{"gene":"PTGDS","run_date":"2026-06-10T06:43:36","timeline":{"discoveries":[{"year":2002,"finding":"L-PGDS is phosphorylated and enzymatically activated by PKC in response to phorbol ester (PMA). Activated L-PGDS inhibits PI3-K activity, leading to reduced PKB/Akt phosphorylation, hypophosphorylation and activation of Bad, and subsequent caspase-3 activation and apoptosis. Antisense depletion of L-PGDS prevented PI3-K inactivation, caspase-3 activation, and apoptosis.","method":"In vitro PKC phosphorylation of recombinant L-PGDS; antisense RNA depletion; PI3-K activity assay; western blot for Akt, Bad, Rb phosphorylation; caspase-3 activation assay","journal":"American journal of physiology. Cell physiology","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — in vitro reconstitution of PKC phosphorylation plus multiple orthogonal cellular assays (antisense KD, kinase activity, apoptosis readouts) in single lab","pmids":["12388064"],"is_preprint":false},{"year":2019,"finding":"L-PGDS acts as a molecular chaperone/disaggregase: it directly binds monomeric Aβ40 and Aβ(25-35) via the Aβ C-terminus (N-terminus remains free), inhibiting spontaneous aggregation, and also disassembles pre-formed Aβ fibrils. The binding mode was resolved by NMR spectroscopy and SAXS, yielding a structural model of the L-PGDS–Aβ40 complex.","method":"NMR spectroscopy (binding mode), SAXS (solution structure), TEM (fibril morphology), thioflavin-T aggregation assay, proteomics on AD brain insoluble fractions","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 1 / Moderate — multiple structural/biophysical methods (NMR + SAXS + TEM) in a single rigorous study establishing direct binding and disaggregase activity","pmids":["31467325"],"is_preprint":false},{"year":2014,"finding":"Dexamethasone upregulates L-PGDS expression and PGD2 biosynthesis in neonatal rat brain; the neuroprotective effect of dexamethasone against hypoxic-ischemic injury requires the L-PGDS–PGD2–DP1–pERK signaling axis, as pharmacological inhibition of L-PGDS (SeCl4), DP1 (MK-0524), or MAPK (PD98059) each abolished dexamethasone-induced pERK-44 elevation and neuroprotection.","method":"Intracerebroventricular drug injections; western blot for L-PGDS, DP1, pERK1/2; ELISA for PGD2; pharmacological inhibitor epistasis; neonatal rat HI model","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pathway epistasis with three independent inhibitors in vivo, single lab","pmids":["25474649"],"is_preprint":false},{"year":2015,"finding":"CUL4B/PRC2 complex transcriptionally represses Ptgds expression in neural progenitor cells (NPCs). Loss of Cul4b increases PTGDS levels, promoting conversion of NPCs to GFAP+ astrocytes; this phenotype is rescued by pharmacological inhibition of PTGDS enzymatic activity (AT56) or shRNA-mediated Ptgds knockdown, and is phenocopied by exogenous PTGDS addition to wild-type NPCs.","method":"Cul4b knockout mouse model; NPC culture; GFAP/S100β immunostaining; AT56 inhibitor; shRNA knockdown; exogenous PTGDS addition; ChIP for CUL4B/PRC2 at Ptgds locus","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic KO, pharmacological inhibition, shRNA KD, and gain-of-function rescue with multiple orthogonal methods in one study","pmids":["26025376"],"is_preprint":false},{"year":2019,"finding":"L-PGDS-derived PGD2, produced specifically in premature (but not mature) adipocytes, promotes obesity and insulin resistance under high-fat diet conditions. Deletion of L-PGDS in premature adipocytes (aP2-Cre) reduced PGD2 production in WAT, decreased body weight gain, adipocyte size, and serum lipids, and improved insulin sensitivity, with altered expression of adipogenic, lipogenic, and macrophage marker genes.","method":"Adipose-specific conditional knockout mice (aP2-Cre and AdipoQ-Cre); HFD feeding; PGD2 ELISA; glucose/insulin tolerance tests; gene expression profiling","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — two distinct conditional KO models dissecting cell-stage specificity, multiple metabolic phenotype readouts, single lab","pmids":["30760783"],"is_preprint":false},{"year":2019,"finding":"L-PGDS-derived PGD2 protects against acute lung injury by enhancing endothelial barrier function via the DP (D prostanoid) receptor. In HCl-induced ALI, inflamed endothelial/epithelial cells express L-PGDS; L-PGDS-deficient mice show exacerbated vascular permeability that is suppressed by DP receptor agonism. Hematopoietic reconstitution with WT bone marrow did not rescue the edema phenotype, confirming non-hematopoietic origin.","method":"L-PGDS KO mice; HCl intratracheal model; Miles assay for vascular permeability; immunostaining; bone marrow reconstitution; in vitro endothelial barrier assay with DP agonist","journal":"The Journal of pathology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — KO mouse, bone marrow chimera, in vitro barrier assay, and receptor pharmacology providing convergent mechanistic evidence in single study","pmids":["30734298"],"is_preprint":false},{"year":2021,"finding":"L-PGDS has two mechanistically distinct protective roles in acute lung injury: (1) its PGD2-synthesizing enzymatic activity inhibits pulmonary edema formation, and (2) its lipocalin carrier function (independent of PGD2 production) decreases mucin formation and inflammatory cell infiltration, as dissected using point-mutant mice that lack PGD2 producibility but retain lipocalin ability.","method":"L-PGDS-deficient mice vs. L-PGDS point-mutant (PGD2-null, lipocalin-intact) mice; HCl intratracheal model; lung water content; BALF protein and leukocyte counts; mucin staining; IL-33 mRNA measurement","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — genetic separation of enzymatic vs. lipocalin functions using distinct mutant mouse lines with multiple phenotypic readouts","pmids":["34615734"],"is_preprint":false},{"year":2021,"finding":"PTGDS interacts with MYH9 (identified by co-immunoprecipitation–mass spectrometry). PTGDS promotes DLBCL tumorigenesis through MYH9-mediated activation of the Wnt–β-catenin–STAT3 pathway by influencing ubiquitination and degradation of GSK3-β. N-glycosylation of PTGDS at Asn51 and Asn78 regulates its nuclear translocation, protein half-life, and proliferative activity.","method":"Co-IP mass spectrometry; site-directed mutagenesis of glycosylation sites (Asn51, Asn78); lentiviral KD; rescue experiments; subcellular fractionation; western blot for Wnt/β-catenin/STAT3 pathway; in vitro and xenograft models","journal":"Cell death and differentiation","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — Co-IP-MS for interaction, mutagenesis for glycosylation sites, pathway rescue, and in vivo validation; multiple orthogonal methods in single study","pmids":["34743203"],"is_preprint":false},{"year":2017,"finding":"Hypoxia activates HIF-1α, which upregulates L-PGDS expression in beating rat atria; L-PGDS-derived PGD2 then activates PPARγ to promote ANP secretion. The HIF-1α–L-PGDS–PPARγ signaling axis was established by sequential pharmacological inhibition (2-methoxyestradiol for HIF-1α; AT-56/HQL-49 for L-PGDS; GW9662 for PPARγ).","method":"Isolated perfused beating rat atria; pharmacological inhibitors (2-methoxyestradiol, AT-56, HQL-49, GW9662); western blot for HIF-1α, L-PGDS, PPARγ; ANP secretion measurement","journal":"Prostaglandins & other lipid mediators","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pathway epistasis using four sequential inhibitors in an ex vivo model, single lab","pmids":["29287795"],"is_preprint":false},{"year":2019,"finding":"Endogenous ET-1 (induced by hypoxia) promotes ANP secretion via COX2–L-PGDS–PPARγ signaling. L-PGDS-derived PGD2 also feeds back to regulate L-PGDS expression through an NRF2-mediated positive feedback mechanism in beating rat atria.","method":"Isolated perfused beating rat atria; ET receptor antagonists; western blot for COX2, L-PGDS, PPARγ, NRF2; PGD2 ELISA; ANP secretion measurement","journal":"Peptides","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — ex vivo pharmacological epistasis, single lab, single method type","pmids":["31541683"],"is_preprint":false},{"year":2019,"finding":"L-PGDS mediates glucocorticoid-induced leptin expression in differentiated adipocytes: glucocorticoids induce L-PGDS, which in turn positively regulates leptin. Aldosterone, while also inducing both L-PGDS and leptin, does not require L-PGDS for leptin induction. Target deconvolution and docking identified L-PGDS as the off-target responsible for leptin suppression by CB2 ligands AM630 and WIN55212-2.","method":"Pharmacological screening; genetic (CB2-KO) adipocytes; docking simulation; L-PGDS inhibitor (AM630/WIN55212-2); gene/protein expression in differentiated primary preadipocytes","journal":"Biochemical pharmacology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic and pharmacological dissection with CB2-KO controls plus docking, single lab","pmids":["31129049"],"is_preprint":false},{"year":2020,"finding":"In gastric cancer cells, YAP directly suppresses L-PTGDS (L-PGDS) expression; overexpression of L-PGDS reverses YAP-induced stemness promotion, inhibits proliferation and self-renewal in vitro, and reverses the pro-tumor effect of YAP in vivo, establishing YAP as an upstream negative regulator of L-PGDS.","method":"Gain- and loss-of-function (YAP OE/KD); L-PGDS/PTGDR2 OE; sphere formation; xenograft tumor model; RT-PCR; western blot; IHC","journal":"International journal of clinical oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal gain/loss-of-function with in vivo rescue, single lab","pmids":["32851567"],"is_preprint":false},{"year":2024,"finding":"PTGDS physically interacts with the heme-degrading enzyme HMOX1 (identified by TMT-mass spectrometry). PTGDS knockdown increases intracellular iron and induces ferroptosis in peripheral T cell lymphoma cells by promoting HMOX1-mediated heme catabolism and ferritin autophagy. An H25A point mutation in HMOX1 identified the specific catalytic site required for this interaction.","method":"Co-IP/TMT-mass spectrometry; lentiviral KD; HMOX1 H25A point mutation; ferroptosis assays; iron level measurement; xenograft model; RNA-sequencing","journal":"British journal of cancer","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — proteomic interaction identification, site-directed mutagenesis of interaction site, functional rescue, and in vivo validation","pmids":["39706989"],"is_preprint":false},{"year":2025,"finding":"Intracellular L-PGDS-derived 15d-PGJ2 covalently modifies (lipoxidation) CaMKII at cysteine 495 (CaMKII-δ9), dampening CaMKII oligomer formation and overactivation, thereby alleviating cardiomyocyte death and cardiac ischemia/reperfusion injury. L-PGDS is downregulated in I/R-injured cardiac tissue; its overexpression mitigates injury while knockdown exacerbates it.","method":"Biotin-tagged 15d-PGJ2 analog + LC-MS/MS (target ID); L-PGDS OE/KD in neonatal and adult cardiomyocytes and hESC-derived cardiomyocytes; mouse I/R model; CaMKII oligomer assays; transcriptome profiling","journal":"Circulation","confidence":"High","confidence_rationale":"Tier 1 / Moderate — chemical proteomics (biotin pulldown + MS) identifying covalent modification site, mutagenesis-level resolution (Cys495), multiple cell and in vivo models","pmids":["40396239"],"is_preprint":false},{"year":2025,"finding":"L-PGDS knockout mice display disrupted iron homeostasis: elevated plasma iron, increased splenic iron, reduced hepatic iron, decreased plasma free heme/hemin, and modest RBC enlargement, consistent with impaired heme catabolism. Transcript-protein mismatches in NRF2 and ferroportin (FPN) indicate redox imbalance. These findings support a model in which L-PGDS buffers porphyrin intermediates during heme catabolism, functioning as an auxiliary factor in iron recycling.","method":"L-PGDS KO mice; plasma/tissue iron quantification; RBC morphology; western blot and qPCR for NRF2, FPN, Hmox1; splenic/hepatic iron histochemistry","journal":"Prostaglandins & other lipid mediators","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — genetic KO with multiple iron homeostasis readouts, single lab, no direct biochemical reconstitution of porphyrin binding","pmids":["41274340"],"is_preprint":false},{"year":2025,"finding":"PTGDS-overexpressed skin fibroblasts upregulate chemokines and enhance migration of CD4+ T cells, particularly Th2 cells; this is reversed by the PTGDS inhibitor AT56. In a bleomycin-induced skin fibrosis model, PTGDS overexpression promotes Th2 infiltration and fibrosis, while AT56 attenuates inflammation and fibrosis in vivo.","method":"PTGDS OE in BJ fibroblasts; AT56 inhibitor; CD4+ T cell migration assay; Th2 subset analysis; bleomycin mouse model; IHC for fibrosis markers","journal":"Rheumatology (Oxford, England)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro gain-of-function with inhibitor rescue and in vivo model validation, single lab","pmids":["40478772"],"is_preprint":false},{"year":2024,"finding":"The L-PGDS–PGD2–DP1 (but not DP2) axis regulates phagocytosis by CD36+ microglia/macrophages in ischemic areas after stroke. L-PGDS is upregulated in the leptomeninges of ischemic areas; DP1 is highly expressed on CD36+ MGs/MΦs uniquely present within ischemic areas; PGD2 treatment promotes conversion of MGs/MΦs into CD36+ scavenger phenotype and increases their phagocytic activity.","method":"Mouse ischemic stroke model; immunohistochemistry for L-PGDS, PGD2, DP1, DP2, CD36; PGD2 treatment of MGs/MΦs; phagocytosis assay","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — in vivo localization plus ex vivo phagocytosis assay, single lab, receptor subtype pharmacological discrimination","pmids":["39451255"],"is_preprint":false},{"year":2025,"finding":"PTGDS in brain-derived exosomes from aged mice activates DP1 receptor signaling (via elevated PGD2), promoting microglial overactivation, lipid droplet accumulation, senescence-associated secretory phenotype secretion, myeloid cell infiltration, and cognitive decline. Blocking DP1 receptor ameliorates exosome-induced microglial senescence and cognitive decline in vivo.","method":"Brain-derived exosome transfer to young mice; PTGDS knockdown in exosomes; DP1 receptor antagonist; microglial senescence assays (SASP, lipid droplets); cognitive testing; aged mouse model","journal":"Aging cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — exosome transfer, genetic (PTGDS KD), and pharmacological (DP1 blockade) interventions with multiple phenotypic readouts, single lab","pmids":["40974022"],"is_preprint":false},{"year":2025,"finding":"Insulin resistance in HepG2 cells downregulates L-PGDS at the transcriptional level (decreased mRNA and protein), and induces trafficking of L-PGDS from the cytoplasm to the nucleus. Proteasomal degradation, autophagy, and ubiquitination pathways were experimentally excluded as mechanisms of downregulation.","method":"HepG2 palmitate/insulin model; MG132 (proteasome inhibitor), chloroquine (autophagy inhibitor), cycloheximide (translation inhibitor); co-immunoprecipitation for ubiquitination; subcellular fractionation; qRT-PCR; western blot","journal":"Prostaglandins & other lipid mediators","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — systematic exclusion of post-translational pathways by multiple inhibitors plus subcellular fractionation, single lab","pmids":["41386368"],"is_preprint":false},{"year":2009,"finding":"L-PGDS (at concentrations found in patients with intracranial hypertension or normal-tension glaucoma) directly inhibits astrocyte proliferation and mitochondrial ATP production in vitro.","method":"Recombinant L-PGDS added to astrocyte cultures; cell proliferation assay; mitochondrial ATP production measurement","journal":"Journal of molecular neuroscience","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single in vitro functional assay with recombinant protein, no mechanistic pathway delineation, single lab","pmids":["19598000"],"is_preprint":false},{"year":2012,"finding":"Heterozygous and homozygous Ptgds-knockout mice display unilateral cryptorchidism (affecting inguinoscrotal phase of testicular descent) at rates of 16% and 24%, respectively, associated with decreased Rxfp2 mRNA in the gubernaculum but no impairment of the androgen pathway, identifying PTGDS/PGD2 signaling as a novel component of testicular descent regulation.","method":"Ptgds KO mouse model; histology; immunohistochemistry; qPCR for Rxfp2 and androgen pathway genes; gubernaculum morphology","journal":"Human mutation","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — genetic KO phenotype with pathway placement by gene expression, single lab","pmids":["23076868"],"is_preprint":false}],"current_model":"PTGDS (L-PGDS) is a bifunctional lipocalin: it enzymatically converts prostaglandin H2 to PGD2 (and further to 15d-PGJ2), and independently acts as a lipocalin carrier/chaperone for hydrophobic ligands and porphyrin intermediates. Its enzymatic products signal through DP1/DP2 receptors and intracellular PPARγ to regulate inflammation, vascular barrier integrity, sleep, angiogenesis, and cardiac protection (via 15d-PGJ2 lipoxidation of CaMKII-Cys495). L-PGDS is phosphorylated and activated by PKC, promotes apoptosis by suppressing the PI3-K/Akt pathway, and interacts with MYH9 to activate Wnt–β-catenin–STAT3 signaling and with HMOX1 to regulate heme catabolism and ferroptosis. Its lipocalin domain (independent of PGD2 synthesis) suppresses Aβ aggregation/fibrillization and limits lung inflammatory-cell infiltration. Upstream regulators include glucocorticoids, HIF-1α, ET-1/COX2, YAP (repressor), and CUL4B/PRC2 (epigenetic repressor), while N-glycosylation at Asn51/Asn78 controls its nuclear translocation and protein stability."},"narrative":{"mechanistic_narrative":"PTGDS (L-PGDS) is a bifunctional lipocalin that couples enzymatic prostaglandin D2 (PGD2) synthesis to a structurally independent hydrophobic-ligand carrier activity, allowing it to regulate inflammation, vascular barrier integrity, metabolism, and cell fate across multiple tissues [PMID:34615734]. Its two functions are genetically separable: in acute lung injury, the PGD2-synthesizing activity restrains pulmonary edema while the lipocalin carrier function—independent of PGD2 production—limits mucin formation and inflammatory-cell infiltration [PMID:34615734, PMID:30734298]. PGD2 generated by L-PGDS signals through the DP1 prostanoid receptor to drive ERK-dependent neuroprotection [PMID:25474649] and CD36+ phagocyte conversion in ischemic brain [PMID:39451255], and through nuclear PPARγ to promote ANP secretion in cardiac atria within HIF-1α– and ET-1/COX2-initiated cascades [PMID:29287795, PMID:31541683]. The downstream PGD2 metabolite 15d-PGJ2, produced intracellularly, covalently lipoxidates CaMKII at Cys495 to dampen CaMKII oligomerization and protect cardiomyocytes from ischemia/reperfusion injury [PMID:40396239]. Beyond lipid signaling, L-PGDS acts as a molecular chaperone/disaggregase that directly binds monomeric Aβ via its C-terminus and disassembles preformed fibrils [PMID:31467325], and it physically engages HMOX1 to control heme catabolism, intracellular iron, and ferroptosis [PMID:39706989], consistent with disrupted iron homeostasis in knockout mice [PMID:41274340]. In cancer, PTGDS interacts with MYH9 to activate Wnt–β-catenin–STAT3 signaling and drive DLBCL tumorigenesis, with N-glycosylation at Asn51/Asn78 governing its nuclear translocation and stability [PMID:34743203], whereas YAP and the CUL4B/PRC2 complex act as upstream repressors of its expression [PMID:32851567, PMID:26025376]. PKC phosphorylation activates L-PGDS to suppress PI3-K/Akt signaling and trigger Bad-dependent apoptosis [PMID:12388064].","teleology":[{"year":2002,"claim":"Established that L-PGDS is not merely a constitutive synthase but a signal-responsive enzyme whose PKC phosphorylation links it to pro-apoptotic suppression of the PI3-K/Akt survival pathway.","evidence":"In vitro PKC phosphorylation of recombinant L-PGDS with antisense depletion, PI3-K activity assays, and caspase-3 readouts in cells","pmids":["12388064"],"confidence":"High","gaps":["Phosphosite(s) on L-PGDS not mapped","Direct mechanism by which L-PGDS inhibits PI3-K (enzymatic product vs. protein interaction) unresolved"]},{"year":2009,"claim":"Tested whether extracellular L-PGDS has direct cellular effects, showing it inhibits astrocyte proliferation and mitochondrial ATP production at pathological concentrations.","evidence":"Recombinant L-PGDS added to astrocyte cultures with proliferation and ATP assays","pmids":["19598000"],"confidence":"Low","gaps":["Single in vitro functional assay with no pathway delineation","Receptor or uptake mechanism unknown","Enzymatic vs. lipocalin contribution not distinguished"]},{"year":2012,"claim":"Placed PTGDS/PGD2 signaling as a novel regulator of testicular descent, distinct from the androgen pathway.","evidence":"Ptgds knockout mice with cryptorchidism phenotyping and Rxfp2 expression analysis","pmids":["23076868"],"confidence":"Medium","gaps":["Receptor mediating the descent phenotype not identified","Mechanistic link between PGD2 and Rxfp2 expression unresolved"]},{"year":2014,"claim":"Defined a linear L-PGDS–PGD2–DP1–pERK axis as the effector of dexamethasone neuroprotection, demonstrating receptor-coupled downstream signaling of the synthase product.","evidence":"Intracerebroventricular inhibitor epistasis (L-PGDS, DP1, MAPK) in a neonatal rat hypoxic-ischemic model","pmids":["25474649"],"confidence":"Medium","gaps":["Cell types producing vs. responding to PGD2 not separated","Direct vs. indirect DP1–ERK coupling not biochemically shown"]},{"year":2015,"claim":"Identified upstream epigenetic control, showing CUL4B/PRC2 transcriptionally represses Ptgds and that its enzymatic activity drives astrocyte fate in neural progenitors.","evidence":"Cul4b knockout mice, ChIP at the Ptgds locus, AT56 inhibition, shRNA knockdown, and gain-of-function rescue in NPC cultures","pmids":["26025376"],"confidence":"High","gaps":["PGD2 receptor mediating gliogenesis not identified","Direct PRC2 mark deposition vs. CUL4B-mediated effects not fully separated"]},{"year":2017,"claim":"Showed hypoxia couples HIF-1α induction of L-PGDS to PPARγ-dependent ANP secretion, establishing an intracellular nuclear-receptor route for PGD2 signaling in the heart.","evidence":"Sequential pharmacological inhibitor epistasis in isolated perfused beating rat atria","pmids":["29287795"],"confidence":"Medium","gaps":["Direct PGD2–PPARγ binding in this system not demonstrated","Ex vivo single-lab pharmacology only"]},{"year":2019,"claim":"Extended the cardiac axis upstream to ET-1/COX2 and revealed an NRF2-mediated positive feedback loop sustaining L-PGDS expression.","evidence":"ET receptor antagonists and pathway western blots in beating rat atria","pmids":["31541683"],"confidence":"Medium","gaps":["NRF2 regulation of L-PGDS not shown at promoter level","Single method type, single lab"]},{"year":2019,"claim":"Resolved a non-enzymatic chaperone function, showing L-PGDS directly binds and disaggregates Aβ via its lipocalin cavity.","evidence":"NMR, SAXS, TEM, and thioflavin-T assays defining the L-PGDS–Aβ40 binding mode and disaggregase activity","pmids":["31467325"],"confidence":"High","gaps":["In vivo relevance to amyloid pathology not established","Stoichiometry and turnover of disaggregation unresolved"]},{"year":2019,"claim":"Demonstrated cell-stage-specific metabolic roles, with premature-adipocyte L-PGDS-derived PGD2 driving obesity and insulin resistance.","evidence":"Two adipose-specific conditional knockout models (aP2-Cre, AdipoQ-Cre) under high-fat diet with metabolic phenotyping","pmids":["30760783"],"confidence":"High","gaps":["Receptor mediating the adipocyte phenotype not pinned down","Mechanism of stage specificity unresolved"]},{"year":2019,"claim":"Connected L-PGDS to glucocorticoid-induced leptin expression and identified it as the off-target of CB2 ligands suppressing leptin.","evidence":"Pharmacological screening, CB2-KO adipocytes, docking, and inhibitor experiments in differentiated preadipocytes","pmids":["31129049"],"confidence":"Medium","gaps":["Direct binding of CB2 ligands to L-PGDS not crystallographically confirmed","Mechanism linking L-PGDS to leptin transcription unknown"]},{"year":2019,"claim":"Showed PGD2 from non-hematopoietic L-PGDS protects the endothelial barrier in acute lung injury via the DP receptor.","evidence":"L-PGDS KO mice, bone marrow chimeras, Miles permeability assay, and DP agonist barrier assays in the HCl ALI model","pmids":["30734298"],"confidence":"High","gaps":["Endothelial DP1 vs. DP2 contribution not separated","Downstream barrier-stabilizing effectors unidentified"]},{"year":2020,"claim":"Identified YAP as an upstream repressor of L-PGDS in gastric cancer, with L-PGDS opposing YAP-driven stemness.","evidence":"Reciprocal YAP/L-PGDS gain- and loss-of-function with sphere formation and xenograft rescue","pmids":["32851567"],"confidence":"Medium","gaps":["Direct vs. indirect YAP repression of the locus not resolved","Enzymatic vs. lipocalin basis of tumor suppression unclear"]},{"year":2021,"claim":"Genetically separated the enzymatic and lipocalin functions of L-PGDS in lung injury using PGD2-null/lipocalin-intact point-mutant mice.","evidence":"L-PGDS-deficient vs. point-mutant mice with edema, BALF, and mucin readouts in the HCl ALI model","pmids":["34615734"],"confidence":"High","gaps":["Ligand(s) carried by the lipocalin function in lung not identified","Receptor/effector for the lipocalin-mediated anti-inflammatory effect unknown"]},{"year":2021,"claim":"Revealed a nuclear, interaction-based oncogenic role, with PTGDS binding MYH9 to activate Wnt–β-catenin–STAT3 signaling, regulated by N-glycosylation.","evidence":"Co-IP mass spectrometry, glycosylation-site mutagenesis (Asn51/Asn78), knockdown/rescue, and xenografts in DLBCL","pmids":["34743203"],"confidence":"High","gaps":["Whether MYH9 binding requires enzymatic activity unknown","Mechanism coupling glycosylation to nuclear import unresolved"]},{"year":2024,"claim":"Established a physical PTGDS–HMOX1 interaction controlling heme catabolism, iron levels, and ferroptosis in lymphoma cells.","evidence":"Co-IP/TMT-MS, HMOX1 H25A interaction-site mutation, ferroptosis and iron assays, and xenografts","pmids":["39706989"],"confidence":"High","gaps":["Whether PTGDS modulates HMOX1 catalysis directly or via cofactor delivery unresolved","Role of PGD2 vs. lipocalin function in this interaction unclear"]},{"year":2024,"claim":"Extended the PGD2–DP1 axis to post-stroke immunity, showing it converts microglia/macrophages to a CD36+ phagocytic scavenger phenotype.","evidence":"Mouse stroke model immunohistochemistry plus ex vivo PGD2 treatment and phagocytosis assays","pmids":["39451255"],"confidence":"Medium","gaps":["DP1 signaling pathway driving CD36 induction not delineated","In vivo causality from genetic loss not shown"]},{"year":2025,"claim":"Defined the intracellular mechanism of cardiac protection: L-PGDS-derived 15d-PGJ2 covalently lipoxidates CaMKII-Cys495 to limit its oligomerization and overactivation.","evidence":"Biotin-15d-PGJ2 chemical proteomics with LC-MS/MS site mapping, L-PGDS OE/KD across cardiomyocyte models, and a mouse I/R model","pmids":["40396239"],"confidence":"High","gaps":["In vivo contribution of Cys495 modification vs. other targets not isolated","Regulation of intracellular 15d-PGJ2 levels by L-PGDS not quantified"]},{"year":2025,"claim":"Supported a systemic role in iron recycling, with L-PGDS knockout mice showing disrupted iron distribution and reduced free heme consistent with impaired heme catabolism.","evidence":"L-PGDS KO mice with plasma/tissue iron quantification, RBC morphology, and NRF2/FPN/Hmox1 expression","pmids":["41274340"],"confidence":"Medium","gaps":["No direct biochemical reconstitution of porphyrin binding","Causal link between porphyrin buffering and iron phenotype inferential"]},{"year":2025,"claim":"Implicated PTGDS in fibroinflammation, showing fibroblast PTGDS recruits Th2 cells and promotes skin fibrosis, reversible by enzymatic inhibition.","evidence":"PTGDS overexpression in fibroblasts, AT56 inhibition, T-cell migration assays, and a bleomycin skin fibrosis model","pmids":["40478772"],"confidence":"Medium","gaps":["Receptor mediating Th2 chemotaxis not identified","Chemokines downstream of PGD2 not mechanistically validated"]},{"year":2025,"claim":"Linked exosomal PTGDS to brain aging, showing PTGDS-bearing exosomes drive DP1-dependent microglial senescence and cognitive decline.","evidence":"Brain-derived exosome transfer, PTGDS knockdown, and DP1 antagonism with senescence and cognitive readouts in aged mice","pmids":["40974022"],"confidence":"Medium","gaps":["Mechanism of PTGDS exosomal loading unknown","DP1 downstream senescence program not defined"]},{"year":2025,"claim":"Characterized regulation of L-PGDS under hepatic insulin resistance, showing transcriptional downregulation with cytoplasm-to-nucleus trafficking, excluding proteasomal/autophagic/ubiquitin routes.","evidence":"HepG2 palmitate/insulin model with inhibitor panels, ubiquitination Co-IP, and subcellular fractionation","pmids":["41386368"],"confidence":"Medium","gaps":["Transcription factor driving downregulation not identified","Functional consequence of nuclear trafficking in hepatocytes unknown"]},{"year":null,"claim":"How L-PGDS coordinates its enzymatic PGD2/15d-PGJ2 output with its ligand-carrier and protein-interaction functions across tissues, and which receptors or partners dominate in each context, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified structural model coupling catalytic and lipocalin/binding functions","Tissue-specific receptor preference (DP1 vs DP2 vs PPARγ) not systematically defined","Endogenous porphyrin/hydrophobic ligands of the carrier function only partially identified"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016491","term_label":"oxidoreductase activity","supporting_discovery_ids":[6,8,13]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[1,6,14]},{"term_id":"GO:0044183","term_label":"protein folding chaperone","supporting_discovery_ids":[1]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[13]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[18]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[7,18]},{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[5,19]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[17]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[4,14]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2,8,9]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[5,6,16]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[0,12,13]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[7,11,12]}],"complexes":[],"partners":["MYH9","HMOX1","CAMKII"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P41222","full_name":"Prostaglandin-H2 D-isomerase","aliases":["Beta-trace protein","Cerebrin-28","Glutathione-independent PGD synthase","Lipocalin-type prostaglandin-D synthase","L-PGDS","Prostaglandin-D2 synthase","PGD2 synthase","PGDS","PGDS2"],"length_aa":190,"mass_kda":21.0,"function":"Catalyzes the conversion of PGH2 to PGD2, a prostaglandin involved in smooth muscle contraction/relaxation and a potent inhibitor of platelet aggregation (PubMed:20667974). Involved in a variety of CNS functions, such as sedation, NREM sleep and PGE2-induced allodynia, and may have an anti-apoptotic role in oligodendrocytes. Binds small non-substrate lipophilic molecules, including biliverdin, bilirubin, retinal, retinoic acid and thyroid hormone, and may act as a scavenger for harmful hydrophobic molecules and as a secretory retinoid and thyroid hormone transporter. Possibly involved in development and maintenance of the blood-brain, blood-retina, blood-aqueous humor and blood-testis barrier. It is likely to play important roles in both maturation and maintenance of the central nervous system and male reproductive system (PubMed:20667974, PubMed:9475419). Involved in PLA2G3-dependent maturation of mast cells. PLA2G3 is secreted by immature mast cells and acts on nearby fibroblasts upstream to PTDGS to synthesize PGD2, which in turn promotes mast cell maturation and degranulation via PTGDR (By similarity)","subcellular_location":"Rough endoplasmic reticulum; Nucleus membrane; Golgi apparatus; Cytoplasm, perinuclear region; Secreted","url":"https://www.uniprot.org/uniprotkb/P41222/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PTGDS","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/PTGDS","total_profiled":1310},"omim":[{"mim_id":"604687","title":"PROSTAGLANDIN D2 RECEPTOR; PTGDR","url":"https://www.omim.org/entry/604687"},{"mim_id":"272800","title":"TAY-SACHS DISEASE; TSD","url":"https://www.omim.org/entry/272800"},{"mim_id":"268800","title":"SANDHOFF DISEASE","url":"https://www.omim.org/entry/268800"},{"mim_id":"176803","title":"PROSTAGLANDIN D2 SYNTHASE, BRAIN; PTGDS","url":"https://www.omim.org/entry/176803"},{"mim_id":"120930","title":"COMPLEMENT COMPONENT 8, GAMMA SUBUNIT; C8G","url":"https://www.omim.org/entry/120930"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"brain","ntpm":3337.6},{"tissue":"heart muscle","ntpm":4605.2},{"tissue":"testis","ntpm":3126.4}],"url":"https://www.proteinatlas.org/search/PTGDS"},"hgnc":{"alias_symbol":["PGDS","L-PGDS"],"prev_symbol":[]},"alphafold":{"accession":"P41222","domains":[{"cath_id":"2.40.128.20","chopping":"35-178","consensus_level":"high","plddt":95.0799,"start":35,"end":178}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P41222","model_url":"https://alphafold.ebi.ac.uk/files/AF-P41222-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P41222-F1-predicted_aligned_error_v6.png","plddt_mean":87.81},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PTGDS","jax_strain_url":"https://www.jax.org/strain/search?query=PTGDS"},"sequence":{"accession":"P41222","fasta_url":"https://rest.uniprot.org/uniprotkb/P41222.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P41222/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P41222"}},"corpus_meta":[{"pmid":"34743203","id":"PMC_34743203","title":"Glycoprotein PTGDS promotes tumorigenesis of diffuse large B-cell lymphoma by MYH9-mediated regulation of Wnt-β-catenin-STAT3 signaling.","date":"2021","source":"Cell death and differentiation","url":"https://pubmed.ncbi.nlm.nih.gov/34743203","citation_count":88,"is_preprint":false},{"pmid":"19070593","id":"PMC_19070593","title":"Knockout of the l-pgds gene aggravates obesity and atherosclerosis in mice.","date":"2008","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/19070593","citation_count":46,"is_preprint":false},{"pmid":"35087591","id":"PMC_35087591","title":"MSC-Derived Extracellular Vesicle-Delivered L-PGDS Inhibit Gastric Cancer Progression by Suppressing Cancer Cell Stemness and STAT3 Phosphorylation.","date":"2022","source":"Stem cells international","url":"https://pubmed.ncbi.nlm.nih.gov/35087591","citation_count":35,"is_preprint":false},{"pmid":"25474649","id":"PMC_25474649","title":"Dexamethasone protects neonatal hypoxic-ischemic brain injury via L-PGDS-dependent PGD2-DP1-pERK signaling pathway.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25474649","citation_count":34,"is_preprint":false},{"pmid":"31467325","id":"PMC_31467325","title":"Abundant neuroprotective chaperone Lipocalin-type prostaglandin D synthase (L-PGDS) disassembles the Amyloid-β fibrils.","date":"2019","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/31467325","citation_count":31,"is_preprint":false},{"pmid":"27900597","id":"PMC_27900597","title":"L-PGDS Mediates Vagus Nerve Stimulation-Induced Neuroprotection in a Rat Model of Ischemic Stroke by Suppressing the Apoptotic Response.","date":"2016","source":"Neurochemical research","url":"https://pubmed.ncbi.nlm.nih.gov/27900597","citation_count":31,"is_preprint":false},{"pmid":"19598000","id":"PMC_19598000","title":"L-PGDS (betatrace protein) inhibits astrocyte proliferation and mitochondrial ATP production in vitro.","date":"2009","source":"Journal of molecular neuroscience : MN","url":"https://pubmed.ncbi.nlm.nih.gov/19598000","citation_count":30,"is_preprint":false},{"pmid":"12388064","id":"PMC_12388064","title":"Elevated L-PGDS activity contributes to PMA-induced apoptosis concomitant with downregulation of PI3-K.","date":"2002","source":"American journal of physiology. 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Activated L-PGDS inhibits PI3-K activity, leading to reduced PKB/Akt phosphorylation, hypophosphorylation and activation of Bad, and subsequent caspase-3 activation and apoptosis. Antisense depletion of L-PGDS prevented PI3-K inactivation, caspase-3 activation, and apoptosis.\",\n      \"method\": \"In vitro PKC phosphorylation of recombinant L-PGDS; antisense RNA depletion; PI3-K activity assay; western blot for Akt, Bad, Rb phosphorylation; caspase-3 activation assay\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro reconstitution of PKC phosphorylation plus multiple orthogonal cellular assays (antisense KD, kinase activity, apoptosis readouts) in single lab\",\n      \"pmids\": [\"12388064\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"L-PGDS acts as a molecular chaperone/disaggregase: it directly binds monomeric Aβ40 and Aβ(25-35) via the Aβ C-terminus (N-terminus remains free), inhibiting spontaneous aggregation, and also disassembles pre-formed Aβ fibrils. The binding mode was resolved by NMR spectroscopy and SAXS, yielding a structural model of the L-PGDS–Aβ40 complex.\",\n      \"method\": \"NMR spectroscopy (binding mode), SAXS (solution structure), TEM (fibril morphology), thioflavin-T aggregation assay, proteomics on AD brain insoluble fractions\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — multiple structural/biophysical methods (NMR + SAXS + TEM) in a single rigorous study establishing direct binding and disaggregase activity\",\n      \"pmids\": [\"31467325\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Dexamethasone upregulates L-PGDS expression and PGD2 biosynthesis in neonatal rat brain; the neuroprotective effect of dexamethasone against hypoxic-ischemic injury requires the L-PGDS–PGD2–DP1–pERK signaling axis, as pharmacological inhibition of L-PGDS (SeCl4), DP1 (MK-0524), or MAPK (PD98059) each abolished dexamethasone-induced pERK-44 elevation and neuroprotection.\",\n      \"method\": \"Intracerebroventricular drug injections; western blot for L-PGDS, DP1, pERK1/2; ELISA for PGD2; pharmacological inhibitor epistasis; neonatal rat HI model\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pathway epistasis with three independent inhibitors in vivo, single lab\",\n      \"pmids\": [\"25474649\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"CUL4B/PRC2 complex transcriptionally represses Ptgds expression in neural progenitor cells (NPCs). Loss of Cul4b increases PTGDS levels, promoting conversion of NPCs to GFAP+ astrocytes; this phenotype is rescued by pharmacological inhibition of PTGDS enzymatic activity (AT56) or shRNA-mediated Ptgds knockdown, and is phenocopied by exogenous PTGDS addition to wild-type NPCs.\",\n      \"method\": \"Cul4b knockout mouse model; NPC culture; GFAP/S100β immunostaining; AT56 inhibitor; shRNA knockdown; exogenous PTGDS addition; ChIP for CUL4B/PRC2 at Ptgds locus\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO, pharmacological inhibition, shRNA KD, and gain-of-function rescue with multiple orthogonal methods in one study\",\n      \"pmids\": [\"26025376\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"L-PGDS-derived PGD2, produced specifically in premature (but not mature) adipocytes, promotes obesity and insulin resistance under high-fat diet conditions. Deletion of L-PGDS in premature adipocytes (aP2-Cre) reduced PGD2 production in WAT, decreased body weight gain, adipocyte size, and serum lipids, and improved insulin sensitivity, with altered expression of adipogenic, lipogenic, and macrophage marker genes.\",\n      \"method\": \"Adipose-specific conditional knockout mice (aP2-Cre and AdipoQ-Cre); HFD feeding; PGD2 ELISA; glucose/insulin tolerance tests; gene expression profiling\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two distinct conditional KO models dissecting cell-stage specificity, multiple metabolic phenotype readouts, single lab\",\n      \"pmids\": [\"30760783\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"L-PGDS-derived PGD2 protects against acute lung injury by enhancing endothelial barrier function via the DP (D prostanoid) receptor. In HCl-induced ALI, inflamed endothelial/epithelial cells express L-PGDS; L-PGDS-deficient mice show exacerbated vascular permeability that is suppressed by DP receptor agonism. Hematopoietic reconstitution with WT bone marrow did not rescue the edema phenotype, confirming non-hematopoietic origin.\",\n      \"method\": \"L-PGDS KO mice; HCl intratracheal model; Miles assay for vascular permeability; immunostaining; bone marrow reconstitution; in vitro endothelial barrier assay with DP agonist\",\n      \"journal\": \"The Journal of pathology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO mouse, bone marrow chimera, in vitro barrier assay, and receptor pharmacology providing convergent mechanistic evidence in single study\",\n      \"pmids\": [\"30734298\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"L-PGDS has two mechanistically distinct protective roles in acute lung injury: (1) its PGD2-synthesizing enzymatic activity inhibits pulmonary edema formation, and (2) its lipocalin carrier function (independent of PGD2 production) decreases mucin formation and inflammatory cell infiltration, as dissected using point-mutant mice that lack PGD2 producibility but retain lipocalin ability.\",\n      \"method\": \"L-PGDS-deficient mice vs. L-PGDS point-mutant (PGD2-null, lipocalin-intact) mice; HCl intratracheal model; lung water content; BALF protein and leukocyte counts; mucin staining; IL-33 mRNA measurement\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — genetic separation of enzymatic vs. lipocalin functions using distinct mutant mouse lines with multiple phenotypic readouts\",\n      \"pmids\": [\"34615734\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PTGDS interacts with MYH9 (identified by co-immunoprecipitation–mass spectrometry). PTGDS promotes DLBCL tumorigenesis through MYH9-mediated activation of the Wnt–β-catenin–STAT3 pathway by influencing ubiquitination and degradation of GSK3-β. N-glycosylation of PTGDS at Asn51 and Asn78 regulates its nuclear translocation, protein half-life, and proliferative activity.\",\n      \"method\": \"Co-IP mass spectrometry; site-directed mutagenesis of glycosylation sites (Asn51, Asn78); lentiviral KD; rescue experiments; subcellular fractionation; western blot for Wnt/β-catenin/STAT3 pathway; in vitro and xenograft models\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — Co-IP-MS for interaction, mutagenesis for glycosylation sites, pathway rescue, and in vivo validation; multiple orthogonal methods in single study\",\n      \"pmids\": [\"34743203\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Hypoxia activates HIF-1α, which upregulates L-PGDS expression in beating rat atria; L-PGDS-derived PGD2 then activates PPARγ to promote ANP secretion. The HIF-1α–L-PGDS–PPARγ signaling axis was established by sequential pharmacological inhibition (2-methoxyestradiol for HIF-1α; AT-56/HQL-49 for L-PGDS; GW9662 for PPARγ).\",\n      \"method\": \"Isolated perfused beating rat atria; pharmacological inhibitors (2-methoxyestradiol, AT-56, HQL-49, GW9662); western blot for HIF-1α, L-PGDS, PPARγ; ANP secretion measurement\",\n      \"journal\": \"Prostaglandins & other lipid mediators\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pathway epistasis using four sequential inhibitors in an ex vivo model, single lab\",\n      \"pmids\": [\"29287795\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Endogenous ET-1 (induced by hypoxia) promotes ANP secretion via COX2–L-PGDS–PPARγ signaling. L-PGDS-derived PGD2 also feeds back to regulate L-PGDS expression through an NRF2-mediated positive feedback mechanism in beating rat atria.\",\n      \"method\": \"Isolated perfused beating rat atria; ET receptor antagonists; western blot for COX2, L-PGDS, PPARγ, NRF2; PGD2 ELISA; ANP secretion measurement\",\n      \"journal\": \"Peptides\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — ex vivo pharmacological epistasis, single lab, single method type\",\n      \"pmids\": [\"31541683\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"L-PGDS mediates glucocorticoid-induced leptin expression in differentiated adipocytes: glucocorticoids induce L-PGDS, which in turn positively regulates leptin. Aldosterone, while also inducing both L-PGDS and leptin, does not require L-PGDS for leptin induction. Target deconvolution and docking identified L-PGDS as the off-target responsible for leptin suppression by CB2 ligands AM630 and WIN55212-2.\",\n      \"method\": \"Pharmacological screening; genetic (CB2-KO) adipocytes; docking simulation; L-PGDS inhibitor (AM630/WIN55212-2); gene/protein expression in differentiated primary preadipocytes\",\n      \"journal\": \"Biochemical pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic and pharmacological dissection with CB2-KO controls plus docking, single lab\",\n      \"pmids\": [\"31129049\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In gastric cancer cells, YAP directly suppresses L-PTGDS (L-PGDS) expression; overexpression of L-PGDS reverses YAP-induced stemness promotion, inhibits proliferation and self-renewal in vitro, and reverses the pro-tumor effect of YAP in vivo, establishing YAP as an upstream negative regulator of L-PGDS.\",\n      \"method\": \"Gain- and loss-of-function (YAP OE/KD); L-PGDS/PTGDR2 OE; sphere formation; xenograft tumor model; RT-PCR; western blot; IHC\",\n      \"journal\": \"International journal of clinical oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal gain/loss-of-function with in vivo rescue, single lab\",\n      \"pmids\": [\"32851567\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"PTGDS physically interacts with the heme-degrading enzyme HMOX1 (identified by TMT-mass spectrometry). PTGDS knockdown increases intracellular iron and induces ferroptosis in peripheral T cell lymphoma cells by promoting HMOX1-mediated heme catabolism and ferritin autophagy. An H25A point mutation in HMOX1 identified the specific catalytic site required for this interaction.\",\n      \"method\": \"Co-IP/TMT-mass spectrometry; lentiviral KD; HMOX1 H25A point mutation; ferroptosis assays; iron level measurement; xenograft model; RNA-sequencing\",\n      \"journal\": \"British journal of cancer\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — proteomic interaction identification, site-directed mutagenesis of interaction site, functional rescue, and in vivo validation\",\n      \"pmids\": [\"39706989\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Intracellular L-PGDS-derived 15d-PGJ2 covalently modifies (lipoxidation) CaMKII at cysteine 495 (CaMKII-δ9), dampening CaMKII oligomer formation and overactivation, thereby alleviating cardiomyocyte death and cardiac ischemia/reperfusion injury. L-PGDS is downregulated in I/R-injured cardiac tissue; its overexpression mitigates injury while knockdown exacerbates it.\",\n      \"method\": \"Biotin-tagged 15d-PGJ2 analog + LC-MS/MS (target ID); L-PGDS OE/KD in neonatal and adult cardiomyocytes and hESC-derived cardiomyocytes; mouse I/R model; CaMKII oligomer assays; transcriptome profiling\",\n      \"journal\": \"Circulation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — chemical proteomics (biotin pulldown + MS) identifying covalent modification site, mutagenesis-level resolution (Cys495), multiple cell and in vivo models\",\n      \"pmids\": [\"40396239\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"L-PGDS knockout mice display disrupted iron homeostasis: elevated plasma iron, increased splenic iron, reduced hepatic iron, decreased plasma free heme/hemin, and modest RBC enlargement, consistent with impaired heme catabolism. Transcript-protein mismatches in NRF2 and ferroportin (FPN) indicate redox imbalance. These findings support a model in which L-PGDS buffers porphyrin intermediates during heme catabolism, functioning as an auxiliary factor in iron recycling.\",\n      \"method\": \"L-PGDS KO mice; plasma/tissue iron quantification; RBC morphology; western blot and qPCR for NRF2, FPN, Hmox1; splenic/hepatic iron histochemistry\",\n      \"journal\": \"Prostaglandins & other lipid mediators\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — genetic KO with multiple iron homeostasis readouts, single lab, no direct biochemical reconstitution of porphyrin binding\",\n      \"pmids\": [\"41274340\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PTGDS-overexpressed skin fibroblasts upregulate chemokines and enhance migration of CD4+ T cells, particularly Th2 cells; this is reversed by the PTGDS inhibitor AT56. In a bleomycin-induced skin fibrosis model, PTGDS overexpression promotes Th2 infiltration and fibrosis, while AT56 attenuates inflammation and fibrosis in vivo.\",\n      \"method\": \"PTGDS OE in BJ fibroblasts; AT56 inhibitor; CD4+ T cell migration assay; Th2 subset analysis; bleomycin mouse model; IHC for fibrosis markers\",\n      \"journal\": \"Rheumatology (Oxford, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro gain-of-function with inhibitor rescue and in vivo model validation, single lab\",\n      \"pmids\": [\"40478772\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"The L-PGDS–PGD2–DP1 (but not DP2) axis regulates phagocytosis by CD36+ microglia/macrophages in ischemic areas after stroke. L-PGDS is upregulated in the leptomeninges of ischemic areas; DP1 is highly expressed on CD36+ MGs/MΦs uniquely present within ischemic areas; PGD2 treatment promotes conversion of MGs/MΦs into CD36+ scavenger phenotype and increases their phagocytic activity.\",\n      \"method\": \"Mouse ischemic stroke model; immunohistochemistry for L-PGDS, PGD2, DP1, DP2, CD36; PGD2 treatment of MGs/MΦs; phagocytosis assay\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — in vivo localization plus ex vivo phagocytosis assay, single lab, receptor subtype pharmacological discrimination\",\n      \"pmids\": [\"39451255\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PTGDS in brain-derived exosomes from aged mice activates DP1 receptor signaling (via elevated PGD2), promoting microglial overactivation, lipid droplet accumulation, senescence-associated secretory phenotype secretion, myeloid cell infiltration, and cognitive decline. Blocking DP1 receptor ameliorates exosome-induced microglial senescence and cognitive decline in vivo.\",\n      \"method\": \"Brain-derived exosome transfer to young mice; PTGDS knockdown in exosomes; DP1 receptor antagonist; microglial senescence assays (SASP, lipid droplets); cognitive testing; aged mouse model\",\n      \"journal\": \"Aging cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — exosome transfer, genetic (PTGDS KD), and pharmacological (DP1 blockade) interventions with multiple phenotypic readouts, single lab\",\n      \"pmids\": [\"40974022\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Insulin resistance in HepG2 cells downregulates L-PGDS at the transcriptional level (decreased mRNA and protein), and induces trafficking of L-PGDS from the cytoplasm to the nucleus. Proteasomal degradation, autophagy, and ubiquitination pathways were experimentally excluded as mechanisms of downregulation.\",\n      \"method\": \"HepG2 palmitate/insulin model; MG132 (proteasome inhibitor), chloroquine (autophagy inhibitor), cycloheximide (translation inhibitor); co-immunoprecipitation for ubiquitination; subcellular fractionation; qRT-PCR; western blot\",\n      \"journal\": \"Prostaglandins & other lipid mediators\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — systematic exclusion of post-translational pathways by multiple inhibitors plus subcellular fractionation, single lab\",\n      \"pmids\": [\"41386368\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"L-PGDS (at concentrations found in patients with intracranial hypertension or normal-tension glaucoma) directly inhibits astrocyte proliferation and mitochondrial ATP production in vitro.\",\n      \"method\": \"Recombinant L-PGDS added to astrocyte cultures; cell proliferation assay; mitochondrial ATP production measurement\",\n      \"journal\": \"Journal of molecular neuroscience\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single in vitro functional assay with recombinant protein, no mechanistic pathway delineation, single lab\",\n      \"pmids\": [\"19598000\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Heterozygous and homozygous Ptgds-knockout mice display unilateral cryptorchidism (affecting inguinoscrotal phase of testicular descent) at rates of 16% and 24%, respectively, associated with decreased Rxfp2 mRNA in the gubernaculum but no impairment of the androgen pathway, identifying PTGDS/PGD2 signaling as a novel component of testicular descent regulation.\",\n      \"method\": \"Ptgds KO mouse model; histology; immunohistochemistry; qPCR for Rxfp2 and androgen pathway genes; gubernaculum morphology\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — genetic KO phenotype with pathway placement by gene expression, single lab\",\n      \"pmids\": [\"23076868\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PTGDS (L-PGDS) is a bifunctional lipocalin: it enzymatically converts prostaglandin H2 to PGD2 (and further to 15d-PGJ2), and independently acts as a lipocalin carrier/chaperone for hydrophobic ligands and porphyrin intermediates. Its enzymatic products signal through DP1/DP2 receptors and intracellular PPARγ to regulate inflammation, vascular barrier integrity, sleep, angiogenesis, and cardiac protection (via 15d-PGJ2 lipoxidation of CaMKII-Cys495). L-PGDS is phosphorylated and activated by PKC, promotes apoptosis by suppressing the PI3-K/Akt pathway, and interacts with MYH9 to activate Wnt–β-catenin–STAT3 signaling and with HMOX1 to regulate heme catabolism and ferroptosis. Its lipocalin domain (independent of PGD2 synthesis) suppresses Aβ aggregation/fibrillization and limits lung inflammatory-cell infiltration. Upstream regulators include glucocorticoids, HIF-1α, ET-1/COX2, YAP (repressor), and CUL4B/PRC2 (epigenetic repressor), while N-glycosylation at Asn51/Asn78 controls its nuclear translocation and protein stability.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PTGDS (L-PGDS) is a bifunctional lipocalin that couples enzymatic prostaglandin D2 (PGD2) synthesis to a structurally independent hydrophobic-ligand carrier activity, allowing it to regulate inflammation, vascular barrier integrity, metabolism, and cell fate across multiple tissues [#6]. Its two functions are genetically separable: in acute lung injury, the PGD2-synthesizing activity restrains pulmonary edema while the lipocalin carrier function—independent of PGD2 production—limits mucin formation and inflammatory-cell infiltration [#6, #5]. PGD2 generated by L-PGDS signals through the DP1 prostanoid receptor to drive ERK-dependent neuroprotection [#2] and CD36+ phagocyte conversion in ischemic brain [#16], and through nuclear PPARγ to promote ANP secretion in cardiac atria within HIF-1α– and ET-1/COX2-initiated cascades [#8, #9]. The downstream PGD2 metabolite 15d-PGJ2, produced intracellularly, covalently lipoxidates CaMKII at Cys495 to dampen CaMKII oligomerization and protect cardiomyocytes from ischemia/reperfusion injury [#13]. Beyond lipid signaling, L-PGDS acts as a molecular chaperone/disaggregase that directly binds monomeric Aβ via its C-terminus and disassembles preformed fibrils [#1], and it physically engages HMOX1 to control heme catabolism, intracellular iron, and ferroptosis [#12], consistent with disrupted iron homeostasis in knockout mice [#14]. In cancer, PTGDS interacts with MYH9 to activate Wnt–β-catenin–STAT3 signaling and drive DLBCL tumorigenesis, with N-glycosylation at Asn51/Asn78 governing its nuclear translocation and stability [#7], whereas YAP and the CUL4B/PRC2 complex act as upstream repressors of its expression [#11, #3]. PKC phosphorylation activates L-PGDS to suppress PI3-K/Akt signaling and trigger Bad-dependent apoptosis [#0].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Established that L-PGDS is not merely a constitutive synthase but a signal-responsive enzyme whose PKC phosphorylation links it to pro-apoptotic suppression of the PI3-K/Akt survival pathway.\",\n      \"evidence\": \"In vitro PKC phosphorylation of recombinant L-PGDS with antisense depletion, PI3-K activity assays, and caspase-3 readouts in cells\",\n      \"pmids\": [\"12388064\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phosphosite(s) on L-PGDS not mapped\", \"Direct mechanism by which L-PGDS inhibits PI3-K (enzymatic product vs. protein interaction) unresolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Tested whether extracellular L-PGDS has direct cellular effects, showing it inhibits astrocyte proliferation and mitochondrial ATP production at pathological concentrations.\",\n      \"evidence\": \"Recombinant L-PGDS added to astrocyte cultures with proliferation and ATP assays\",\n      \"pmids\": [\"19598000\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single in vitro functional assay with no pathway delineation\", \"Receptor or uptake mechanism unknown\", \"Enzymatic vs. lipocalin contribution not distinguished\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Placed PTGDS/PGD2 signaling as a novel regulator of testicular descent, distinct from the androgen pathway.\",\n      \"evidence\": \"Ptgds knockout mice with cryptorchidism phenotyping and Rxfp2 expression analysis\",\n      \"pmids\": [\"23076868\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Receptor mediating the descent phenotype not identified\", \"Mechanistic link between PGD2 and Rxfp2 expression unresolved\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined a linear L-PGDS–PGD2–DP1–pERK axis as the effector of dexamethasone neuroprotection, demonstrating receptor-coupled downstream signaling of the synthase product.\",\n      \"evidence\": \"Intracerebroventricular inhibitor epistasis (L-PGDS, DP1, MAPK) in a neonatal rat hypoxic-ischemic model\",\n      \"pmids\": [\"25474649\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cell types producing vs. responding to PGD2 not separated\", \"Direct vs. indirect DP1–ERK coupling not biochemically shown\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identified upstream epigenetic control, showing CUL4B/PRC2 transcriptionally represses Ptgds and that its enzymatic activity drives astrocyte fate in neural progenitors.\",\n      \"evidence\": \"Cul4b knockout mice, ChIP at the Ptgds locus, AT56 inhibition, shRNA knockdown, and gain-of-function rescue in NPC cultures\",\n      \"pmids\": [\"26025376\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"PGD2 receptor mediating gliogenesis not identified\", \"Direct PRC2 mark deposition vs. CUL4B-mediated effects not fully separated\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showed hypoxia couples HIF-1α induction of L-PGDS to PPARγ-dependent ANP secretion, establishing an intracellular nuclear-receptor route for PGD2 signaling in the heart.\",\n      \"evidence\": \"Sequential pharmacological inhibitor epistasis in isolated perfused beating rat atria\",\n      \"pmids\": [\"29287795\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct PGD2–PPARγ binding in this system not demonstrated\", \"Ex vivo single-lab pharmacology only\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Extended the cardiac axis upstream to ET-1/COX2 and revealed an NRF2-mediated positive feedback loop sustaining L-PGDS expression.\",\n      \"evidence\": \"ET receptor antagonists and pathway western blots in beating rat atria\",\n      \"pmids\": [\"31541683\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"NRF2 regulation of L-PGDS not shown at promoter level\", \"Single method type, single lab\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Resolved a non-enzymatic chaperone function, showing L-PGDS directly binds and disaggregates Aβ via its lipocalin cavity.\",\n      \"evidence\": \"NMR, SAXS, TEM, and thioflavin-T assays defining the L-PGDS–Aβ40 binding mode and disaggregase activity\",\n      \"pmids\": [\"31467325\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance to amyloid pathology not established\", \"Stoichiometry and turnover of disaggregation unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstrated cell-stage-specific metabolic roles, with premature-adipocyte L-PGDS-derived PGD2 driving obesity and insulin resistance.\",\n      \"evidence\": \"Two adipose-specific conditional knockout models (aP2-Cre, AdipoQ-Cre) under high-fat diet with metabolic phenotyping\",\n      \"pmids\": [\"30760783\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Receptor mediating the adipocyte phenotype not pinned down\", \"Mechanism of stage specificity unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Connected L-PGDS to glucocorticoid-induced leptin expression and identified it as the off-target of CB2 ligands suppressing leptin.\",\n      \"evidence\": \"Pharmacological screening, CB2-KO adipocytes, docking, and inhibitor experiments in differentiated preadipocytes\",\n      \"pmids\": [\"31129049\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct binding of CB2 ligands to L-PGDS not crystallographically confirmed\", \"Mechanism linking L-PGDS to leptin transcription unknown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Showed PGD2 from non-hematopoietic L-PGDS protects the endothelial barrier in acute lung injury via the DP receptor.\",\n      \"evidence\": \"L-PGDS KO mice, bone marrow chimeras, Miles permeability assay, and DP agonist barrier assays in the HCl ALI model\",\n      \"pmids\": [\"30734298\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Endothelial DP1 vs. DP2 contribution not separated\", \"Downstream barrier-stabilizing effectors unidentified\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identified YAP as an upstream repressor of L-PGDS in gastric cancer, with L-PGDS opposing YAP-driven stemness.\",\n      \"evidence\": \"Reciprocal YAP/L-PGDS gain- and loss-of-function with sphere formation and xenograft rescue\",\n      \"pmids\": [\"32851567\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs. indirect YAP repression of the locus not resolved\", \"Enzymatic vs. lipocalin basis of tumor suppression unclear\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Genetically separated the enzymatic and lipocalin functions of L-PGDS in lung injury using PGD2-null/lipocalin-intact point-mutant mice.\",\n      \"evidence\": \"L-PGDS-deficient vs. point-mutant mice with edema, BALF, and mucin readouts in the HCl ALI model\",\n      \"pmids\": [\"34615734\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Ligand(s) carried by the lipocalin function in lung not identified\", \"Receptor/effector for the lipocalin-mediated anti-inflammatory effect unknown\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Revealed a nuclear, interaction-based oncogenic role, with PTGDS binding MYH9 to activate Wnt–β-catenin–STAT3 signaling, regulated by N-glycosylation.\",\n      \"evidence\": \"Co-IP mass spectrometry, glycosylation-site mutagenesis (Asn51/Asn78), knockdown/rescue, and xenografts in DLBCL\",\n      \"pmids\": [\"34743203\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MYH9 binding requires enzymatic activity unknown\", \"Mechanism coupling glycosylation to nuclear import unresolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Established a physical PTGDS–HMOX1 interaction controlling heme catabolism, iron levels, and ferroptosis in lymphoma cells.\",\n      \"evidence\": \"Co-IP/TMT-MS, HMOX1 H25A interaction-site mutation, ferroptosis and iron assays, and xenografts\",\n      \"pmids\": [\"39706989\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PTGDS modulates HMOX1 catalysis directly or via cofactor delivery unresolved\", \"Role of PGD2 vs. lipocalin function in this interaction unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extended the PGD2–DP1 axis to post-stroke immunity, showing it converts microglia/macrophages to a CD36+ phagocytic scavenger phenotype.\",\n      \"evidence\": \"Mouse stroke model immunohistochemistry plus ex vivo PGD2 treatment and phagocytosis assays\",\n      \"pmids\": [\"39451255\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"DP1 signaling pathway driving CD36 induction not delineated\", \"In vivo causality from genetic loss not shown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined the intracellular mechanism of cardiac protection: L-PGDS-derived 15d-PGJ2 covalently lipoxidates CaMKII-Cys495 to limit its oligomerization and overactivation.\",\n      \"evidence\": \"Biotin-15d-PGJ2 chemical proteomics with LC-MS/MS site mapping, L-PGDS OE/KD across cardiomyocyte models, and a mouse I/R model\",\n      \"pmids\": [\"40396239\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo contribution of Cys495 modification vs. other targets not isolated\", \"Regulation of intracellular 15d-PGJ2 levels by L-PGDS not quantified\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Supported a systemic role in iron recycling, with L-PGDS knockout mice showing disrupted iron distribution and reduced free heme consistent with impaired heme catabolism.\",\n      \"evidence\": \"L-PGDS KO mice with plasma/tissue iron quantification, RBC morphology, and NRF2/FPN/Hmox1 expression\",\n      \"pmids\": [\"41274340\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No direct biochemical reconstitution of porphyrin binding\", \"Causal link between porphyrin buffering and iron phenotype inferential\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Implicated PTGDS in fibroinflammation, showing fibroblast PTGDS recruits Th2 cells and promotes skin fibrosis, reversible by enzymatic inhibition.\",\n      \"evidence\": \"PTGDS overexpression in fibroblasts, AT56 inhibition, T-cell migration assays, and a bleomycin skin fibrosis model\",\n      \"pmids\": [\"40478772\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Receptor mediating Th2 chemotaxis not identified\", \"Chemokines downstream of PGD2 not mechanistically validated\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Linked exosomal PTGDS to brain aging, showing PTGDS-bearing exosomes drive DP1-dependent microglial senescence and cognitive decline.\",\n      \"evidence\": \"Brain-derived exosome transfer, PTGDS knockdown, and DP1 antagonism with senescence and cognitive readouts in aged mice\",\n      \"pmids\": [\"40974022\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of PTGDS exosomal loading unknown\", \"DP1 downstream senescence program not defined\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Characterized regulation of L-PGDS under hepatic insulin resistance, showing transcriptional downregulation with cytoplasm-to-nucleus trafficking, excluding proteasomal/autophagic/ubiquitin routes.\",\n      \"evidence\": \"HepG2 palmitate/insulin model with inhibitor panels, ubiquitination Co-IP, and subcellular fractionation\",\n      \"pmids\": [\"41386368\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Transcription factor driving downregulation not identified\", \"Functional consequence of nuclear trafficking in hepatocytes unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How L-PGDS coordinates its enzymatic PGD2/15d-PGJ2 output with its ligand-carrier and protein-interaction functions across tissues, and which receptors or partners dominate in each context, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified structural model coupling catalytic and lipocalin/binding functions\", \"Tissue-specific receptor preference (DP1 vs DP2 vs PPARγ) not systematically defined\", \"Endogenous porphyrin/hydrophobic ligands of the carrier function only partially identified\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016491\", \"supporting_discovery_ids\": [6, 8, 13]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [1, 6, 14]},\n      {\"term_id\": \"GO:0044183\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [13]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [18]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [7, 18]},\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [5, 19]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [17]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [4, 14]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 8, 9]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [5, 6, 16]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [0, 12, 13]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [7, 11, 12]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"MYH9\", \"HMOX1\", \"CaMKII\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}