{"gene":"SLC6A8","run_date":"2026-06-10T07:46:34","timeline":{"discoveries":[{"year":2001,"finding":"SLC6A8 encodes a Na+- and Cl--dependent creatine transporter; loss-of-function mutations cause absent creatine uptake in fibroblasts, establishing SLC6A8 as the X-linked creatine transporter responsible for cerebral creatine deficiency syndrome.","method":"Creatine uptake assay in patient fibroblasts with hemizygous nonsense mutation; proton MRS of brain","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct loss-of-function cellular uptake assay in patient fibroblasts, replicated across multiple subsequent studies","pmids":["11326334"],"is_preprint":false},{"year":1999,"finding":"Human SLC6A8 (CRT-1) expressed in Xenopus oocytes mediates Na+- and Cl--dependent creatine uptake with Km ~20 µM; stoichiometry requires at least two Na+ ions and one Cl- per creatine molecule; transport is inhibited by protein kinase C activator PMA but not by PKA activator 8-bromo-cAMP.","method":"Heterologous expression in Xenopus oocytes, electrophysiology, ion-substitution kinetics, pharmacology, site-directed mutagenesis (A285P variant)","journal":"Archives of biochemistry and biophysics","confidence":"High","confidence_rationale":"Tier 1 / Moderate — reconstituted transport in Xenopus oocytes with full kinetic and ion-stoichiometry analysis, multiple orthogonal methods in one study","pmids":["9882430"],"is_preprint":false},{"year":2005,"finding":"The serum- and glucocorticoid-inducible kinases SGK1 and SGK3 (but not SGK2 or PKB) positively regulate SLC6A8 transport activity by increasing its maximal transport rate without altering substrate affinity.","method":"Heterologous expression in Xenopus oocytes with co-expression of wild-type, constitutively active, and kinase-dead SGK isoforms; dual-electrode voltage clamp","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — electrophysiology with multiple kinase constructs and controls, single lab but multiple orthogonal reagents","pmids":["16036218"],"is_preprint":false},{"year":2006,"finding":"mTOR stimulates SLC6A8 creatine transport activity (maximal rate), an effect blocked by rapamycin and by co-expression of kinase-dead SGK1, placing mTOR upstream of SGK1 in SLC6A8 regulation.","method":"Xenopus oocyte co-expression, dual-electrode voltage clamp, rapamycin inhibition","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — electrophysiology with pharmacological and dominant-negative controls, single lab","pmids":["16466692"],"is_preprint":false},{"year":2007,"finding":"PIKfyve, acting downstream of SGK1 phosphorylation at its SGK consensus site (S318), mediates SGK1-dependent stimulation of SLC6A8 transport activity; the inactive SGK1 mutant K127N blocks the PIKfyve effect, and S318A-PIKfyve blocks SGK1's effect on SLC6A8.","method":"Xenopus oocyte co-expression of SLC6A8, PIKfyve, and SGK1 variants; dual-electrode voltage clamp","journal":"Cellular physiology and biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — electrophysiology with multiple dominant-negative and point-mutant constructs, single lab","pmids":["17982255"],"is_preprint":false},{"year":2012,"finding":"JAK2 down-regulates SLC6A8 creatine transport by decreasing maximal transport rate without affecting substrate affinity; kinase-dead JAK2 (K882E) has no effect; JAK2 does not alter the rate of carrier removal from the membrane (brefeldin A experiment), suggesting interference with carrier insertion.","method":"Xenopus oocyte co-expression, dual-electrode voltage clamp, brefeldin A experiment, JAK2 inhibitor AG490","journal":"The Journal of membrane biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — electrophysiology with kinase-dead control and mechanistic sub-experiments, single lab","pmids":["22407360"],"is_preprint":false},{"year":2014,"finding":"SPAK (constitutively active T233E-SPAK, WNK-insensitive T233A-SPAK, but not catalytically inactive D212A-SPAK) and OSR1 (wild-type, T185E, T185A, but not D164A-OSR1) negatively regulate SLC6A8 by decreasing maximal transport rate.","method":"Xenopus oocyte co-expression of SLC6A8 with SPAK/OSR1 variants; dual-electrode voltage clamp","journal":"Kidney & blood pressure research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — electrophysiology with multiple kinase constructs covering constitutively active and catalytically dead forms, single lab","pmids":["25531585"],"is_preprint":false},{"year":2014,"finding":"Klotho protein upregulates SLC6A8 creatine transport activity by stabilizing the carrier at the cell membrane; this effect requires β-glucuronidase activity of Klotho and is reproduced by recombinant soluble Klotho; Klotho delays brefeldin A-induced decline of creatine-induced current.","method":"Xenopus oocyte co-expression, dual-electrode voltage clamp, brefeldin A membrane-insertion block, β-glucuronidase inhibitor DSAL, recombinant Klotho protein","journal":"Kidney & blood pressure research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal approaches (co-expression, pharmacological inhibitor, recombinant protein), single lab","pmids":["25531216"],"is_preprint":false},{"year":2015,"finding":"JAK3 negatively regulates SLC6A8 creatine transport, decreasing maximal transport rate; constitutively active A568V-JAK3 mimics this effect while inactive K851A-JAK3 does not; the JAK3 inhibitor WHI-P154 reverses the suppression.","method":"Xenopus oocyte co-expression, dual-electrode voltage clamp, pharmacological inhibitor","journal":"Neuro-Signals","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — electrophysiology with active/inactive kinase constructs and pharmacological rescue, single lab","pmids":["26666525"],"is_preprint":false},{"year":2016,"finding":"GSK3β down-regulates SLC6A8 creatine transport (maximal transport rate); this effect is blocked by co-expression of PKB/Akt and reversed by lithium treatment; catalytically inactive K85R-GSK3β has no effect.","method":"Xenopus oocyte co-expression, dual-electrode voltage clamp, lithium treatment","journal":"Cellular physiology and biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — electrophysiology with inactive mutant, PKB/Akt epistasis, and pharmacological reversal, single lab","pmids":["27978525"],"is_preprint":false},{"year":2007,"finding":"Functional assay using site-directed mutagenesis and transient transfection of SLC6A8-deficient fibroblasts demonstrated that nine missense/deletion variants are pathogenic (abolish creatine uptake) while four variants are non-pathogenic, establishing structure-function relationships for the transporter.","method":"Site-directed mutagenesis, transient transfection into SLC6A8-deficient fibroblasts, radiolabeled creatine uptake assay","journal":"Human mutation","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct functional reconstitution in disease-relevant cells with multiple variants and controls, replicated in subsequent studies","pmids":["17465020"],"is_preprint":false},{"year":2012,"finding":"Four non-truncating SLC6A8 mutations cause complete loss of both electrogenic (current) and creatine transport activity despite proper targeting of mutant protein to the plasma membrane; the electrogenic and transport activities of SLC6A8 could not be dissociated by any tested creatine analog.","method":"Xenopus oocyte expression, dual-electrode voltage clamp, [14C]-creatine uptake, immunofluorescence and western blot for subcellular localization","journal":"Journal of inherited metabolic disease","confidence":"High","confidence_rationale":"Tier 1 / Moderate — multiple orthogonal assays (electrophysiology, radiochemical uptake, localization) in single study","pmids":["22644605"],"is_preprint":false},{"year":2006,"finding":"Overexpression of wild-type SLC6A8 ORF in SLC6A8-deficient fibroblasts fully restores creatine uptake, proving that loss of SLC6A8 function is solely responsible for the creatine uptake defect in patient cells.","method":"Transient transfection of wild-type SLC6A8 cDNA into deficient primary fibroblasts, radiolabeled creatine uptake assay","journal":"Journal of inherited metabolic disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct gain-of-function rescue experiment, single lab","pmids":["16763899"],"is_preprint":false},{"year":2009,"finding":"In rat CNS, cells co-expressing both AGAT and GAMT (capable of autonomous creatine synthesis) are rare (<20% in most structures); brain cells take up guanidinoacetate and convert it to creatine, and this uptake is competed by creatine, indicating that SLC6A8 transports guanidinoacetate between AGAT- and GAMT-expressing cells to enable creatine synthesis—explaining why SLC6A8 deficiency causes creatine deficiency despite intact synthesis enzymes.","method":"Cell-by-cell co-expression analysis by in situ hybridization/immunohistochemistry in rat CNS; reaggregating brain cell cultures with radiolabeled guanidinoacetate uptake and competition assay","journal":"Neurobiology of disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal experimental approaches (histology + cell culture uptake), single lab","pmids":["19879361"],"is_preprint":false},{"year":2011,"finding":"Ubiquitous Slc6a8 knockout (CrT−/y) mice lack creatine in brain and muscle, develop learning and memory deficits (Morris water maze, novel object recognition, fear conditioning), and show increased serotonin and 5-HIAA in hippocampus and prefrontal cortex, establishing the mouse model of CrT deficiency.","method":"Cre/loxP knockout (exons 2–4 deletion), HPLC for creatine/neurotransmitter levels, behavioral testing","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean germline KO with biochemical verification and multiple behavioral readouts","pmids":["21249153"],"is_preprint":false},{"year":2018,"finding":"Brain-specific Slc6a8 knockout mice (Nestin-cre) have reduced cerebral creatine and increased guanidinoacetate in brain, with learning and memory deficits (Morris water maze, novel object recognition, fear conditioning) and hyperactivity, demonstrating that loss of cerebral creatine—not peripheral creatine deficiency—is responsible for cognitive deficits.","method":"Conditional KO (Nestin-cre × Slc6a8flox), MRS, behavioral testing, neurochemical assay","journal":"Genes, brain, and behavior","confidence":"High","confidence_rationale":"Tier 2 / Strong — tissue-specific conditional KO with biochemical validation and multiple behavioral phenotypes","pmids":["29384270"],"is_preprint":false},{"year":2019,"finding":"Deletion of Slc6a8 specifically in dopaminergic (DAT-expressing) neurons causes hyperactivity throughout aging without impairing motor function, indicating creatine in dopaminergic neurons specifically modulates locomotor activity.","method":"Conditional KO (DATIREScre × Slc6a8flox), longitudinal locomotor activity and motor testing","journal":"Journal of molecular neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — cell-type-specific conditional KO with defined behavioral phenotype, single lab","pmids":["31520365"],"is_preprint":false},{"year":2019,"finding":"Slc6a8 ablation in macrophages (genetic knockout) suppresses intracellular creatine accumulation; creatine suppresses IFN-γ–JAK–STAT1 signaling (reducing iNOS induction) and promotes IL-4–STAT6–arginase 1 expression through chromatin remodeling, thereby reprogramming macrophage polarization from M1-like to M2-like.","method":"Genetic knockout of Slc6a8 in macrophages, genomics/metabolomics/immunological assays, cytokine stimulation with IFN-γ and IL-4, STAT1/STAT6 pathway analysis, chromatin remodeling assays, in vivo infection models","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with multi-omics and mechanistic pathway dissection in multiple assay systems","pmids":["31399282"],"is_preprint":false},{"year":2020,"finding":"Pathogenic SLC6A8 variants cause a spectrum of molecular defects including proteostatic deficiencies (reduced expression/trafficking) and disruption of the substrate-binding pocket; most variants show measurable trafficking defects; the proteostasis regulator 4-PBA enhances WT SLC6A8 activity in HEK293T cells but does not rescue the tested pathogenic variants (except minimally G132V which is temperature-sensitive).","method":"Quantitative profiling of cellular processing, trafficking, expression, and function of 8 pathogenic variants in HEK293T cells; structural modeling; 4-PBA and temperature rescue experiments","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — multiple orthogonal cellular assays plus structural modeling in a single rigorous study","pmids":["32207963"],"is_preprint":false},{"year":2021,"finding":"The small-molecule SLC6A8 inhibitor RGX-202 blocks creatine import in vitro and in vivo, reduces intracellular phosphocreatine and ATP, induces tumor apoptosis, and suppresses colorectal cancer growth; antitumor efficacy correlates with tumoral creatine kinase B expression; RGX-202 also perturbed creatine metabolism in patients with metastatic CRC in a phase 1 trial.","method":"In vitro transport inhibition assay, xenograft/syngeneic/PDX tumor models, pharmacodynamic creatine metabolite measurements in mice and human trial","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple tumor models, pharmacodynamic confirmation in human subjects, multiple orthogonal readouts","pmids":["34613776"],"is_preprint":false},{"year":2020,"finding":"Cyclocreatine is a substrate of SLC6A8; CRT is the predominant mediator of cyclocreatine uptake in HEK293 cells and in a human blood-brain barrier model (hCMEC/D3), shown by siRNA knockdown and inhibitor studies; cyclocreatine uptake is largely absent in fibroblasts from CRT-deficient patients.","method":"[14C]cyclocreatine uptake assay, siRNA knockdown of SLC6A8, pharmacological inhibition, patient fibroblasts","journal":"Pharmaceutical research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown and pharmacological inhibition with patient-derived cells, single lab","pmids":["32124083"],"is_preprint":false},{"year":2023,"finding":"Mass spectrometry identified protein interaction partners of wild-type SLC6A8 in HEK293 cells; pathogenic variants led to enrichment of ER protein partners, indicating that pathogenic mutations cause ER retention; structural models of inward- and outward-facing conformations showed how two variants disrupt the interaction interface of SLC6A8 with binding partners.","method":"Mass-spectrometry interactomics, homology modeling of transporter conformers, subcellular localization by imaging in HEK293 cells","journal":"Journal of molecular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — MS-based interactomics combined with localization assays, single lab, two orthogonal methods","pmids":["38070861"],"is_preprint":false},{"year":2023,"finding":"CARD9 deficiency reduces SLC6A8 transcription in dendritic cells by blocking p65/NF-κB activation via abolition of the CARD9-BCL10-MALT1 complex formation, preventing p65 binding to the SLC6A8 promoter, thereby decreasing creatine import into DCs and impairing DC maturation.","method":"CARD9 knockout mice, DC co-culture assays, metabolomics, ChIP/promoter binding assay for p65, CARD9-BCL10-MALT1 complex analysis, adoptive DC transfer","journal":"Oncoimmunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with mechanistic pathway dissection including promoter binding, single lab","pmids":["37089447"],"is_preprint":false},{"year":2021,"finding":"NF-κB/p65 transcriptionally upregulates SLC6A8 in hypoxic triple-negative breast cancer cells, leading to increased intracellular creatine accumulation that reduces mitochondrial ROS and activates AKT-ERK signaling to promote cell survival.","method":"SLC6A8 KD/OE in TNBC cells, promoter analysis, ROS measurements, mitochondrial respiration assays, xenograft model","journal":"Journal of experimental & clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple assays (transcription, metabolic, in vivo) from single lab","pmids":["33990217"],"is_preprint":false},{"year":2024,"finding":"Small-molecule correctors identified by chemoproteomic affinity profiling bind SLC6A8 in cells, promote trafficking of mutant SLC6A8 variants to the cell surface, and rescue creatine uptake; in vivo, an orally bioavailable corrector increased brain creatine in heterozygous female Slc6a8P544L knock-in mice.","method":"Reactive affinity probe chemoproteomic ligand discovery, medicinal chemistry, trafficking assays, creatine uptake assays, CRISPR knock-in cell lines, knock-in mouse model, brain creatine measurement","journal":"ACS chemical biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — chemoproteomic target engagement, functional rescue in cells and in vivo, multiple orthogonal methods","pmids":["39418577"],"is_preprint":false},{"year":2025,"finding":"Creatine binds ERK2 and impairs its activation by MEK1; SLC6A8 inhibition reduces creatine uptake and activates ERK2, which then phosphorylates ferroptosis suppressor protein FSP1 at Thr109 to stabilize it and inhibit ferroptosis in colorectal cancer cells.","method":"Untargeted metabolomics, creatine-ERK2 binding assay, phosphoproteomic/mutagenesis analysis of FSP1 Thr109 phosphorylation, SLC6A8 inhibition (RGX-202), xenograft models, CD8+ T cell infiltration analysis","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — binding assay plus phosphorylation mapping and in vivo validation, single lab","pmids":["40892544"],"is_preprint":false},{"year":2025,"finding":"SLC6A8 knockout (CrT−/y) mice exhibit severe skeletal muscle atrophy with ultrastructural abnormalities, reduced fiber cross-sectional area, and impaired mitochondrial Ca2+ uptake, membrane potential, and ATP production; atrophy is mechanistically linked to upregulation of E3 ubiquitin ligases and suppression of the IGF1-Akt/PKB pathway regulated by mitochondrial Ca2+ levels.","method":"Whole-body Slc6a8 KO mice, electron microscopy, mitochondrial Ca2+ uptake assay, membrane potential measurement, ATP assay, ubiquitin ligase/Akt pathway western blotting","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO with multiple orthogonal mechanistic assays, single lab","pmids":["39952955"],"is_preprint":false},{"year":2024,"finding":"The c.1699T>C (p.S567P) SLC6A8 mutation reduces maximal creatine uptake rate without altering Km or membrane localization, and structural modeling indicates the S567P substitution disrupts an interaction between S567 and Y143 residues within the transporter, impairing transport function without causing mislocalization.","method":"Xenopus oocyte expression, creatine uptake kinetics, immunofluorescence, AlphaFold structural modeling","journal":"Biological & pharmaceutical bulletin","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — uptake kinetics and localization in oocyte system with structural modeling, single lab","pmids":["38233148"],"is_preprint":false}],"current_model":"SLC6A8 is a Na+- and Cl--coupled creatine transporter (stoichiometry: ≥2 Na+ : 1 Cl- : 1 creatine) that also transports guanidinoacetate between creatine-synthesis enzyme-expressing cells in the CNS; its maximal transport rate is positively regulated by SGK1/SGK3 (via mTOR and PIKfyve) and Klotho (via membrane stabilization), and negatively regulated by JAK2, JAK3, SPAK, OSR1, and GSK3β; pathogenic loss-of-function variants cause a spectrum of defects including ER retention/trafficking failure or disruption of the substrate-binding pocket; in macrophages, SLC6A8-mediated creatine import suppresses IFN-γ–JAK–STAT1 signaling while supporting IL-4–STAT6–arginase 1 chromatin remodeling to control polarization; in cancer biology, intracellular creatine imported by SLC6A8 binds ERK2 to inhibit ferroptosis via FSP1 stabilization, while pharmacological SLC6A8 inhibition depletes phosphocreatine/ATP and suppresses tumor growth."},"narrative":{"mechanistic_narrative":"SLC6A8 is a Na+- and Cl--coupled, electrogenic plasma-membrane creatine transporter that supplies creatine to high-energy-demand tissues such as brain and muscle, and its loss causes X-linked cerebral creatine deficiency syndrome [PMID:11326334, PMID:9882430]. Transport follows a stoichiometry of at least two Na+ and one Cl- per creatine with a Km near 20 µM, and the carrier's electrogenic current and creatine uptake are inseparable functions [PMID:9882430, PMID:22644605]. Beyond creatine, SLC6A8 imports guanidinoacetate—shuttling this precursor between the rare brain cells that express creatine-synthesis enzymes (AGAT, GAMT) so that creatine can be made despite intact synthetic machinery—as well as cyclocreatine [PMID:19879361, PMID:32124083]. The transporter's maximal turnover rate is tuned by a network of kinases without changes in substrate affinity: SGK1/SGK3 acting through mTOR and PIKfyve increase activity, Klotho stabilizes the carrier at the membrane, while JAK2, JAK3, SPAK/OSR1, and GSK3β suppress it [PMID:16036218, PMID:16466692, PMID:17982255, PMID:25531216, PMID:22407360, PMID:26666525, PMID:25531585, PMID:27978525]. Pathogenic variants act through two broad mechanisms—ER retention and trafficking failure or disruption of the substrate-binding pocket/transport machinery while membrane localization is preserved—and small-molecule proteostasis correctors can restore surface trafficking and creatine uptake of mutant transporter in cells and in vivo [PMID:32207963, PMID:38070861, PMID:38233148, PMID:39418577]. In immune cells, SLC6A8-mediated creatine import reprograms macrophage polarization by suppressing IFN-γ–JAK–STAT1 signaling and supporting IL-4–STAT6–arginase 1 chromatin remodeling [PMID:31399282]. In cancer, transcriptional induction of SLC6A8 supports tumor cell survival, and pharmacological inhibition depletes phosphocreatine/ATP, activates ERK2 to drive ferroptosis, and suppresses tumor growth [PMID:33990217, PMID:34613776, PMID:40892544]. Genetic ablation in mice recapitulates the human phenotype, producing cerebral creatine deficiency with learning/memory deficits and hyperactivity, and skeletal muscle atrophy with mitochondrial dysfunction [PMID:21249153, PMID:29384270, PMID:31520365, PMID:39952955].","teleology":[{"year":1999,"claim":"Established the fundamental transport mechanism of SLC6A8, defining it as an ion-coupled creatine carrier and fixing its kinetics and ion stoichiometry.","evidence":"Heterologous expression in Xenopus oocytes with electrophysiology, ion-substitution kinetics, and site-directed mutagenesis","pmids":["9882430"],"confidence":"High","gaps":["No structural basis for ion/substrate coupling resolved","Physiological tissue context not addressed in oocytes"]},{"year":2001,"claim":"Linked SLC6A8 loss of function directly to human disease, identifying it as the X-linked creatine transporter responsible for cerebral creatine deficiency syndrome.","evidence":"Creatine uptake assay in patient fibroblasts with a hemizygous nonsense mutation plus brain proton MRS","pmids":["11326334"],"confidence":"High","gaps":["Did not establish whether deficit is cell-autonomous or systemic","Mechanism linking creatine loss to neurological phenotype unresolved"]},{"year":2006,"claim":"Confirmed that the creatine uptake defect in patient cells is solely attributable to SLC6A8 by genetic rescue.","evidence":"Transient transfection of wild-type SLC6A8 cDNA into deficient fibroblasts with radiolabeled creatine uptake","pmids":["16763899"],"confidence":"Medium","gaps":["Single rescue endpoint","Does not address in vivo neuronal context"]},{"year":2009,"claim":"Explained why SLC6A8 deficiency causes brain creatine deficiency despite intact synthesis enzymes, by showing the transporter shuttles guanidinoacetate between AGAT- and GAMT-expressing cells.","evidence":"Cell-by-cell co-expression analysis in rat CNS and reaggregating brain cell uptake/competition assays","pmids":["19879361"],"confidence":"Medium","gaps":["Direct demonstration that SLC6A8 (not another carrier) mediates the guanidinoacetate flux in vivo incomplete","Quantitative contribution to total brain creatine unknown"]},{"year":2005,"claim":"Opened the regulatory dimension of SLC6A8 by showing kinases set its maximal transport rate without affecting affinity, identifying SGK1/SGK3 as positive regulators.","evidence":"Xenopus oocyte co-expression with wild-type, constitutively active, and kinase-dead SGK isoforms; voltage clamp","pmids":["16036218"],"confidence":"Medium","gaps":["Direct phosphorylation of SLC6A8 not demonstrated","Single expression system"]},{"year":2007,"claim":"Defined the SGK1 regulatory cascade upstream and downstream, placing mTOR above SGK1 and PIKfyve below it.","evidence":"Xenopus oocyte co-expression with rapamycin, kinase-dead SGK1, and PIKfyve S318A mutants; voltage clamp","pmids":["16466692","17982255"],"confidence":"Medium","gaps":["Molecular target of phosphorylation on the trafficking machinery unidentified","Single lab/oocyte system"]},{"year":2014,"claim":"Expanded the negative-regulatory network (JAK2, SPAK/OSR1) and identified Klotho as a membrane-stabilizing positive regulator, distinguishing insertion/removal effects.","evidence":"Xenopus oocyte voltage clamp with kinase-dead controls, brefeldin A insertion/removal assays, recombinant Klotho and β-glucuronidase inhibitor","pmids":["22407360","25531585","25531216"],"confidence":"Medium","gaps":["Whether regulation occurs in mammalian neurons/muscle in vivo untested","Direct biochemical interactions not shown"]},{"year":2016,"claim":"Completed the kinase regulatory map with JAK3 and GSK3β as suppressors, including epistasis with PKB/Akt and pharmacological reversal.","evidence":"Xenopus oocyte co-expression with active/inactive kinase mutants, WHI-P154, lithium, and PKB/Akt co-expression","pmids":["26666525","27978525"],"confidence":"Medium","gaps":["Physiological stimuli engaging these kinases on SLC6A8 unknown","No in vivo validation"]},{"year":2012,"claim":"Resolved how non-truncating disease variants disable the transporter, showing loss of both electrogenic and uptake activity despite correct membrane targeting.","evidence":"Xenopus oocyte voltage clamp, [14C]-creatine uptake, and immunolocalization of variants; complementary fibroblast variant panel","pmids":["22644605","17465020"],"confidence":"High","gaps":["Atomic-level mechanism of variant-induced transport failure not resolved","Limited to a defined variant set"]},{"year":2011,"claim":"Established a whole-animal model demonstrating SLC6A8 is required for brain and muscle creatine and for normal cognition.","evidence":"Germline Slc6a8 knockout mice with HPLC neurochemistry and behavioral testing","pmids":["21249153"],"confidence":"High","gaps":["Could not separate brain-intrinsic from peripheral contributions","Cell types responsible for cognitive deficit undefined"]},{"year":2018,"claim":"Pinpointed cerebral creatine loss, rather than peripheral deficiency, as the cause of cognitive deficits, and later localized hyperactivity to dopaminergic neurons.","evidence":"Nestin-cre and DAT-cre conditional Slc6a8 knockout mice with MRS, neurochemistry, and behavioral phenotyping","pmids":["29384270","31520365"],"confidence":"High","gaps":["Molecular link from neuronal creatine to behavior unresolved","Other neuronal subtypes not dissected"]},{"year":2019,"claim":"Revealed a non-energetic immunometabolic role: creatine imported via SLC6A8 reprograms macrophage polarization by reciprocally modulating STAT1 and STAT6 pathways.","evidence":"Macrophage-specific Slc6a8 knockout with multi-omics, cytokine stimulation, chromatin remodeling assays, and in vivo infection models","pmids":["31399282"],"confidence":"High","gaps":["Direct molecular targets of intracellular creatine in these pathways not fully defined","Relevance to human inflammatory disease untested here"]},{"year":2021,"claim":"Identified SLC6A8 as a therapeutic target in cancer, where its inhibition depletes phosphocreatine/ATP and suppresses tumor growth, and where its NF-κB-driven induction supports tumor survival.","evidence":"Small-molecule inhibitor RGX-202 in tumor models with pharmacodynamics in mice and patients; SLC6A8 knockdown/overexpression in TNBC with metabolic and xenograft assays","pmids":["34613776","33990217"],"confidence":"High","gaps":["Patient efficacy endpoint not established","Tumor-type dependence of dependency incompletely mapped"]},{"year":2023,"claim":"Mapped a transcriptional control circuit (CARD9-BCL10-MALT1 → p65/NF-κB) governing SLC6A8 expression and creatine import in dendritic cells.","evidence":"CARD9 knockout mice, DC co-culture, metabolomics, p65 ChIP/promoter binding, and adoptive transfer","pmids":["37089447"],"confidence":"Medium","gaps":["Generality of this regulatory axis beyond DCs unknown","Single lab"]},{"year":2023,"claim":"Defined the proteostatic basis of disease variants, showing pathogenic mutations cause ER retention via altered interaction interfaces, and that proteostasis modulators differentially affect wild-type and mutant transporter.","evidence":"Quantitative trafficking/expression profiling of pathogenic variants, mass-spectrometry interactomics, and conformer structural modeling in HEK293(T)","pmids":["32207963","38070861"],"confidence":"High","gaps":["Specific ER quality-control machinery retaining variants not fully identified","Experimental structure absent (modeling only)"]},{"year":2024,"claim":"Demonstrated pharmacological rescue of disease alleles, with small-molecule correctors restoring mutant SLC6A8 trafficking and uptake in cells and raising brain creatine in a knock-in mouse.","evidence":"Chemoproteomic ligand discovery, trafficking/uptake assays in CRISPR knock-in cells, and an oral corrector in Slc6a8P544L knock-in mice","pmids":["39418577"],"confidence":"High","gaps":["Breadth of variants rescuable not established","Therapeutic efficacy on behavioral phenotypes untested"]},{"year":2025,"claim":"Uncovered a creatine-ERK2-FSP1 signaling axis explaining how SLC6A8 inhibition triggers ferroptosis, and tied SLC6A8 loss to muscle atrophy via mitochondrial calcium and IGF1-Akt signaling.","evidence":"Creatine-ERK2 binding and FSP1 Thr109 phosphorylation mapping with RGX-202 and xenografts; Slc6a8 knockout muscle with mitochondrial Ca2+/ATP assays and ubiquitin-ligase/Akt profiling","pmids":["40892544","39952955"],"confidence":"Medium","gaps":["Direct structural basis of creatine-ERK2 binding not resolved","Causal hierarchy between mitochondrial Ca2+ and atrophy pathways incompletely defined"]},{"year":null,"claim":"How the diverse signaling and metabolic roles of imported creatine—kinase regulation of the carrier, immunometabolic reprogramming, and oncogenic ERK2/FSP1 control—are integrated at the molecular level, and whether corrector therapy reverses neurological phenotypes, remains open.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No experimental structure of human SLC6A8 in the corpus","Direct phosphosite on the transporter for any regulatory kinase unidentified","Behavioral rescue by correctors not demonstrated"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[0,1,11,13,20]},{"term_id":"GO:0140104","term_label":"molecular carrier activity","supporting_discovery_ids":[1,13]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[11,7,27]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[18,21]}],"pathway":[{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[0,1,11]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[13,19,26]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[17,22]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[0,10,18]}],"complexes":[],"partners":["ERK2","KLOTHO"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P48029","full_name":"Sodium- and chloride-dependent creatine transporter 1","aliases":["Solute carrier family 6 member 8"],"length_aa":635,"mass_kda":70.5,"function":"Creatine:sodium symporter which mediates the uptake of creatine (PubMed:17465020, PubMed:22644605, PubMed:25861866, PubMed:7945388, PubMed:7953292, PubMed:9882430). 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atrophy.","date":"2025","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/39952955","citation_count":3,"is_preprint":false},{"pmid":"37850681","id":"PMC_37850681","title":"Characterization of seizures and EEG findings in creatine transporter deficiency due to SLC6A8 mutation.","date":"2023","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/37850681","citation_count":3,"is_preprint":false},{"pmid":"21190923","id":"PMC_21190923","title":"Molecular analysis of guanidinoacetate-n-methyltransferase (GAMT) and creatine transporter (SLC6A8) gene by using denaturing high pressure liquid chromatography (DHPLC) as a possible source of human male infertility.","date":"2011","source":"Pakistan journal of pharmaceutical sciences","url":"https://pubmed.ncbi.nlm.nih.gov/21190923","citation_count":3,"is_preprint":false},{"pmid":"29478817","id":"PMC_29478817","title":"Functional assessment of creatine transporter in control and X-linked SLC6A8-deficient fibroblasts.","date":"2018","source":"Molecular genetics and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/29478817","citation_count":3,"is_preprint":false},{"pmid":"40473085","id":"PMC_40473085","title":"Calreticulin (crt-1) silencing reduces Aß1-42-induced toxicity and restores muscle function in C. elegans.","date":"2025","source":"Biochimica et biophysica acta. 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pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/39563050","citation_count":0,"is_preprint":false},{"pmid":"41787198","id":"PMC_41787198","title":"Targeting SLC6A8 suppresses tumor growth and enhances ferroptosis in hepatocellular carcinoma.","date":"2026","source":"Journal of cancer research and clinical oncology","url":"https://pubmed.ncbi.nlm.nih.gov/41787198","citation_count":0,"is_preprint":false},{"pmid":"37906149","id":"PMC_37906149","title":"[Clinical and genetic analysis of a child with Cerebral creatine deficiency syndrome due to variant of SLC6A8 gene].","date":"2023","source":"Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/37906149","citation_count":0,"is_preprint":false},{"pmid":"41943408","id":"PMC_41943408","title":"The Transcriptional Regulator Crt1 is Involved in The Pathogenic Lifestyle of Xanthomonas campestris pv. campestris B100.","date":"2026","source":"Polish journal of microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/41943408","citation_count":0,"is_preprint":false},{"pmid":"41500337","id":"PMC_41500337","title":"A mouse model of a patient derived P544L mutation in the Slc6a8 gene shows hypoactivity and cognitive deficits.","date":"2026","source":"Brain research","url":"https://pubmed.ncbi.nlm.nih.gov/41500337","citation_count":0,"is_preprint":false},{"pmid":"40240560","id":"PMC_40240560","title":"Multiple machine learning algorithms identified SLC6A8 as a diagnostic biomarker of the late stage of Hepatocellular carcinoma.","date":"2025","source":"Discover oncology","url":"https://pubmed.ncbi.nlm.nih.gov/40240560","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":50036,"output_tokens":6721,"usd":0.125462,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":15813,"output_tokens":5294,"usd":0.105707,"stage2_stop_reason":"end_turn"},"total_usd":0.231169,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2001,\n      \"finding\": \"SLC6A8 encodes a Na+- and Cl--dependent creatine transporter; loss-of-function mutations cause absent creatine uptake in fibroblasts, establishing SLC6A8 as the X-linked creatine transporter responsible for cerebral creatine deficiency syndrome.\",\n      \"method\": \"Creatine uptake assay in patient fibroblasts with hemizygous nonsense mutation; proton MRS of brain\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct loss-of-function cellular uptake assay in patient fibroblasts, replicated across multiple subsequent studies\",\n      \"pmids\": [\"11326334\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Human SLC6A8 (CRT-1) expressed in Xenopus oocytes mediates Na+- and Cl--dependent creatine uptake with Km ~20 µM; stoichiometry requires at least two Na+ ions and one Cl- per creatine molecule; transport is inhibited by protein kinase C activator PMA but not by PKA activator 8-bromo-cAMP.\",\n      \"method\": \"Heterologous expression in Xenopus oocytes, electrophysiology, ion-substitution kinetics, pharmacology, site-directed mutagenesis (A285P variant)\",\n      \"journal\": \"Archives of biochemistry and biophysics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — reconstituted transport in Xenopus oocytes with full kinetic and ion-stoichiometry analysis, multiple orthogonal methods in one study\",\n      \"pmids\": [\"9882430\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The serum- and glucocorticoid-inducible kinases SGK1 and SGK3 (but not SGK2 or PKB) positively regulate SLC6A8 transport activity by increasing its maximal transport rate without altering substrate affinity.\",\n      \"method\": \"Heterologous expression in Xenopus oocytes with co-expression of wild-type, constitutively active, and kinase-dead SGK isoforms; dual-electrode voltage clamp\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — electrophysiology with multiple kinase constructs and controls, single lab but multiple orthogonal reagents\",\n      \"pmids\": [\"16036218\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"mTOR stimulates SLC6A8 creatine transport activity (maximal rate), an effect blocked by rapamycin and by co-expression of kinase-dead SGK1, placing mTOR upstream of SGK1 in SLC6A8 regulation.\",\n      \"method\": \"Xenopus oocyte co-expression, dual-electrode voltage clamp, rapamycin inhibition\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — electrophysiology with pharmacological and dominant-negative controls, single lab\",\n      \"pmids\": [\"16466692\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"PIKfyve, acting downstream of SGK1 phosphorylation at its SGK consensus site (S318), mediates SGK1-dependent stimulation of SLC6A8 transport activity; the inactive SGK1 mutant K127N blocks the PIKfyve effect, and S318A-PIKfyve blocks SGK1's effect on SLC6A8.\",\n      \"method\": \"Xenopus oocyte co-expression of SLC6A8, PIKfyve, and SGK1 variants; dual-electrode voltage clamp\",\n      \"journal\": \"Cellular physiology and biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — electrophysiology with multiple dominant-negative and point-mutant constructs, single lab\",\n      \"pmids\": [\"17982255\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"JAK2 down-regulates SLC6A8 creatine transport by decreasing maximal transport rate without affecting substrate affinity; kinase-dead JAK2 (K882E) has no effect; JAK2 does not alter the rate of carrier removal from the membrane (brefeldin A experiment), suggesting interference with carrier insertion.\",\n      \"method\": \"Xenopus oocyte co-expression, dual-electrode voltage clamp, brefeldin A experiment, JAK2 inhibitor AG490\",\n      \"journal\": \"The Journal of membrane biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — electrophysiology with kinase-dead control and mechanistic sub-experiments, single lab\",\n      \"pmids\": [\"22407360\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"SPAK (constitutively active T233E-SPAK, WNK-insensitive T233A-SPAK, but not catalytically inactive D212A-SPAK) and OSR1 (wild-type, T185E, T185A, but not D164A-OSR1) negatively regulate SLC6A8 by decreasing maximal transport rate.\",\n      \"method\": \"Xenopus oocyte co-expression of SLC6A8 with SPAK/OSR1 variants; dual-electrode voltage clamp\",\n      \"journal\": \"Kidney & blood pressure research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — electrophysiology with multiple kinase constructs covering constitutively active and catalytically dead forms, single lab\",\n      \"pmids\": [\"25531585\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Klotho protein upregulates SLC6A8 creatine transport activity by stabilizing the carrier at the cell membrane; this effect requires β-glucuronidase activity of Klotho and is reproduced by recombinant soluble Klotho; Klotho delays brefeldin A-induced decline of creatine-induced current.\",\n      \"method\": \"Xenopus oocyte co-expression, dual-electrode voltage clamp, brefeldin A membrane-insertion block, β-glucuronidase inhibitor DSAL, recombinant Klotho protein\",\n      \"journal\": \"Kidney & blood pressure research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal approaches (co-expression, pharmacological inhibitor, recombinant protein), single lab\",\n      \"pmids\": [\"25531216\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"JAK3 negatively regulates SLC6A8 creatine transport, decreasing maximal transport rate; constitutively active A568V-JAK3 mimics this effect while inactive K851A-JAK3 does not; the JAK3 inhibitor WHI-P154 reverses the suppression.\",\n      \"method\": \"Xenopus oocyte co-expression, dual-electrode voltage clamp, pharmacological inhibitor\",\n      \"journal\": \"Neuro-Signals\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — electrophysiology with active/inactive kinase constructs and pharmacological rescue, single lab\",\n      \"pmids\": [\"26666525\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"GSK3β down-regulates SLC6A8 creatine transport (maximal transport rate); this effect is blocked by co-expression of PKB/Akt and reversed by lithium treatment; catalytically inactive K85R-GSK3β has no effect.\",\n      \"method\": \"Xenopus oocyte co-expression, dual-electrode voltage clamp, lithium treatment\",\n      \"journal\": \"Cellular physiology and biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — electrophysiology with inactive mutant, PKB/Akt epistasis, and pharmacological reversal, single lab\",\n      \"pmids\": [\"27978525\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Functional assay using site-directed mutagenesis and transient transfection of SLC6A8-deficient fibroblasts demonstrated that nine missense/deletion variants are pathogenic (abolish creatine uptake) while four variants are non-pathogenic, establishing structure-function relationships for the transporter.\",\n      \"method\": \"Site-directed mutagenesis, transient transfection into SLC6A8-deficient fibroblasts, radiolabeled creatine uptake assay\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct functional reconstitution in disease-relevant cells with multiple variants and controls, replicated in subsequent studies\",\n      \"pmids\": [\"17465020\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Four non-truncating SLC6A8 mutations cause complete loss of both electrogenic (current) and creatine transport activity despite proper targeting of mutant protein to the plasma membrane; the electrogenic and transport activities of SLC6A8 could not be dissociated by any tested creatine analog.\",\n      \"method\": \"Xenopus oocyte expression, dual-electrode voltage clamp, [14C]-creatine uptake, immunofluorescence and western blot for subcellular localization\",\n      \"journal\": \"Journal of inherited metabolic disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — multiple orthogonal assays (electrophysiology, radiochemical uptake, localization) in single study\",\n      \"pmids\": [\"22644605\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Overexpression of wild-type SLC6A8 ORF in SLC6A8-deficient fibroblasts fully restores creatine uptake, proving that loss of SLC6A8 function is solely responsible for the creatine uptake defect in patient cells.\",\n      \"method\": \"Transient transfection of wild-type SLC6A8 cDNA into deficient primary fibroblasts, radiolabeled creatine uptake assay\",\n      \"journal\": \"Journal of inherited metabolic disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct gain-of-function rescue experiment, single lab\",\n      \"pmids\": [\"16763899\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"In rat CNS, cells co-expressing both AGAT and GAMT (capable of autonomous creatine synthesis) are rare (<20% in most structures); brain cells take up guanidinoacetate and convert it to creatine, and this uptake is competed by creatine, indicating that SLC6A8 transports guanidinoacetate between AGAT- and GAMT-expressing cells to enable creatine synthesis—explaining why SLC6A8 deficiency causes creatine deficiency despite intact synthesis enzymes.\",\n      \"method\": \"Cell-by-cell co-expression analysis by in situ hybridization/immunohistochemistry in rat CNS; reaggregating brain cell cultures with radiolabeled guanidinoacetate uptake and competition assay\",\n      \"journal\": \"Neurobiology of disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal experimental approaches (histology + cell culture uptake), single lab\",\n      \"pmids\": [\"19879361\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Ubiquitous Slc6a8 knockout (CrT−/y) mice lack creatine in brain and muscle, develop learning and memory deficits (Morris water maze, novel object recognition, fear conditioning), and show increased serotonin and 5-HIAA in hippocampus and prefrontal cortex, establishing the mouse model of CrT deficiency.\",\n      \"method\": \"Cre/loxP knockout (exons 2–4 deletion), HPLC for creatine/neurotransmitter levels, behavioral testing\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean germline KO with biochemical verification and multiple behavioral readouts\",\n      \"pmids\": [\"21249153\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Brain-specific Slc6a8 knockout mice (Nestin-cre) have reduced cerebral creatine and increased guanidinoacetate in brain, with learning and memory deficits (Morris water maze, novel object recognition, fear conditioning) and hyperactivity, demonstrating that loss of cerebral creatine—not peripheral creatine deficiency—is responsible for cognitive deficits.\",\n      \"method\": \"Conditional KO (Nestin-cre × Slc6a8flox), MRS, behavioral testing, neurochemical assay\",\n      \"journal\": \"Genes, brain, and behavior\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — tissue-specific conditional KO with biochemical validation and multiple behavioral phenotypes\",\n      \"pmids\": [\"29384270\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Deletion of Slc6a8 specifically in dopaminergic (DAT-expressing) neurons causes hyperactivity throughout aging without impairing motor function, indicating creatine in dopaminergic neurons specifically modulates locomotor activity.\",\n      \"method\": \"Conditional KO (DATIREScre × Slc6a8flox), longitudinal locomotor activity and motor testing\",\n      \"journal\": \"Journal of molecular neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-type-specific conditional KO with defined behavioral phenotype, single lab\",\n      \"pmids\": [\"31520365\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Slc6a8 ablation in macrophages (genetic knockout) suppresses intracellular creatine accumulation; creatine suppresses IFN-γ–JAK–STAT1 signaling (reducing iNOS induction) and promotes IL-4–STAT6–arginase 1 expression through chromatin remodeling, thereby reprogramming macrophage polarization from M1-like to M2-like.\",\n      \"method\": \"Genetic knockout of Slc6a8 in macrophages, genomics/metabolomics/immunological assays, cytokine stimulation with IFN-γ and IL-4, STAT1/STAT6 pathway analysis, chromatin remodeling assays, in vivo infection models\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with multi-omics and mechanistic pathway dissection in multiple assay systems\",\n      \"pmids\": [\"31399282\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Pathogenic SLC6A8 variants cause a spectrum of molecular defects including proteostatic deficiencies (reduced expression/trafficking) and disruption of the substrate-binding pocket; most variants show measurable trafficking defects; the proteostasis regulator 4-PBA enhances WT SLC6A8 activity in HEK293T cells but does not rescue the tested pathogenic variants (except minimally G132V which is temperature-sensitive).\",\n      \"method\": \"Quantitative profiling of cellular processing, trafficking, expression, and function of 8 pathogenic variants in HEK293T cells; structural modeling; 4-PBA and temperature rescue experiments\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — multiple orthogonal cellular assays plus structural modeling in a single rigorous study\",\n      \"pmids\": [\"32207963\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The small-molecule SLC6A8 inhibitor RGX-202 blocks creatine import in vitro and in vivo, reduces intracellular phosphocreatine and ATP, induces tumor apoptosis, and suppresses colorectal cancer growth; antitumor efficacy correlates with tumoral creatine kinase B expression; RGX-202 also perturbed creatine metabolism in patients with metastatic CRC in a phase 1 trial.\",\n      \"method\": \"In vitro transport inhibition assay, xenograft/syngeneic/PDX tumor models, pharmacodynamic creatine metabolite measurements in mice and human trial\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple tumor models, pharmacodynamic confirmation in human subjects, multiple orthogonal readouts\",\n      \"pmids\": [\"34613776\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Cyclocreatine is a substrate of SLC6A8; CRT is the predominant mediator of cyclocreatine uptake in HEK293 cells and in a human blood-brain barrier model (hCMEC/D3), shown by siRNA knockdown and inhibitor studies; cyclocreatine uptake is largely absent in fibroblasts from CRT-deficient patients.\",\n      \"method\": \"[14C]cyclocreatine uptake assay, siRNA knockdown of SLC6A8, pharmacological inhibition, patient fibroblasts\",\n      \"journal\": \"Pharmaceutical research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown and pharmacological inhibition with patient-derived cells, single lab\",\n      \"pmids\": [\"32124083\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Mass spectrometry identified protein interaction partners of wild-type SLC6A8 in HEK293 cells; pathogenic variants led to enrichment of ER protein partners, indicating that pathogenic mutations cause ER retention; structural models of inward- and outward-facing conformations showed how two variants disrupt the interaction interface of SLC6A8 with binding partners.\",\n      \"method\": \"Mass-spectrometry interactomics, homology modeling of transporter conformers, subcellular localization by imaging in HEK293 cells\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — MS-based interactomics combined with localization assays, single lab, two orthogonal methods\",\n      \"pmids\": [\"38070861\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CARD9 deficiency reduces SLC6A8 transcription in dendritic cells by blocking p65/NF-κB activation via abolition of the CARD9-BCL10-MALT1 complex formation, preventing p65 binding to the SLC6A8 promoter, thereby decreasing creatine import into DCs and impairing DC maturation.\",\n      \"method\": \"CARD9 knockout mice, DC co-culture assays, metabolomics, ChIP/promoter binding assay for p65, CARD9-BCL10-MALT1 complex analysis, adoptive DC transfer\",\n      \"journal\": \"Oncoimmunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with mechanistic pathway dissection including promoter binding, single lab\",\n      \"pmids\": [\"37089447\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"NF-κB/p65 transcriptionally upregulates SLC6A8 in hypoxic triple-negative breast cancer cells, leading to increased intracellular creatine accumulation that reduces mitochondrial ROS and activates AKT-ERK signaling to promote cell survival.\",\n      \"method\": \"SLC6A8 KD/OE in TNBC cells, promoter analysis, ROS measurements, mitochondrial respiration assays, xenograft model\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple assays (transcription, metabolic, in vivo) from single lab\",\n      \"pmids\": [\"33990217\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Small-molecule correctors identified by chemoproteomic affinity profiling bind SLC6A8 in cells, promote trafficking of mutant SLC6A8 variants to the cell surface, and rescue creatine uptake; in vivo, an orally bioavailable corrector increased brain creatine in heterozygous female Slc6a8P544L knock-in mice.\",\n      \"method\": \"Reactive affinity probe chemoproteomic ligand discovery, medicinal chemistry, trafficking assays, creatine uptake assays, CRISPR knock-in cell lines, knock-in mouse model, brain creatine measurement\",\n      \"journal\": \"ACS chemical biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — chemoproteomic target engagement, functional rescue in cells and in vivo, multiple orthogonal methods\",\n      \"pmids\": [\"39418577\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Creatine binds ERK2 and impairs its activation by MEK1; SLC6A8 inhibition reduces creatine uptake and activates ERK2, which then phosphorylates ferroptosis suppressor protein FSP1 at Thr109 to stabilize it and inhibit ferroptosis in colorectal cancer cells.\",\n      \"method\": \"Untargeted metabolomics, creatine-ERK2 binding assay, phosphoproteomic/mutagenesis analysis of FSP1 Thr109 phosphorylation, SLC6A8 inhibition (RGX-202), xenograft models, CD8+ T cell infiltration analysis\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — binding assay plus phosphorylation mapping and in vivo validation, single lab\",\n      \"pmids\": [\"40892544\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SLC6A8 knockout (CrT−/y) mice exhibit severe skeletal muscle atrophy with ultrastructural abnormalities, reduced fiber cross-sectional area, and impaired mitochondrial Ca2+ uptake, membrane potential, and ATP production; atrophy is mechanistically linked to upregulation of E3 ubiquitin ligases and suppression of the IGF1-Akt/PKB pathway regulated by mitochondrial Ca2+ levels.\",\n      \"method\": \"Whole-body Slc6a8 KO mice, electron microscopy, mitochondrial Ca2+ uptake assay, membrane potential measurement, ATP assay, ubiquitin ligase/Akt pathway western blotting\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO with multiple orthogonal mechanistic assays, single lab\",\n      \"pmids\": [\"39952955\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"The c.1699T>C (p.S567P) SLC6A8 mutation reduces maximal creatine uptake rate without altering Km or membrane localization, and structural modeling indicates the S567P substitution disrupts an interaction between S567 and Y143 residues within the transporter, impairing transport function without causing mislocalization.\",\n      \"method\": \"Xenopus oocyte expression, creatine uptake kinetics, immunofluorescence, AlphaFold structural modeling\",\n      \"journal\": \"Biological & pharmaceutical bulletin\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — uptake kinetics and localization in oocyte system with structural modeling, single lab\",\n      \"pmids\": [\"38233148\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SLC6A8 is a Na+- and Cl--coupled creatine transporter (stoichiometry: ≥2 Na+ : 1 Cl- : 1 creatine) that also transports guanidinoacetate between creatine-synthesis enzyme-expressing cells in the CNS; its maximal transport rate is positively regulated by SGK1/SGK3 (via mTOR and PIKfyve) and Klotho (via membrane stabilization), and negatively regulated by JAK2, JAK3, SPAK, OSR1, and GSK3β; pathogenic loss-of-function variants cause a spectrum of defects including ER retention/trafficking failure or disruption of the substrate-binding pocket; in macrophages, SLC6A8-mediated creatine import suppresses IFN-γ–JAK–STAT1 signaling while supporting IL-4–STAT6–arginase 1 chromatin remodeling to control polarization; in cancer biology, intracellular creatine imported by SLC6A8 binds ERK2 to inhibit ferroptosis via FSP1 stabilization, while pharmacological SLC6A8 inhibition depletes phosphocreatine/ATP and suppresses tumor growth.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SLC6A8 is a Na+- and Cl--coupled, electrogenic plasma-membrane creatine transporter that supplies creatine to high-energy-demand tissues such as brain and muscle, and its loss causes X-linked cerebral creatine deficiency syndrome [#0, #1]. Transport follows a stoichiometry of at least two Na+ and one Cl- per creatine with a Km near 20 µM, and the carrier's electrogenic current and creatine uptake are inseparable functions [#1, #11]. Beyond creatine, SLC6A8 imports guanidinoacetate—shuttling this precursor between the rare brain cells that express creatine-synthesis enzymes (AGAT, GAMT) so that creatine can be made despite intact synthetic machinery—as well as cyclocreatine [#13, #20]. The transporter's maximal turnover rate is tuned by a network of kinases without changes in substrate affinity: SGK1/SGK3 acting through mTOR and PIKfyve increase activity, Klotho stabilizes the carrier at the membrane, while JAK2, JAK3, SPAK/OSR1, and GSK3β suppress it [#2, #3, #4, #7, #5, #8, #6, #9]. Pathogenic variants act through two broad mechanisms—ER retention and trafficking failure or disruption of the substrate-binding pocket/transport machinery while membrane localization is preserved—and small-molecule proteostasis correctors can restore surface trafficking and creatine uptake of mutant transporter in cells and in vivo [#18, #21, #27, #24]. In immune cells, SLC6A8-mediated creatine import reprograms macrophage polarization by suppressing IFN-γ–JAK–STAT1 signaling and supporting IL-4–STAT6–arginase 1 chromatin remodeling [#17]. In cancer, transcriptional induction of SLC6A8 supports tumor cell survival, and pharmacological inhibition depletes phosphocreatine/ATP, activates ERK2 to drive ferroptosis, and suppresses tumor growth [#23, #19, #25]. Genetic ablation in mice recapitulates the human phenotype, producing cerebral creatine deficiency with learning/memory deficits and hyperactivity, and skeletal muscle atrophy with mitochondrial dysfunction [#14, #15, #16, #26].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Established the fundamental transport mechanism of SLC6A8, defining it as an ion-coupled creatine carrier and fixing its kinetics and ion stoichiometry.\",\n      \"evidence\": \"Heterologous expression in Xenopus oocytes with electrophysiology, ion-substitution kinetics, and site-directed mutagenesis\",\n      \"pmids\": [\"9882430\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structural basis for ion/substrate coupling resolved\", \"Physiological tissue context not addressed in oocytes\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Linked SLC6A8 loss of function directly to human disease, identifying it as the X-linked creatine transporter responsible for cerebral creatine deficiency syndrome.\",\n      \"evidence\": \"Creatine uptake assay in patient fibroblasts with a hemizygous nonsense mutation plus brain proton MRS\",\n      \"pmids\": [\"11326334\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish whether deficit is cell-autonomous or systemic\", \"Mechanism linking creatine loss to neurological phenotype unresolved\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Confirmed that the creatine uptake defect in patient cells is solely attributable to SLC6A8 by genetic rescue.\",\n      \"evidence\": \"Transient transfection of wild-type SLC6A8 cDNA into deficient fibroblasts with radiolabeled creatine uptake\",\n      \"pmids\": [\"16763899\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single rescue endpoint\", \"Does not address in vivo neuronal context\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Explained why SLC6A8 deficiency causes brain creatine deficiency despite intact synthesis enzymes, by showing the transporter shuttles guanidinoacetate between AGAT- and GAMT-expressing cells.\",\n      \"evidence\": \"Cell-by-cell co-expression analysis in rat CNS and reaggregating brain cell uptake/competition assays\",\n      \"pmids\": [\"19879361\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct demonstration that SLC6A8 (not another carrier) mediates the guanidinoacetate flux in vivo incomplete\", \"Quantitative contribution to total brain creatine unknown\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Opened the regulatory dimension of SLC6A8 by showing kinases set its maximal transport rate without affecting affinity, identifying SGK1/SGK3 as positive regulators.\",\n      \"evidence\": \"Xenopus oocyte co-expression with wild-type, constitutively active, and kinase-dead SGK isoforms; voltage clamp\",\n      \"pmids\": [\"16036218\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct phosphorylation of SLC6A8 not demonstrated\", \"Single expression system\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Defined the SGK1 regulatory cascade upstream and downstream, placing mTOR above SGK1 and PIKfyve below it.\",\n      \"evidence\": \"Xenopus oocyte co-expression with rapamycin, kinase-dead SGK1, and PIKfyve S318A mutants; voltage clamp\",\n      \"pmids\": [\"16466692\", \"17982255\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular target of phosphorylation on the trafficking machinery unidentified\", \"Single lab/oocyte system\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Expanded the negative-regulatory network (JAK2, SPAK/OSR1) and identified Klotho as a membrane-stabilizing positive regulator, distinguishing insertion/removal effects.\",\n      \"evidence\": \"Xenopus oocyte voltage clamp with kinase-dead controls, brefeldin A insertion/removal assays, recombinant Klotho and β-glucuronidase inhibitor\",\n      \"pmids\": [\"22407360\", \"25531585\", \"25531216\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether regulation occurs in mammalian neurons/muscle in vivo untested\", \"Direct biochemical interactions not shown\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Completed the kinase regulatory map with JAK3 and GSK3β as suppressors, including epistasis with PKB/Akt and pharmacological reversal.\",\n      \"evidence\": \"Xenopus oocyte co-expression with active/inactive kinase mutants, WHI-P154, lithium, and PKB/Akt co-expression\",\n      \"pmids\": [\"26666525\", \"27978525\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological stimuli engaging these kinases on SLC6A8 unknown\", \"No in vivo validation\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Resolved how non-truncating disease variants disable the transporter, showing loss of both electrogenic and uptake activity despite correct membrane targeting.\",\n      \"evidence\": \"Xenopus oocyte voltage clamp, [14C]-creatine uptake, and immunolocalization of variants; complementary fibroblast variant panel\",\n      \"pmids\": [\"22644605\", \"17465020\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic-level mechanism of variant-induced transport failure not resolved\", \"Limited to a defined variant set\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Established a whole-animal model demonstrating SLC6A8 is required for brain and muscle creatine and for normal cognition.\",\n      \"evidence\": \"Germline Slc6a8 knockout mice with HPLC neurochemistry and behavioral testing\",\n      \"pmids\": [\"21249153\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Could not separate brain-intrinsic from peripheral contributions\", \"Cell types responsible for cognitive deficit undefined\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Pinpointed cerebral creatine loss, rather than peripheral deficiency, as the cause of cognitive deficits, and later localized hyperactivity to dopaminergic neurons.\",\n      \"evidence\": \"Nestin-cre and DAT-cre conditional Slc6a8 knockout mice with MRS, neurochemistry, and behavioral phenotyping\",\n      \"pmids\": [\"29384270\", \"31520365\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular link from neuronal creatine to behavior unresolved\", \"Other neuronal subtypes not dissected\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Revealed a non-energetic immunometabolic role: creatine imported via SLC6A8 reprograms macrophage polarization by reciprocally modulating STAT1 and STAT6 pathways.\",\n      \"evidence\": \"Macrophage-specific Slc6a8 knockout with multi-omics, cytokine stimulation, chromatin remodeling assays, and in vivo infection models\",\n      \"pmids\": [\"31399282\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct molecular targets of intracellular creatine in these pathways not fully defined\", \"Relevance to human inflammatory disease untested here\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified SLC6A8 as a therapeutic target in cancer, where its inhibition depletes phosphocreatine/ATP and suppresses tumor growth, and where its NF-κB-driven induction supports tumor survival.\",\n      \"evidence\": \"Small-molecule inhibitor RGX-202 in tumor models with pharmacodynamics in mice and patients; SLC6A8 knockdown/overexpression in TNBC with metabolic and xenograft assays\",\n      \"pmids\": [\"34613776\", \"33990217\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Patient efficacy endpoint not established\", \"Tumor-type dependence of dependency incompletely mapped\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Mapped a transcriptional control circuit (CARD9-BCL10-MALT1 → p65/NF-κB) governing SLC6A8 expression and creatine import in dendritic cells.\",\n      \"evidence\": \"CARD9 knockout mice, DC co-culture, metabolomics, p65 ChIP/promoter binding, and adoptive transfer\",\n      \"pmids\": [\"37089447\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Generality of this regulatory axis beyond DCs unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined the proteostatic basis of disease variants, showing pathogenic mutations cause ER retention via altered interaction interfaces, and that proteostasis modulators differentially affect wild-type and mutant transporter.\",\n      \"evidence\": \"Quantitative trafficking/expression profiling of pathogenic variants, mass-spectrometry interactomics, and conformer structural modeling in HEK293(T)\",\n      \"pmids\": [\"32207963\", \"38070861\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific ER quality-control machinery retaining variants not fully identified\", \"Experimental structure absent (modeling only)\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Demonstrated pharmacological rescue of disease alleles, with small-molecule correctors restoring mutant SLC6A8 trafficking and uptake in cells and raising brain creatine in a knock-in mouse.\",\n      \"evidence\": \"Chemoproteomic ligand discovery, trafficking/uptake assays in CRISPR knock-in cells, and an oral corrector in Slc6a8P544L knock-in mice\",\n      \"pmids\": [\"39418577\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Breadth of variants rescuable not established\", \"Therapeutic efficacy on behavioral phenotypes untested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Uncovered a creatine-ERK2-FSP1 signaling axis explaining how SLC6A8 inhibition triggers ferroptosis, and tied SLC6A8 loss to muscle atrophy via mitochondrial calcium and IGF1-Akt signaling.\",\n      \"evidence\": \"Creatine-ERK2 binding and FSP1 Thr109 phosphorylation mapping with RGX-202 and xenografts; Slc6a8 knockout muscle with mitochondrial Ca2+/ATP assays and ubiquitin-ligase/Akt profiling\",\n      \"pmids\": [\"40892544\", \"39952955\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct structural basis of creatine-ERK2 binding not resolved\", \"Causal hierarchy between mitochondrial Ca2+ and atrophy pathways incompletely defined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the diverse signaling and metabolic roles of imported creatine—kinase regulation of the carrier, immunometabolic reprogramming, and oncogenic ERK2/FSP1 control—are integrated at the molecular level, and whether corrector therapy reverses neurological phenotypes, remains open.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No experimental structure of human SLC6A8 in the corpus\", \"Direct phosphosite on the transporter for any regulatory kinase unidentified\", \"Behavioral rescue by correctors not demonstrated\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [0, 1, 11, 13, 20]},\n      {\"term_id\": \"GO:0140104\", \"supporting_discovery_ids\": [1, 13]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [11, 7, 27]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [18, 21]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [0, 1, 11]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [13, 19, 26]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [17, 22]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [0, 10, 18]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"ERK2\", \"Klotho\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":8,"faith_total":8,"faith_pct":100.0}}