{"gene":"EGLN3","run_date":"2026-06-09T23:54:42","timeline":{"discoveries":[{"year":2002,"finding":"PHD3 (EGLN3) hydroxylates specific proline residues in HIF-1α within a conserved LXXLAP sequence motif; the hydroxylacceptor proline itself is the only obligatory residue for this reaction. PHD2 shows highest specific activity toward the primary hydroxylation site, while PHD3 shows restricted substrate specificity.","method":"In vitro prolyl hydroxylase assay with mutant HIF-1α peptides; sequence analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct in vitro enzymatic assay with systematic mutagenesis, replicated across PHD family members","pmids":["12181324"],"is_preprint":false},{"year":2004,"finding":"PHD3 contributes in a non-redundant manner to oxygen-dependent regulation of both HIF-1α and HIF-2α subunits; PHD isoforms show specificity for different prolyl hydroxylation sites within HIF-α subunits and a degree of selectivity between HIF-1α and HIF-2α.","method":"siRNA-mediated knockdown of individual PHD isoforms followed by measurement of HIF-α protein levels in multiple cell types under various culture conditions","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal siRNA knockdowns across multiple cell types with multiple oxygen/hormone conditions, independently replicated concept","pmids":["15247232"],"is_preprint":false},{"year":2004,"finding":"PHD3 interacts with the cytosolic chaperonin TRiC (TCP-1 ring complex), identified by co-purification and mass spectrometry, suggesting PHD3 is a TRiC substrate and that TRiC may regulate PHD3 activity.","method":"Co-purification of PHD3 from cell extracts followed by mass spectrometry identification of TRiC subunits","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — single co-purification experiment, single lab, no mutagenesis or functional validation of TRiC-PHD3 interaction consequences","pmids":["15251459"],"is_preprint":false},{"year":2005,"finding":"EglN3 (PHD3) acts downstream of c-Jun and is specifically required among EglN family members for neuronal apoptosis when NGF becomes limiting; EglN3 proapoptotic activity is feedback-inhibited by succinate (a product of SDH), placing EglN3 in a pathway linking SDH activity to developmental apoptosis.","method":"Genetic epistasis in sympathetic neuronal progenitor cells: selective EglN3 knockdown, NGF withdrawal apoptosis assay, succinate supplementation inhibition","journal":"Cancer cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — specific isoform requirement established by knockdown epistasis, functional link to succinate confirmed biochemically, published in high-impact journal","pmids":["16098468"],"is_preprint":false},{"year":2005,"finding":"A functional hypoxia response element (HRE) located in the first intron of the EGLN3 gene (12 kb downstream of transcription start) binds HIF in vivo and drives HIF-dependent transcriptional induction of EGLN3 under hypoxia, establishing a negative feedback loop.","method":"Bioinformatics HRE identification, reporter gene assays, chromatin immunoprecipitation (ChIP)","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 2 / Moderate — ChIP demonstrating in vivo HIF binding plus reporter assay showing HRE sufficiency, two orthogonal methods in one study","pmids":["15823097"],"is_preprint":false},{"year":2006,"finding":"PHD3 physically interacts with the novel WD-repeat scaffold protein Morg1 (MAPK organizer 1); co-expression of Morg1 with PHD3 decreases HIF-mediated reporter gene activity, and siRNA knockdown of either Morg1 or PHD3 increases HIF-1 activity. Both proteins co-localize in the cytoplasm and nucleus.","method":"Yeast two-hybrid screen, in vitro and in vivo co-immunoprecipitation, confocal microscopy co-localization, HIF reporter assay with siRNA knockdown","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid plus reciprocal co-IP plus functional reporter assay, multiple orthogonal methods in one study","pmids":["16407229"],"is_preprint":false},{"year":2007,"finding":"PHD3 interacts with the zipper II domain of ATF-4 and hydroxylates ATF-4 within a novel oxygen-dependent degradation (ODD) domain; siRNA knockdown of PHD3 (but not PHD2) stabilizes ATF-4 under normoxia, identifying ATF-4 as a PHD3-specific substrate independent of pVHL.","method":"Co-IP, siRNA knockdown of PHD isoforms, mutational analysis of ATF-4 prolyl residues (5-proline mutations stabilize ATF-4), PHD inhibitor treatment","journal":"Blood","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — isoform-specific siRNA knockdown, mutagenesis of substrate proline residues, pharmacological inhibitor confirmation, multiple orthogonal methods","pmids":["17684156"],"is_preprint":false},{"year":2007,"finding":"EGLN3 levels increase during C2C12 skeletal myoblast differentiation; EGLN3 interacts with and stabilizes myogenin protein, while VHL associates with and destabilizes myogenin via the ubiquitin-proteasome pathway. Overexpression of EGLN3 reverses VHL-mediated myogenin degradation, revealing a novel HIF-independent role for EGLN3 in myogenic differentiation.","method":"siRNA/antisense knockdown of EGLN3, co-immunoprecipitation of EGLN3 with myogenin, ubiquitination assay, EGLN3 overexpression rescue of VHL-mediated myogenin degradation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — co-IP, ubiquitination assay, loss-of-function and gain-of-function with defined phenotypic readout, multiple orthogonal methods","pmids":["17344222"],"is_preprint":false},{"year":2007,"finding":"Catalytically active human PHD3 was expressed and purified from E. coli; the enzyme hydroxylates Pro567 (a novel site) in addition to the canonical Pro564 of HIF-1α. PHD3 activity is inhibited by Zn2+, desferrioxamine, and imidazole, consistent with its iron- and 2-oxoglutarate-dependent dioxygenase mechanism.","method":"Heterologous expression in E. coli, Ni-affinity chromatography purification, in vitro hydroxylation assay with HIF-1α-derived peptide, mass spectrometry verification of hydroxylation","journal":"Protein expression and purification","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with mass spectrometry verification of hydroxylation site, single lab","pmids":["17434750"],"is_preprint":false},{"year":2008,"finding":"PHD3 forms oxygen-dependent subcellular aggregates under normoxia in an activity-dependent manner; aggregates contain 26S proteasome components, chaperones, and ubiquitin (aggresome-like features); forced expression of active PHD3 induces protein aggregation and apoptosis. Aggregate formation depends on microtubular integrity and is reversed by hypoxia or PHD3 catalytic inactivation.","method":"Fluorescence microscopy of PHD3-GFP aggregates, fractionation, co-localization with proteasome/ubiquitin markers, pharmacological inhibition, active-site mutant comparison","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — live imaging, biochemical fractionation, active-site mutagenesis, single lab","pmids":["18337469"],"is_preprint":false},{"year":2008,"finding":"PHD3 knockout mice (PHD3−/−) show reduced apoptosis in superior cervical ganglion (SCG) neurons, increased SCG and adrenal medulla cell numbers, and hypofunctional sympathoadrenal development. Genetic intercrossing with HIF-1α+/− and HIF-2α+/− mice demonstrates a PHD3–HIF-2α interaction (but not HIF-1α) in sympathoadrenal development.","method":"PHD3−/− mouse generation, neuronal apoptosis assay (cultured SCG neurons), genetic epistasis (PHD3−/− × HIF-1α+/−; PHD3−/− × HIF-2α+/−), sympathoadrenal functional assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic loss-of-function with clear phenotypic readout, genetic epistasis to define pathway partner, multiple assays","pmids":["18332118"],"is_preprint":false},{"year":2008,"finding":"The kinesin KIF1Bβ acts downstream of EglN3 in the NGF-withdrawal apoptotic pathway; KIF1Bβ is both necessary and sufficient for neuronal apoptosis when NGF becomes limiting, placing it genetically downstream of EglN3.","method":"Unbiased shRNA screen, epistasis analysis in neuronal progenitor cells with EglN3 and KIF1Bβ knockdown/overexpression, apoptosis assays","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 / Strong — unbiased screen plus epistasis validation, necessity and sufficiency tested, published in high-impact journal","pmids":["18334619"],"is_preprint":false},{"year":2008,"finding":"Siah2 E3 ligase preferentially targets PHD3 for degradation because PHD3 lacks the N-terminal extension present in PHD1/PHD2; deletion of this extension from PHD1/PHD2 renders them susceptible to Siah2-mediated degradation. PHD3 homo- and hetero-multimerizes with other PHDs; the lower-molecular-mass PHD3 form has higher specific activity toward HIF-1α hydroxylation and co-localizes with Siah2.","method":"Co-immunoprecipitation, size-exclusion fractionation, in vitro HIF-1α hydroxylation assay with different PHD3 complexes, N-terminal deletion mutagenesis of PHD1/PHD2","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — in vitro hydroxylation assay, mutagenesis defining degradation determinants, fractionation, co-IP, multiple orthogonal methods","pmids":["16958618"],"is_preprint":false},{"year":2009,"finding":"EGLN3 directly interacts with the β2-adrenergic receptor (β2AR) and hydroxylates it at proline-382 and proline-395, enabling recognition and ubiquitylation by pVHL, leading to proteasomal degradation of β2AR. Hypoxia reduces receptor hydroxylation, attenuating receptor degradation, thereby expanding the functional scope of prolyl hydroxylation beyond HIF.","method":"Co-IP of EGLN3 with β2AR, mass spectrometry identification of hydroxylation sites, mutagenesis of proline residues, pVHL ubiquitylation assay, hypoxic condition experiments, endogenous receptor abundance measurement","journal":"Science signaling","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — mass spectrometry identification of hydroxylation sites, mutagenesis, co-IP, functional ubiquitylation assay, endogenous validation in cells and tissue","pmids":["19584355"],"is_preprint":false},{"year":2009,"finding":"Phd3 loss in mice exacerbates HIF activation, hepatic steatosis, dilated cardiomyopathy, and premature mortality caused by Phd2 loss alone, demonstrating that Phd3 participates in a HIF-regulatory feedback loop in vivo and can partially compensate for Phd2.","method":"Phd2/Phd3 double-knockout mice, HIF target gene expression analysis, histopathology","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic double-knockout epistasis with defined molecular and pathological phenotypes","pmids":["19720742"],"is_preprint":false},{"year":2010,"finding":"EGLN3 prolyl hydroxylase activity is required to suppress canonical NF-κB signaling during skeletal myoblast differentiation; catalytically inactive EGLN3 fails to inhibit NF-κB, and NF-κB activation (via DMOG, hypoxia, or EGLN3 knockdown) blocks myogenic differentiation through a HIF-independent mechanism.","method":"Pharmacological PHD inhibition (DMOG, DFO, hypoxia), HIF dominant-negative/siRNA (to confirm HIF independence), IκBα dominant-negative, wild-type vs. catalytically-inactive EGLN3 overexpression, NF-κB reporter assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — active-site mutant comparison, dominant-negative epistasis, pharmacological and genetic approaches, multiple orthogonal methods","pmids":["20089853"],"is_preprint":false},{"year":2011,"finding":"PKM2 (but not PKM1) is hydroxylated by PHD3 at proline-403/408; this hydroxylation enhances PKM2 binding to HIF-1α and promotes PKM2 coactivator function for HIF-1 target genes. PHD3 knockdown inhibits PKM2 coactivator activity, reduces glucose uptake and lactate production, and increases O2 consumption in cancer cells.","method":"Mass spectrometry and anti-hydroxyproline antibody identification of PKM2 hydroxylation sites, Co-IP of PHD3/PKM2/HIF-1α, PHD3 knockdown, glucose uptake/lactate/O2 consumption assays, PKM1 vs PKM2 comparison","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — mass spectrometry identification of hydroxylation sites, anti-hydroxyproline antibody, Co-IP, functional metabolic assays, PKM1/PKM2 isoform comparison, published in Cell","pmids":["21620138"],"is_preprint":false},{"year":2011,"finding":"PHD3 is uniquely required among PHD isoforms for prolonging neutrophil survival during hypoxia; PHD3-deficient neutrophils show increased apoptosis associated with upregulation of proapoptotic Siva1 and loss of Bcl-xL binding, independent of altered HIF transcriptional activity. In vivo, PHD3-deficient mice show increased neutrophil clearance in acute lung injury and reduced neutrophilic inflammation in colitis.","method":"Phd3−/− mouse neutrophils, apoptosis assays, Siva1/Bcl-xL expression measurement, HIF transcriptional activity assay, acute lung injury model, colitis model","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — specific isoform knockout with defined molecular mechanism (Siva1/Bcl-xL), in vivo validation in two models, HIF independence confirmed","pmids":["21317538"],"is_preprint":false},{"year":2012,"finding":"PHD3 hydroxylates HCLK2 (human CLK-2), an essential component of the ATR/CHK1 signaling pathway; HCLK2 hydroxylation is required for its interaction with ATR and subsequent ATR/CHK1/p53 activation. PHD3 inhibition (pharmacologically with DMOG or genetically) prevents ATR/CHK1/p53 pathway activation and decreases DNA-damage-induced apoptosis. PHD3−/− mice are resistant to ionizing radiation.","method":"Co-IP of PHD3 with HCLK2 and ATR, DMOG/hypoxia inhibition, PHD3 knockout mice, thymic apoptosis assay, CHK1/p53 phosphorylation western blot","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — co-IP, pharmacological and genetic inhibition, in vivo mouse model, pathway activation assays, multiple orthogonal methods","pmids":["22797300"],"is_preprint":false},{"year":2012,"finding":"PHD3 acts as a co-activator of NF-κB/p65 signaling in nucleus pulposus cells independently of its hydroxylase activity; PHD3 physically interacts with and co-localizes with p65. PHD3 silencing decreases TNF-α-induced expression of catabolic markers (ADAMTS5, MMP13, COX2) and restores aggrecan/collagen type II expression.","method":"Co-IP and co-localization of PHD3 with p65, lentiviral shRNA knockdown, NF-κB reporter assay, cytokine gene expression measurement, HRE reporter confirming HIF-independence","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — co-IP, co-localization, genetic knockdown with defined gene expression phenotype, hydroxylase-independence tested, multiple orthogonal methods","pmids":["22948157"],"is_preprint":false},{"year":2013,"finding":"EGLN3 specifically interacts with IKKγ (NEMO) and inhibits K63-linked ubiquitination of IKKγ by competing with cIAP1 for IKKγ binding; this suppresses IKK-NF-κB signaling. The effect is independent of EGLN3 hydroxylase activity but requires physical interaction with IKKγ. EGLN1 and EGLN2 do not share this function.","method":"Co-IP of EGLN3 with IKKγ, ubiquitination assay (K63-linked), EGLN3 catalytic mutant comparison, cIAP1 competition assay, NF-κB reporter assay with EGLN isoform comparison","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — co-IP, ubiquitination assay, catalytic mutant, isoform specificity, competition assay, multiple orthogonal methods","pmids":["23732909"],"is_preprint":false},{"year":2013,"finding":"p62/SQSTM1 interacts with PHD3 in normoxic cytosolic aggregates, promotes PHD3 aggregation and degradation under normoxia, and limits PHD3 activity. Under hypoxia, p62 decreases, allowing PHD3 to distribute evenly in cells and interact more with HIF-α. Loss of p62 elevates PHD3 levels and reduces HIF-α via enhanced PHD3–HIF-α interaction.","method":"Co-IP of p62 with PHD3, siRNA knockdown of p62, fluorescence microscopy of PHD3 localization, HIF-α protein level measurement","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — co-IP, imaging, knockdown with functional readout, single lab with multiple methods","pmids":["23345396"],"is_preprint":false},{"year":2013,"finding":"Acute hepatic deletion of Phd3 in mice improves insulin sensitivity and ameliorates diabetes by specifically stabilizing HIF-2α (not HIF-1α), which increases Irs2 transcription and insulin-stimulated Akt activation. Both HIF-2α and Irs2 are required for the metabolic benefit of Phd3 knockout.","method":"Acute hepatic Phd3 knockout, glucose tolerance/insulin tolerance tests, Akt phosphorylation, shRNA knockdown of HIF-2α and Irs2 (epistasis), comparison with other PHD isoforms","journal":"Nature medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic knockout, epistasis (double knockdown to define pathway), isoform specificity, multiple metabolic phenotype assays","pmids":["24037093"],"is_preprint":false},{"year":2014,"finding":"PHD3 interacts with the endocytic adaptor Eps15 and promotes internalization of EGFR as a scaffolding protein, independent of its hydroxylase activity; loss of PHD3 suppresses EGFR internalization and hyperactivates EGFR signaling to enhance cell proliferation and survival. This is independent of HIF and NF-κB.","method":"Co-IP of PHD3 with Eps15, EGFR internalization assay, PHD3 siRNA/shRNA knockdown, EGFR phosphorylation measurement, PHD3 catalytic mutant","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — co-IP identifying scaffold interaction, internalization assay, catalytic mutant confirming hydroxylase independence, genetic knockdown, multiple orthogonal methods","pmids":["25420589"],"is_preprint":false},{"year":2014,"finding":"PHD3-mediated prolyl hydroxylation of nonmuscle actin at proline-307 and proline-322 inhibits actin polymerization and cell motility; PHD3 knockdown increases F-actin assembly and cell migration velocity, while PHD3 overexpression reverses this effect.","method":"Mass spectrometry identification of actin hydroxylation sites, Co-IP of PHD3 with actin, shRNA knockdown, PHD3 overexpression, F-actin/G-actin fractionation, pharmacological PHD inhibition (DMOG), cell migration assay","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — mass spectrometry identification of hydroxylation sites, co-IP, functional gain/loss of function, pharmacological confirmation, multiple methods","pmids":["25079693"],"is_preprint":false},{"year":2014,"finding":"PHD3 interacts with pyruvate dehydrogenase E1β subunit (PDH-E1β); PHD3 depletion destabilizes the PDH complex (PDC) and decreases cellular PDH activity without affecting PDH subunit expression or E1α phosphorylation status.","method":"Proteomics (MS) to identify PHD3-interacting proteins, co-IP validation of PHD3–PDH-E1β interaction, PDH activity assay in PHD3-depleted cells and PHD3−/− MEFs, PDH complex stability measurement","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — MS-based interactome followed by co-IP, functional enzymatic assay, genetic and cell-based validation, single lab","pmids":["25088999"],"is_preprint":false},{"year":2014,"finding":"PHD3 stabilizes the tight junction protein occludin by preventing interaction between the E3 ligase Itch and occludin, in a hydroxylase-independent manner; intestinal epithelial-specific Phd3 knockout in mice leads to decreased occludin levels and spontaneous colitis.","method":"Intestinal epithelial-specific Phd3 knockout mice, Co-IP of PHD3/occludin/Itch, tight junction/permeability assays, hydroxylase-independent PHD3 mutant","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vivo conditional knockout with colitis phenotype, co-IP defining mechanism, hydroxylase independence demonstrated, multiple methods","pmids":["26124271"],"is_preprint":false},{"year":2014,"finding":"PHD3 SUMOylation at a C-terminal cluster of four lysines (by SUMO2/SUMO3) represses HIF-1 transcriptional activity without affecting PHD3 hydroxylase activity or HIF-1α stability, revealing a catalysis-independent mechanism of HIF-1 regulation; hypoxia modulates PHD3 SUMOylation inversely with HIF-1 activation.","method":"SUMOylation assay, lysine cluster mutagenesis, HIF-1 reporter assay, HIF-1α protein level measurement, hydroxylase activity assay","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutagenesis, SUMOylation assay, functional reporter, hydroxylase independence confirmed; single lab","pmids":["25380826"],"is_preprint":false},{"year":2015,"finding":"PHD3 decreases the half-life of CDK inhibitor p27/CDKN1B under hypoxia via a mechanism involving reduced p27 phosphorylation at serine-10, promoting G1/S cell cycle entry; this effect is HIF-independent and requires intact p27-Ser10.","method":"PHD3 siRNA/shRNA knockdown, flow cytometry cell cycle analysis, cycloheximide chase for p27 half-life, phospho-specific antibody for p27-S10, p27-S10A mutant, HIF-independence confirmed","journal":"Molecular cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function, protein stability assay, phospho-mutagenesis, HIF independence tested, single lab","pmids":["26223520"],"is_preprint":false},{"year":2016,"finding":"PHD3 hydroxylates acetyl-CoA carboxylase 2 (ACC2) at a proline residue in response to nutrient abundance, activating ACC2 to suppress fatty acid oxidation (FAO); loss of PHD3 prevents ACC2 hydroxylation and enables elevated FAO. Overexpressing PHD3 limits FAO and impedes leukemia cell proliferation.","method":"PHD3 knockdown/overexpression, ACC2 hydroxylation assay, fatty acid oxidation measurement (isotopic tracing), PHD3-null cancer cell analysis, AML/leukemia proliferation assay","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — identification of novel substrate (ACC2), hydroxylation assay, FAO measurement, gain/loss-of-function, published in Molecular Cell","pmids":["27635760"],"is_preprint":false},{"year":2018,"finding":"PHD3 hydroxylates p53 at proline-359, a residue in the p53-DUB binding domain; this hydroxylation regulates p53 interaction with deubiquitinases USP7 and USP10. Inhibiting PHD3 decreases p53 association with USP7/USP10, increases p53 ubiquitination, and rapidly reduces p53 protein levels independent of mRNA.","method":"Co-IP of PHD3 with p53, mass spectrometry identification of Pro359 hydroxylation, USP7/USP10 interaction assay, ubiquitination assay, mRNA expression control","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — mass spectrometry identification of hydroxylation site, co-IP, ubiquitination assay, USP7/USP10 interaction measurement, multiple methods","pmids":["30067985"],"is_preprint":false},{"year":2019,"finding":"EglN3 hydroxylates BIM-EL (proapoptotic BH3-only protein); hydroxylated BIM-EL is subsequently bound by VHL, which inhibits ERK-mediated phosphorylation at Ser69, allowing BIM-EL to escape proteasomal degradation and enhance EglN3-induced apoptosis. VHL type 2C mutants fail to bind hydroxylated BIM-EL, linking this pathway to pheochromocytoma pathogenesis.","method":"Co-IP of BIM-EL with VHL and EglN3, hydroxylation assay, phosphorylation assay (ERK/Ser69), genetic EglN3 inactivation, VHL mutant panel, cisplatin resistance assay, ERK inhibitor rescue","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — co-IP, hydroxylation assay, phosphorylation assay, genetic inactivation, VHL mutant panel, mechanistic rescue experiments","pmids":["31375625"],"is_preprint":false},{"year":2019,"finding":"In clear cell renal cell carcinoma (ccRCC) cells, PHD3 silencing leads to downregulation of HIF-2α protein and mRNA (opposite to canonical pathway), by reducing HIF2A mRNA stability. This effect is PHD3-specific (other PHD family members have no effect) and cell-type-specific (non-RCC cells show expected HIF-2α increase upon PHD3 knockdown).","method":"siRNA-mediated PHD3 knockdown, HIF-2α protein/mRNA measurement by immunoblot and qRT-PCR, mRNA stability assay, comparison with PHD1/PHD2 knockdown, forced HIF-2α expression rescue","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — isoform-specific knockdown, mRNA stability assay, rescue experiment, cell-type comparison, single lab with multiple orthogonal methods","pmids":["30617181"],"is_preprint":false},{"year":2020,"finding":"PHD3 hydroxylates ACC2; in skeletal muscle, ACC2 hydroxylation and AMPK-mediated phosphorylation of ACC2 occur inversely. PHD3-null mice show loss of ACC2 hydroxylation in heart and skeletal muscle, elevated fatty acid oxidation, and enhanced endurance exercise capacity. Skeletal muscle-specific PHD3 loss is sufficient to enhance exercise capacity.","method":"PHD3 whole-body and skeletal muscle-specific knockout mice, ACC2 hydroxylation measurement, fatty acid oxidation measurement, endurance exercise treadmill assay, AMPK phosphorylation comparison","journal":"Cell metabolism","confidence":"High","confidence_rationale":"Tier 2 / Strong — tissue-specific knockout, hydroxylation measurement, metabolic functional assay in vivo, replicated ACC2 hydroxylation finding from 2016 paper","pmids":["32663458"],"is_preprint":false},{"year":2020,"finding":"CDC20 binds to a destruction-box (D-box) motif in PHD3 protein and promotes its polyubiquitination and proteasomal degradation via the APC/CDC20 complex, thereby stabilizing HIF-1α and promoting VEGF secretion in hepatocellular carcinoma cells.","method":"Co-IP of CDC20 with PHD3, ubiquitination assay, genetic ablation and pharmacological inhibition of CDC20, HIF-1α/VEGF measurement, non-degradable PHD3 D-box mutant rescue, xenograft tumor assay","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, ubiquitination assay, non-degradable mutant rescue, functional in vivo validation, single lab","pmids":["33039559"],"is_preprint":false},{"year":2021,"finding":"USP9X deubiquitinates EGLN3, preventing its proteasomal degradation; loss of USP9X leads to EGLN3 degradation, reducing the apoptotic KIF1Bβ pathway and promoting cholangiocarcinoma proliferation.","method":"Co-IP of USP9X with EGLN3, ubiquitination assay, shRNA knockdown of USP9X and EGLN3, xenograft tumor model, KIF1Bβ expression measurement","journal":"Journal of biomedical science","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — co-IP, ubiquitination assay, genetic knockdown epistasis, in vivo validation, single lab","pmids":["34112167"],"is_preprint":false},{"year":2022,"finding":"EGLN3 hydroxylates ERK3, preventing its interaction with LAMP2A and HSC70 (core CMA components), thereby blocking chaperone-mediated autophagy (CMA)-lysosomal degradation of ERK3; inactivation of EGLN3 catalytic activity promotes ERK3 degradation via CMA.","method":"Co-IP of ERK3 with HSC70 and LAMP2A, EGLN3 catalytically inactive knock-in mice, CMA-lysosome inhibition assay, hydroxylation assay, LAMP2A/ERK3 interaction rescue experiment","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — catalytic knock-in mice, co-IP, mechanistic rescue, CMA assay, multiple orthogonal methods in single study","pmids":["35124697"],"is_preprint":false},{"year":2023,"finding":"MAEA E3 ligase targets PHD3 at lysine-159 to promote K48-linked polyubiquitination and proteasomal degradation of PHD3, thereby stabilizing HIF-1α and upregulating CD133 to promote glioblastoma stemness and temozolomide resistance.","method":"TMT-based quantitative proteomics, co-IP of MAEA with PHD3, ubiquitination assay (K48-linked), K159 mutagenesis, HIF-1α/CD133 protein level measurement, xenograft tumor assay","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, ubiquitination assay with site mutagenesis, functional rescue, in vivo validation, single lab","pmids":["36882523"],"is_preprint":false},{"year":2009,"finding":"IFNγ induces PHD3 (but not PHD1 or PHD2) expression in human endothelial cells through a JAK/STAT1-dependent mechanism, as demonstrated by pharmacological inhibition of JAK, siRNA knockdown of STAT1, and chromatin immunoprecipitation showing STAT1 binding to the PHD3 promoter. This induction is independent of HIF-1α.","method":"qRT-PCR, immunoblotting, JAK inhibitor, STAT1 siRNA knockdown, chromatin immunoprecipitation (ChIP) for STAT1 at PHD3 promoter","journal":"Arteriosclerosis, thrombosis, and vascular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP demonstrating STAT1 binding, pharmacological and genetic confirmation of JAK/STAT1 pathway, HIF-independence tested, single lab","pmids":["19574556"],"is_preprint":false},{"year":2010,"finding":"Human PRP19 interacts with PHD3 via its C-terminal WD40 region; interaction is enhanced under hypoxia through PRP19's N-terminal coiled-coil domain. PRP19 overexpression suppresses PHD3-dependent cell death under prolonged hypoxia; PRP19 silencing increases caspase activity and cell death, and this is rescued by co-silencing PHD3.","method":"Co-IP of PHD3 with PRP19, domain deletion mapping, siRNA knockdown and overexpression, caspase activity assay, cell death assay","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — co-IP with domain mapping, genetic epistasis (double siRNA rescue), functional cell death assay, single lab","pmids":["20599946"],"is_preprint":false},{"year":2005,"finding":"An alternatively spliced PHD3 transcript (PHD3Δ4) retains prolyl hydroxylase activity as demonstrated in transfection experiments; a second variant (PHD3Δ1) is also expressed ubiquitously, while PHD3Δ4 expression appears restricted to primary cancer tissues.","method":"RT-PCR identification of splice variants, transfection-based functional hydroxylase activity assay","journal":"Cancer letters","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single transfection-based assay for catalytic activity of splice variant, no detailed mechanistic follow-up","pmids":["16473674"],"is_preprint":false}],"current_model":"EGLN3/PHD3 is an oxygen-sensing 2-oxoglutarate- and iron-dependent dioxygenase that hydroxylates proline residues on multiple substrates beyond HIF-α (including PKM2, ACC2, ATF-4, HCLK2, β2AR, BIM-EL, actin, ERK3, and p53) to regulate their stability, interactions, and activity; it also acts as a scaffold or co-activator independently of catalytic activity (e.g., with IKKγ/NF-κB, Eps15/EGFR internalization, occludin/Itch, p65), operates in a HIF-driven negative feedback loop, and is subject to regulation by Siah2-mediated ubiquitination, CDC20/APC-mediated degradation, MAEA-mediated ubiquitination, USP9X-mediated deubiquitination, SUMOylation, p62-mediated aggregation, and STAT1/IFNγ-dependent transcriptional induction, with cell-type-specific roles ranging from neuronal developmental apoptosis (via KIF1Bβ/BIM-EL downstream) to control of fatty acid oxidation, skeletal muscle differentiation, neutrophil survival, and DNA damage response."},"narrative":{"mechanistic_narrative":"EGLN3/PHD3 is an iron- and 2-oxoglutarate-dependent prolyl hydroxylase that functions both as an oxygen sensor in the HIF pathway and as a broad post-translational regulator of substrate stability, interactions, and activity across diverse cellular processes [PMID:12181324, PMID:17434750, PMID:21620138]. In its canonical role it hydroxylates conserved prolines in HIF-1α and HIF-2α within the LXXLAP motif, contributing non-redundantly to oxygen-dependent HIF-α turnover, and is itself transcriptionally induced by HIF through an intronic hypoxia-response element, establishing a negative-feedback loop [PMID:15247232, PMID:15823097, PMID:19720742]. Beyond HIF, PHD3 hydroxylates an expanding substrate repertoire — PKM2 to promote its HIF-1 coactivator function and aerobic glycolysis, ACC2 to activate it and suppress fatty acid oxidation in muscle and leukemia cells, ATF-4, the β2-adrenergic receptor and p53 to govern their VHL- or deubiquitinase-dependent stability, HCLK2 to enable ATR/CHK1/p53 DNA-damage signaling, actin to limit polymerization and motility, and ERK3 to block its chaperone-mediated autophagy — thereby coupling oxygen and nutrient status to metabolism, apoptosis, and genome maintenance [PMID:21620138, PMID:27635760, PMID:32663458, PMID:17684156, PMID:19584355, PMID:30067985, PMID:22797300, PMID:25079693, PMID:35124697]. A major branch of PHD3 biology is catalysis-independent: it acts as a scaffold or co-activator by binding IKKγ/NEMO and p65 to modulate NF-κB signaling, Eps15 to drive EGFR internalization, occludin to protect tight junctions from Itch-mediated degradation, and myogenin to oppose VHL-mediated destabilization during myogenesis [PMID:23732909, PMID:22948157, PMID:25420589, PMID:26124271, PMID:17344222]. PHD3 drives developmental neuronal apoptosis downstream of c-Jun and upstream of KIF1Bβ and BIM-EL, a function relevant to sympathoadrenal development and pheochromocytoma [PMID:16098468, PMID:18334619, PMID:18332118, PMID:31375625]. Its abundance and activity are tightly controlled by Siah2-, CDC20/APC-, and MAEA-mediated ubiquitination, USP9X-mediated deubiquitination, SUMOylation, p62-driven aggregation, and STAT1/IFNγ-dependent transcription [PMID:16958618, PMID:33039559, PMID:36882523, PMID:34112167, PMID:25380826, PMID:23345396, PMID:19574556].","teleology":[{"year":2002,"claim":"Established the molecular basis of PHD3 substrate recognition by defining the proline acceptor within the HIF-1α LXXLAP motif and showing PHD3 has restricted specificity relative to PHD2.","evidence":"In vitro prolyl hydroxylase assay with mutant HIF-1α peptides and sequence analysis","pmids":["12181324"],"confidence":"High","gaps":["Did not define full substrate range beyond HIF-1α","Structural basis of restricted specificity not resolved"]},{"year":2004,"claim":"Showed PHD3 contributes non-redundantly to oxygen-dependent regulation of both HIF-1α and HIF-2α with site and isoform selectivity, distinguishing its cellular role from other PHDs.","evidence":"siRNA knockdown of individual PHD isoforms across multiple cell types and conditions","pmids":["15247232"],"confidence":"High","gaps":["Relative quantitative contribution per cell type not fully resolved","Does not address non-HIF substrates"]},{"year":2005,"claim":"Placed PHD3 in a HIF-driven negative feedback loop by identifying a functional intronic HRE bound by HIF in vivo.","evidence":"HRE bioinformatics, reporter assays, and ChIP for HIF binding","pmids":["15823097"],"confidence":"High","gaps":["Quantitative impact of feedback on HIF dynamics not modeled"]},{"year":2005,"claim":"Defined a HIF-independent proapoptotic role: PHD3 acts downstream of c-Jun and is uniquely required for neuronal apoptosis on NGF withdrawal, feedback-inhibited by succinate, linking SDH/metabolism to developmental apoptosis.","evidence":"Genetic epistasis in sympathetic neuronal progenitors with NGF withdrawal and succinate supplementation","pmids":["16098468"],"confidence":"High","gaps":["Substrate mediating apoptosis not identified at this stage","Catalytic requirement vs scaffold role unresolved here"]},{"year":2007,"claim":"Expanded the PHD3 substrate repertoire beyond HIF by identifying ATF-4 hydroxylation within a novel ODD domain in a PHD3-specific, pVHL-independent manner.","evidence":"Co-IP, isoform-specific siRNA, substrate proline mutagenesis, and PHD inhibitor treatment","pmids":["17684156"],"confidence":"High","gaps":["Downstream physiological consequences of ATF-4 stabilization not fully mapped","E3 ligase for hydroxylated ATF-4 not defined"]},{"year":2007,"claim":"Demonstrated a HIF-independent scaffold function in myogenesis: PHD3 binds and stabilizes myogenin, opposing VHL-mediated degradation during myoblast differentiation.","evidence":"Co-IP, ubiquitination assay, EGLN3 loss/gain-of-function and rescue of VHL-mediated degradation in C2C12 cells","pmids":["17344222"],"confidence":"High","gaps":["Whether myogenin stabilization requires hydroxylase activity not resolved here","In vivo muscle relevance not tested"]},{"year":2007,"claim":"Confirmed PHD3 as a bona fide iron/2-OG dioxygenase by reconstituting recombinant enzyme and identifying an additional HIF-1α hydroxylation site (Pro567).","evidence":"E. coli expression, purification, in vitro hydroxylation assay, and mass spectrometry verification","pmids":["17434750"],"confidence":"High","gaps":["Physiological significance of Pro567 hydroxylation not established"]},{"year":2006,"claim":"Identified Morg1 as a WD-repeat scaffold partner that modulates PHD3 suppression of HIF activity.","evidence":"Yeast two-hybrid, reciprocal co-IP, co-localization, and HIF reporter assays with siRNA","pmids":["16407229"],"confidence":"High","gaps":["Structural interface and stoichiometry not defined","Whether Morg1 targets PHD3 to specific substrates unknown"]},{"year":2008,"claim":"Established in vivo that PHD3 drives sympathoadrenal developmental apoptosis specifically through HIF-2α, validating the neuronal pathway genetically.","evidence":"PHD3-/- mice with HIF-1α+/- and HIF-2α+/- genetic intercrosses and neuronal apoptosis assays","pmids":["18332118"],"confidence":"High","gaps":["Molecular mechanism downstream of HIF-2α in this context not fully detailed"]},{"year":2008,"claim":"Defined the apoptotic effector axis by placing KIF1Bβ genetically downstream of EglN3 as necessary and sufficient for NGF-withdrawal apoptosis.","evidence":"Unbiased shRNA screen and epistasis with knockdown/overexpression in neuronal progenitors","pmids":["18334619"],"confidence":"High","gaps":["Direct biochemical link between PHD3 catalysis and KIF1Bβ not established"]},{"year":2008,"claim":"Explained isoform-selective PHD3 turnover: Siah2 targets PHD3 because it lacks the N-terminal extension of PHD1/2, and a low-mass PHD3 form has higher HIF-1α activity.","evidence":"Co-IP, size-exclusion fractionation, in vitro hydroxylation, and N-terminal deletion mutagenesis","pmids":["16958618"],"confidence":"High","gaps":["Cellular triggers regulating Siah2-PHD3 turnover not fully defined"]},{"year":2008,"claim":"Described activity-dependent PHD3 aggresome-like aggregation under normoxia coupled to apoptosis, linking localization to function.","evidence":"PHD3-GFP imaging, fractionation, co-localization with proteasome/ubiquitin markers, and active-site mutants","pmids":["18337469"],"confidence":"Medium","gaps":["Single lab; physiological role of aggregation not confirmed in vivo","Composition of aggregates incompletely defined"]},{"year":2009,"claim":"Broadened prolyl hydroxylation signaling to GPCRs by showing PHD3 hydroxylates β2AR at Pro382/Pro395 to enable pVHL-mediated degradation, oxygen-dependently.","evidence":"Co-IP, MS site identification, proline mutagenesis, pVHL ubiquitylation assay, and hypoxia experiments","pmids":["19584355"],"confidence":"High","gaps":["Physiological adrenergic consequences in vivo not fully characterized"]},{"year":2009,"claim":"Demonstrated in vivo that Phd3 participates in a HIF feedback loop and partially compensates for Phd2 loss.","evidence":"Phd2/Phd3 double-knockout mice with HIF target analysis and histopathology","pmids":["19720742"],"confidence":"High","gaps":["Tissue-specific compensation thresholds not delineated"]},{"year":2009,"claim":"Identified a HIF-independent transcriptional input: IFNγ induces PHD3 specifically via JAK/STAT1, linking inflammatory signaling to PHD3 levels.","evidence":"JAK inhibitor, STAT1 siRNA, and ChIP for STAT1 at the PHD3 promoter in endothelial cells","pmids":["19574556"],"confidence":"Medium","gaps":["Single lab; functional consequence of IFNγ-induced PHD3 not defined","Cell-type generality untested"]},{"year":2010,"claim":"Established that PHD3's NF-κB-suppressive activity in myogenesis requires catalytic activity, distinguishing it from scaffold roles.","evidence":"Pharmacological PHD inhibition, catalytically inactive EGLN3, and dominant-negative epistasis with NF-κB reporters","pmids":["20089853"],"confidence":"High","gaps":["Direct hydroxylation target in the NF-κB axis in this context not identified"]},{"year":2010,"claim":"Identified PRP19 as a hypoxia-enhanced partner that suppresses PHD3-dependent cell death.","evidence":"Co-IP, domain-deletion mapping, siRNA/overexpression, and caspase/cell death assays with double-silencing rescue","pmids":["20599946"],"confidence":"Medium","gaps":["Single lab; mechanism by which PRP19 restrains PHD3-driven death unclear"]},{"year":2011,"claim":"Connected PHD3 to cancer metabolism by showing PKM2 hydroxylation enhances its HIF-1 coactivator role and aerobic glycolysis.","evidence":"MS/anti-hydroxyproline site identification, co-IP, knockdown, and metabolic flux assays with PKM1/PKM2 comparison","pmids":["21620138"],"confidence":"High","gaps":["In vivo tumor relevance of PKM2 hydroxylation not detailed here"]},{"year":2011,"claim":"Defined a HIF-independent survival role: PHD3 uniquely prolongs neutrophil survival in hypoxia via Siva1/Bcl-xL, with in vivo inflammatory consequences.","evidence":"Phd3-/- neutrophils, apoptosis assays, Siva1/Bcl-xL measurement, and acute lung injury/colitis models","pmids":["21317538"],"confidence":"High","gaps":["Whether PHD3 catalysis or scaffolding mediates the effect not resolved"]},{"year":2012,"claim":"Linked PHD3 to the DNA-damage response by showing HCLK2 hydroxylation is required for ATR binding and ATR/CHK1/p53 activation.","evidence":"Co-IP, DMOG/hypoxia inhibition, PHD3-/- mice, thymic apoptosis, and CHK1/p53 phosphorylation assays","pmids":["22797300"],"confidence":"High","gaps":["HCLK2 hydroxylation site not mapped here","Crosstalk with HIF pathway in DDR unaddressed"]},{"year":2012,"claim":"Established a hydroxylase-independent NF-κB co-activator function via physical interaction with p65 in nucleus pulposus catabolism.","evidence":"Co-IP, co-localization, shRNA knockdown, NF-κB and HRE reporters confirming HIF-independence","pmids":["22948157"],"confidence":"High","gaps":["Structural basis of p65 interaction undefined","Apparent context-dependent opposite NF-κB effects vs catalytic suppression unreconciled"]},{"year":2013,"claim":"Defined a catalysis-independent NF-κB-suppressive mechanism: EGLN3 binds IKKγ/NEMO and competes with cIAP1 to block K63 ubiquitination.","evidence":"Co-IP, K63 ubiquitination assay, catalytic mutant, cIAP1 competition, and isoform comparison","pmids":["23732909"],"confidence":"High","gaps":["Reconciliation with co-activator p65 role context-dependent and not fully explained"]},{"year":2013,"claim":"Showed p62/SQSTM1 controls PHD3 by promoting normoxic aggregation/degradation, tuning PHD3-HIF-α engagement with oxygen.","evidence":"Co-IP, p62 siRNA, PHD3 localization imaging, and HIF-α level measurement","pmids":["23345396"],"confidence":"Medium","gaps":["Single lab; molecular trigger for hypoxic p62 decrease unclear"]},{"year":2013,"claim":"Revealed an in vivo HIF-2α-specific metabolic axis: hepatic Phd3 loss improves insulin sensitivity via HIF-2α-driven Irs2 induction.","evidence":"Acute hepatic Phd3 knockout, glucose/insulin tolerance tests, Akt phosphorylation, and HIF-2α/Irs2 double-knockdown epistasis","pmids":["24037093"],"confidence":"High","gaps":["Whether direct HIF-2α hydroxylation or other mechanism drives selectivity not resolved"]},{"year":2014,"claim":"Demonstrated a scaffold role in receptor trafficking: PHD3 binds Eps15 to promote EGFR internalization, restraining EGFR signaling independent of catalysis, HIF, and NF-κB.","evidence":"Co-IP, EGFR internalization assay, knockdown, catalytic mutant, and EGFR phosphorylation measurement","pmids":["25420589"],"confidence":"High","gaps":["Structural basis of Eps15 interaction not defined"]},{"year":2014,"claim":"Extended hydroxylation to the cytoskeleton: PHD3 hydroxylates actin at Pro307/Pro322 to inhibit polymerization and motility.","evidence":"MS site identification, co-IP, knockdown/overexpression, F-/G-actin fractionation, DMOG, and migration assays","pmids":["25079693"],"confidence":"High","gaps":["In vivo relevance of actin hydroxylation untested"]},{"year":2014,"claim":"Linked PHD3 to mitochondrial metabolism via interaction with PDH-E1β and stabilization of the PDH complex.","evidence":"MS interactome, co-IP, and PDH activity/stability assays in PHD3-depleted cells and -/- MEFs","pmids":["25088999"],"confidence":"Medium","gaps":["Single lab; whether interaction is direct or catalytic unclear"]},{"year":2014,"claim":"Defined a hydroxylase-independent barrier-protective role: PHD3 shields occludin from Itch, with intestinal Phd3 loss causing spontaneous colitis.","evidence":"Intestinal epithelial-specific Phd3 knockout, co-IP of PHD3/occludin/Itch, permeability assays, and hydroxylase-dead mutant","pmids":["26124271"],"confidence":"High","gaps":["Mechanism of Itch competition not structurally defined"]},{"year":2014,"claim":"Identified a catalysis-independent SUMOylation mechanism repressing HIF-1 transcriptional activity without affecting HIF-1α stability.","evidence":"SUMOylation assay, lysine cluster mutagenesis, HIF-1 reporter, and hydroxylase activity controls","pmids":["25380826"],"confidence":"Medium","gaps":["Single lab; SUMO E3 ligase and downstream effector not identified"]},{"year":2015,"claim":"Connected PHD3 to cell cycle control by HIF-independent reduction of p27 half-life via reduced Ser10 phosphorylation, promoting G1/S entry.","evidence":"Knockdown, flow cytometry, cycloheximide chase, phospho-S10 antibody, and p27-S10A mutant","pmids":["26223520"],"confidence":"Medium","gaps":["Single lab; molecular intermediary linking PHD3 to p27-S10 phosphorylation unknown"]},{"year":2016,"claim":"Established PHD3 as a nutrient-responsive metabolic brake: ACC2 hydroxylation activates ACC2 to suppress fatty acid oxidation, with consequences for leukemia proliferation.","evidence":"Knockdown/overexpression, ACC2 hydroxylation assay, isotopic FAO tracing, and leukemia proliferation assay","pmids":["27635760"],"confidence":"High","gaps":["ACC2 hydroxylation site not mapped here"]},{"year":2018,"claim":"Showed PHD3 hydroxylates p53 at Pro359 to regulate USP7/USP10 binding and thus p53 stability.","evidence":"Co-IP, MS site identification, USP7/USP10 interaction and ubiquitination assays with mRNA controls","pmids":["30067985"],"confidence":"High","gaps":["In vivo p53-dependent phenotypes of this hydroxylation not defined"]},{"year":2019,"claim":"Resolved the apoptotic effector mechanism: EglN3 hydroxylates BIM-EL to enable VHL binding that blocks ERK-Ser69 phosphorylation, stabilizing BIM-EL; VHL type 2C mutants fail, linking to pheochromocytoma.","evidence":"Co-IP, hydroxylation/phosphorylation assays, genetic inactivation, VHL mutant panel, and ERK-inhibitor rescue","pmids":["31375625"],"confidence":"High","gaps":["Integration with the KIF1Bβ axis not fully reconciled"]},{"year":2019,"claim":"Uncovered a cell-type-specific reversal: in ccRCC, PHD3 silencing lowers HIF-2α by destabilizing HIF2A mRNA, opposite to the canonical pathway.","evidence":"Isoform-specific siRNA, protein/mRNA measurement, mRNA stability assay, and rescue with cell-type comparison","pmids":["30617181"],"confidence":"High","gaps":["Single lab; mechanism by which PHD3 affects HIF2A mRNA stability unknown"]},{"year":2020,"claim":"Validated the ACC2 metabolic axis in vivo: tissue-specific PHD3 loss abolishes ACC2 hydroxylation, elevates FAO, and enhances endurance exercise capacity.","evidence":"Whole-body and muscle-specific PHD3 knockout mice, ACC2 hydroxylation/FAO measurement, treadmill and AMPK assays","pmids":["32663458"],"confidence":"High","gaps":["Interplay between hydroxylation and AMPK phosphorylation of ACC2 not fully mechanistic"]},{"year":2020,"claim":"Identified CDC20/APC-mediated D-box-dependent PHD3 degradation that stabilizes HIF-1α and promotes VEGF in HCC.","evidence":"Co-IP, ubiquitination assay, CDC20 ablation/inhibition, non-degradable D-box mutant rescue, and xenograft","pmids":["33039559"],"confidence":"Medium","gaps":["Single lab; cell-cycle context of PHD3 destruction not detailed"]},{"year":2021,"claim":"Showed USP9X deubiquitinates EGLN3 to prevent degradation, sustaining the apoptotic KIF1Bβ pathway and restraining cholangiocarcinoma growth.","evidence":"Co-IP, ubiquitination assay, USP9X/EGLN3 knockdown, xenograft, and KIF1Bβ measurement","pmids":["34112167"],"confidence":"Medium","gaps":["Single lab; deubiquitination site not mapped"]},{"year":2022,"claim":"Demonstrated PHD3 catalysis blocks chaperone-mediated autophagy of ERK3 by preventing LAMP2A/HSC70 binding.","evidence":"Co-IP, catalytically inactive EGLN3 knock-in mice, CMA-lysosome assays, and interaction rescue","pmids":["35124697"],"confidence":"High","gaps":["ERK3 hydroxylation site not defined here","Physiological context of ERK3 regulation broad"]},{"year":2023,"claim":"Identified MAEA as an E3 ligase ubiquitinating PHD3 at K159 to stabilize HIF-1α and promote glioblastoma stemness and temozolomide resistance.","evidence":"TMT proteomics, co-IP, K48 ubiquitination assay, K159 mutagenesis, and xenograft","pmids":["36882523"],"confidence":"Medium","gaps":["Single lab; regulation of MAEA-PHD3 axis upstream unclear"]},{"year":null,"claim":"It remains unresolved how the cell selects between PHD3's catalytic substrate hydroxylation and its catalysis-independent scaffold/co-activator functions, and what determines the cell-type-specific and context-dependent (even opposite) outcomes on HIF-2α and NF-κB.","evidence":"No single study in the corpus integrates the catalytic vs scaffold decision or the divergent HIF-2α/NF-κB outcomes","pmids":[],"confidence":"Low","gaps":["No unifying structural model distinguishing catalytic from scaffold engagement","Determinants of cell-type-specific HIF-2α regulation unknown","Reconciliation of opposing NF-κB effects across tissues lacking"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016491","term_label":"oxidoreductase activity","supporting_discovery_ids":[0,8,16,29,33]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,6,13,16,24,30,36]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[20,23,26,7]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[19]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[5,9,21]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[5,19]}],"pathway":[{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[0,1,4,14]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[16,29,33,22,25]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[3,11,17,31]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[13,20,23]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[18,30]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[6,12,34,37,35,27]}],"complexes":[],"partners":["HIF1A","VHL","PKM2","ACC2","IKBKG","EPS15","OCLN","TP53"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9H6Z9","full_name":"Prolyl hydroxylase EGLN3","aliases":["Egl nine homolog 3","HPH-1","Hypoxia-inducible factor prolyl hydroxylase 3","HIF-PH3","HIF-prolyl hydroxylase 3","HPH-3","Prolyl hydroxylase domain-containing protein 3","PHD3"],"length_aa":239,"mass_kda":27.3,"function":"Prolyl hydroxylase that mediates hydroxylation of proline residues in target proteins, such as PKM, TELO2, ATF4, GPX4 and HIF1A (PubMed:19584355, PubMed:20978507, PubMed:21483450, PubMed:21575608, PubMed:21620138, PubMed:22797300, PubMed:40281343). Target proteins are preferentially recognized via a LXXLAP motif. Cellular oxygen sensor that catalyzes, under normoxic conditions, the post-translational formation of 4-hydroxyproline in hypoxia-inducible factor (HIF) alpha proteins (PubMed:11595184, PubMed:12181324). Hydroxylates a specific proline found in each of the oxygen-dependent degradation (ODD) domains (N-terminal, NODD, and C-terminal, CODD) of HIF1A (PubMed:11595184, PubMed:12181324). Also hydroxylates HIF2A (PubMed:11595184, PubMed:12181324). Has a preference for the CODD site for both HIF1A and HIF2A (PubMed:11595184, PubMed:12181324). Hydroxylation on the NODD site by EGLN3 appears to require prior hydroxylation on the CODD site (PubMed:11595184, PubMed:12181324). Hydroxylated HIFs are then targeted for proteasomal degradation via the von Hippel-Lindau ubiquitination complex (PubMed:11595184, PubMed:12181324). Under hypoxic conditions, the hydroxylation reaction is attenuated allowing HIFs to escape degradation resulting in their translocation to the nucleus, heterodimerization with HIF1B, and increased expression of hypoxy-inducible genes (PubMed:11595184, PubMed:12181324). Acts as an inhibitor of ferroptosis by mediating hydroxylation of GPX4, thereby preventing GPX4 degradation via chaperone-mediated autophagy (PubMed:40281343). GPX4 hydroxylation is promoted by PSAT1, which provides 2-oxoglutarate substrate to EGLN3 (PubMed:40281343). ELGN3 is the most important isozyme in limiting physiological activation of HIFs (particularly HIF2A) in hypoxia. Also hydroxylates PKM in hypoxia, limiting glycolysis (PubMed:21483450, PubMed:21620138). Under normoxia, hydroxylates and regulates the stability of ADRB2 (PubMed:19584355). Regulator of cardiomyocyte and neuronal apoptosis. In cardiomyocytes, inhibits the anti-apoptotic effect of BCL2 by disrupting the BAX-BCL2 complex (PubMed:20849813). In neurons, has a NGF-induced proapoptotic effect, probably through regulating CASP3 activity (PubMed:16098468). Also essential for hypoxic regulation of neutrophilic inflammation (PubMed:21317538). Plays a crucial role in DNA damage response (DDR) by hydroxylating TELO2, promoting its interaction with ATR which is required for activation of the ATR/CHK1/p53 pathway (PubMed:22797300). Also mediates hydroxylation of ATF4, leading to decreased protein stability of ATF4 (Probable)","subcellular_location":"Nucleus; Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q9H6Z9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/EGLN3","classification":"Not Classified","n_dependent_lines":15,"n_total_lines":1208,"dependency_fraction":0.012417218543046357},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/EGLN3","total_profiled":1310},"omim":[{"mim_id":"621489","title":"PROTEIN PHOSPHATASE 1, REGULATORY INHIBITOR SUBUNIT 2, PSEUDOGENE 1; PPP1R2P1","url":"https://www.omim.org/entry/621489"},{"mim_id":"616850","title":"WD REPEAT-CONTAINING PROTEIN 83; WDR83","url":"https://www.omim.org/entry/616850"},{"mim_id":"614584","title":"PROLYL 4-HYDROXYLASE, TRANSMEMBRANE; P4HTM","url":"https://www.omim.org/entry/614584"},{"mim_id":"606426","title":"EGL9 FAMILY HYPOXIA-INDUCIBLE FACTOR 3; EGLN3","url":"https://www.omim.org/entry/606426"},{"mim_id":"605995","title":"KINESIN FAMILY MEMBER 1B; KIF1B","url":"https://www.omim.org/entry/605995"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"heart muscle","ntpm":101.7},{"tissue":"skin 1","ntpm":114.3}],"url":"https://www.proteinatlas.org/search/EGLN3"},"hgnc":{"alias_symbol":["PHD3","HIFPH3"],"prev_symbol":[]},"alphafold":{"accession":"Q9H6Z9","domains":[{"cath_id":"2.60.120.620","chopping":"2-236","consensus_level":"high","plddt":91.8487,"start":2,"end":236}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H6Z9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H6Z9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H6Z9-F1-predicted_aligned_error_v6.png","plddt_mean":91.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=EGLN3","jax_strain_url":"https://www.jax.org/strain/search?query=EGLN3"},"sequence":{"accession":"Q9H6Z9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9H6Z9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9H6Z9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H6Z9"}},"corpus_meta":[{"pmid":"21620138","id":"PMC_21620138","title":"Pyruvate kinase M2 is a PHD3-stimulated coactivator for hypoxia-inducible factor 1.","date":"2011","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/21620138","citation_count":1213,"is_preprint":false},{"pmid":"15247232","id":"PMC_15247232","title":"Differential function of the prolyl hydroxylases PHD1, PHD2, and PHD3 in the regulation of hypoxia-inducible factor.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15247232","citation_count":905,"is_preprint":false},{"pmid":"16098468","id":"PMC_16098468","title":"Neuronal apoptosis linked to EglN3 prolyl hydroxylase and familial pheochromocytoma genes: developmental culling and cancer.","date":"2005","source":"Cancer cell","url":"https://pubmed.ncbi.nlm.nih.gov/16098468","citation_count":439,"is_preprint":false},{"pmid":"18334619","id":"PMC_18334619","title":"The kinesin KIF1Bbeta acts downstream from EglN3 to induce apoptosis and is a potential 1p36 tumor suppressor.","date":"2008","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/18334619","citation_count":275,"is_preprint":false},{"pmid":"12181324","id":"PMC_12181324","title":"Sequence determinants in hypoxia-inducible factor-1alpha for hydroxylation by the prolyl hydroxylases PHD1, PHD2, and PHD3.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12181324","citation_count":258,"is_preprint":false},{"pmid":"15823097","id":"PMC_15823097","title":"Identification of a functional hypoxia-responsive element that regulates the expression of the egl nine homologue 3 (egln3/phd3) gene.","date":"2005","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/15823097","citation_count":185,"is_preprint":false},{"pmid":"17684156","id":"PMC_17684156","title":"Oxygen-dependent ATF-4 stability is mediated by the PHD3 oxygen 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American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/33749901","citation_count":8,"is_preprint":false},{"pmid":"40087582","id":"PMC_40087582","title":"Sirtuin1 mitigates hypoxia-induced cardiomyocyte apoptosis in myocardial infarction via PHD3/HIF-1α.","date":"2025","source":"Molecular medicine (Cambridge, Mass.)","url":"https://pubmed.ncbi.nlm.nih.gov/40087582","citation_count":8,"is_preprint":false},{"pmid":"33408523","id":"PMC_33408523","title":"Circ_101341 Deteriorates the Progression of Clear Cell Renal Cell Carcinoma Through the miR- 411/EGLN3 Axis.","date":"2020","source":"Cancer management and research","url":"https://pubmed.ncbi.nlm.nih.gov/33408523","citation_count":8,"is_preprint":false},{"pmid":"29543898","id":"PMC_29543898","title":"Polymorphisms in the Egl nine homolog 3 (EGLN3) and Peroxisome proliferator activated receptor-alpha (PPARα) genes and their correlation with hypoxia adaptation in Tibetan chickens.","date":"2018","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/29543898","citation_count":8,"is_preprint":false},{"pmid":"37804810","id":"PMC_37804810","title":"DPP-4i versus SGLT2i as modulators of PHD3/HIF-2α pathway in the diabetic kidney.","date":"2023","source":"Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie","url":"https://pubmed.ncbi.nlm.nih.gov/37804810","citation_count":8,"is_preprint":false},{"pmid":"31714753","id":"PMC_31714753","title":"Interactions between PHD3-Bromo of MLL1 and H3K4me3 Revealed by Single-Molecule Magnetic Tweezers in a Parallel DNA Circuit.","date":"2019","source":"Bioconjugate chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/31714753","citation_count":8,"is_preprint":false},{"pmid":"39226709","id":"PMC_39226709","title":"Trans-resveratrol mitigates miR-204-3p mediated progression of allergic rhinitis by regulating the EGLN3/HIF-1α/IL33/ST2 signalling pathway.","date":"2024","source":"Phytomedicine : international journal of phytotherapy and phytopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/39226709","citation_count":7,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":52118,"output_tokens":10777,"usd":0.159004,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":22037,"output_tokens":9900,"usd":0.178842,"stage2_stop_reason":"end_turn"},"total_usd":0.337846,"stage1_batch_id":"msgbatch_01AsR7g8dGTEiEw9U83bJeWn","stage2_batch_id":"msgbatch_01YV5ZyxtFNUZEjxRcpd9jzb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"PHD3 (EGLN3) hydroxylates specific proline residues in HIF-1α within a conserved LXXLAP sequence motif; the hydroxylacceptor proline itself is the only obligatory residue for this reaction. PHD2 shows highest specific activity toward the primary hydroxylation site, while PHD3 shows restricted substrate specificity.\",\n      \"method\": \"In vitro prolyl hydroxylase assay with mutant HIF-1α peptides; sequence analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct in vitro enzymatic assay with systematic mutagenesis, replicated across PHD family members\",\n      \"pmids\": [\"12181324\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"PHD3 contributes in a non-redundant manner to oxygen-dependent regulation of both HIF-1α and HIF-2α subunits; PHD isoforms show specificity for different prolyl hydroxylation sites within HIF-α subunits and a degree of selectivity between HIF-1α and HIF-2α.\",\n      \"method\": \"siRNA-mediated knockdown of individual PHD isoforms followed by measurement of HIF-α protein levels in multiple cell types under various culture conditions\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal siRNA knockdowns across multiple cell types with multiple oxygen/hormone conditions, independently replicated concept\",\n      \"pmids\": [\"15247232\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"PHD3 interacts with the cytosolic chaperonin TRiC (TCP-1 ring complex), identified by co-purification and mass spectrometry, suggesting PHD3 is a TRiC substrate and that TRiC may regulate PHD3 activity.\",\n      \"method\": \"Co-purification of PHD3 from cell extracts followed by mass spectrometry identification of TRiC subunits\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single co-purification experiment, single lab, no mutagenesis or functional validation of TRiC-PHD3 interaction consequences\",\n      \"pmids\": [\"15251459\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"EglN3 (PHD3) acts downstream of c-Jun and is specifically required among EglN family members for neuronal apoptosis when NGF becomes limiting; EglN3 proapoptotic activity is feedback-inhibited by succinate (a product of SDH), placing EglN3 in a pathway linking SDH activity to developmental apoptosis.\",\n      \"method\": \"Genetic epistasis in sympathetic neuronal progenitor cells: selective EglN3 knockdown, NGF withdrawal apoptosis assay, succinate supplementation inhibition\",\n      \"journal\": \"Cancer cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — specific isoform requirement established by knockdown epistasis, functional link to succinate confirmed biochemically, published in high-impact journal\",\n      \"pmids\": [\"16098468\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"A functional hypoxia response element (HRE) located in the first intron of the EGLN3 gene (12 kb downstream of transcription start) binds HIF in vivo and drives HIF-dependent transcriptional induction of EGLN3 under hypoxia, establishing a negative feedback loop.\",\n      \"method\": \"Bioinformatics HRE identification, reporter gene assays, chromatin immunoprecipitation (ChIP)\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP demonstrating in vivo HIF binding plus reporter assay showing HRE sufficiency, two orthogonal methods in one study\",\n      \"pmids\": [\"15823097\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"PHD3 physically interacts with the novel WD-repeat scaffold protein Morg1 (MAPK organizer 1); co-expression of Morg1 with PHD3 decreases HIF-mediated reporter gene activity, and siRNA knockdown of either Morg1 or PHD3 increases HIF-1 activity. Both proteins co-localize in the cytoplasm and nucleus.\",\n      \"method\": \"Yeast two-hybrid screen, in vitro and in vivo co-immunoprecipitation, confocal microscopy co-localization, HIF reporter assay with siRNA knockdown\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid plus reciprocal co-IP plus functional reporter assay, multiple orthogonal methods in one study\",\n      \"pmids\": [\"16407229\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"PHD3 interacts with the zipper II domain of ATF-4 and hydroxylates ATF-4 within a novel oxygen-dependent degradation (ODD) domain; siRNA knockdown of PHD3 (but not PHD2) stabilizes ATF-4 under normoxia, identifying ATF-4 as a PHD3-specific substrate independent of pVHL.\",\n      \"method\": \"Co-IP, siRNA knockdown of PHD isoforms, mutational analysis of ATF-4 prolyl residues (5-proline mutations stabilize ATF-4), PHD inhibitor treatment\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — isoform-specific siRNA knockdown, mutagenesis of substrate proline residues, pharmacological inhibitor confirmation, multiple orthogonal methods\",\n      \"pmids\": [\"17684156\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"EGLN3 levels increase during C2C12 skeletal myoblast differentiation; EGLN3 interacts with and stabilizes myogenin protein, while VHL associates with and destabilizes myogenin via the ubiquitin-proteasome pathway. Overexpression of EGLN3 reverses VHL-mediated myogenin degradation, revealing a novel HIF-independent role for EGLN3 in myogenic differentiation.\",\n      \"method\": \"siRNA/antisense knockdown of EGLN3, co-immunoprecipitation of EGLN3 with myogenin, ubiquitination assay, EGLN3 overexpression rescue of VHL-mediated myogenin degradation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, ubiquitination assay, loss-of-function and gain-of-function with defined phenotypic readout, multiple orthogonal methods\",\n      \"pmids\": [\"17344222\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Catalytically active human PHD3 was expressed and purified from E. coli; the enzyme hydroxylates Pro567 (a novel site) in addition to the canonical Pro564 of HIF-1α. PHD3 activity is inhibited by Zn2+, desferrioxamine, and imidazole, consistent with its iron- and 2-oxoglutarate-dependent dioxygenase mechanism.\",\n      \"method\": \"Heterologous expression in E. coli, Ni-affinity chromatography purification, in vitro hydroxylation assay with HIF-1α-derived peptide, mass spectrometry verification of hydroxylation\",\n      \"journal\": \"Protein expression and purification\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with mass spectrometry verification of hydroxylation site, single lab\",\n      \"pmids\": [\"17434750\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PHD3 forms oxygen-dependent subcellular aggregates under normoxia in an activity-dependent manner; aggregates contain 26S proteasome components, chaperones, and ubiquitin (aggresome-like features); forced expression of active PHD3 induces protein aggregation and apoptosis. Aggregate formation depends on microtubular integrity and is reversed by hypoxia or PHD3 catalytic inactivation.\",\n      \"method\": \"Fluorescence microscopy of PHD3-GFP aggregates, fractionation, co-localization with proteasome/ubiquitin markers, pharmacological inhibition, active-site mutant comparison\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — live imaging, biochemical fractionation, active-site mutagenesis, single lab\",\n      \"pmids\": [\"18337469\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PHD3 knockout mice (PHD3−/−) show reduced apoptosis in superior cervical ganglion (SCG) neurons, increased SCG and adrenal medulla cell numbers, and hypofunctional sympathoadrenal development. Genetic intercrossing with HIF-1α+/− and HIF-2α+/− mice demonstrates a PHD3–HIF-2α interaction (but not HIF-1α) in sympathoadrenal development.\",\n      \"method\": \"PHD3−/− mouse generation, neuronal apoptosis assay (cultured SCG neurons), genetic epistasis (PHD3−/− × HIF-1α+/−; PHD3−/− × HIF-2α+/−), sympathoadrenal functional assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic loss-of-function with clear phenotypic readout, genetic epistasis to define pathway partner, multiple assays\",\n      \"pmids\": [\"18332118\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"The kinesin KIF1Bβ acts downstream of EglN3 in the NGF-withdrawal apoptotic pathway; KIF1Bβ is both necessary and sufficient for neuronal apoptosis when NGF becomes limiting, placing it genetically downstream of EglN3.\",\n      \"method\": \"Unbiased shRNA screen, epistasis analysis in neuronal progenitor cells with EglN3 and KIF1Bβ knockdown/overexpression, apoptosis assays\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — unbiased screen plus epistasis validation, necessity and sufficiency tested, published in high-impact journal\",\n      \"pmids\": [\"18334619\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Siah2 E3 ligase preferentially targets PHD3 for degradation because PHD3 lacks the N-terminal extension present in PHD1/PHD2; deletion of this extension from PHD1/PHD2 renders them susceptible to Siah2-mediated degradation. PHD3 homo- and hetero-multimerizes with other PHDs; the lower-molecular-mass PHD3 form has higher specific activity toward HIF-1α hydroxylation and co-localizes with Siah2.\",\n      \"method\": \"Co-immunoprecipitation, size-exclusion fractionation, in vitro HIF-1α hydroxylation assay with different PHD3 complexes, N-terminal deletion mutagenesis of PHD1/PHD2\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro hydroxylation assay, mutagenesis defining degradation determinants, fractionation, co-IP, multiple orthogonal methods\",\n      \"pmids\": [\"16958618\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"EGLN3 directly interacts with the β2-adrenergic receptor (β2AR) and hydroxylates it at proline-382 and proline-395, enabling recognition and ubiquitylation by pVHL, leading to proteasomal degradation of β2AR. Hypoxia reduces receptor hydroxylation, attenuating receptor degradation, thereby expanding the functional scope of prolyl hydroxylation beyond HIF.\",\n      \"method\": \"Co-IP of EGLN3 with β2AR, mass spectrometry identification of hydroxylation sites, mutagenesis of proline residues, pVHL ubiquitylation assay, hypoxic condition experiments, endogenous receptor abundance measurement\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — mass spectrometry identification of hydroxylation sites, mutagenesis, co-IP, functional ubiquitylation assay, endogenous validation in cells and tissue\",\n      \"pmids\": [\"19584355\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Phd3 loss in mice exacerbates HIF activation, hepatic steatosis, dilated cardiomyopathy, and premature mortality caused by Phd2 loss alone, demonstrating that Phd3 participates in a HIF-regulatory feedback loop in vivo and can partially compensate for Phd2.\",\n      \"method\": \"Phd2/Phd3 double-knockout mice, HIF target gene expression analysis, histopathology\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic double-knockout epistasis with defined molecular and pathological phenotypes\",\n      \"pmids\": [\"19720742\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"EGLN3 prolyl hydroxylase activity is required to suppress canonical NF-κB signaling during skeletal myoblast differentiation; catalytically inactive EGLN3 fails to inhibit NF-κB, and NF-κB activation (via DMOG, hypoxia, or EGLN3 knockdown) blocks myogenic differentiation through a HIF-independent mechanism.\",\n      \"method\": \"Pharmacological PHD inhibition (DMOG, DFO, hypoxia), HIF dominant-negative/siRNA (to confirm HIF independence), IκBα dominant-negative, wild-type vs. catalytically-inactive EGLN3 overexpression, NF-κB reporter assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — active-site mutant comparison, dominant-negative epistasis, pharmacological and genetic approaches, multiple orthogonal methods\",\n      \"pmids\": [\"20089853\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PKM2 (but not PKM1) is hydroxylated by PHD3 at proline-403/408; this hydroxylation enhances PKM2 binding to HIF-1α and promotes PKM2 coactivator function for HIF-1 target genes. PHD3 knockdown inhibits PKM2 coactivator activity, reduces glucose uptake and lactate production, and increases O2 consumption in cancer cells.\",\n      \"method\": \"Mass spectrometry and anti-hydroxyproline antibody identification of PKM2 hydroxylation sites, Co-IP of PHD3/PKM2/HIF-1α, PHD3 knockdown, glucose uptake/lactate/O2 consumption assays, PKM1 vs PKM2 comparison\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — mass spectrometry identification of hydroxylation sites, anti-hydroxyproline antibody, Co-IP, functional metabolic assays, PKM1/PKM2 isoform comparison, published in Cell\",\n      \"pmids\": [\"21620138\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PHD3 is uniquely required among PHD isoforms for prolonging neutrophil survival during hypoxia; PHD3-deficient neutrophils show increased apoptosis associated with upregulation of proapoptotic Siva1 and loss of Bcl-xL binding, independent of altered HIF transcriptional activity. In vivo, PHD3-deficient mice show increased neutrophil clearance in acute lung injury and reduced neutrophilic inflammation in colitis.\",\n      \"method\": \"Phd3−/− mouse neutrophils, apoptosis assays, Siva1/Bcl-xL expression measurement, HIF transcriptional activity assay, acute lung injury model, colitis model\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — specific isoform knockout with defined molecular mechanism (Siva1/Bcl-xL), in vivo validation in two models, HIF independence confirmed\",\n      \"pmids\": [\"21317538\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PHD3 hydroxylates HCLK2 (human CLK-2), an essential component of the ATR/CHK1 signaling pathway; HCLK2 hydroxylation is required for its interaction with ATR and subsequent ATR/CHK1/p53 activation. PHD3 inhibition (pharmacologically with DMOG or genetically) prevents ATR/CHK1/p53 pathway activation and decreases DNA-damage-induced apoptosis. PHD3−/− mice are resistant to ionizing radiation.\",\n      \"method\": \"Co-IP of PHD3 with HCLK2 and ATR, DMOG/hypoxia inhibition, PHD3 knockout mice, thymic apoptosis assay, CHK1/p53 phosphorylation western blot\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — co-IP, pharmacological and genetic inhibition, in vivo mouse model, pathway activation assays, multiple orthogonal methods\",\n      \"pmids\": [\"22797300\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PHD3 acts as a co-activator of NF-κB/p65 signaling in nucleus pulposus cells independently of its hydroxylase activity; PHD3 physically interacts with and co-localizes with p65. PHD3 silencing decreases TNF-α-induced expression of catabolic markers (ADAMTS5, MMP13, COX2) and restores aggrecan/collagen type II expression.\",\n      \"method\": \"Co-IP and co-localization of PHD3 with p65, lentiviral shRNA knockdown, NF-κB reporter assay, cytokine gene expression measurement, HRE reporter confirming HIF-independence\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, co-localization, genetic knockdown with defined gene expression phenotype, hydroxylase-independence tested, multiple orthogonal methods\",\n      \"pmids\": [\"22948157\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"EGLN3 specifically interacts with IKKγ (NEMO) and inhibits K63-linked ubiquitination of IKKγ by competing with cIAP1 for IKKγ binding; this suppresses IKK-NF-κB signaling. The effect is independent of EGLN3 hydroxylase activity but requires physical interaction with IKKγ. EGLN1 and EGLN2 do not share this function.\",\n      \"method\": \"Co-IP of EGLN3 with IKKγ, ubiquitination assay (K63-linked), EGLN3 catalytic mutant comparison, cIAP1 competition assay, NF-κB reporter assay with EGLN isoform comparison\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — co-IP, ubiquitination assay, catalytic mutant, isoform specificity, competition assay, multiple orthogonal methods\",\n      \"pmids\": [\"23732909\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"p62/SQSTM1 interacts with PHD3 in normoxic cytosolic aggregates, promotes PHD3 aggregation and degradation under normoxia, and limits PHD3 activity. Under hypoxia, p62 decreases, allowing PHD3 to distribute evenly in cells and interact more with HIF-α. Loss of p62 elevates PHD3 levels and reduces HIF-α via enhanced PHD3–HIF-α interaction.\",\n      \"method\": \"Co-IP of p62 with PHD3, siRNA knockdown of p62, fluorescence microscopy of PHD3 localization, HIF-α protein level measurement\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — co-IP, imaging, knockdown with functional readout, single lab with multiple methods\",\n      \"pmids\": [\"23345396\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Acute hepatic deletion of Phd3 in mice improves insulin sensitivity and ameliorates diabetes by specifically stabilizing HIF-2α (not HIF-1α), which increases Irs2 transcription and insulin-stimulated Akt activation. Both HIF-2α and Irs2 are required for the metabolic benefit of Phd3 knockout.\",\n      \"method\": \"Acute hepatic Phd3 knockout, glucose tolerance/insulin tolerance tests, Akt phosphorylation, shRNA knockdown of HIF-2α and Irs2 (epistasis), comparison with other PHD isoforms\",\n      \"journal\": \"Nature medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic knockout, epistasis (double knockdown to define pathway), isoform specificity, multiple metabolic phenotype assays\",\n      \"pmids\": [\"24037093\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PHD3 interacts with the endocytic adaptor Eps15 and promotes internalization of EGFR as a scaffolding protein, independent of its hydroxylase activity; loss of PHD3 suppresses EGFR internalization and hyperactivates EGFR signaling to enhance cell proliferation and survival. This is independent of HIF and NF-κB.\",\n      \"method\": \"Co-IP of PHD3 with Eps15, EGFR internalization assay, PHD3 siRNA/shRNA knockdown, EGFR phosphorylation measurement, PHD3 catalytic mutant\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP identifying scaffold interaction, internalization assay, catalytic mutant confirming hydroxylase independence, genetic knockdown, multiple orthogonal methods\",\n      \"pmids\": [\"25420589\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PHD3-mediated prolyl hydroxylation of nonmuscle actin at proline-307 and proline-322 inhibits actin polymerization and cell motility; PHD3 knockdown increases F-actin assembly and cell migration velocity, while PHD3 overexpression reverses this effect.\",\n      \"method\": \"Mass spectrometry identification of actin hydroxylation sites, Co-IP of PHD3 with actin, shRNA knockdown, PHD3 overexpression, F-actin/G-actin fractionation, pharmacological PHD inhibition (DMOG), cell migration assay\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — mass spectrometry identification of hydroxylation sites, co-IP, functional gain/loss of function, pharmacological confirmation, multiple methods\",\n      \"pmids\": [\"25079693\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PHD3 interacts with pyruvate dehydrogenase E1β subunit (PDH-E1β); PHD3 depletion destabilizes the PDH complex (PDC) and decreases cellular PDH activity without affecting PDH subunit expression or E1α phosphorylation status.\",\n      \"method\": \"Proteomics (MS) to identify PHD3-interacting proteins, co-IP validation of PHD3–PDH-E1β interaction, PDH activity assay in PHD3-depleted cells and PHD3−/− MEFs, PDH complex stability measurement\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — MS-based interactome followed by co-IP, functional enzymatic assay, genetic and cell-based validation, single lab\",\n      \"pmids\": [\"25088999\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PHD3 stabilizes the tight junction protein occludin by preventing interaction between the E3 ligase Itch and occludin, in a hydroxylase-independent manner; intestinal epithelial-specific Phd3 knockout in mice leads to decreased occludin levels and spontaneous colitis.\",\n      \"method\": \"Intestinal epithelial-specific Phd3 knockout mice, Co-IP of PHD3/occludin/Itch, tight junction/permeability assays, hydroxylase-independent PHD3 mutant\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo conditional knockout with colitis phenotype, co-IP defining mechanism, hydroxylase independence demonstrated, multiple methods\",\n      \"pmids\": [\"26124271\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PHD3 SUMOylation at a C-terminal cluster of four lysines (by SUMO2/SUMO3) represses HIF-1 transcriptional activity without affecting PHD3 hydroxylase activity or HIF-1α stability, revealing a catalysis-independent mechanism of HIF-1 regulation; hypoxia modulates PHD3 SUMOylation inversely with HIF-1 activation.\",\n      \"method\": \"SUMOylation assay, lysine cluster mutagenesis, HIF-1 reporter assay, HIF-1α protein level measurement, hydroxylase activity assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis, SUMOylation assay, functional reporter, hydroxylase independence confirmed; single lab\",\n      \"pmids\": [\"25380826\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PHD3 decreases the half-life of CDK inhibitor p27/CDKN1B under hypoxia via a mechanism involving reduced p27 phosphorylation at serine-10, promoting G1/S cell cycle entry; this effect is HIF-independent and requires intact p27-Ser10.\",\n      \"method\": \"PHD3 siRNA/shRNA knockdown, flow cytometry cell cycle analysis, cycloheximide chase for p27 half-life, phospho-specific antibody for p27-S10, p27-S10A mutant, HIF-independence confirmed\",\n      \"journal\": \"Molecular cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function, protein stability assay, phospho-mutagenesis, HIF independence tested, single lab\",\n      \"pmids\": [\"26223520\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"PHD3 hydroxylates acetyl-CoA carboxylase 2 (ACC2) at a proline residue in response to nutrient abundance, activating ACC2 to suppress fatty acid oxidation (FAO); loss of PHD3 prevents ACC2 hydroxylation and enables elevated FAO. Overexpressing PHD3 limits FAO and impedes leukemia cell proliferation.\",\n      \"method\": \"PHD3 knockdown/overexpression, ACC2 hydroxylation assay, fatty acid oxidation measurement (isotopic tracing), PHD3-null cancer cell analysis, AML/leukemia proliferation assay\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — identification of novel substrate (ACC2), hydroxylation assay, FAO measurement, gain/loss-of-function, published in Molecular Cell\",\n      \"pmids\": [\"27635760\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PHD3 hydroxylates p53 at proline-359, a residue in the p53-DUB binding domain; this hydroxylation regulates p53 interaction with deubiquitinases USP7 and USP10. Inhibiting PHD3 decreases p53 association with USP7/USP10, increases p53 ubiquitination, and rapidly reduces p53 protein levels independent of mRNA.\",\n      \"method\": \"Co-IP of PHD3 with p53, mass spectrometry identification of Pro359 hydroxylation, USP7/USP10 interaction assay, ubiquitination assay, mRNA expression control\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — mass spectrometry identification of hydroxylation site, co-IP, ubiquitination assay, USP7/USP10 interaction measurement, multiple methods\",\n      \"pmids\": [\"30067985\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"EglN3 hydroxylates BIM-EL (proapoptotic BH3-only protein); hydroxylated BIM-EL is subsequently bound by VHL, which inhibits ERK-mediated phosphorylation at Ser69, allowing BIM-EL to escape proteasomal degradation and enhance EglN3-induced apoptosis. VHL type 2C mutants fail to bind hydroxylated BIM-EL, linking this pathway to pheochromocytoma pathogenesis.\",\n      \"method\": \"Co-IP of BIM-EL with VHL and EglN3, hydroxylation assay, phosphorylation assay (ERK/Ser69), genetic EglN3 inactivation, VHL mutant panel, cisplatin resistance assay, ERK inhibitor rescue\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — co-IP, hydroxylation assay, phosphorylation assay, genetic inactivation, VHL mutant panel, mechanistic rescue experiments\",\n      \"pmids\": [\"31375625\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In clear cell renal cell carcinoma (ccRCC) cells, PHD3 silencing leads to downregulation of HIF-2α protein and mRNA (opposite to canonical pathway), by reducing HIF2A mRNA stability. This effect is PHD3-specific (other PHD family members have no effect) and cell-type-specific (non-RCC cells show expected HIF-2α increase upon PHD3 knockdown).\",\n      \"method\": \"siRNA-mediated PHD3 knockdown, HIF-2α protein/mRNA measurement by immunoblot and qRT-PCR, mRNA stability assay, comparison with PHD1/PHD2 knockdown, forced HIF-2α expression rescue\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — isoform-specific knockdown, mRNA stability assay, rescue experiment, cell-type comparison, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"30617181\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PHD3 hydroxylates ACC2; in skeletal muscle, ACC2 hydroxylation and AMPK-mediated phosphorylation of ACC2 occur inversely. PHD3-null mice show loss of ACC2 hydroxylation in heart and skeletal muscle, elevated fatty acid oxidation, and enhanced endurance exercise capacity. Skeletal muscle-specific PHD3 loss is sufficient to enhance exercise capacity.\",\n      \"method\": \"PHD3 whole-body and skeletal muscle-specific knockout mice, ACC2 hydroxylation measurement, fatty acid oxidation measurement, endurance exercise treadmill assay, AMPK phosphorylation comparison\",\n      \"journal\": \"Cell metabolism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — tissue-specific knockout, hydroxylation measurement, metabolic functional assay in vivo, replicated ACC2 hydroxylation finding from 2016 paper\",\n      \"pmids\": [\"32663458\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CDC20 binds to a destruction-box (D-box) motif in PHD3 protein and promotes its polyubiquitination and proteasomal degradation via the APC/CDC20 complex, thereby stabilizing HIF-1α and promoting VEGF secretion in hepatocellular carcinoma cells.\",\n      \"method\": \"Co-IP of CDC20 with PHD3, ubiquitination assay, genetic ablation and pharmacological inhibition of CDC20, HIF-1α/VEGF measurement, non-degradable PHD3 D-box mutant rescue, xenograft tumor assay\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, ubiquitination assay, non-degradable mutant rescue, functional in vivo validation, single lab\",\n      \"pmids\": [\"33039559\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"USP9X deubiquitinates EGLN3, preventing its proteasomal degradation; loss of USP9X leads to EGLN3 degradation, reducing the apoptotic KIF1Bβ pathway and promoting cholangiocarcinoma proliferation.\",\n      \"method\": \"Co-IP of USP9X with EGLN3, ubiquitination assay, shRNA knockdown of USP9X and EGLN3, xenograft tumor model, KIF1Bβ expression measurement\",\n      \"journal\": \"Journal of biomedical science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — co-IP, ubiquitination assay, genetic knockdown epistasis, in vivo validation, single lab\",\n      \"pmids\": [\"34112167\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"EGLN3 hydroxylates ERK3, preventing its interaction with LAMP2A and HSC70 (core CMA components), thereby blocking chaperone-mediated autophagy (CMA)-lysosomal degradation of ERK3; inactivation of EGLN3 catalytic activity promotes ERK3 degradation via CMA.\",\n      \"method\": \"Co-IP of ERK3 with HSC70 and LAMP2A, EGLN3 catalytically inactive knock-in mice, CMA-lysosome inhibition assay, hydroxylation assay, LAMP2A/ERK3 interaction rescue experiment\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — catalytic knock-in mice, co-IP, mechanistic rescue, CMA assay, multiple orthogonal methods in single study\",\n      \"pmids\": [\"35124697\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"MAEA E3 ligase targets PHD3 at lysine-159 to promote K48-linked polyubiquitination and proteasomal degradation of PHD3, thereby stabilizing HIF-1α and upregulating CD133 to promote glioblastoma stemness and temozolomide resistance.\",\n      \"method\": \"TMT-based quantitative proteomics, co-IP of MAEA with PHD3, ubiquitination assay (K48-linked), K159 mutagenesis, HIF-1α/CD133 protein level measurement, xenograft tumor assay\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, ubiquitination assay with site mutagenesis, functional rescue, in vivo validation, single lab\",\n      \"pmids\": [\"36882523\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"IFNγ induces PHD3 (but not PHD1 or PHD2) expression in human endothelial cells through a JAK/STAT1-dependent mechanism, as demonstrated by pharmacological inhibition of JAK, siRNA knockdown of STAT1, and chromatin immunoprecipitation showing STAT1 binding to the PHD3 promoter. This induction is independent of HIF-1α.\",\n      \"method\": \"qRT-PCR, immunoblotting, JAK inhibitor, STAT1 siRNA knockdown, chromatin immunoprecipitation (ChIP) for STAT1 at PHD3 promoter\",\n      \"journal\": \"Arteriosclerosis, thrombosis, and vascular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP demonstrating STAT1 binding, pharmacological and genetic confirmation of JAK/STAT1 pathway, HIF-independence tested, single lab\",\n      \"pmids\": [\"19574556\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Human PRP19 interacts with PHD3 via its C-terminal WD40 region; interaction is enhanced under hypoxia through PRP19's N-terminal coiled-coil domain. PRP19 overexpression suppresses PHD3-dependent cell death under prolonged hypoxia; PRP19 silencing increases caspase activity and cell death, and this is rescued by co-silencing PHD3.\",\n      \"method\": \"Co-IP of PHD3 with PRP19, domain deletion mapping, siRNA knockdown and overexpression, caspase activity assay, cell death assay\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — co-IP with domain mapping, genetic epistasis (double siRNA rescue), functional cell death assay, single lab\",\n      \"pmids\": [\"20599946\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"An alternatively spliced PHD3 transcript (PHD3Δ4) retains prolyl hydroxylase activity as demonstrated in transfection experiments; a second variant (PHD3Δ1) is also expressed ubiquitously, while PHD3Δ4 expression appears restricted to primary cancer tissues.\",\n      \"method\": \"RT-PCR identification of splice variants, transfection-based functional hydroxylase activity assay\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single transfection-based assay for catalytic activity of splice variant, no detailed mechanistic follow-up\",\n      \"pmids\": [\"16473674\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"EGLN3/PHD3 is an oxygen-sensing 2-oxoglutarate- and iron-dependent dioxygenase that hydroxylates proline residues on multiple substrates beyond HIF-α (including PKM2, ACC2, ATF-4, HCLK2, β2AR, BIM-EL, actin, ERK3, and p53) to regulate their stability, interactions, and activity; it also acts as a scaffold or co-activator independently of catalytic activity (e.g., with IKKγ/NF-κB, Eps15/EGFR internalization, occludin/Itch, p65), operates in a HIF-driven negative feedback loop, and is subject to regulation by Siah2-mediated ubiquitination, CDC20/APC-mediated degradation, MAEA-mediated ubiquitination, USP9X-mediated deubiquitination, SUMOylation, p62-mediated aggregation, and STAT1/IFNγ-dependent transcriptional induction, with cell-type-specific roles ranging from neuronal developmental apoptosis (via KIF1Bβ/BIM-EL downstream) to control of fatty acid oxidation, skeletal muscle differentiation, neutrophil survival, and DNA damage response.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"EGLN3/PHD3 is an iron- and 2-oxoglutarate-dependent prolyl hydroxylase that functions both as an oxygen sensor in the HIF pathway and as a broad post-translational regulator of substrate stability, interactions, and activity across diverse cellular processes [#0, #8, #16]. In its canonical role it hydroxylates conserved prolines in HIF-1\\u03b1 and HIF-2\\u03b1 within the LXXLAP motif, contributing non-redundantly to oxygen-dependent HIF-\\u03b1 turnover, and is itself transcriptionally induced by HIF through an intronic hypoxia-response element, establishing a negative-feedback loop [#1, #4, #14]. Beyond HIF, PHD3 hydroxylates an expanding substrate repertoire \\u2014 PKM2 to promote its HIF-1 coactivator function and aerobic glycolysis, ACC2 to activate it and suppress fatty acid oxidation in muscle and leukemia cells, ATF-4, the \\u03b22-adrenergic receptor and p53 to govern their VHL- or deubiquitinase-dependent stability, HCLK2 to enable ATR/CHK1/p53 DNA-damage signaling, actin to limit polymerization and motility, and ERK3 to block its chaperone-mediated autophagy \\u2014 thereby coupling oxygen and nutrient status to metabolism, apoptosis, and genome maintenance [#16, #29, #33, #6, #13, #30, #18, #24, #36]. A major branch of PHD3 biology is catalysis-independent: it acts as a scaffold or co-activator by binding IKK\\u03b3/NEMO and p65 to modulate NF-\\u03baB signaling, Eps15 to drive EGFR internalization, occludin to protect tight junctions from Itch-mediated degradation, and myogenin to oppose VHL-mediated destabilization during myogenesis [#20, #19, #23, #26, #7]. PHD3 drives developmental neuronal apoptosis downstream of c-Jun and upstream of KIF1B\\u03b2 and BIM-EL, a function relevant to sympathoadrenal development and pheochromocytoma [#3, #11, #10, #31]. Its abundance and activity are tightly controlled by Siah2-, CDC20/APC-, and MAEA-mediated ubiquitination, USP9X-mediated deubiquitination, SUMOylation, p62-driven aggregation, and STAT1/IFN\\u03b3-dependent transcription [#12, #34, #37, #35, #27, #21, #38].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Established the molecular basis of PHD3 substrate recognition by defining the proline acceptor within the HIF-1\\u03b1 LXXLAP motif and showing PHD3 has restricted specificity relative to PHD2.\",\n      \"evidence\": \"In vitro prolyl hydroxylase assay with mutant HIF-1\\u03b1 peptides and sequence analysis\",\n      \"pmids\": [\"12181324\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define full substrate range beyond HIF-1\\u03b1\", \"Structural basis of restricted specificity not resolved\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Showed PHD3 contributes non-redundantly to oxygen-dependent regulation of both HIF-1\\u03b1 and HIF-2\\u03b1 with site and isoform selectivity, distinguishing its cellular role from other PHDs.\",\n      \"evidence\": \"siRNA knockdown of individual PHD isoforms across multiple cell types and conditions\",\n      \"pmids\": [\"15247232\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative quantitative contribution per cell type not fully resolved\", \"Does not address non-HIF substrates\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Placed PHD3 in a HIF-driven negative feedback loop by identifying a functional intronic HRE bound by HIF in vivo.\",\n      \"evidence\": \"HRE bioinformatics, reporter assays, and ChIP for HIF binding\",\n      \"pmids\": [\"15823097\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative impact of feedback on HIF dynamics not modeled\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Defined a HIF-independent proapoptotic role: PHD3 acts downstream of c-Jun and is uniquely required for neuronal apoptosis on NGF withdrawal, feedback-inhibited by succinate, linking SDH/metabolism to developmental apoptosis.\",\n      \"evidence\": \"Genetic epistasis in sympathetic neuronal progenitors with NGF withdrawal and succinate supplementation\",\n      \"pmids\": [\"16098468\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Substrate mediating apoptosis not identified at this stage\", \"Catalytic requirement vs scaffold role unresolved here\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Expanded the PHD3 substrate repertoire beyond HIF by identifying ATF-4 hydroxylation within a novel ODD domain in a PHD3-specific, pVHL-independent manner.\",\n      \"evidence\": \"Co-IP, isoform-specific siRNA, substrate proline mutagenesis, and PHD inhibitor treatment\",\n      \"pmids\": [\"17684156\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream physiological consequences of ATF-4 stabilization not fully mapped\", \"E3 ligase for hydroxylated ATF-4 not defined\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Demonstrated a HIF-independent scaffold function in myogenesis: PHD3 binds and stabilizes myogenin, opposing VHL-mediated degradation during myoblast differentiation.\",\n      \"evidence\": \"Co-IP, ubiquitination assay, EGLN3 loss/gain-of-function and rescue of VHL-mediated degradation in C2C12 cells\",\n      \"pmids\": [\"17344222\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether myogenin stabilization requires hydroxylase activity not resolved here\", \"In vivo muscle relevance not tested\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Confirmed PHD3 as a bona fide iron/2-OG dioxygenase by reconstituting recombinant enzyme and identifying an additional HIF-1\\u03b1 hydroxylation site (Pro567).\",\n      \"evidence\": \"E. coli expression, purification, in vitro hydroxylation assay, and mass spectrometry verification\",\n      \"pmids\": [\"17434750\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological significance of Pro567 hydroxylation not established\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identified Morg1 as a WD-repeat scaffold partner that modulates PHD3 suppression of HIF activity.\",\n      \"evidence\": \"Yeast two-hybrid, reciprocal co-IP, co-localization, and HIF reporter assays with siRNA\",\n      \"pmids\": [\"16407229\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural interface and stoichiometry not defined\", \"Whether Morg1 targets PHD3 to specific substrates unknown\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Established in vivo that PHD3 drives sympathoadrenal developmental apoptosis specifically through HIF-2\\u03b1, validating the neuronal pathway genetically.\",\n      \"evidence\": \"PHD3-/- mice with HIF-1\\u03b1+/- and HIF-2\\u03b1+/- genetic intercrosses and neuronal apoptosis assays\",\n      \"pmids\": [\"18332118\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular mechanism downstream of HIF-2\\u03b1 in this context not fully detailed\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Defined the apoptotic effector axis by placing KIF1B\\u03b2 genetically downstream of EglN3 as necessary and sufficient for NGF-withdrawal apoptosis.\",\n      \"evidence\": \"Unbiased shRNA screen and epistasis with knockdown/overexpression in neuronal progenitors\",\n      \"pmids\": [\"18334619\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct biochemical link between PHD3 catalysis and KIF1B\\u03b2 not established\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Explained isoform-selective PHD3 turnover: Siah2 targets PHD3 because it lacks the N-terminal extension of PHD1/2, and a low-mass PHD3 form has higher HIF-1\\u03b1 activity.\",\n      \"evidence\": \"Co-IP, size-exclusion fractionation, in vitro hydroxylation, and N-terminal deletion mutagenesis\",\n      \"pmids\": [\"16958618\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cellular triggers regulating Siah2-PHD3 turnover not fully defined\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Described activity-dependent PHD3 aggresome-like aggregation under normoxia coupled to apoptosis, linking localization to function.\",\n      \"evidence\": \"PHD3-GFP imaging, fractionation, co-localization with proteasome/ubiquitin markers, and active-site mutants\",\n      \"pmids\": [\"18337469\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; physiological role of aggregation not confirmed in vivo\", \"Composition of aggregates incompletely defined\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Broadened prolyl hydroxylation signaling to GPCRs by showing PHD3 hydroxylates \\u03b22AR at Pro382/Pro395 to enable pVHL-mediated degradation, oxygen-dependently.\",\n      \"evidence\": \"Co-IP, MS site identification, proline mutagenesis, pVHL ubiquitylation assay, and hypoxia experiments\",\n      \"pmids\": [\"19584355\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological adrenergic consequences in vivo not fully characterized\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Demonstrated in vivo that Phd3 participates in a HIF feedback loop and partially compensates for Phd2 loss.\",\n      \"evidence\": \"Phd2/Phd3 double-knockout mice with HIF target analysis and histopathology\",\n      \"pmids\": [\"19720742\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue-specific compensation thresholds not delineated\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Identified a HIF-independent transcriptional input: IFN\\u03b3 induces PHD3 specifically via JAK/STAT1, linking inflammatory signaling to PHD3 levels.\",\n      \"evidence\": \"JAK inhibitor, STAT1 siRNA, and ChIP for STAT1 at the PHD3 promoter in endothelial cells\",\n      \"pmids\": [\"19574556\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; functional consequence of IFN\\u03b3-induced PHD3 not defined\", \"Cell-type generality untested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Established that PHD3's NF-\\u03baB-suppressive activity in myogenesis requires catalytic activity, distinguishing it from scaffold roles.\",\n      \"evidence\": \"Pharmacological PHD inhibition, catalytically inactive EGLN3, and dominant-negative epistasis with NF-\\u03baB reporters\",\n      \"pmids\": [\"20089853\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct hydroxylation target in the NF-\\u03baB axis in this context not identified\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identified PRP19 as a hypoxia-enhanced partner that suppresses PHD3-dependent cell death.\",\n      \"evidence\": \"Co-IP, domain-deletion mapping, siRNA/overexpression, and caspase/cell death assays with double-silencing rescue\",\n      \"pmids\": [\"20599946\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; mechanism by which PRP19 restrains PHD3-driven death unclear\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Connected PHD3 to cancer metabolism by showing PKM2 hydroxylation enhances its HIF-1 coactivator role and aerobic glycolysis.\",\n      \"evidence\": \"MS/anti-hydroxyproline site identification, co-IP, knockdown, and metabolic flux assays with PKM1/PKM2 comparison\",\n      \"pmids\": [\"21620138\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo tumor relevance of PKM2 hydroxylation not detailed here\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defined a HIF-independent survival role: PHD3 uniquely prolongs neutrophil survival in hypoxia via Siva1/Bcl-xL, with in vivo inflammatory consequences.\",\n      \"evidence\": \"Phd3-/- neutrophils, apoptosis assays, Siva1/Bcl-xL measurement, and acute lung injury/colitis models\",\n      \"pmids\": [\"21317538\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PHD3 catalysis or scaffolding mediates the effect not resolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Linked PHD3 to the DNA-damage response by showing HCLK2 hydroxylation is required for ATR binding and ATR/CHK1/p53 activation.\",\n      \"evidence\": \"Co-IP, DMOG/hypoxia inhibition, PHD3-/- mice, thymic apoptosis, and CHK1/p53 phosphorylation assays\",\n      \"pmids\": [\"22797300\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"HCLK2 hydroxylation site not mapped here\", \"Crosstalk with HIF pathway in DDR unaddressed\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Established a hydroxylase-independent NF-\\u03baB co-activator function via physical interaction with p65 in nucleus pulposus catabolism.\",\n      \"evidence\": \"Co-IP, co-localization, shRNA knockdown, NF-\\u03baB and HRE reporters confirming HIF-independence\",\n      \"pmids\": [\"22948157\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of p65 interaction undefined\", \"Apparent context-dependent opposite NF-\\u03baB effects vs catalytic suppression unreconciled\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Defined a catalysis-independent NF-\\u03baB-suppressive mechanism: EGLN3 binds IKK\\u03b3/NEMO and competes with cIAP1 to block K63 ubiquitination.\",\n      \"evidence\": \"Co-IP, K63 ubiquitination assay, catalytic mutant, cIAP1 competition, and isoform comparison\",\n      \"pmids\": [\"23732909\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Reconciliation with co-activator p65 role context-dependent and not fully explained\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Showed p62/SQSTM1 controls PHD3 by promoting normoxic aggregation/degradation, tuning PHD3-HIF-\\u03b1 engagement with oxygen.\",\n      \"evidence\": \"Co-IP, p62 siRNA, PHD3 localization imaging, and HIF-\\u03b1 level measurement\",\n      \"pmids\": [\"23345396\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; molecular trigger for hypoxic p62 decrease unclear\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Revealed an in vivo HIF-2\\u03b1-specific metabolic axis: hepatic Phd3 loss improves insulin sensitivity via HIF-2\\u03b1-driven Irs2 induction.\",\n      \"evidence\": \"Acute hepatic Phd3 knockout, glucose/insulin tolerance tests, Akt phosphorylation, and HIF-2\\u03b1/Irs2 double-knockdown epistasis\",\n      \"pmids\": [\"24037093\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether direct HIF-2\\u03b1 hydroxylation or other mechanism drives selectivity not resolved\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Demonstrated a scaffold role in receptor trafficking: PHD3 binds Eps15 to promote EGFR internalization, restraining EGFR signaling independent of catalysis, HIF, and NF-\\u03baB.\",\n      \"evidence\": \"Co-IP, EGFR internalization assay, knockdown, catalytic mutant, and EGFR phosphorylation measurement\",\n      \"pmids\": [\"25420589\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of Eps15 interaction not defined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Extended hydroxylation to the cytoskeleton: PHD3 hydroxylates actin at Pro307/Pro322 to inhibit polymerization and motility.\",\n      \"evidence\": \"MS site identification, co-IP, knockdown/overexpression, F-/G-actin fractionation, DMOG, and migration assays\",\n      \"pmids\": [\"25079693\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance of actin hydroxylation untested\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Linked PHD3 to mitochondrial metabolism via interaction with PDH-E1\\u03b2 and stabilization of the PDH complex.\",\n      \"evidence\": \"MS interactome, co-IP, and PDH activity/stability assays in PHD3-depleted cells and -/- MEFs\",\n      \"pmids\": [\"25088999\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; whether interaction is direct or catalytic unclear\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Defined a hydroxylase-independent barrier-protective role: PHD3 shields occludin from Itch, with intestinal Phd3 loss causing spontaneous colitis.\",\n      \"evidence\": \"Intestinal epithelial-specific Phd3 knockout, co-IP of PHD3/occludin/Itch, permeability assays, and hydroxylase-dead mutant\",\n      \"pmids\": [\"26124271\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of Itch competition not structurally defined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identified a catalysis-independent SUMOylation mechanism repressing HIF-1 transcriptional activity without affecting HIF-1\\u03b1 stability.\",\n      \"evidence\": \"SUMOylation assay, lysine cluster mutagenesis, HIF-1 reporter, and hydroxylase activity controls\",\n      \"pmids\": [\"25380826\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; SUMO E3 ligase and downstream effector not identified\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Connected PHD3 to cell cycle control by HIF-independent reduction of p27 half-life via reduced Ser10 phosphorylation, promoting G1/S entry.\",\n      \"evidence\": \"Knockdown, flow cytometry, cycloheximide chase, phospho-S10 antibody, and p27-S10A mutant\",\n      \"pmids\": [\"26223520\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; molecular intermediary linking PHD3 to p27-S10 phosphorylation unknown\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Established PHD3 as a nutrient-responsive metabolic brake: ACC2 hydroxylation activates ACC2 to suppress fatty acid oxidation, with consequences for leukemia proliferation.\",\n      \"evidence\": \"Knockdown/overexpression, ACC2 hydroxylation assay, isotopic FAO tracing, and leukemia proliferation assay\",\n      \"pmids\": [\"27635760\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"ACC2 hydroxylation site not mapped here\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showed PHD3 hydroxylates p53 at Pro359 to regulate USP7/USP10 binding and thus p53 stability.\",\n      \"evidence\": \"Co-IP, MS site identification, USP7/USP10 interaction and ubiquitination assays with mRNA controls\",\n      \"pmids\": [\"30067985\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo p53-dependent phenotypes of this hydroxylation not defined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Resolved the apoptotic effector mechanism: EglN3 hydroxylates BIM-EL to enable VHL binding that blocks ERK-Ser69 phosphorylation, stabilizing BIM-EL; VHL type 2C mutants fail, linking to pheochromocytoma.\",\n      \"evidence\": \"Co-IP, hydroxylation/phosphorylation assays, genetic inactivation, VHL mutant panel, and ERK-inhibitor rescue\",\n      \"pmids\": [\"31375625\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Integration with the KIF1B\\u03b2 axis not fully reconciled\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Uncovered a cell-type-specific reversal: in ccRCC, PHD3 silencing lowers HIF-2\\u03b1 by destabilizing HIF2A mRNA, opposite to the canonical pathway.\",\n      \"evidence\": \"Isoform-specific siRNA, protein/mRNA measurement, mRNA stability assay, and rescue with cell-type comparison\",\n      \"pmids\": [\"30617181\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Single lab; mechanism by which PHD3 affects HIF2A mRNA stability unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Validated the ACC2 metabolic axis in vivo: tissue-specific PHD3 loss abolishes ACC2 hydroxylation, elevates FAO, and enhances endurance exercise capacity.\",\n      \"evidence\": \"Whole-body and muscle-specific PHD3 knockout mice, ACC2 hydroxylation/FAO measurement, treadmill and AMPK assays\",\n      \"pmids\": [\"32663458\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Interplay between hydroxylation and AMPK phosphorylation of ACC2 not fully mechanistic\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identified CDC20/APC-mediated D-box-dependent PHD3 degradation that stabilizes HIF-1\\u03b1 and promotes VEGF in HCC.\",\n      \"evidence\": \"Co-IP, ubiquitination assay, CDC20 ablation/inhibition, non-degradable D-box mutant rescue, and xenograft\",\n      \"pmids\": [\"33039559\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; cell-cycle context of PHD3 destruction not detailed\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Showed USP9X deubiquitinates EGLN3 to prevent degradation, sustaining the apoptotic KIF1B\\u03b2 pathway and restraining cholangiocarcinoma growth.\",\n      \"evidence\": \"Co-IP, ubiquitination assay, USP9X/EGLN3 knockdown, xenograft, and KIF1B\\u03b2 measurement\",\n      \"pmids\": [\"34112167\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; deubiquitination site not mapped\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrated PHD3 catalysis blocks chaperone-mediated autophagy of ERK3 by preventing LAMP2A/HSC70 binding.\",\n      \"evidence\": \"Co-IP, catalytically inactive EGLN3 knock-in mice, CMA-lysosome assays, and interaction rescue\",\n      \"pmids\": [\"35124697\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"ERK3 hydroxylation site not defined here\", \"Physiological context of ERK3 regulation broad\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Identified MAEA as an E3 ligase ubiquitinating PHD3 at K159 to stabilize HIF-1\\u03b1 and promote glioblastoma stemness and temozolomide resistance.\",\n      \"evidence\": \"TMT proteomics, co-IP, K48 ubiquitination assay, K159 mutagenesis, and xenograft\",\n      \"pmids\": [\"36882523\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; regulation of MAEA-PHD3 axis upstream unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how the cell selects between PHD3's catalytic substrate hydroxylation and its catalysis-independent scaffold/co-activator functions, and what determines the cell-type-specific and context-dependent (even opposite) outcomes on HIF-2\\u03b1 and NF-\\u03baB.\",\n      \"evidence\": \"No single study in the corpus integrates the catalytic vs scaffold decision or the divergent HIF-2\\u03b1/NF-\\u03baB outcomes\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No unifying structural model distinguishing catalytic from scaffold engagement\", \"Determinants of cell-type-specific HIF-2\\u03b1 regulation unknown\", \"Reconciliation of opposing NF-\\u03baB effects across tissues lacking\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016491\", \"supporting_discovery_ids\": [0, 8, 16, 29, 33]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 6, 13, 16, 24, 30, 36]},\n      {\"term_id\": \"GO:0016706\", \"supporting_discovery_ids\": [8]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [20, 23, 26, 7]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [19]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [5, 9, 21]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [5, 19]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [0, 1, 4, 14]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [16, 29, 33, 22, 25]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [3, 11, 17, 31]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [13, 20, 23]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [18, 30]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [6, 12, 34, 37, 35, 27]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"HIF1A\", \"VHL\", \"PKM2\", \"ACC2\", \"IKBKG\", \"EPS15\", \"OCLN\", \"TP53\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}