cell-attached and inside-out) in rat DRG neurons; RT-PCR\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct single-channel recording in native cells with biophysical and pharmacological identity confirmation\",\n      \"pmids\": [\"16495368\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Mouse TRESK channels contribute approximately 20% of the standing outward current (IKso) in DRG neurons. TRESK functional knockout mice (TRESK[G339R]) show no change in resting membrane potential but display significantly altered action potential duration, amplitude of after-hyperpolarization, and increased excitability (reduced rheobase). A single histidine residue adjacent to the GYG selectivity filter confers pH sensitivity to mouse (but not human) TRESK.\",\n      \"method\": \"Whole-cell patch clamp and current-clamp in DRG neurons from TRESK functional knockout mice vs. wild-type; site-directed mutagenesis; in situ hybridization\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function genetic model with defined electrophysiological phenotype plus mutagenesis identifying pH-sensitivity determinant\",\n      \"pmids\": [\"17962323\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"14-3-3 proteins (γ and η isoforms) directly bind to the intracellular loop of TRESK and control the kinetics of calcineurin-dependent regulation by slowing the return of K+ current to resting state after activation. Phosphorylation of serine 264 in mouse TRESK is required for 14-3-3η binding. A tethered 14-3-3η construct retained the same regulatory effect, demonstrating direct action on TRESK. Competing phosphopeptide (Ser(P)-Raf259) abolished the 14-3-3 effect. β, ζ, ε, σ, and τ isoforms of 14-3-3 did not significantly influence TRESK regulation.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes; coexpression of 14-3-3 isoforms and dominant-negative constructs; phosphopeptide microinjection; site-directed mutagenesis (S264)\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple orthogonal approaches (coexpression, tethered construct, competing peptide, mutagenesis) rigorously establishing 14-3-3 docking mechanism\",\n      \"pmids\": [\"18397886\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"TRESK in DRG neurons is activated by GPCR agonists (acetylcholine, glutamate, histamine) and inhibited by lamotrigine (~50% inhibition at 30 µM in COS-7 cells). Native TRESK in DRG shares pharmacological properties (inhibited by acid, arachidonic acid; not by zinc) with cloned TRESK.\",\n      \"method\": \"Whole-cell patch clamp in DRG neurons and COS-7 cells transfected with mouse TRESK; pharmacological analysis\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct electrophysiology in native and transfected cells; single lab, two experimental systems\",\n      \"pmids\": [\"18190784\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"N-linked glycosylation at a single residue in the first external loop is required for proper cell surface expression of TRESK. Glycosylation-deficient mutants show >80% reduction in current amplitude and >50% reduction in cell surface fluorescence in confocal microscopy of GFP-tagged TRESK.\",\n      \"method\": \"Site-directed mutagenesis; Western immunoblotting; two-electrode voltage clamp in Xenopus oocytes; confocal microscopy of GFP-tagged constructs\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis plus biochemical and imaging evidence in a single study with multiple orthogonal approaches\",\n      \"pmids\": [\"20006580\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"TRESK is inhibited by phosphorylation via two distinct pathways converging on the intracellular loop: (1) PKA phosphorylates Ser-264 (the 14-3-3 binding site), accelerating current return to resting state; (2) a separate kinase phosphorylates the cluster of Ser-274, Ser-276, and Ser-279. 14-3-3 binding to Ser-264 additionally inhibits the kinase targeting the Ser-274/276/279 cluster, independently of direct TRESK–14-3-3 interaction.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes; site-directed mutagenesis (S264E, S276E, S274/276/279 cluster); coexpression experiments\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — systematic mutagenesis combined with functional electrophysiology dissecting two distinct phosphorylation inhibitory pathways\",\n      \"pmids\": [\"20215114\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"The TRESK frameshift mutation F139WfsX24 causes complete loss of TRESK channel function, and the mutant subunit suppresses wild-type TRESK channel function through a dominant-negative mechanism (demonstrated in Xenopus oocytes). The mutation segregates perfectly with typical migraine with aura in a large pedigree.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes; co-expression of wild-type and mutant subunits; genetic linkage analysis\",\n      \"journal\": \"Nature medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — functional electrophysiology demonstrating dominant-negative mechanism replicated with genetic evidence in a large pedigree\",\n      \"pmids\": [\"20871611\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"TRESK knockout mice show a discrete 8% increase in isoflurane minimum alveolar concentration compared to wild-type, supporting a contribution of TRESK to volatile anesthetic sensitivity, though TRESK alone is not critical for baseline CNS function.\",\n      \"method\": \"Homologous recombination knockout mice; minimum alveolar concentration determination for volatile anesthetics\",\n      \"journal\": \"Anesthesiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo genetic loss-of-function with defined quantitative anesthetic phenotype; single lab\",\n      \"pmids\": [\"21042202\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"MARK1, MARK2, and MARK3 (microtubule affinity-regulating kinases; PAR-1/MARK family) inhibit TRESK by phosphorylating the cluster of Ser-274, Ser-276, and Ser-279 in the intracellular loop, accelerating return of TRESK current to resting state after calcineurin-dependent activation. MARK2 does not phosphorylate Ser-264 (the 14-3-3 binding site). Several other serine-threonine kinases tested had no effect.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes; coexpression of MARK isoforms; site-directed mutagenesis of the S274/276/279 cluster\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — functional electrophysiology plus mutagenesis identifying specific kinase and phosphorylation sites; selectivity established by testing multiple kinases\",\n      \"pmids\": [\"22145024\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The mutant TRESK F139WfsX24 subunit exerts dominant-negative effects on whole-cell TRESK current AND on the level of TRESK channels at the plasma membrane through heterodimerization with wild-type subunits in HEK293T cells. Expression of mutant TRESK in mouse trigeminal ganglion neurons decreases lamotrigine-sensitive K+ current and causes hyperexcitability (higher input resistance, lower current threshold for action potentials, higher spike frequency).\",\n      \"method\": \"Whole-cell patch clamp in HEK293T cells and cultured trigeminal ganglion neurons; surface biotinylation assay; current-clamp recordings\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (patch clamp, surface trafficking assay) in both heterologous and native neuronal systems\",\n      \"pmids\": [\"23904616\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The TRESK C110R variant causes complete loss of function and dominant-negative suppression of wild-type TRESK current in Xenopus oocytes, similar to the migraine-associated frameshift mutant, yet C110R is present in both migraine and control cohorts, indicating that loss of TRESK function alone is not sufficient to cause migraine.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes; functional characterization of missense variants\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct electrophysiological characterization with genetic epidemiological context, single lab but clear mechanistic result\",\n      \"pmids\": [\"22355750\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Membrane stretch (laminar shear stress, hypotonic cell swelling) increases TRESK currents by 22–40%, while cell shrinkage (hypertonic solution) decreases them. Negative pressure applied to trigeminal neurons increases TRESK channel open probability 1.51-fold. TRESK currents are additively inhibited by arachidonic acid, acidic pH, and hypertonic stimulation.\",\n      \"method\": \"Whole-cell patch clamp and single-channel recordings in heterologous systems (F-11 cells) and trigeminal neurons; osmotic swelling/shrinkage; shear stress application\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct electrophysiological recording in both heterologous and native cells with multiple mechanical stimuli\",\n      \"pmids\": [\"23691227\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Cloxyquin (5-chloroquinolin-8-ol) activates TRESK with an EC50 of 3.8 µM (thallium flux assay) and approximately 2-fold increase in outward current (patch clamp), with good selectivity against other potassium channels tested.\",\n      \"method\": \"Thallium flux assay; whole-cell patch clamp electrophysiology in U2OS cells\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal functional assays confirming activation; single lab\",\n      \"pmids\": [\"24383077\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Human TRESK contains a second calcineurin docking site, LQLP, in its intracellular loop in addition to PQIIIS. The LQLP→AQAP mutation alone did not change the amplitude of TRESK activation at high calcium but slowed the response and prevented activation by modest calcium elevation. Combined mutations of both PQIIIS and LQLP were required to eliminate calcium-dependent regulation. LQLP acts as a distinct determinant of calcium sensitivity, separate from the affinity-determining role of PQIIIS.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes; site-directed mutagenesis of LQLP and PQIIIS motifs; calcium calibration experiments\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — systematic mutagenesis with functional electrophysiology identifying two distinct calcineurin docking sites with distinct roles\",\n      \"pmids\": [\"25202008\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Overexpression of TRESK in mouse trigeminal ganglion neurons (via lipofectamine transfection) produces a 2-fold increase in lamotrigine-sensitive persistent K+ current and total background K+ current, with decreased input resistance and 2-fold higher current threshold for action potential initiation in both IB4+ and IB4- neurons. TRESK overexpression also inhibits capsaicin-evoked action potentials.\",\n      \"method\": \"Whole-cell patch clamp and current-clamp in cultured mouse TG neurons overexpressing TRESK; Western blot for TRESK protein levels\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gain-of-function experiment in native neurons with defined electrophysiological readouts and protein-level verification\",\n      \"pmids\": [\"24466320\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"The non-migraine-associated C110R variant reduces endogenous TRESK currents in trigeminal ganglion neurons, but to a significantly smaller degree than the migraine-associated frameshift mutant, and only the frameshift mutant (not C110R) produces significant hyperexcitability of TG neurons.\",\n      \"method\": \"Whole-cell patch clamp in HEK293T cells and cultured mouse TG neurons expressing C110R or mutant TRESK; current-clamp recordings\",\n      \"journal\": \"Journal of neurophysiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct comparison of two variants in native neurons with quantitative electrophysiological outcome measures\",\n      \"pmids\": [\"24805079\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Tubulin binds specifically to the intracellular loop of TRESK in vitro at a 16 amino acid sequence (LVLGRLSYSIISNLDE). The tubulin-binding site overlaps with the PKA-dependent 14-3-3 docking region, and 14-3-3 competes with tubulin for binding to the TRESK cytoplasmic loop.\",\n      \"method\": \"Affinity chromatography with GST-TRESK loop as bait; pulldown from mouse brain cytosol; successive truncation experiments; competitive binding assay\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — affinity chromatography and competitive binding in vitro; authors note interaction in living cells remains to be established\",\n      \"pmids\": [\"24830385\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Lysophosphatidic acid (LPA) activates TRESK through LPA receptors in DRG neurons, increasing background K+ current (IKso) and attenuating nociceptor excitability. In TRESK knockout DRG neurons, LPA does not increase IKso, confirming TRESK mediates this effect. LPA simultaneously activates both TRPV1 (depolarizing) and TRESK (hyperpolarizing) in co-expression experiments.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes co-expressing TRESK and LPA receptors; whole-cell patch clamp in DRG neurons from TRESK-wt and TRESK-ko mice; current-clamp recordings\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout plus heterologous co-expression confirming receptor-mediated TRESK activation with defined functional consequence in native neurons\",\n      \"pmids\": [\"26224542\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Cloxyquin selectively activates mouse and human TRESK (~4-fold) in a state-dependent manner: it potently activates TRESK in the resting (phosphorylated) state but does not further activate TRESK after calcineurin-dependent activation or in constitutively active mutants (S276A, F156A, F364A). Cloxyquin activates TRESK via a Ca2+/calcineurin-independent mechanism and is selective for TRESK within the K2P family. It also activates background K+ current in a subpopulation of DRG neurons.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes; whole-cell patch clamp in mouse DRG neurons; site-directed mutagenesis; pharmacological selectivity screen of K2P channels\",\n      \"journal\": \"British journal of pharmacology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic mutagenesis plus electrophysiology in both heterologous and native cells establishing state-dependent, calcineurin-independent mechanism\",\n      \"pmids\": [\"28419410\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"The TRESK frameshift mutation F139WfsX24 (TRESK-MT) generates via alternative translation initiation (fsATI) a second protein fragment, TRESK-MT2, from the same mRNA. TRESK-MT2 co-assembles with TREK1 and TREK2 and inhibits their activity, increasing trigeminal sensory neuron excitability and producing a migraine-like phenotype in rodents. The non-migraine-associated C110R mutant does not produce fsATI or TRESK-MT2, explaining the differential migraine association of the two mutations.\",\n      \"method\": \"In vitro translation assays; co-immunoprecipitation; patch clamp electrophysiology in heterologous cells and primary neurons; in vivo rodent behavioral assays\",\n      \"journal\": \"Neuron\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (biochemistry, electrophysiology, in vivo) establishing a new mechanism (fsATI) with functional and behavioral validation\",\n      \"pmids\": [\"30573346\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Anionic phospholipids (PIP2 analog, Folch fraction MLVs) activate human TRESK but not rat TRESK through electrostatic binding to a 14 amino acid sequence in the large cytoplasmic loop at the membrane-cytosol interface. Disruption of this sequence inhibits hTRESK. Replacing the equivalent rat sequence with the human anionic phospholipid-binding site confers PIP2 sensitivity to rat TRESK. Gq/11-linked GPCR stimulation (with calcineurin inhibition) reduces hTRESK current, consistent with PIP2 hydrolysis-dependent inhibition.\",\n      \"method\": \"Binding assay with multilamellar vesicles; whole-cell patch clamp; site-directed mutagenesis; chimeric channel constructs; GPCR stimulation experiments\",\n      \"journal\": \"Molecular neurobiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — biochemical binding, mutagenesis, chimeric channels, and functional electrophysiology in multiple cell types establishing novel regulatory mechanism\",\n      \"pmids\": [\"30039335\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Tumor-produced VEGF activates VEGFR2 on DRG neurons, increasing DSCR1 (calcineurin inhibitor) abundance, which reduces calcineurin-mediated NFAT activation and thereby decreases TRESK transcription, resulting in sensory neuron hyperexcitability and pain. Intrathecal calcineurin restored TRESK expression and abolished DRG hyperexcitability and pain in tumor-bearing rats.\",\n      \"method\": \"In vivo bone metastasis model; TRESK overexpression/knockdown in DRG; patch clamp; immunohistochemistry; VEGF pathway manipulation\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo pathway dissection with gain and loss of function, but complex multi-step signaling pathway; single lab\",\n      \"pmids\": [\"30327410\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Novel-type PKC isoforms η and ε activate human TRESK by indirect dephosphorylation of Ser-264 via inhibition of the kinase that rephosphorylates this site, not via calcineurin. S264A and S264E mutations abolished PMA-induced TRESK activation. Mutations of calcineurin-binding sites did not prevent PKC-dependent activation. PKC-dependent dephosphorylation of TRESK was confirmed by Phos-tag SDS-PAGE.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes; coexpression of PKC isoforms; site-directed mutagenesis (S264A/E, calcineurin-binding site mutations); Phos-tag SDS-PAGE\",\n      \"journal\": \"Molecular pharmacology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — functional electrophysiology, biochemical phosphorylation assay, and mutagenesis establishing distinct PKC-dependent activation mechanism\",\n      \"pmids\": [\"30992311\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"TRESK knockout mice show enhanced mechanical and cold sensitivity in behavioral tests and in skin nerve C-fiber recordings, without altered heat sensitivity. TRESK deletion also enhances excitability of isolated nociceptors and exacerbates cold allodynia (but not thermal hyperalgesia) in chronic pain states.\",\n      \"method\": \"TRESK knockout mice; behavioral testing (von Frey, cold plate, heat); skin-nerve fiber preparation; whole-cell patch clamp of isolated nociceptors\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout with multiple complementary behavioral, electrophysiological, and ex vivo approaches establishing modality-specific sensory function\",\n      \"pmids\": [\"31919847\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In iPSC-derived nociceptors from migraine patients with F139WfsX24 mutation, there is loss of functional TRESK at the membrane with significantly increased neuronal excitability. CRISPR-Cas9 correction of the F139WfsX24 mutation reverses the heightened excitability. C110R nociceptors show no change in excitability and preserved TRESK current. The TRESK activator cloxyquin reduces spontaneous firing of nociceptors in an in vitro human pain model.\",\n      \"method\": \"iPSC-derived nociceptors; CRISPR-Cas9 gene correction; patch clamp electrophysiology; in vitro human pain model with cloxyquin\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — CRISPR causal rescue experiment in human iPSC neurons plus pharmacological validation; multiple orthogonal approaches\",\n      \"pmids\": [\"31742594\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TRESK and TREK-2 subunits form functional heterodimers in primary somatosensory neurons. Using a covalently linked TRESK/TREK-2 tandem construct, the heterodimer shows an intermediate single-channel conductance between TRESK and TREK-2 homodimers, retains calcineurin-dependent regulation (conferred by the TRESK subunit), and acquires sensitivity to the TREK-2-selective activator T2A3 (conferred by the TREK-2 subunit). In trigeminal neurons, native channels with biophysical and pharmacological properties matching the TRESK/TREK-2 tandem were detected.\",\n      \"method\": \"Covalently linked tandem channel constructs; two-electrode voltage clamp in Xenopus oocytes; single-channel patch clamp in native trigeminal neurons; pharmacological characterization with TREK-2 selective activator T2A3\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — tandem construct reconstitution plus native cell single-channel recordings with pharmacological fingerprinting confirming physiological heterodimerization\",\n      \"pmids\": [\"32641496\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"TRESK inhibition increases TRPV1-mediated calcium signals in DRG neurons and potentiates capsaicin-induced CGRP release from trigeminal afferents and meningeal blood flow. TRESK activation decreases capsaicin sensitivity of sensory neurons. These effects are absent in TRESK knockout animals, confirming that TRESK modulates TRPV1-mediated nociceptor function.\",\n      \"method\": \"Calcium imaging in DRG neurons; CGRP release assay from trigeminal afferents; meningeal blood flow measurement; pharmacological TRESK activation/inhibition; TRESK knockout mice\",\n      \"journal\": \"Cephalalgia\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — pharmacological manipulation confirmed by genetic knockout with multiple functional readouts in native tissue\",\n      \"pmids\": [\"33525904\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"The short intracellular C-terminal region (iCtr) following the fourth transmembrane segment of TRESK is a critical determinant of channel activity. Mutations of positive residues in proximal iCtr lock TRESK in a low-activity, calcineurin-insensitive state. Replacing distal iCtr with a sequence designed to interact with the inner plasma membrane surface increases TRESK activity to unprecedented levels. The ENaR (epithelial Na+ current ratio) method was developed to normalize K+ current to channel surface expression.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes; ENaR (epithelial sodium current ratio) method using ENaC as internal reference; single-channel recordings; site-directed mutagenesis of iCtr residues\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — novel functional method combined with systematic mutagenesis and single-channel recordings revealing iCtr as major gating determinant\",\n      \"pmids\": [\"37084812\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"NDFIP1 (Nedd4 family-interacting protein 1) interacts with TRESK (confirmed by co-immunoprecipitation) and negatively regulates TRESK current. NDFIP1 coexpression induces ubiquitination of TRESK and abolishes TRESK current. Mutations in the three PPxY motifs of NDFIP1 (required for Nedd4 ubiquitin ligase binding) prevented TRESK current reduction. Dominant-negative Nedd4 partially reversed NDFIP1's effect on TRESK current.\",\n      \"method\": \"Two-electrode voltage clamp in Xenopus oocytes; co-immunoprecipitation; ubiquitination assay; site-directed mutagenesis of NDFIP1 PPxY motifs; dominant-negative Nedd4 coexpression\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal biochemical and functional methods (Co-IP, ubiquitination assay, mutagenesis, dominant-negative) establishing NDFIP1-Nedd4 ubiquitin-mediated regulation\",\n      \"pmids\": [\"39201565\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"TRESK regulates the excitability of MrgprA3-expressing pruriceptors. TRESK knockout mice show enhanced firing of MrgprA3+ neurons and increased acute itch response to chloroquine (but not histamine, BAM8-22, or leukotriene C4). TRESK deletion exacerbates chronic itch in models of allergic contact dermatitis, dry skin, and imiquimod-induced psoriasis. Pharmacological TRESK activation reduces both acute and chronic itch in wild-type but not TRESK KO mice.\",\n      \"method\": \"TRESK knockout mice; behavioral itch assays; electrophysiological recordings from MrgprA3+ neurons; pharmacological TRESK activation; chronic itch mouse models\",\n      \"journal\": \"Pain\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout combined with pharmacological rescue in multiple itch models, confirming TRESK role in specific pruriceptor subpopulation\",\n      \"pmids\": [\"40062712\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TRESK (KCNK18/K2P18.1) is a two-pore-domain background K+ channel constitutively phosphorylated (inhibited) at two intracellular loop regions: a Ser-264 site (targeted by PKA, bound by 14-3-3η/γ) and a Ser-274/276/279 cluster (phosphorylated by MARK1/2/3 kinases); calcium signals activate TRESK via calcineurin, which docks to two non-catalytic binding motifs (PQIVID/PQIIIS and LQLP) and dephosphorylates these serines, with novel-type PKC providing an additional calcineurin-independent activation pathway through indirect Ser-264 dephosphorylation; TRESK forms both homodimers and functional heterodimers with TREK-2 in primary sensory neurons; cell-surface expression requires N-linked glycosylation; activity is further modulated by anionic phospholipids (human-specific), membrane stretch, and NDFIP1-Nedd4-mediated ubiquitination; the channel is the dominant background K+ conductance in dorsal root and trigeminal ganglion neurons, setting resting membrane potential and suppressing nociceptor excitability, with loss-of-function (frameshift mutation generating fsATI-derived TRESK-MT2 that additionally inhibits TREK1/TREK2) causally linked to familial migraine with aura.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"KCNK18 encodes TRESK (K2P18.1), a two-pore-domain background K+ channel that produces an outwardly-rectifying, time-independent, non-inactivating K+-selective current and serves as a dominant background K+ conductance in dorsal root and trigeminal ganglion sensory neurons, where it sets excitability and suppresses nociceptor firing [#0, #6, #20]. The channel's defining regulatory feature is reversible phosphorylation of its large intracellular loop: it is held inhibited in the resting state by phosphorylation of Ser-264 (a PKA site and 14-3-3 binding site) and of a Ser-274/276/279 cluster targeted by MARK1/2/3 kinases, and is activated several-fold when cytoplasmic calcium rises and the phosphatase calcineurin docks to non-catalytic PQIVID/PQIIIS and LQLP motifs in the loop to dephosphorylate these serines [#1, #5, #8, #11, #14, #19]. Calcineurin-independent activation also occurs through novel-type PKC isoforms (η, ε) that drive indirect Ser-264 dephosphorylation [#28]. TRESK activity is further tuned by N-linked glycosylation required for surface expression, membrane stretch, anionic phospholipids acting at a human-specific cytoplasmic site, the intracellular C-terminal region as a gating determinant, and NDFIP1–Nedd4-mediated ubiquitination that suppresses current [#10, #17, #26, #33, #34]. TRESK assembles as homodimers and as functional heterodimers with TREK-2 in somatosensory neurons, and its loss enhances mechanical, cold, and itch sensitivity and potentiates TRPV1/CGRP signaling [#29, #31, #32, #35]. A dominant-negative frameshift mutation (F139WfsX24) that abolishes TRESK function and, via alternative translation initiation, generates a TRESK-MT2 fragment that additionally inhibits TREK1/TREK2 is causally linked to familial migraine with aura, with CRISPR correction in patient iPSC nociceptors reversing the associated hyperexcitability [#12, #25, #30].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Established the molecular and biophysical identity of TRESK, defining it as a background K+ channel and resolving what kind of conductance KCNK18 produces.\",\n      \"evidence\": \"Whole-cell and patch-clamp electrophysiology with pharmacology in heterologous systems\",\n      \"pmids\": [\"12754259\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No physiological regulator or native cellular role identified\", \"Pharmacology limited to blockers without endogenous modulators\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Showed that calcium activates TRESK indirectly through calcineurin acting on intracellular serines, answering how a background channel is dynamically regulated by signaling.\",\n      \"evidence\": \"Voltage clamp in Xenopus oocytes, microinjection, calcineurin pharmacology, and alanine-scanning mutagenesis (Ser-276); parallel cloning of the mouse ortholog confirmed conserved biophysics\",\n      \"pmids\": [\"14981085\", \"15123670\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of calcineurin recruitment to the channel not yet defined\", \"Kinases that re-phosphorylate the sites unknown\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Identified TRESK as a target of clinical anesthetics, linking the channel to drug-modifiable excitability.\",\n      \"evidence\": \"Voltage-clamp in oocytes and COS-7 cells with systematic anesthetic and local-anesthetic panels\",\n      \"pmids\": [\"15562060\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Binding site for volatile anesthetics not mapped\", \"In vivo relevance not established\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Defined metal-ion pharmacology and a molecular determinant (His132) of species-specific zinc sensitivity, providing tools to distinguish TRESK from other K2P channels.\",\n      \"evidence\": \"Voltage clamp, outside-out single-channel recordings, and H132 mutagenesis with cross-species comparison\",\n      \"pmids\": [\"16354767\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological role of zinc/mercury modulation unknown\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Resolved the molecular basis of calcineurin docking, demonstrating that an NFAT-like PQIVID motif recruits the phosphatase, explaining how a non-substrate-like channel is targeted by calcineurin.\",\n      \"evidence\": \"GST pulldown with purified proteins, VIVIT peptide microinjection, mutagenesis, and voltage clamp\",\n      \"pmids\": [\"16569637\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"A second docking determinant not yet recognized\", \"Re-phosphorylating kinases still unidentified\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Demonstrated that native TRESK-like channels carry a substantial fraction of background K+ conductance in DRG neurons, anchoring the channel's physiological role in sensory neurons.\",\n      \"evidence\": \"Single-channel patch clamp in rat DRG neurons with RT-PCR and pharmacological identity matching\",\n      \"pmids\": [\"16495368\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Channel identity inferred from biophysics/pharmacology, not genetic ablation\", \"Contribution to behavior untested\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Genetic loss-of-function established TRESK's contribution to DRG action-potential properties and excitability, and mapped a pH-sensitivity residue near the selectivity filter.\",\n      \"evidence\": \"Patch/current clamp in TRESK[G339R] knockout DRG neurons plus mutagenesis and in situ hybridization\",\n      \"pmids\": [\"17962323\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Resting membrane potential unchanged, implying redundancy\", \"Behavioral consequences not assessed\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Identified 14-3-3γ/η as phospho-Ser-264-dependent loop partners controlling the kinetics of calcineurin regulation, adding a layer of temporal control to channel gating.\",\n      \"evidence\": \"Voltage clamp with 14-3-3 coexpression, tethered constructs, competing phosphopeptide, and S264 mutagenesis\",\n      \"pmids\": [\"18397886\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinase generating phospho-Ser-264 not yet defined\", \"Isoform selectivity in native neurons untested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Dissected two distinct inhibitory phosphorylation pathways (PKA at Ser-264 and a separate kinase at the Ser-274/276/279 cluster) and showed cross-talk via 14-3-3, building the integrated phospho-regulatory model.\",\n      \"evidence\": \"Voltage clamp in oocytes with phosphomimetic and cluster mutagenesis and coexpression; pharmacological GPCR activation in DRG identified upstream agonists\",\n      \"pmids\": [\"20215114\", \"18190784\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the Ser-274/276/279 kinase still unknown at this stage\", \"PKA recruitment mechanism unclear\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Established N-linked glycosylation as a requirement for TRESK surface expression, defining a post-translational checkpoint for channel availability.\",\n      \"evidence\": \"Mutagenesis with Western blot, voltage clamp, and confocal imaging of GFP-tagged channel\",\n      \"pmids\": [\"20006580\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Trafficking machinery downstream of glycosylation not identified\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Linked a dominant-negative TRESK frameshift mutation to familial migraine with aura, providing the first human disease connection and a mechanism (suppression of wild-type subunits).\",\n      \"evidence\": \"Voltage clamp with wild-type/mutant co-expression and genetic linkage in a large pedigree\",\n      \"pmids\": [\"20871611\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How loss of a DRG/TG channel produces aura not explained\", \"Penetrance and modifiers unknown\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"In vivo knockout linked TRESK quantitatively to volatile anesthetic sensitivity while showing it is dispensable for baseline CNS function.\",\n      \"evidence\": \"Homologous-recombination knockout mice with minimum alveolar concentration measurement\",\n      \"pmids\": [\"21042202\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Small effect size implies redundancy with other K2P channels\", \"Single-lab in vivo result\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identified MARK1/2/3 as the kinases phosphorylating the Ser-274/276/279 cluster, completing the assignment of the two inhibitory phosphorylation pathways.\",\n      \"evidence\": \"Voltage clamp with MARK isoform coexpression and cluster mutagenesis, with selectivity testing of multiple kinases\",\n      \"pmids\": [\"22145024\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological signals that engage MARK kinases on TRESK unknown\", \"Direct phosphorylation not confirmed biochemically in this assay\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Distinguished a migraine-causing frameshift mutant from a functionally null but non-migraine C110R variant, showing that loss of TRESK current alone is insufficient for disease and demanding a further mechanism.\",\n      \"evidence\": \"Voltage clamp characterization of missense and frameshift variants in oocytes with epidemiological context\",\n      \"pmids\": [\"22355750\", \"23904616\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"What distinguishes the frameshift from C110R molecularly unresolved at this point\", \"Native neuronal consequences then incompletely tested\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Resolved a second calcineurin docking site (LQLP) acting as a calcium-sensitivity determinant distinct from the affinity-setting PQIIIS, refining the bipartite recruitment model.\",\n      \"evidence\": \"Voltage clamp with LQLP/PQIIIS mutagenesis and calcium calibration in oocytes\",\n      \"pmids\": [\"25202008\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of dual docking not determined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Demonstrated tubulin binding to the TRESK loop overlapping the 14-3-3 site, suggesting cytoskeletal cross-regulation of the channel.\",\n      \"evidence\": \"Affinity chromatography, brain-cytosol pulldown, truncation, and competitive binding in vitro\",\n      \"pmids\": [\"24830385\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Interaction in living cells not established\", \"Functional consequence on current not shown\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Gain-of-function in native TG neurons confirmed TRESK as a brake on nociceptor firing, including capsaicin-evoked spiking, and comparative variant work tied excitability changes to the migraine mutant.\",\n      \"evidence\": \"TRESK overexpression with patch/current clamp and Western blot in TG neurons; parallel C110R vs frameshift comparison in TG neurons\",\n      \"pmids\": [\"24466320\", \"24805079\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Endogenous stimuli driving these changes in vivo not defined\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Showed TRESK is mechanosensitive, responding to stretch and osmotic changes, broadening its role as an integrator of physical and chemical stimuli.\",\n      \"evidence\": \"Whole-cell and single-channel recordings in F-11 cells and trigeminal neurons under shear, swelling, and shrinkage\",\n      \"pmids\": [\"23691227\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular mechanism of mechanotransduction unmapped\", \"Physiological role of stretch sensitivity untested in vivo\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identified LPA-receptor signaling as a physiological GPCR input that activates TRESK to attenuate nociceptor excitability, with knockout confirming specificity.\",\n      \"evidence\": \"Co-expression voltage clamp plus patch/current clamp in TRESK-wt and -ko DRG neurons\",\n      \"pmids\": [\"26224542\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Signaling steps from LPA receptor to channel dephosphorylation not fully mapped\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Resolved why only the frameshift mutation causes migraine: alternative translation initiation produces TRESK-MT2, which co-assembles with and inhibits TREK1/TREK2, providing a gain-of-pathology mechanism beyond simple TRESK loss.\",\n      \"evidence\": \"In vitro translation, co-IP, patch clamp in heterologous and primary neurons, and in vivo rodent behavior\",\n      \"pmids\": [\"30573346\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of TRESK-MT2/TREK heterodimer inhibition not determined\", \"Human in vivo validation pending\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined anionic phospholipids as a human-specific activating input acting at a cytoplasmic loop site, and novel-type PKC as a calcineurin-independent activator, expanding the regulatory repertoire.\",\n      \"evidence\": \"MLV binding, mutagenesis, chimeras and GPCR experiments for phospholipids; PKC coexpression, mutagenesis, and Phos-tag SDS-PAGE for PKC pathway\",\n      \"pmids\": [\"30039335\", \"30992311\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Why phospholipid sensitivity is species-restricted not explained\", \"Identity of the PKC-inhibited Ser-264 kinase unknown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Connected TRESK transcriptional downregulation to a tumor VEGF–DSCR1–calcineurin–NFAT axis as a driver of cancer pain, extending TRESK regulation to gene-expression control.\",\n      \"evidence\": \"In vivo bone metastasis model with DRG overexpression/knockdown, patch clamp, IHC, and pathway manipulation\",\n      \"pmids\": [\"30327410\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Multi-step pathway from single lab\", \"Direct NFAT regulation of the KCNK18 promoter not shown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Knockout phenotyping defined modality-specific sensory roles, showing TRESK constrains mechanical and cold (but not heat) sensitivity and nociceptor excitability.\",\n      \"evidence\": \"Behavioral testing, skin-nerve C-fiber recordings, and patch clamp of isolated nociceptors in knockout mice\",\n      \"pmids\": [\"31919847\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cellular basis of modality specificity unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Provided causal human evidence that the migraine frameshift mutation drives nociceptor hyperexcitability, since CRISPR correction reversed it, and validated cloxyquin as a corrective activator.\",\n      \"evidence\": \"iPSC-derived nociceptors with CRISPR-Cas9 correction, patch clamp, and an in vitro human pain model\",\n      \"pmids\": [\"31742594\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Link from nociceptor hyperexcitability to migraine aura still indirect\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Demonstrated functional TRESK/TREK-2 heterodimers in somatosensory neurons, revealing that native background conductance is a composite channel with mixed regulatory and pharmacological properties.\",\n      \"evidence\": \"Covalently linked tandem constructs, voltage clamp, and native single-channel recordings with TREK-2-selective T2A3\",\n      \"pmids\": [\"32641496\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and relative abundance of heterodimers in vivo not quantified\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Showed TRESK gates TRPV1-mediated calcium signaling and CGRP release, mechanistically linking the channel to peripheral nociceptive and migraine-relevant signaling.\",\n      \"evidence\": \"Calcium imaging, CGRP release and meningeal blood-flow assays with pharmacology confirmed in knockout mice\",\n      \"pmids\": [\"33525904\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether TRESK and TRPV1 physically interact not addressed\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified the intracellular C-terminal region as a major gating determinant whose membrane interaction sets channel activity, deepening the structural understanding of TRESK regulation.\",\n      \"evidence\": \"Voltage clamp with the ENaR normalization method, single-channel recordings, and iCtr mutagenesis in oocytes\",\n      \"pmids\": [\"37084812\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"High-resolution structure of the iCtr–membrane interface lacking\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Established NDFIP1–Nedd4-mediated ubiquitination as a degradative/regulatory pathway suppressing TRESK current, adding protein turnover to the regulatory model.\",\n      \"evidence\": \"Co-IP, ubiquitination assay, PPxY-motif mutagenesis, dominant-negative Nedd4, and voltage clamp in oocytes\",\n      \"pmids\": [\"39201565\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological/disease contexts engaging NDFIP1-Nedd4 on TRESK unknown\", \"Confirmation in native neurons pending\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extended TRESK's role to itch, showing it constrains MrgprA3+ pruriceptor excitability and chronic itch, broadening its sensory remit beyond pain.\",\n      \"evidence\": \"Knockout mice with itch behavior, MrgprA3+ neuron recordings, pharmacological activation, and chronic itch models\",\n      \"pmids\": [\"40062712\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stimulus specificity (chloroquine but not histamine) mechanistically unexplained\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How TRESK's diverse regulatory inputs are integrated at the structural level and how loss of a peripheral sensory K+ channel produces centrally-perceived migraine aura remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No high-resolution structure of the regulated intracellular loop/iCtr\", \"Mechanistic link from nociceptor hyperexcitability to migraine aura unestablished\", \"Re-phosphorylating kinase for Ser-264 not definitively identified\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [0, 2, 6]},\n      {\"term_id\": \"GO:0005267\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [10, 15, 20]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [6, 20, 29]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 5, 23, 28]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [12, 25, 30]}\n    ],\n    \"complexes\": [\n      \"TRESK homodimer\",\n      \"TRESK/TREK-2 heterodimer\"\n    ],\n    \"partners\": [\n      \"PPP3CA\",\n      \"YWHAH\",\n      \"YWHAG\",\n      \"MARK2\",\n      \"TREK-2\",\n      \"NDFIP1\",\n      \"NEDD4\",\n      \"TREK1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":6,"faith_pct":83.33333333333333}}