{"gene":"ASS1","run_date":"2026-06-09T22:02:44","timeline":{"discoveries":[{"year":2015,"finding":"ASS1 deficiency in cancer increases cytosolic aspartate levels, which activates the CAD complex (carbamoyl-phosphate synthase 2, aspartate transcarbamylase, and dihydroorotase) by upregulating substrate availability and increasing CAD phosphorylation by S6K1 through the mTOR pathway, thereby facilitating de novo pyrimidine synthesis and supporting proliferation.","method":"Metabolic flux analysis, citrullinemia patient studies, mTOR/S6K1 pathway inhibition experiments, CAD activity assays in ASS1-deficient cancer cells","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (metabolomics, patient data, pathway inhibition, enzymatic assays) across cancer cells and human disease contexts, replicated across multiple cancer types","pmids":["26560030"],"is_preprint":false},{"year":2017,"finding":"CLOCK directly acetylates ASS1 at lysine residues K165 and K176 (facilitated by BMAL1) to inactivate ASS1, and this acetylation exhibits circadian oscillation in human cells and mouse liver, driven by rhythmic CLOCK–ASS1 interaction, thereby imposing circadian regulation on arginine biosynthesis and ureagenesis.","method":"In vitro acetylation assay, mass spectrometry identification of acetylation sites, site-directed mutagenesis of K165 and K176, co-immunoprecipitation of CLOCK–ASS1 complex, circadian oscillation profiling in cells and mouse liver","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro enzymatic assay with mutagenesis validation, reciprocal Co-IP, and oscillation profiling in two biological systems (human cells and mouse liver) in a single study","pmids":["28985504"],"is_preprint":false},{"year":2017,"finding":"HIF-1α and c-MYC act as reciprocal negative and positive transcriptional regulators of ASS1 expression by binding to the ASS1 promoter; DEC1 functions as the master regulator controlling both HIF-1α and c-MYC levels to regulate ASS1 transcription independently of ASS1 promoter DNA methylation.","method":"Promoter binding assays (ChIP), overexpression and knockdown of HIF-1α, c-MYC, and DEC1, use of proteasomal inhibitors (bortezomib, carfilzomib) to modulate HIF-1α, cisplatin and 5-aza-dC treatment to alter ASS1 expression","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP and genetic manipulation in single lab with multiple orthogonal approaches but no structural validation","pmids":["27765932"],"is_preprint":false},{"year":2017,"finding":"At the ASS1 promoter, the histone acetyltransferase p300 maintains H3K14ac and H3K27ac marks that support HIF-1α-mediated ASS1 silencing; arginine starvation induces p300 dissociation, allowing HDAC2 and Sin3A to deacetylate these histone marks, which facilitates PHD2-driven proteasomal degradation of HIF-1α in situ, leading to ASS1 de-repression.","method":"Chromatin immunoprecipitation (ChIP) for histone marks and transcription factor binding, knockdown/overexpression of p300, HDAC2, Sin3A, PHD2, antioxidant sensitivity assays","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP with multiple histone marks and factor knockdowns, single lab, orthogonal methods","pmids":["28883660"],"is_preprint":false},{"year":2014,"finding":"Prolonged arginine starvation (via ADI-PEG20) in ASS1-deficient breast cancer cells induces mitochondrial oxidative stress, impairs mitochondrial bioenergetics and integrity, and triggers cytotoxic autophagy; cell death requires autophagy competence, placing mitochondrial damage upstream of autophagic cell death in the arginine starvation pathway.","method":"ADI-PEG20 treatment of ASS1-deficient breast cancer cells in vitro and in vivo, mitochondrial ROS/bioenergetics assays, autophagy-deficient cell lines, genetic suppression of autophagy","journal":"Science signaling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis (autophagy-deficient cells) plus mitochondrial functional assays and in vivo validation, single lab","pmids":["24692592"],"is_preprint":false},{"year":2017,"finding":"PRMT7 directly interacts with ASS1 (confirmed by yeast two-hybrid and pull-down assays), and ASS1 mutations associated with citrullinemia type I disrupt the PRMT7–ASS1 interaction, implicating loss of this interaction in the molecular pathogenesis of the disease.","method":"Yeast two-hybrid screening, pull-down assay, site-directed mutagenesis of ASS1 citrullinemia-associated residues, computational interface mapping","journal":"Journal of molecular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal interaction confirmed by two independent binding assays with mutagenesis, single lab","pmids":["28587924"],"is_preprint":false},{"year":2021,"finding":"Snail prevents LOC113230-mediated ubiquitination and degradation of ASS1: LOC113230 acts as a scaffold to recruit LRPPRC and the TRAF2 E3 ubiquitin ligase to ASS1, resulting in ASS1 ubiquitination and degradation; Snail represses LOC113230 transcription (via E-box binding) in response to TGF-β, thereby stabilizing ASS1 and promoting arginine synthesis for colorectal cancer migration.","method":"Co-immunoprecipitation identifying LRPPRC/TRAF2/ASS1 complex, ubiquitination assays, LOC113230 overexpression/knockdown, Snail ChIP at E-boxes in LOC113230 promoter, xenograft metastasis experiments","journal":"EMBO reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP identifying complex components, ubiquitination assay, ChIP, and in vivo validation, single lab","pmids":["34184805"],"is_preprint":false},{"year":2024,"finding":"ASS1 directly binds to PHGDH and promotes its ubiquitination-mediated proteasomal degradation, thereby inhibiting de novo serine synthesis; the tumor-suppressive effect of ASS1 in triple-negative breast cancer is strongly dependent on this mechanism, as PHGDH knockout abrogates ASS1's anti-proliferative activity.","method":"Co-immunoprecipitation identifying ASS1–PHGDH interaction, ubiquitination assays, PHGDH knockout epistasis experiments, serine/glycine rescue experiments, in vitro and in vivo tumor models","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding (Co-IP), ubiquitination assay, and genetic epistasis (PHGDH KO rescue), single lab with multiple orthogonal methods","pmids":["38710705"],"is_preprint":false},{"year":2024,"finding":"Following DNA damage, ASS1 expression is elevated in both cytosol and nucleus (partly p53-dependent); in the nucleus, ASS1 and ASL generate fumarate that succينates SMARCC1, destabilizing the SMARCC1–SNF5 chromatin-remodeling complex and decreasing transcription of a subset of p53-regulated cell cycle genes; in the cytosol, ASS1 restrains nucleotide synthesis to pause cell cycle progression.","method":"Subcellular fractionation, metabolomics with isotope tracing, succination assays, SMARCC1–SNF5 complex disruption analysis, doxorubicin-induced DNA damage in colon cancer cells and citrullinemia fibroblasts","journal":"Nature metabolism","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal methods (fractionation, metabolomics, protein complex disruption, genetic models including disease fibroblasts) establishing distinct nuclear and cytosolic mechanisms, in a single rigorous study","pmids":["38858597"],"is_preprint":false},{"year":2023,"finding":"ASS1 promotes reductive carboxylation of cytosolic glutamine, reducing mitochondrial-derived lipid ROS; additionally, ASS1 activates the mTORC1–SREBP1–SCD5 axis to promote de novo monounsaturated fatty acid synthesis using acetyl-CoA derived from the glutamine reductive pathway, conferring resistance to ferroptosis in non-small cell lung cancer cells.","method":"Stable isotope-labeled glutamine metabolomics, ASS1 loss-of-function (knockdown/knockout), transcriptome sequencing, erastin-induced ferroptosis assays in vitro and in vivo xenograft models","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — isotope tracing metabolomics plus transcriptomics and in vivo validation, single lab","pmids":["36892426"],"is_preprint":false},{"year":2020,"finding":"Under glucose deprivation, ASS1 expression is induced by c-MYC, and ASS1 increases nitric oxide synthesis and activates gluconeogenic enzymes pyruvate carboxylase and phosphoenolpyruvate carboxykinase via S-nitrosylation, enhancing flux through gluconeogenesis to support serine, glycine, and subsequent purine synthesis.","method":"ASS1 overexpression/knockdown under glucose deprivation, c-MYC ChIP and expression manipulation, S-nitrosylation assays of gluconeogenic enzymes, metabolic flux analysis","journal":"Nature cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP, S-nitrosylation biochemistry, and metabolic flux analysis in single lab with multiple orthogonal methods","pmids":["35121952"],"is_preprint":false},{"year":2018,"finding":"In hypoxia, ASS1 expression is further downregulated via HIF-1α-mediated induction of miR-224-5p; ASS1-depleted cancer cells maintain higher intracellular pH, depend less on extracellular glutamine, and display higher glutathione levels, indicating that ASS1 regulation under acidic/hypoxic conditions provides a redox and pH advantage to cancer cells.","method":"miR-224-5p gain/loss-of-function, intracellular pH measurements, glutamine dependence assays, glutathione quantification, ASS1 knockdown/overexpression under hypoxic and acidic conditions","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — miRNA functional manipulation, pH measurements, and metabolite quantification, single lab with multiple endpoints","pmids":["30573518"],"is_preprint":false},{"year":2017,"finding":"Arginine deprivation in ASS1-deficient cancer cells inhibits the Warburg effect by reducing aerobic glycolysis with decreased PKM2 expression and phosphorylation, while increasing serine biosynthesis (via PHGDH upregulation), glutamine anaplerosis, and oxidative phosphorylation; concurrent arginine deprivation and glutaminase inhibition is synthetic lethal across ASS1-deficient tumor lines.","method":"Metabolite profiling, Western blotting for PKM2/PHGDH, arginine starvation (ADI-PEG20), glutaminase inhibitor combination studies in vitro and in vivo xenograft models","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — metabolomics plus genetic/pharmacologic manipulation with in vivo validation, single lab","pmids":["28122247"],"is_preprint":false},{"year":2021,"finding":"Recombinant ASS1 physically binds to bacterial lipopolysaccharide (LPS) as shown by gel-shift assay and suppresses E. coli growth in culture; endogenous hepatic ASS1 is released into circulation within 1 hour of LPS challenge, acting as a component of the innate immune response to reduce LPS cytotoxicity, suppress TNF-α production, and increase survival in rodent endotoxemia models.","method":"Gel-shift assay for LPS binding, bacterial growth inhibition assay, mouse macrophage cytotoxicity assays, in vivo LPS endotoxemia model with recombinant ASS injection","journal":"International immunopharmacology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding assay plus in vitro and in vivo functional experiments, single lab","pmids":["21481813"],"is_preprint":false},{"year":2022,"finding":"MANF (mesencephalic astrocyte-derived neurotrophic factor) resides in the same immunoprecipitated complex as ASS1; MANF knockout decreases ASS1 activity while MANF overexpression enhances ASS1 activity; ASS1 activates AMPK by generating an intracellular pool of AMP from the urea cycle, and this MANF–ASS1–AMPK axis regulates hepatic lipid homeostasis.","method":"Immunoprecipitation-coupled mass spectrometry proteomics, hepatocyte-specific MANF knockout and overexpression, ASS1 enzymatic activity assays, urea cycle metabolite profiling, AMPK phosphorylation assays","journal":"Acta pharmacologica Sinica","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP/MS identifying complex, enzymatic activity measurement in KO and OE models, metabolite profiling, single lab","pmids":["35655095"],"is_preprint":false},{"year":2024,"finding":"ASS1 overexpression activates AMPK and its downstream effector CPT1A by disrupting the AMP/ATP balance, enhancing fatty acid oxidation (FAO) and ATP generation in ovarian cancer cells; CPT1A inhibition reverses ASS1-induced FAO and disrupts AMPK activation, placing CPT1A downstream of the ASS1/AMPK axis in anoikis resistance.","method":"ASS1 overexpression/knockdown, CPT1A inhibition, AMP/ATP ratio measurements, FAO assays, AMPK phosphorylation analysis, anoikis resistance assays","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — enzymatic pathway epistasis with rescue experiments and metabolic measurements, single lab","pmids":["38914306"],"is_preprint":false},{"year":2021,"finding":"Re-expression of both ASS1 and ASL in ccRCC cell lines suppresses tumor growth in 2D, 3D, and in vivo xenograft models in an enzymatic-activity-dependent manner; the growth suppression involves conservation of cellular aspartate (diverting it away from pyrimidine synthesis), regulation of nitric oxide synthesis, and altered pyrimidine production.","method":"Genetic re-expression of ASS1 and ASL in ccRCC cell lines, catalytically inactive mutant controls, 2D/3D growth assays, xenograft models, metabolomics","journal":"Cancer & metabolism","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — enzymatic activity-dependent rescue with in vivo validation and metabolomics, single lab","pmids":["34861885"],"is_preprint":false},{"year":2022,"finding":"PGAM1 negatively regulates ASS1 expression through the cAMP/AMPK/CEBPB transcriptional axis; PGAM1 knockdown markedly upregulates ASS1 expression, and ASS1 upregulation is required for the anti-proliferative effect of PGAM1 depletion in breast cancer cells.","method":"RNA sequencing after PGAM1 knockdown, CEBPB transcription factor pathway analysis, ASS1 knockdown epistasis experiments, in vivo tumor growth assays","journal":"Molecular oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RNA-seq plus genetic epistasis (double knockdown) and in vivo validation, single lab","pmids":["35674458"],"is_preprint":false},{"year":2019,"finding":"Androgen receptor (AR) decreases ASS1 protein expression to promote renal cell carcinoma proliferation via the pseudogene ASS1P3: AR binds ASS1P3, which acts as a competing endogenous RNA (ceRNA) decoy for miR-34a-5p; miR-34a-5p binds the 3'UTR of ASS1 to suppress ASS1 protein expression, and AR-driven ASS1P3 upregulation sequesters miR-34a-5p to reduce ASS1.","method":"RIP assay demonstrating AR binding to ASS1P3, AGO2 assay, luciferase reporter for miR-34a-5p targeting ASS1 3'UTR, AR/ASS1P3/miR-34a-5p knockdown/overexpression, in vivo xenograft experiments","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — RIP and AGO2 assays with 3'UTR reporter and genetic epistasis, single lab","pmids":["31000693"],"is_preprint":false},{"year":2022,"finding":"FXR (Farnesoid X receptor) directly promotes ASS1 transcription; FXR agonist obeticholic acid (OCA) upregulates ASS1 expression and enhances arginine synthesis, reducing hepatocyte apoptosis (decreased Cyt C, PARP, and Caspase 3 levels) in TAA-induced acute liver injury.","method":"FXR agonist/antagonist treatment, ASS1 transcriptional reporter assays, single-cell RNA-seq data analysis, apoptosis marker measurement, in vivo TAA liver injury model","journal":"Biochemical and biophysical research communications","confidence":"Low","confidence_rationale":"Tier 3 / Moderate — transcriptional regulation and apoptosis assays but abstract does not clearly describe direct FXR–ASS1 promoter binding experiment","pmids":["35477090"],"is_preprint":false},{"year":2019,"finding":"Arginine starvation with ADI-PEG20 combined with docetaxel stabilizes c-MYC and causes its nuclear translocation in ASS1-negative tumor cells, which increases hENT1 cell-surface expression and renders cells susceptible to gemcitabine; c-MYC inhibition blocks hENT1 upregulation, placing c-MYC as a required mediator between arginine starvation and gemcitabine sensitization.","method":"Protein expression analysis (Western blot), c-MYC activity assays, live-cell immunofluorescence for hENT1 surface localization, FITC-cytosine uptake assay, c-MYC inhibitor rescue experiments, in vivo tumor growth studies","journal":"Clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (immunofluorescence, uptake assay, genetic rescue) in single lab with in vivo validation","pmids":["31113844"],"is_preprint":false},{"year":2009,"finding":"ASS1 was chromosomally localized to the distal long arm of chromosome 9, region 9q34–9qter, by somatic cell hybrid mapping using human cells carrying balanced reciprocal translocations involving chromosome 9.","method":"Somatic cell hybrid mapping with balanced reciprocal translocations, subchromosomal assignment","journal":"Cytogenetics and cell genetics","confidence":"Low","confidence_rationale":"Tier 3 / Moderate — chromosomal mapping is a direct experiment replicated across multiple hybrid panels, but provides genomic localization only, not molecular mechanism","pmids":["219990"],"is_preprint":false},{"year":2021,"finding":"ASS1 loss in fibroblastic foci of IPF-patient lung fibroblasts promotes fibroblast proliferation, migration, and invasion; mechanistically, ASS1 knockdown activates the hepatocyte growth factor receptor Met and its downstream Src–STAT3 signaling axis.","method":"ASS1 knockdown/overexpression, proliferation/migration/invasion assays, Western blot for Met, Src, STAT3 activation, bleomycin mouse model","journal":"Molecular therapy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic manipulation with defined downstream pathway (Met/Src/STAT3) and in vivo model, single lab","pmids":["33508432"],"is_preprint":false},{"year":2024,"finding":"β-sitosterol selectively targets ASS1 (identified by network pharmacology and validated in vitro); inhibition of ASS1 by β-sitosterol enhances the interaction between Nrf2 and Keap1, promoting ubiquitin-dependent degradation of Nrf2, which decreases transcription of antioxidant genes HO-1 and NQO1, causing ROS accumulation that upregulates PTEN and suppresses AKT phosphorylation in ovarian cancer cells.","method":"Network pharmacology target prediction, ASS1 overexpression/knockdown, Nrf2–Keap1 co-immunoprecipitation, ubiquitination assays, ROS measurement, PTEN/AKT pathway analysis, in vitro and in vivo tumor models","journal":"Free radical biology & medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP for Nrf2–Keap1 interaction change, ubiquitination assay, ROS and pathway measurements, single lab with multiple methods","pmids":["38364944"],"is_preprint":false}],"current_model":"ASS1 is a cytosolic urea cycle enzyme (catalyzing the rate-limiting condensation of citrulline and aspartate to argininosuccinate) that controls aspartate availability for pyrimidine synthesis and ferroptosis resistance, is subject to circadian acetylation by CLOCK at K165/K176 to inactivate it, undergoes p53-dependent nuclear translocation after DNA damage where it and ASL generate fumarate to succinate SMARCC1 and remodel chromatin, is regulated transcriptionally by HIF-1α (repressor) and c-MYC (activator) via a DEC1-controlled chromatin remodeling mechanism, interacts with PRMT7 and PHGDH (promoting PHGDH ubiquitination), and through its enzymatic production of AMP activates AMPK to regulate fatty acid oxidation and lipid homeostasis."},"narrative":{"mechanistic_narrative":"ASS1 is a cytosolic urea-cycle enzyme whose control over aspartate and arginine flux makes it a metabolic checkpoint with broad effects on proliferation, redox balance, and cell death [PMID:26560030, PMID:34861885]. Loss of ASS1 raises cytosolic aspartate, which activates the CAD complex through mTOR/S6K1-driven CAD phosphorylation to fuel de novo pyrimidine synthesis and tumor proliferation, and re-expression of ASS1 with ASL suppresses tumor growth in an enzymatic-activity-dependent manner by diverting aspartate away from nucleotide synthesis [PMID:26560030, PMID:34861885]. Beyond canonical catalysis, ASS1 acts as a tumor suppressor by directly binding PHGDH and driving its ubiquitination-mediated degradation to restrain serine synthesis [PMID:38710705]. ASS1 activity is gated post-translationally: CLOCK acetylates ASS1 at K165/K176 to inactivate it, imposing a circadian rhythm on arginine biosynthesis and ureagenesis [PMID:28985504]. Following DNA damage, ASS1 accumulates in both compartments — in the nucleus it cooperates with ASL to generate fumarate that succinates SMARCC1 and destabilizes the SMARCC1–SNF5 chromatin-remodeling complex, repressing p53-regulated cell-cycle genes, while in the cytosol it restrains nucleotide synthesis to pause the cell cycle [PMID:38858597]. ASS1 transcription is governed by opposing regulators, with HIF-1α repressing and c-MYC activating expression under control of DEC1 and p300/HDAC2-dependent histone acetylation at the promoter [PMID:27765932, PMID:28883660]. Through its enzymatic generation of AMP, ASS1 activates AMPK to drive fatty acid oxidation and govern hepatic and tumor lipid homeostasis [PMID:35655095, PMID:38914306]. ASS1 mutations associated with citrullinemia type I disrupt its interaction with PRMT7, linking the enzyme to the molecular pathogenesis of that disease [PMID:28587924].","teleology":[{"year":2009,"claim":"Before molecular characterization, the genomic position of ASS1 was unknown; mapping it provided the physical anchor for later genetic and disease studies.","evidence":"Somatic cell hybrid mapping using balanced reciprocal translocations of chromosome 9","pmids":["219990"],"confidence":"Low","gaps":["Provides genomic localization only, no molecular mechanism","Does not address enzymatic or regulatory function"]},{"year":2014,"claim":"It was unclear how arginine starvation kills ASS1-deficient cancers; this work established mitochondrial damage as the upstream trigger of autophagic cell death.","evidence":"ADI-PEG20 treatment of ASS1-deficient breast cancer cells with mitochondrial assays and autophagy-deficient lines, in vitro and in vivo","pmids":["24692592"],"confidence":"Medium","gaps":["Molecular link between mitochondrial ROS and autophagy initiation not defined","Single tumor type"]},{"year":2015,"claim":"The metabolic consequence of ASS1 loss in cancer was unresolved; this study showed aspartate accumulation activates CAD via mTOR/S6K1 to drive pyrimidine synthesis and proliferation.","evidence":"Metabolic flux analysis, citrullinemia patient studies, mTOR/S6K1 inhibition, and CAD assays in ASS1-deficient cancer cells","pmids":["26560030"],"confidence":"High","gaps":["Does not address non-metabolic ASS1 functions","Mechanism of aspartate-driven CAD phosphorylation not structurally resolved"]},{"year":2017,"claim":"How ASS1 activity is tuned over time was unknown; CLOCK-mediated acetylation at K165/K176 was shown to inactivate ASS1 and impose circadian control on ureagenesis.","evidence":"In vitro acetylation assay, MS site mapping, K165/K176 mutagenesis, Co-IP, and oscillation profiling in human cells and mouse liver","pmids":["28985504"],"confidence":"High","gaps":["Deacetylase that reverses the modification not identified","Whether acetylation alters localization is unaddressed"]},{"year":2017,"claim":"The transcriptional logic of ASS1 silencing in cancer was unclear; DEC1 was identified as a master regulator coordinating HIF-1α repression and c-MYC activation at the ASS1 promoter.","evidence":"ChIP, knockdown/overexpression of HIF-1α/c-MYC/DEC1, proteasome inhibitors, and demethylation treatment","pmids":["27765932"],"confidence":"Medium","gaps":["DNA-methylation-independent mechanism not fully resolved","No structural validation of promoter complexes"]},{"year":2017,"claim":"The chromatin basis of HIF-1α-mediated ASS1 silencing was undefined; p300/HDAC2/Sin3A control of H3K14ac/H3K27ac was shown to gate in situ HIF-1α degradation and ASS1 de-repression upon arginine starvation.","evidence":"ChIP for histone marks and factors, knockdown/overexpression of p300/HDAC2/Sin3A/PHD2, antioxidant assays","pmids":["28883660"],"confidence":"Medium","gaps":["Generality across tumor types unknown","Connection to DEC1 axis not integrated"]},{"year":2017,"claim":"Whether ASS1 has protein partners relevant to disease was unknown; PRMT7 was identified as a direct interactor disrupted by citrullinemia mutations.","evidence":"Yeast two-hybrid, pull-down assays, and mutagenesis of citrullinemia-associated residues","pmids":["28587924"],"confidence":"Medium","gaps":["Functional consequence of PRMT7 binding on ASS1 activity not defined","No methylation of ASS1 demonstrated"]},{"year":2017,"claim":"The metabolic rewiring underlying arginine-deprivation therapy was unclear; arginine deprivation was shown to suppress the Warburg effect and create synthetic lethality with glutaminase inhibition in ASS1-deficient tumors.","evidence":"Metabolite profiling, PKM2/PHGDH Westerns, ADI-PEG20 plus glutaminase inhibitor combinations in vitro and in vivo","pmids":["28122247"],"confidence":"Medium","gaps":["Durability of synthetic lethality not assessed","Single therapeutic combination"]},{"year":2018,"claim":"How hypoxia further suppresses ASS1 and benefits cancer cells was unknown; HIF-1α-induced miR-224-5p was shown to downregulate ASS1, conferring pH and redox advantages.","evidence":"miR-224-5p gain/loss-of-function, intracellular pH, glutamine-dependence, and glutathione assays under hypoxia/acidosis","pmids":["30573518"],"confidence":"Medium","gaps":["Direct miR-224-5p:ASS1 target site not validated in this entry","Causal link between pH and growth not isolated"]},{"year":2019,"claim":"Mechanisms of ASS1 repression beyond transcription factors were unclear; AR was shown to drive the ASS1P3 pseudogene as a ceRNA decoy sequestering miR-34a-5p to suppress ASS1 in renal carcinoma.","evidence":"RIP, AGO2 assay, miR-34a-5p 3'UTR luciferase reporter, and genetic manipulation with xenografts","pmids":["31000693"],"confidence":"Medium","gaps":["Specificity of ASS1P3 ceRNA activity in other tissues unknown","Quantitative contribution versus other regulators not defined"]},{"year":2019,"claim":"How arginine starvation sensitizes tumors to chemotherapy was unclear; c-MYC nuclear translocation was shown to upregulate hENT1 and confer gemcitabine susceptibility.","evidence":"Western blot, c-MYC assays, hENT1 surface immunofluorescence, FITC-cytosine uptake, and c-MYC inhibitor rescue in vivo","pmids":["31113844"],"confidence":"Medium","gaps":["Direct transcriptional control of hENT1 by c-MYC not shown here","Restricted to ASS1-negative context"]},{"year":2020,"claim":"ASS1's role under nutrient stress was unknown; c-MYC-induced ASS1 was shown to drive nitric-oxide-dependent S-nitrosylation of gluconeogenic enzymes to support purine synthesis during glucose deprivation.","evidence":"ASS1 manipulation under glucose deprivation, c-MYC ChIP, S-nitrosylation assays, and metabolic flux analysis","pmids":["35121952"],"confidence":"Medium","gaps":["Source/regulation of NO production by ASS1 not detailed","Generality beyond glucose-deprived state unknown"]},{"year":2021,"claim":"Whether ASS1 is degradation-controlled in cancer was unknown; a LOC113230 scaffold recruiting LRPPRC/TRAF2 was shown to ubiquitinate ASS1, an axis Snail represses via TGF-β to stabilize ASS1 and promote metastasis.","evidence":"Co-IP of LRPPRC/TRAF2/ASS1, ubiquitination assays, Snail ChIP at LOC113230 E-boxes, and xenograft metastasis models","pmids":["34184805"],"confidence":"Medium","gaps":["Direct E3 ubiquitin transfer by TRAF2 to ASS1 not structurally shown","Single cancer type"]},{"year":2021,"claim":"The therapeutic value of restoring urea-cycle enzymes in renal cancer was untested; ASS1/ASL re-expression was shown to suppress tumor growth dependent on enzymatic activity.","evidence":"Genetic re-expression with catalytically inactive controls, 2D/3D and xenograft growth assays, and metabolomics in ccRCC","pmids":["34861885"],"confidence":"Medium","gaps":["Relative contributions of aspartate conservation versus NO regulation not separated","Limited to ccRCC lines"]},{"year":2021,"claim":"An extra-metabolic role for ASS1 in fibrosis was unknown; ASS1 loss in IPF fibroblasts was shown to activate Met–Src–STAT3 signaling driving fibroblast proliferation and invasion.","evidence":"ASS1 knockdown/overexpression, proliferation/migration/invasion assays, Met/Src/STAT3 Westerns, and bleomycin mouse model","pmids":["33508432"],"confidence":"Medium","gaps":["Mechanism linking ASS1 metabolism to Met activation undefined","Whether enzymatic activity is required not tested"]},{"year":2021,"claim":"A non-metabolic immune function was unsuspected; secreted ASS1 was shown to bind LPS, inhibit bacterial growth, and protect against endotoxemia.","evidence":"Gel-shift LPS binding, bacterial growth inhibition, macrophage cytotoxicity, and rodent endotoxemia models with recombinant ASS","pmids":["21481813"],"confidence":"Medium","gaps":["Structural basis of LPS binding unknown","Mechanism of hepatic ASS1 release into circulation undefined"]},{"year":2022,"claim":"How ASS1 connects to lipid metabolism was unclear; the MANF–ASS1–AMPK axis was shown to operate through ASS1-derived AMP generation regulating hepatic lipid homeostasis.","evidence":"Co-IP/MS, hepatocyte MANF knockout/overexpression, ASS1 activity assays, urea-cycle metabolite profiling, and AMPK phosphorylation","pmids":["35655095"],"confidence":"Medium","gaps":["Whether MANF directly binds ASS1 not resolved","Mechanism by which MANF modulates ASS1 activity unknown"]},{"year":2022,"claim":"Additional upstream repressors of ASS1 were sought; PGAM1 was shown to suppress ASS1 via a cAMP/AMPK/CEBPB axis, with ASS1 induction required for the anti-proliferative effect of PGAM1 loss.","evidence":"RNA-seq after PGAM1 knockdown, CEBPB pathway analysis, double-knockdown epistasis, and in vivo tumor assays","pmids":["35674458"],"confidence":"Medium","gaps":["Direct CEBPB binding to ASS1 promoter not shown","Single tumor type"]},{"year":2022,"claim":"Whether ASS1 protects hepatocytes was unclear; FXR was shown to promote ASS1 transcription, enhancing arginine synthesis and reducing apoptosis in acute liver injury.","evidence":"FXR agonist/antagonist, ASS1 reporter assays, scRNA-seq, apoptosis markers, and TAA liver-injury model","pmids":["35477090"],"confidence":"Low","gaps":["Direct FXR–ASS1 promoter binding not clearly demonstrated","Causal role of ASS1 in apoptosis reduction not isolated"]},{"year":2023,"claim":"How ASS1 affects ferroptosis was unknown; ASS1 was shown to drive glutamine reductive carboxylation and an mTORC1–SREBP1–SCD5 axis producing monounsaturated fatty acids to resist ferroptosis.","evidence":"Glutamine isotope metabolomics, ASS1 loss-of-function, transcriptomics, and erastin ferroptosis assays in NSCLC, in vivo","pmids":["36892426"],"confidence":"Medium","gaps":["Direct effect of ASS1 enzymatic products on SREBP1 not defined","Context-dependence versus tumor-suppressive role unresolved"]},{"year":2024,"claim":"A direct tumor-suppressive partner of ASS1 was unknown; ASS1 was shown to bind PHGDH and promote its ubiquitination, restraining serine synthesis as the basis of its anti-proliferative activity in TNBC.","evidence":"Co-IP, ubiquitination assays, PHGDH knockout epistasis, serine/glycine rescue, and in vitro/in vivo tumor models","pmids":["38710705"],"confidence":"Medium","gaps":["E3 ligase mediating PHGDH ubiquitination not identified","Whether ASS1 catalytic activity is required not defined"]},{"year":2024,"claim":"A moonlighting nuclear function in the DNA-damage response was unknown; ASS1 with ASL was shown to generate fumarate that succinates SMARCC1, remodeling chromatin and pausing the cell cycle alongside cytosolic nucleotide restraint.","evidence":"Subcellular fractionation, isotope-tracing metabolomics, succination assays, SMARCC1–SNF5 disruption analysis in colon cancer cells and citrullinemia fibroblasts","pmids":["38858597"],"confidence":"High","gaps":["Mechanism of ASS1 nuclear import not defined","Selectivity of SMARCC1 succination over other targets unclear"]},{"year":2024,"claim":"How ASS1 supports tumor survival under detachment was unclear; ASS1 was shown to activate AMPK/CPT1A to enhance fatty acid oxidation and anoikis resistance in ovarian cancer.","evidence":"ASS1 overexpression/knockdown, CPT1A inhibition, AMP/ATP ratio and FAO assays, AMPK phosphorylation, and anoikis assays","pmids":["38914306"],"confidence":"Medium","gaps":["Reconciliation with tumor-suppressive ASS1 roles not addressed","Direct AMP supply mechanism not quantified"]},{"year":null,"claim":"It remains unresolved how ASS1's opposing context-dependent roles — tumor suppressor via PHGDH degradation and aspartate conservation versus tumor promoter via AMPK/FAO and ferroptosis resistance — are determined within a given cell.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying model reconciling pro- and anti-tumor functions","Determinants of nuclear versus cytosolic ASS1 partitioning unknown","How post-translational acetylation integrates with degradation control undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016874","term_label":"ligase activity","supporting_discovery_ids":[0,16]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[7]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[13]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0,8]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[8]},{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[13]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0,16]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[8]},{"term_id":"R-HSA-9909396","term_label":"Circadian clock","supporting_discovery_ids":[1]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[8]}],"complexes":[],"partners":["ASL","PHGDH","PRMT7","CLOCK","MANF","SMARCC1","LRPPRC","TRAF2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P00966","full_name":"Argininosuccinate synthase","aliases":["Citrulline--aspartate ligase"],"length_aa":412,"mass_kda":46.5,"function":"One of the enzymes of the urea cycle, the metabolic pathway transforming neurotoxic amonia produced by protein catabolism into inocuous urea in the liver of ureotelic animals. 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CDNI","url":"https://www.omim.org/entry/605814"},{"mim_id":"603471","title":"CITRIN DEFICIENCY, ADOLESCENT OR ADULT ONSET; CDAA","url":"https://www.omim.org/entry/603471"},{"mim_id":"603470","title":"ARGININOSUCCINATE SYNTHETASE 1; ASS1","url":"https://www.omim.org/entry/603470"},{"mim_id":"215700","title":"CITRULLINEMIA, CLASSIC","url":"https://www.omim.org/entry/215700"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"},{"location":"Nucleoplasm","reliability":"Additional"}],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in 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a prospective drug study on its antiinflammatory effects].","date":"2001","source":"Laryngo- rhino- otologie","url":"https://pubmed.ncbi.nlm.nih.gov/11602930","citation_count":22,"is_preprint":false},{"pmid":"34184805","id":"PMC_34184805","title":"Snail enhances arginine synthesis by inhibiting ubiquitination-mediated degradation of ASS1.","date":"2021","source":"EMBO reports","url":"https://pubmed.ncbi.nlm.nih.gov/34184805","citation_count":20,"is_preprint":false},{"pmid":"29422017","id":"PMC_29422017","title":"Metabolomic profiling identifies distinct phenotypes for ASS1 positive and negative GBM.","date":"2018","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/29422017","citation_count":19,"is_preprint":false},{"pmid":"32678125","id":"PMC_32678125","title":"Prolongation of metallothionein induction combats Aß and α-synuclein toxicity in aged transgenic Caenorhabditis elegans.","date":"2020","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/32678125","citation_count":19,"is_preprint":false},{"pmid":"31511125","id":"PMC_31511125","title":"Nocardioides yefusunii sp. nov., isolated from Equus kiang (Tibetan wild ass) faeces.","date":"2019","source":"International journal of systematic and evolutionary microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/31511125","citation_count":19,"is_preprint":false},{"pmid":"20435063","id":"PMC_20435063","title":"A highly sensitive peptide substrate for detecting two Aß-degrading enzymes: neprilysin and insulin-degrading enzyme.","date":"2010","source":"Journal of neuroscience methods","url":"https://pubmed.ncbi.nlm.nih.gov/20435063","citation_count":19,"is_preprint":false},{"pmid":"34382365","id":"PMC_34382365","title":"Phase 1, pharmacogenomic, dose-expansion study of pegargiminase plus pemetrexed and cisplatin in patients with ASS1-deficient non-squamous non-small cell lung cancer.","date":"2021","source":"Cancer medicine","url":"https://pubmed.ncbi.nlm.nih.gov/34382365","citation_count":17,"is_preprint":false},{"pmid":"21525986","id":"PMC_21525986","title":"Association of plasma Aß peptides with blood pressure in the elderly.","date":"2011","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/21525986","citation_count":17,"is_preprint":false},{"pmid":"25551704","id":"PMC_25551704","title":"Aggregation of Aß(25-35) on DOPC and DOPC/DHA bilayers: an atomic force microscopy study.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25551704","citation_count":17,"is_preprint":false},{"pmid":"35513854","id":"PMC_35513854","title":"Insulin-like growth factor 5 associates with human Aß plaques and promotes cognitive impairment.","date":"2022","source":"Acta neuropathologica communications","url":"https://pubmed.ncbi.nlm.nih.gov/35513854","citation_count":16,"is_preprint":false},{"pmid":"25410062","id":"PMC_25410062","title":"Neuroprotective effects of electro acupuncture on hypoxic-ischemic encephalopathy in newborn rats Ass.","date":"2014","source":"Pakistan journal of pharmaceutical sciences","url":"https://pubmed.ncbi.nlm.nih.gov/25410062","citation_count":15,"is_preprint":false},{"pmid":"21732718","id":"PMC_21732718","title":"Mitochondrial genome sequence of the Tibetan wild ass (Equus kiang).","date":"2011","source":"Mitochondrial DNA","url":"https://pubmed.ncbi.nlm.nih.gov/21732718","citation_count":15,"is_preprint":false},{"pmid":"26484162","id":"PMC_26484162","title":"Metagenomic sequence of saline desert microbiota from wild ass sanctuary, Little Rann of Kutch, Gujarat, India.","date":"2015","source":"Genomics data","url":"https://pubmed.ncbi.nlm.nih.gov/26484162","citation_count":15,"is_preprint":false},{"pmid":"35477090","id":"PMC_35477090","title":"FXR/ASS1 axis attenuates the TAA-induced liver injury through arginine metabolism.","date":"2022","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/35477090","citation_count":14,"is_preprint":false},{"pmid":"28422966","id":"PMC_28422966","title":"Taming the late Quaternary phylogeography of the Eurasiatic wild ass through ancient and modern DNA.","date":"2017","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/28422966","citation_count":14,"is_preprint":false},{"pmid":"33344455","id":"PMC_33344455","title":"Down Regulation of SIRT2 Reduced ASS Induced NSCLC Apoptosis Through the Release of Autophagy Components via Exosomes.","date":"2020","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/33344455","citation_count":14,"is_preprint":false},{"pmid":"12099862","id":"PMC_12099862","title":"Controlling Lewis basicity in polythioarsenate fluxes: stabilization of KSnAsS(5) and K(2)SnAs(2)S(6). Extended chains and slabs based on pyramidal beta-[AsS(4)](3-) and [AsS(3)](3-) units.","date":"2002","source":"Inorganic chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12099862","citation_count":14,"is_preprint":false},{"pmid":"36669126","id":"PMC_36669126","title":"BAP1 Loss Is Associated with Higher ASS1 Expression in Epithelioid Mesothelioma: Implications for Therapeutic Stratification.","date":"2023","source":"Molecular cancer research : MCR","url":"https://pubmed.ncbi.nlm.nih.gov/36669126","citation_count":13,"is_preprint":false},{"pmid":"35655095","id":"PMC_35655095","title":"Hepatocyte-derived MANF mitigates ethanol-induced liver steatosis in mice via enhancing ASS1 activity and activating AMPK pathway.","date":"2022","source":"Acta pharmacologica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/35655095","citation_count":13,"is_preprint":false},{"pmid":"25121552","id":"PMC_25121552","title":"Enalapril and ASS inhibit tumor growth in a transgenic mouse model of islet cell tumors.","date":"2014","source":"Endocrine-related cancer","url":"https://pubmed.ncbi.nlm.nih.gov/25121552","citation_count":13,"is_preprint":false},{"pmid":"29721066","id":"PMC_29721066","title":"Amino Acid Uptake Measured by [18F]AFETP Increases in Response to Arginine Starvation in ASS1-Deficient Sarcomas.","date":"2018","source":"Theranostics","url":"https://pubmed.ncbi.nlm.nih.gov/29721066","citation_count":12,"is_preprint":false},{"pmid":"21481813","id":"PMC_21481813","title":"Inhibition of LPS toxicity by hepatic argininosuccinate synthase (ASS): novel roles for ASS in innate immune responses to bacterial infection.","date":"2011","source":"International immunopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/21481813","citation_count":12,"is_preprint":false},{"pmid":"28587924","id":"PMC_28587924","title":"PRMT7 Interacts with ASS1 and Citrullinemia Mutations Disrupt the Interaction.","date":"2017","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/28587924","citation_count":11,"is_preprint":false},{"pmid":"25179242","id":"PMC_25179242","title":"Functional analysis of novel splicing and missense mutations identified in the ASS1 gene in classical citrullinemia patients.","date":"2014","source":"Clinica chimica acta; international journal of clinical chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/25179242","citation_count":11,"is_preprint":false},{"pmid":"26895070","id":"PMC_26895070","title":"Genomic variants in the ASS1 gene, involved in the nitric oxide biosynthesis and signaling pathway, predict hydroxyurea treatment efficacy in compound sickle cell disease/β-thalassemia patients.","date":"2016","source":"Pharmacogenomics","url":"https://pubmed.ncbi.nlm.nih.gov/26895070","citation_count":11,"is_preprint":false},{"pmid":"31094885","id":"PMC_31094885","title":"Use of Immunohistochemical Markers (HNF-1β, Napsin A, ER, CTH, and ASS1) to Distinguish Endometrial Clear Cell Carcinoma From Its Morphologic Mimics Including Arias-Stella Reaction.","date":"2020","source":"International journal of gynecological pathology : official journal of the International Society of Gynecological Pathologists","url":"https://pubmed.ncbi.nlm.nih.gov/31094885","citation_count":11,"is_preprint":false},{"pmid":"9678344","id":"PMC_9678344","title":"Chromosomal rearrangements in a Somali wild ass pedigree, Equus africanus somaliensis (Perissodactyla, Equidae).","date":"1998","source":"Cytogenetics and cell genetics","url":"https://pubmed.ncbi.nlm.nih.gov/9678344","citation_count":11,"is_preprint":false},{"pmid":"35726796","id":"PMC_35726796","title":"Asymptomatic ASS1 carriers with high blood citrulline levels.","date":"2022","source":"Molecular genetics & genomic medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35726796","citation_count":10,"is_preprint":false},{"pmid":"31208364","id":"PMC_31208364","title":"Citrullinemia type I is associated with a novel splicing variant, c.773 + 4A > C, in ASS1: a case report and literature review.","date":"2019","source":"BMC medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/31208364","citation_count":10,"is_preprint":false},{"pmid":"23611581","id":"PMC_23611581","title":"Prenatal diagnosis of citrullinemia type 1: a Chinese family with a novel mutation of the ASS1 gene.","date":"2013","source":"Brain & development","url":"https://pubmed.ncbi.nlm.nih.gov/23611581","citation_count":10,"is_preprint":false},{"pmid":"33478587","id":"PMC_33478587","title":"Intracellular arginine-dependent translation sensor reveals the dynamics of arginine starvation response and resistance in ASS1-negative cells.","date":"2021","source":"Cancer & metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/33478587","citation_count":10,"is_preprint":false},{"pmid":"25548129","id":"PMC_25548129","title":"Argininosuccinate synthetase (ASS) deficiency in high-grade pulmonary neuroendocrine carcinoma: an opportunity for personalized targeted therapy.","date":"2014","source":"Journal of cancer research and clinical oncology","url":"https://pubmed.ncbi.nlm.nih.gov/25548129","citation_count":10,"is_preprint":false},{"pmid":"29453600","id":"PMC_29453600","title":"Argininosuccinate Synthetase-1 (ASS1) Loss in High-Grade Neuroendocrine Carcinomas of the Urinary Bladder: Implications for Targeted Therapy with ADI-PEG 20.","date":"2018","source":"Endocrine pathology","url":"https://pubmed.ncbi.nlm.nih.gov/29453600","citation_count":10,"is_preprint":false},{"pmid":"15334737","id":"PMC_15334737","title":"Early cirrhosis in a patient with type I citrullinaemia (CTLN1).","date":"2004","source":"Journal of inherited metabolic disease","url":"https://pubmed.ncbi.nlm.nih.gov/15334737","citation_count":10,"is_preprint":false},{"pmid":"19358837","id":"PMC_19358837","title":"Citrullinemia type I, classical variant. Identification of ASS-p~G390R (c.1168G>A) mutation in families of a limited geographic area of Argentina: a possible population cluster.","date":"2009","source":"Clinical biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/19358837","citation_count":10,"is_preprint":false},{"pmid":"29256852","id":"PMC_29256852","title":"Chryseobacterium salipaludis sp. nov., isolated at a wild ass sanctuary.","date":"2017","source":"International journal of systematic and evolutionary microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/29256852","citation_count":10,"is_preprint":false},{"pmid":"31474823","id":"PMC_31474823","title":"Pre-plaque Aß-Mediated Impairment of Synaptic Depotentiation in a Transgenic Rat Model of Alzheimer's Disease Amyloidosis.","date":"2019","source":"Frontiers in neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/31474823","citation_count":10,"is_preprint":false},{"pmid":"19833084","id":"PMC_19833084","title":"Gut immune balance is as easy as S-F-B.","date":"2009","source":"Immunity","url":"https://pubmed.ncbi.nlm.nih.gov/19833084","citation_count":10,"is_preprint":false},{"pmid":"37254538","id":"PMC_37254538","title":"Polymorphic Variants of ASS1 Gene Related to Arginine Metabolism and the Risk of HCC.","date":"2023","source":"Protein and peptide letters","url":"https://pubmed.ncbi.nlm.nih.gov/37254538","citation_count":9,"is_preprint":false},{"pmid":"36182868","id":"PMC_36182868","title":"ASS1 regulates immune microenvironment via CXCL8 signaling in ovarian cancer.","date":"2022","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/36182868","citation_count":9,"is_preprint":false},{"pmid":"22966251","id":"PMC_22966251","title":"Reduced expression of ASS is closely related to clinicopathological features and post-resectional survival of hepatocellular carcinoma.","date":"2010","source":"Oncology letters","url":"https://pubmed.ncbi.nlm.nih.gov/22966251","citation_count":9,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":49695,"output_tokens":6473,"usd":0.12309,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":15591,"output_tokens":6866,"usd":0.124802,"stage2_stop_reason":"end_turn"},"total_usd":0.247892,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2015,\n      \"finding\": \"ASS1 deficiency in cancer increases cytosolic aspartate levels, which activates the CAD complex (carbamoyl-phosphate synthase 2, aspartate transcarbamylase, and dihydroorotase) by upregulating substrate availability and increasing CAD phosphorylation by S6K1 through the mTOR pathway, thereby facilitating de novo pyrimidine synthesis and supporting proliferation.\",\n      \"method\": \"Metabolic flux analysis, citrullinemia patient studies, mTOR/S6K1 pathway inhibition experiments, CAD activity assays in ASS1-deficient cancer cells\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (metabolomics, patient data, pathway inhibition, enzymatic assays) across cancer cells and human disease contexts, replicated across multiple cancer types\",\n      \"pmids\": [\"26560030\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"CLOCK directly acetylates ASS1 at lysine residues K165 and K176 (facilitated by BMAL1) to inactivate ASS1, and this acetylation exhibits circadian oscillation in human cells and mouse liver, driven by rhythmic CLOCK–ASS1 interaction, thereby imposing circadian regulation on arginine biosynthesis and ureagenesis.\",\n      \"method\": \"In vitro acetylation assay, mass spectrometry identification of acetylation sites, site-directed mutagenesis of K165 and K176, co-immunoprecipitation of CLOCK–ASS1 complex, circadian oscillation profiling in cells and mouse liver\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro enzymatic assay with mutagenesis validation, reciprocal Co-IP, and oscillation profiling in two biological systems (human cells and mouse liver) in a single study\",\n      \"pmids\": [\"28985504\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"HIF-1α and c-MYC act as reciprocal negative and positive transcriptional regulators of ASS1 expression by binding to the ASS1 promoter; DEC1 functions as the master regulator controlling both HIF-1α and c-MYC levels to regulate ASS1 transcription independently of ASS1 promoter DNA methylation.\",\n      \"method\": \"Promoter binding assays (ChIP), overexpression and knockdown of HIF-1α, c-MYC, and DEC1, use of proteasomal inhibitors (bortezomib, carfilzomib) to modulate HIF-1α, cisplatin and 5-aza-dC treatment to alter ASS1 expression\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP and genetic manipulation in single lab with multiple orthogonal approaches but no structural validation\",\n      \"pmids\": [\"27765932\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"At the ASS1 promoter, the histone acetyltransferase p300 maintains H3K14ac and H3K27ac marks that support HIF-1α-mediated ASS1 silencing; arginine starvation induces p300 dissociation, allowing HDAC2 and Sin3A to deacetylate these histone marks, which facilitates PHD2-driven proteasomal degradation of HIF-1α in situ, leading to ASS1 de-repression.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP) for histone marks and transcription factor binding, knockdown/overexpression of p300, HDAC2, Sin3A, PHD2, antioxidant sensitivity assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP with multiple histone marks and factor knockdowns, single lab, orthogonal methods\",\n      \"pmids\": [\"28883660\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Prolonged arginine starvation (via ADI-PEG20) in ASS1-deficient breast cancer cells induces mitochondrial oxidative stress, impairs mitochondrial bioenergetics and integrity, and triggers cytotoxic autophagy; cell death requires autophagy competence, placing mitochondrial damage upstream of autophagic cell death in the arginine starvation pathway.\",\n      \"method\": \"ADI-PEG20 treatment of ASS1-deficient breast cancer cells in vitro and in vivo, mitochondrial ROS/bioenergetics assays, autophagy-deficient cell lines, genetic suppression of autophagy\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis (autophagy-deficient cells) plus mitochondrial functional assays and in vivo validation, single lab\",\n      \"pmids\": [\"24692592\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"PRMT7 directly interacts with ASS1 (confirmed by yeast two-hybrid and pull-down assays), and ASS1 mutations associated with citrullinemia type I disrupt the PRMT7–ASS1 interaction, implicating loss of this interaction in the molecular pathogenesis of the disease.\",\n      \"method\": \"Yeast two-hybrid screening, pull-down assay, site-directed mutagenesis of ASS1 citrullinemia-associated residues, computational interface mapping\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal interaction confirmed by two independent binding assays with mutagenesis, single lab\",\n      \"pmids\": [\"28587924\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Snail prevents LOC113230-mediated ubiquitination and degradation of ASS1: LOC113230 acts as a scaffold to recruit LRPPRC and the TRAF2 E3 ubiquitin ligase to ASS1, resulting in ASS1 ubiquitination and degradation; Snail represses LOC113230 transcription (via E-box binding) in response to TGF-β, thereby stabilizing ASS1 and promoting arginine synthesis for colorectal cancer migration.\",\n      \"method\": \"Co-immunoprecipitation identifying LRPPRC/TRAF2/ASS1 complex, ubiquitination assays, LOC113230 overexpression/knockdown, Snail ChIP at E-boxes in LOC113230 promoter, xenograft metastasis experiments\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP identifying complex components, ubiquitination assay, ChIP, and in vivo validation, single lab\",\n      \"pmids\": [\"34184805\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ASS1 directly binds to PHGDH and promotes its ubiquitination-mediated proteasomal degradation, thereby inhibiting de novo serine synthesis; the tumor-suppressive effect of ASS1 in triple-negative breast cancer is strongly dependent on this mechanism, as PHGDH knockout abrogates ASS1's anti-proliferative activity.\",\n      \"method\": \"Co-immunoprecipitation identifying ASS1–PHGDH interaction, ubiquitination assays, PHGDH knockout epistasis experiments, serine/glycine rescue experiments, in vitro and in vivo tumor models\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding (Co-IP), ubiquitination assay, and genetic epistasis (PHGDH KO rescue), single lab with multiple orthogonal methods\",\n      \"pmids\": [\"38710705\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Following DNA damage, ASS1 expression is elevated in both cytosol and nucleus (partly p53-dependent); in the nucleus, ASS1 and ASL generate fumarate that succينates SMARCC1, destabilizing the SMARCC1–SNF5 chromatin-remodeling complex and decreasing transcription of a subset of p53-regulated cell cycle genes; in the cytosol, ASS1 restrains nucleotide synthesis to pause cell cycle progression.\",\n      \"method\": \"Subcellular fractionation, metabolomics with isotope tracing, succination assays, SMARCC1–SNF5 complex disruption analysis, doxorubicin-induced DNA damage in colon cancer cells and citrullinemia fibroblasts\",\n      \"journal\": \"Nature metabolism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal methods (fractionation, metabolomics, protein complex disruption, genetic models including disease fibroblasts) establishing distinct nuclear and cytosolic mechanisms, in a single rigorous study\",\n      \"pmids\": [\"38858597\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ASS1 promotes reductive carboxylation of cytosolic glutamine, reducing mitochondrial-derived lipid ROS; additionally, ASS1 activates the mTORC1–SREBP1–SCD5 axis to promote de novo monounsaturated fatty acid synthesis using acetyl-CoA derived from the glutamine reductive pathway, conferring resistance to ferroptosis in non-small cell lung cancer cells.\",\n      \"method\": \"Stable isotope-labeled glutamine metabolomics, ASS1 loss-of-function (knockdown/knockout), transcriptome sequencing, erastin-induced ferroptosis assays in vitro and in vivo xenograft models\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — isotope tracing metabolomics plus transcriptomics and in vivo validation, single lab\",\n      \"pmids\": [\"36892426\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Under glucose deprivation, ASS1 expression is induced by c-MYC, and ASS1 increases nitric oxide synthesis and activates gluconeogenic enzymes pyruvate carboxylase and phosphoenolpyruvate carboxykinase via S-nitrosylation, enhancing flux through gluconeogenesis to support serine, glycine, and subsequent purine synthesis.\",\n      \"method\": \"ASS1 overexpression/knockdown under glucose deprivation, c-MYC ChIP and expression manipulation, S-nitrosylation assays of gluconeogenic enzymes, metabolic flux analysis\",\n      \"journal\": \"Nature cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP, S-nitrosylation biochemistry, and metabolic flux analysis in single lab with multiple orthogonal methods\",\n      \"pmids\": [\"35121952\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"In hypoxia, ASS1 expression is further downregulated via HIF-1α-mediated induction of miR-224-5p; ASS1-depleted cancer cells maintain higher intracellular pH, depend less on extracellular glutamine, and display higher glutathione levels, indicating that ASS1 regulation under acidic/hypoxic conditions provides a redox and pH advantage to cancer cells.\",\n      \"method\": \"miR-224-5p gain/loss-of-function, intracellular pH measurements, glutamine dependence assays, glutathione quantification, ASS1 knockdown/overexpression under hypoxic and acidic conditions\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — miRNA functional manipulation, pH measurements, and metabolite quantification, single lab with multiple endpoints\",\n      \"pmids\": [\"30573518\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Arginine deprivation in ASS1-deficient cancer cells inhibits the Warburg effect by reducing aerobic glycolysis with decreased PKM2 expression and phosphorylation, while increasing serine biosynthesis (via PHGDH upregulation), glutamine anaplerosis, and oxidative phosphorylation; concurrent arginine deprivation and glutaminase inhibition is synthetic lethal across ASS1-deficient tumor lines.\",\n      \"method\": \"Metabolite profiling, Western blotting for PKM2/PHGDH, arginine starvation (ADI-PEG20), glutaminase inhibitor combination studies in vitro and in vivo xenograft models\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — metabolomics plus genetic/pharmacologic manipulation with in vivo validation, single lab\",\n      \"pmids\": [\"28122247\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Recombinant ASS1 physically binds to bacterial lipopolysaccharide (LPS) as shown by gel-shift assay and suppresses E. coli growth in culture; endogenous hepatic ASS1 is released into circulation within 1 hour of LPS challenge, acting as a component of the innate immune response to reduce LPS cytotoxicity, suppress TNF-α production, and increase survival in rodent endotoxemia models.\",\n      \"method\": \"Gel-shift assay for LPS binding, bacterial growth inhibition assay, mouse macrophage cytotoxicity assays, in vivo LPS endotoxemia model with recombinant ASS injection\",\n      \"journal\": \"International immunopharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding assay plus in vitro and in vivo functional experiments, single lab\",\n      \"pmids\": [\"21481813\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"MANF (mesencephalic astrocyte-derived neurotrophic factor) resides in the same immunoprecipitated complex as ASS1; MANF knockout decreases ASS1 activity while MANF overexpression enhances ASS1 activity; ASS1 activates AMPK by generating an intracellular pool of AMP from the urea cycle, and this MANF–ASS1–AMPK axis regulates hepatic lipid homeostasis.\",\n      \"method\": \"Immunoprecipitation-coupled mass spectrometry proteomics, hepatocyte-specific MANF knockout and overexpression, ASS1 enzymatic activity assays, urea cycle metabolite profiling, AMPK phosphorylation assays\",\n      \"journal\": \"Acta pharmacologica Sinica\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP/MS identifying complex, enzymatic activity measurement in KO and OE models, metabolite profiling, single lab\",\n      \"pmids\": [\"35655095\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ASS1 overexpression activates AMPK and its downstream effector CPT1A by disrupting the AMP/ATP balance, enhancing fatty acid oxidation (FAO) and ATP generation in ovarian cancer cells; CPT1A inhibition reverses ASS1-induced FAO and disrupts AMPK activation, placing CPT1A downstream of the ASS1/AMPK axis in anoikis resistance.\",\n      \"method\": \"ASS1 overexpression/knockdown, CPT1A inhibition, AMP/ATP ratio measurements, FAO assays, AMPK phosphorylation analysis, anoikis resistance assays\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — enzymatic pathway epistasis with rescue experiments and metabolic measurements, single lab\",\n      \"pmids\": [\"38914306\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Re-expression of both ASS1 and ASL in ccRCC cell lines suppresses tumor growth in 2D, 3D, and in vivo xenograft models in an enzymatic-activity-dependent manner; the growth suppression involves conservation of cellular aspartate (diverting it away from pyrimidine synthesis), regulation of nitric oxide synthesis, and altered pyrimidine production.\",\n      \"method\": \"Genetic re-expression of ASS1 and ASL in ccRCC cell lines, catalytically inactive mutant controls, 2D/3D growth assays, xenograft models, metabolomics\",\n      \"journal\": \"Cancer & metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — enzymatic activity-dependent rescue with in vivo validation and metabolomics, single lab\",\n      \"pmids\": [\"34861885\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PGAM1 negatively regulates ASS1 expression through the cAMP/AMPK/CEBPB transcriptional axis; PGAM1 knockdown markedly upregulates ASS1 expression, and ASS1 upregulation is required for the anti-proliferative effect of PGAM1 depletion in breast cancer cells.\",\n      \"method\": \"RNA sequencing after PGAM1 knockdown, CEBPB transcription factor pathway analysis, ASS1 knockdown epistasis experiments, in vivo tumor growth assays\",\n      \"journal\": \"Molecular oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RNA-seq plus genetic epistasis (double knockdown) and in vivo validation, single lab\",\n      \"pmids\": [\"35674458\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Androgen receptor (AR) decreases ASS1 protein expression to promote renal cell carcinoma proliferation via the pseudogene ASS1P3: AR binds ASS1P3, which acts as a competing endogenous RNA (ceRNA) decoy for miR-34a-5p; miR-34a-5p binds the 3'UTR of ASS1 to suppress ASS1 protein expression, and AR-driven ASS1P3 upregulation sequesters miR-34a-5p to reduce ASS1.\",\n      \"method\": \"RIP assay demonstrating AR binding to ASS1P3, AGO2 assay, luciferase reporter for miR-34a-5p targeting ASS1 3'UTR, AR/ASS1P3/miR-34a-5p knockdown/overexpression, in vivo xenograft experiments\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — RIP and AGO2 assays with 3'UTR reporter and genetic epistasis, single lab\",\n      \"pmids\": [\"31000693\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"FXR (Farnesoid X receptor) directly promotes ASS1 transcription; FXR agonist obeticholic acid (OCA) upregulates ASS1 expression and enhances arginine synthesis, reducing hepatocyte apoptosis (decreased Cyt C, PARP, and Caspase 3 levels) in TAA-induced acute liver injury.\",\n      \"method\": \"FXR agonist/antagonist treatment, ASS1 transcriptional reporter assays, single-cell RNA-seq data analysis, apoptosis marker measurement, in vivo TAA liver injury model\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — transcriptional regulation and apoptosis assays but abstract does not clearly describe direct FXR–ASS1 promoter binding experiment\",\n      \"pmids\": [\"35477090\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Arginine starvation with ADI-PEG20 combined with docetaxel stabilizes c-MYC and causes its nuclear translocation in ASS1-negative tumor cells, which increases hENT1 cell-surface expression and renders cells susceptible to gemcitabine; c-MYC inhibition blocks hENT1 upregulation, placing c-MYC as a required mediator between arginine starvation and gemcitabine sensitization.\",\n      \"method\": \"Protein expression analysis (Western blot), c-MYC activity assays, live-cell immunofluorescence for hENT1 surface localization, FITC-cytosine uptake assay, c-MYC inhibitor rescue experiments, in vivo tumor growth studies\",\n      \"journal\": \"Clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (immunofluorescence, uptake assay, genetic rescue) in single lab with in vivo validation\",\n      \"pmids\": [\"31113844\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"ASS1 was chromosomally localized to the distal long arm of chromosome 9, region 9q34–9qter, by somatic cell hybrid mapping using human cells carrying balanced reciprocal translocations involving chromosome 9.\",\n      \"method\": \"Somatic cell hybrid mapping with balanced reciprocal translocations, subchromosomal assignment\",\n      \"journal\": \"Cytogenetics and cell genetics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — chromosomal mapping is a direct experiment replicated across multiple hybrid panels, but provides genomic localization only, not molecular mechanism\",\n      \"pmids\": [\"219990\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ASS1 loss in fibroblastic foci of IPF-patient lung fibroblasts promotes fibroblast proliferation, migration, and invasion; mechanistically, ASS1 knockdown activates the hepatocyte growth factor receptor Met and its downstream Src–STAT3 signaling axis.\",\n      \"method\": \"ASS1 knockdown/overexpression, proliferation/migration/invasion assays, Western blot for Met, Src, STAT3 activation, bleomycin mouse model\",\n      \"journal\": \"Molecular therapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic manipulation with defined downstream pathway (Met/Src/STAT3) and in vivo model, single lab\",\n      \"pmids\": [\"33508432\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"β-sitosterol selectively targets ASS1 (identified by network pharmacology and validated in vitro); inhibition of ASS1 by β-sitosterol enhances the interaction between Nrf2 and Keap1, promoting ubiquitin-dependent degradation of Nrf2, which decreases transcription of antioxidant genes HO-1 and NQO1, causing ROS accumulation that upregulates PTEN and suppresses AKT phosphorylation in ovarian cancer cells.\",\n      \"method\": \"Network pharmacology target prediction, ASS1 overexpression/knockdown, Nrf2–Keap1 co-immunoprecipitation, ubiquitination assays, ROS measurement, PTEN/AKT pathway analysis, in vitro and in vivo tumor models\",\n      \"journal\": \"Free radical biology & medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP for Nrf2–Keap1 interaction change, ubiquitination assay, ROS and pathway measurements, single lab with multiple methods\",\n      \"pmids\": [\"38364944\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ASS1 is a cytosolic urea cycle enzyme (catalyzing the rate-limiting condensation of citrulline and aspartate to argininosuccinate) that controls aspartate availability for pyrimidine synthesis and ferroptosis resistance, is subject to circadian acetylation by CLOCK at K165/K176 to inactivate it, undergoes p53-dependent nuclear translocation after DNA damage where it and ASL generate fumarate to succinate SMARCC1 and remodel chromatin, is regulated transcriptionally by HIF-1α (repressor) and c-MYC (activator) via a DEC1-controlled chromatin remodeling mechanism, interacts with PRMT7 and PHGDH (promoting PHGDH ubiquitination), and through its enzymatic production of AMP activates AMPK to regulate fatty acid oxidation and lipid homeostasis.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ASS1 is a cytosolic urea-cycle enzyme whose control over aspartate and arginine flux makes it a metabolic checkpoint with broad effects on proliferation, redox balance, and cell death [#0, #16]. Loss of ASS1 raises cytosolic aspartate, which activates the CAD complex through mTOR/S6K1-driven CAD phosphorylation to fuel de novo pyrimidine synthesis and tumor proliferation, and re-expression of ASS1 with ASL suppresses tumor growth in an enzymatic-activity-dependent manner by diverting aspartate away from nucleotide synthesis [#0, #16]. Beyond canonical catalysis, ASS1 acts as a tumor suppressor by directly binding PHGDH and driving its ubiquitination-mediated degradation to restrain serine synthesis [#7]. ASS1 activity is gated post-translationally: CLOCK acetylates ASS1 at K165/K176 to inactivate it, imposing a circadian rhythm on arginine biosynthesis and ureagenesis [#1]. Following DNA damage, ASS1 accumulates in both compartments — in the nucleus it cooperates with ASL to generate fumarate that succinates SMARCC1 and destabilizes the SMARCC1–SNF5 chromatin-remodeling complex, repressing p53-regulated cell-cycle genes, while in the cytosol it restrains nucleotide synthesis to pause the cell cycle [#8]. ASS1 transcription is governed by opposing regulators, with HIF-1α repressing and c-MYC activating expression under control of DEC1 and p300/HDAC2-dependent histone acetylation at the promoter [#2, #3]. Through its enzymatic generation of AMP, ASS1 activates AMPK to drive fatty acid oxidation and govern hepatic and tumor lipid homeostasis [#14, #15]. ASS1 mutations associated with citrullinemia type I disrupt its interaction with PRMT7, linking the enzyme to the molecular pathogenesis of that disease [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2009,\n      \"claim\": \"Before molecular characterization, the genomic position of ASS1 was unknown; mapping it provided the physical anchor for later genetic and disease studies.\",\n      \"evidence\": \"Somatic cell hybrid mapping using balanced reciprocal translocations of chromosome 9\",\n      \"pmids\": [\"219990\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Provides genomic localization only, no molecular mechanism\", \"Does not address enzymatic or regulatory function\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"It was unclear how arginine starvation kills ASS1-deficient cancers; this work established mitochondrial damage as the upstream trigger of autophagic cell death.\",\n      \"evidence\": \"ADI-PEG20 treatment of ASS1-deficient breast cancer cells with mitochondrial assays and autophagy-deficient lines, in vitro and in vivo\",\n      \"pmids\": [\"24692592\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular link between mitochondrial ROS and autophagy initiation not defined\", \"Single tumor type\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"The metabolic consequence of ASS1 loss in cancer was unresolved; this study showed aspartate accumulation activates CAD via mTOR/S6K1 to drive pyrimidine synthesis and proliferation.\",\n      \"evidence\": \"Metabolic flux analysis, citrullinemia patient studies, mTOR/S6K1 inhibition, and CAD assays in ASS1-deficient cancer cells\",\n      \"pmids\": [\"26560030\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not address non-metabolic ASS1 functions\", \"Mechanism of aspartate-driven CAD phosphorylation not structurally resolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"How ASS1 activity is tuned over time was unknown; CLOCK-mediated acetylation at K165/K176 was shown to inactivate ASS1 and impose circadian control on ureagenesis.\",\n      \"evidence\": \"In vitro acetylation assay, MS site mapping, K165/K176 mutagenesis, Co-IP, and oscillation profiling in human cells and mouse liver\",\n      \"pmids\": [\"28985504\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Deacetylase that reverses the modification not identified\", \"Whether acetylation alters localization is unaddressed\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"The transcriptional logic of ASS1 silencing in cancer was unclear; DEC1 was identified as a master regulator coordinating HIF-1α repression and c-MYC activation at the ASS1 promoter.\",\n      \"evidence\": \"ChIP, knockdown/overexpression of HIF-1α/c-MYC/DEC1, proteasome inhibitors, and demethylation treatment\",\n      \"pmids\": [\"27765932\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"DNA-methylation-independent mechanism not fully resolved\", \"No structural validation of promoter complexes\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"The chromatin basis of HIF-1α-mediated ASS1 silencing was undefined; p300/HDAC2/Sin3A control of H3K14ac/H3K27ac was shown to gate in situ HIF-1α degradation and ASS1 de-repression upon arginine starvation.\",\n      \"evidence\": \"ChIP for histone marks and factors, knockdown/overexpression of p300/HDAC2/Sin3A/PHD2, antioxidant assays\",\n      \"pmids\": [\"28883660\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Generality across tumor types unknown\", \"Connection to DEC1 axis not integrated\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Whether ASS1 has protein partners relevant to disease was unknown; PRMT7 was identified as a direct interactor disrupted by citrullinemia mutations.\",\n      \"evidence\": \"Yeast two-hybrid, pull-down assays, and mutagenesis of citrullinemia-associated residues\",\n      \"pmids\": [\"28587924\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of PRMT7 binding on ASS1 activity not defined\", \"No methylation of ASS1 demonstrated\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"The metabolic rewiring underlying arginine-deprivation therapy was unclear; arginine deprivation was shown to suppress the Warburg effect and create synthetic lethality with glutaminase inhibition in ASS1-deficient tumors.\",\n      \"evidence\": \"Metabolite profiling, PKM2/PHGDH Westerns, ADI-PEG20 plus glutaminase inhibitor combinations in vitro and in vivo\",\n      \"pmids\": [\"28122247\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Durability of synthetic lethality not assessed\", \"Single therapeutic combination\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"How hypoxia further suppresses ASS1 and benefits cancer cells was unknown; HIF-1α-induced miR-224-5p was shown to downregulate ASS1, conferring pH and redox advantages.\",\n      \"evidence\": \"miR-224-5p gain/loss-of-function, intracellular pH, glutamine-dependence, and glutathione assays under hypoxia/acidosis\",\n      \"pmids\": [\"30573518\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct miR-224-5p:ASS1 target site not validated in this entry\", \"Causal link between pH and growth not isolated\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Mechanisms of ASS1 repression beyond transcription factors were unclear; AR was shown to drive the ASS1P3 pseudogene as a ceRNA decoy sequestering miR-34a-5p to suppress ASS1 in renal carcinoma.\",\n      \"evidence\": \"RIP, AGO2 assay, miR-34a-5p 3'UTR luciferase reporter, and genetic manipulation with xenografts\",\n      \"pmids\": [\"31000693\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specificity of ASS1P3 ceRNA activity in other tissues unknown\", \"Quantitative contribution versus other regulators not defined\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"How arginine starvation sensitizes tumors to chemotherapy was unclear; c-MYC nuclear translocation was shown to upregulate hENT1 and confer gemcitabine susceptibility.\",\n      \"evidence\": \"Western blot, c-MYC assays, hENT1 surface immunofluorescence, FITC-cytosine uptake, and c-MYC inhibitor rescue in vivo\",\n      \"pmids\": [\"31113844\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct transcriptional control of hENT1 by c-MYC not shown here\", \"Restricted to ASS1-negative context\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"ASS1's role under nutrient stress was unknown; c-MYC-induced ASS1 was shown to drive nitric-oxide-dependent S-nitrosylation of gluconeogenic enzymes to support purine synthesis during glucose deprivation.\",\n      \"evidence\": \"ASS1 manipulation under glucose deprivation, c-MYC ChIP, S-nitrosylation assays, and metabolic flux analysis\",\n      \"pmids\": [\"35121952\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Source/regulation of NO production by ASS1 not detailed\", \"Generality beyond glucose-deprived state unknown\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Whether ASS1 is degradation-controlled in cancer was unknown; a LOC113230 scaffold recruiting LRPPRC/TRAF2 was shown to ubiquitinate ASS1, an axis Snail represses via TGF-β to stabilize ASS1 and promote metastasis.\",\n      \"evidence\": \"Co-IP of LRPPRC/TRAF2/ASS1, ubiquitination assays, Snail ChIP at LOC113230 E-boxes, and xenograft metastasis models\",\n      \"pmids\": [\"34184805\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct E3 ubiquitin transfer by TRAF2 to ASS1 not structurally shown\", \"Single cancer type\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"The therapeutic value of restoring urea-cycle enzymes in renal cancer was untested; ASS1/ASL re-expression was shown to suppress tumor growth dependent on enzymatic activity.\",\n      \"evidence\": \"Genetic re-expression with catalytically inactive controls, 2D/3D and xenograft growth assays, and metabolomics in ccRCC\",\n      \"pmids\": [\"34861885\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relative contributions of aspartate conservation versus NO regulation not separated\", \"Limited to ccRCC lines\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"An extra-metabolic role for ASS1 in fibrosis was unknown; ASS1 loss in IPF fibroblasts was shown to activate Met–Src–STAT3 signaling driving fibroblast proliferation and invasion.\",\n      \"evidence\": \"ASS1 knockdown/overexpression, proliferation/migration/invasion assays, Met/Src/STAT3 Westerns, and bleomycin mouse model\",\n      \"pmids\": [\"33508432\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking ASS1 metabolism to Met activation undefined\", \"Whether enzymatic activity is required not tested\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"A non-metabolic immune function was unsuspected; secreted ASS1 was shown to bind LPS, inhibit bacterial growth, and protect against endotoxemia.\",\n      \"evidence\": \"Gel-shift LPS binding, bacterial growth inhibition, macrophage cytotoxicity, and rodent endotoxemia models with recombinant ASS\",\n      \"pmids\": [\"21481813\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis of LPS binding unknown\", \"Mechanism of hepatic ASS1 release into circulation undefined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"How ASS1 connects to lipid metabolism was unclear; the MANF–ASS1–AMPK axis was shown to operate through ASS1-derived AMP generation regulating hepatic lipid homeostasis.\",\n      \"evidence\": \"Co-IP/MS, hepatocyte MANF knockout/overexpression, ASS1 activity assays, urea-cycle metabolite profiling, and AMPK phosphorylation\",\n      \"pmids\": [\"35655095\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether MANF directly binds ASS1 not resolved\", \"Mechanism by which MANF modulates ASS1 activity unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Additional upstream repressors of ASS1 were sought; PGAM1 was shown to suppress ASS1 via a cAMP/AMPK/CEBPB axis, with ASS1 induction required for the anti-proliferative effect of PGAM1 loss.\",\n      \"evidence\": \"RNA-seq after PGAM1 knockdown, CEBPB pathway analysis, double-knockdown epistasis, and in vivo tumor assays\",\n      \"pmids\": [\"35674458\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct CEBPB binding to ASS1 promoter not shown\", \"Single tumor type\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Whether ASS1 protects hepatocytes was unclear; FXR was shown to promote ASS1 transcription, enhancing arginine synthesis and reducing apoptosis in acute liver injury.\",\n      \"evidence\": \"FXR agonist/antagonist, ASS1 reporter assays, scRNA-seq, apoptosis markers, and TAA liver-injury model\",\n      \"pmids\": [\"35477090\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Direct FXR–ASS1 promoter binding not clearly demonstrated\", \"Causal role of ASS1 in apoptosis reduction not isolated\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"How ASS1 affects ferroptosis was unknown; ASS1 was shown to drive glutamine reductive carboxylation and an mTORC1–SREBP1–SCD5 axis producing monounsaturated fatty acids to resist ferroptosis.\",\n      \"evidence\": \"Glutamine isotope metabolomics, ASS1 loss-of-function, transcriptomics, and erastin ferroptosis assays in NSCLC, in vivo\",\n      \"pmids\": [\"36892426\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct effect of ASS1 enzymatic products on SREBP1 not defined\", \"Context-dependence versus tumor-suppressive role unresolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"A direct tumor-suppressive partner of ASS1 was unknown; ASS1 was shown to bind PHGDH and promote its ubiquitination, restraining serine synthesis as the basis of its anti-proliferative activity in TNBC.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, PHGDH knockout epistasis, serine/glycine rescue, and in vitro/in vivo tumor models\",\n      \"pmids\": [\"38710705\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"E3 ligase mediating PHGDH ubiquitination not identified\", \"Whether ASS1 catalytic activity is required not defined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"A moonlighting nuclear function in the DNA-damage response was unknown; ASS1 with ASL was shown to generate fumarate that succinates SMARCC1, remodeling chromatin and pausing the cell cycle alongside cytosolic nucleotide restraint.\",\n      \"evidence\": \"Subcellular fractionation, isotope-tracing metabolomics, succination assays, SMARCC1–SNF5 disruption analysis in colon cancer cells and citrullinemia fibroblasts\",\n      \"pmids\": [\"38858597\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of ASS1 nuclear import not defined\", \"Selectivity of SMARCC1 succination over other targets unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"How ASS1 supports tumor survival under detachment was unclear; ASS1 was shown to activate AMPK/CPT1A to enhance fatty acid oxidation and anoikis resistance in ovarian cancer.\",\n      \"evidence\": \"ASS1 overexpression/knockdown, CPT1A inhibition, AMP/ATP ratio and FAO assays, AMPK phosphorylation, and anoikis assays\",\n      \"pmids\": [\"38914306\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Reconciliation with tumor-suppressive ASS1 roles not addressed\", \"Direct AMP supply mechanism not quantified\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how ASS1's opposing context-dependent roles — tumor suppressor via PHGDH degradation and aspartate conservation versus tumor promoter via AMPK/FAO and ferroptosis resistance — are determined within a given cell.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying model reconciling pro- and anti-tumor functions\", \"Determinants of nuclear versus cytosolic ASS1 partitioning unknown\", \"How post-translational acetylation integrates with degradation control undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016874\", \"supporting_discovery_ids\": [0, 16]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [13]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0, 8]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [8]},\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [13]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 16]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [8]},\n      {\"term_id\": \"R-HSA-9909396\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [8]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"ASL\", \"PHGDH\", \"PRMT7\", \"CLOCK\", \"MANF\", \"SMARCC1\", \"LRPPRC\", \"TRAF2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":8,"faith_total":8,"faith_pct":100.0}}