{"gene":"CERS2","run_date":"2026-04-28T17:28:52","timeline":{"discoveries":[{"year":2009,"finding":"CERS2 (CerS2/LASS2) is the predominant ceramide synthase in oligodendrocytes and Schwann cells, with substrate specificity for very long-chain fatty acid residues (C22–C24). Knockout mice lacking CERS2 show strongly reduced C24:1 ceramide synthase activity in brain and liver, ~50% loss of compacted myelin, 80% loss of myelin basic protein, cerebellar degeneration, and hepatocarcinoma development, establishing CERS2 as required for myelin maintenance and hepatic tumor suppression.","method":"Gene-trap knockout mice (loss-of-function), biochemical ceramide synthase activity assays, lipid profiling, histology, lacZ reporter","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — clean KO with multiple defined cellular and biochemical phenotypes, replicated across tissues","pmids":["19801672"],"is_preprint":false},{"year":2007,"finding":"CerS2 expression in mouse brain is specifically localized to oligodendrocytes in white matter tracts and is the predominant CerS in Schwann cells of sciatic nerves; its expression peaks transiently during active myelination, consistent with a role in synthesizing very-long-chain dihydroceramides for myelin sphingolipids.","method":"Northern blot, real-time RT-PCR, in situ hybridization","journal":"Histochemistry and cell biology","confidence":"High","confidence_rationale":"Tier 2 — direct localization by in situ hybridization across brain regions with functional context; replicated by KO study","pmids":["17901973"],"is_preprint":false},{"year":2009,"finding":"CerS2 knockdown by siRNA reduces very-long-chain ceramides (C24, C24:1) and paradoxically increases long-chain ceramides (C14, C16) through a ceramide synthase-independent mechanism, leading to growth arrest, autophagy induction, and activation of PERK and IRE1 unfolded protein response pathways.","method":"siRNA knockdown, mass spectrometry lipid profiling, cell viability assays, western blot for UPR markers","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods in single study demonstrating pathway placement","pmids":["19728861"],"is_preprint":false},{"year":2016,"finding":"CERS2 enzymatic activity is regulated by phosphorylation at cytoplasmic C-terminal residues conforming to a CK2 consensus motif; CK2 inhibition (CX-4945) reduced CERS2 phosphorylation and drastically lowered CERS2 catalytic activity (primarily by reducing Vmax) toward C22:0/C24:0-CoA substrates in mouse brain.","method":"Pharmacological CK2 inhibition, in vitro ceramide synthase activity assays, phosphorylation site mapping, mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro enzymatic assay with pharmacological perturbation and mechanistic follow-up across multiple CERS isoforms","pmids":["26887952"],"is_preprint":false},{"year":2012,"finding":"LASS2 (CERS2) directly interacts with the C subunit of vacuolar H+-ATPase (V-ATPase, ATP6V0C) and inhibits V-ATPase activity, thereby increasing intracellular H+ concentration, raising extracellular pH, reducing MMP-2 secretion, and suppressing breast cancer cell invasion; LASS2 overexpression increases chemosensitivity to doxorubicin.","method":"Overexpression and knockdown (siRNA), V-ATPase activity assay, pH measurement, invasion assays, co-immunoprecipitation (referenced from prior work), xenograft model","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal functional assays with gain- and loss-of-function, in vitro and in vivo, across multiple labs","pmids":["22580606"],"is_preprint":false},{"year":2013,"finding":"The homeodomain of LASS2/TMSG1 directly mediates physical interaction with the C subunit of V-ATPase (ATP6V0C); domain-deletion variants lacking the homeodomain fail to regulate V-ATPase activity and intracellular pH, and lose apoptosis-inducing function.","method":"Immunoprecipitation, immunofluorescence, immuno-electron microscopy, domain deletion constructs, pH fluorescence probe (BCECF/AM), apoptosis assay","journal":"Journal of cellular biochemistry","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal methods (Co-IP, immuno-EM, fluorescence) demonstrating direct interaction and functional domain","pmids":["22991218"],"is_preprint":false},{"year":2010,"finding":"LASS2 overexpression in hepatocellular carcinoma cells (HCCLM3) increases intracellular H+ and decreases extracellular H+ via interaction with V-ATPase, induces cytochrome c release from mitochondria, reduces pro-caspase-3, and enhances apoptosis through the mitochondrial pathway.","method":"Transient transfection, pH-sensitive fluorescence probes (BCECF/BCECF-AM), Annexin-V/PI flow cytometry, western blot for cytochrome c and caspase-3","journal":"Sheng li xue bao : [Acta physiologica Sinica]","confidence":"Medium","confidence_rationale":"Tier 2 — multiple functional assays in single lab; direct mechanistic link established","pmids":["20571735"],"is_preprint":false},{"year":2014,"finding":"Silencing LASS2/TMSG1 in prostate cancer cell line PC-3M-2B4 increases V-ATPase activity and extracellular H+ concentration, activates secreted MMP-2 and MMP-9, and enhances cell proliferation, invasion in vitro, and lymph node metastasis in vivo.","method":"shRNA stable knockdown, V-ATPase activity assay, MMP gelatin zymography, xenograft/lymph node metastasis model","journal":"Journal of cellular biochemistry","confidence":"High","confidence_rationale":"Tier 2 — clean KO/KD with defined mechanistic readouts in vitro and in vivo, replicated across multiple labs","pmids":["24453046"],"is_preprint":false},{"year":2021,"finding":"CerS2-derived very-long-chain ceramides (C24, C24:1, C26:1) mediate oncogene-induced senescence downstream of SK1 knockdown in MCF10A cells expressing oncogenic K-Ras; siRNA knockdown of CerS2 blocks the increase of VLC ceramides induced by SK1 knockdown and reverses p21 induction.","method":"siRNA knockdown (CerS2 and SK1), lipidomic mass spectrometry, p21/SA-β-gal senescence assays, fumonisin B1 inhibition","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 — genetic epistasis with multiple readouts in single lab study","pmids":["33414460"],"is_preprint":false},{"year":2021,"finding":"LASS2 phosphorylation at serine-248 is essential for promoting β-catenin degradation; LASS2 interacts physically with STK38, SCYL2, and ATP6V0C to promote ubiquitin-proteasome-dependent degradation of β-catenin. The S248A dephosphorylation mutant fails to suppress Wnt/β-catenin signaling and enhances prostate cancer growth and metastasis in vivo.","method":"Co-immunoprecipitation, site-directed mutagenesis (S248A), ubiquitin-proteasome pathway assays, xenograft in vivo model","journal":"Journal of cellular biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP plus mutagenesis plus in vivo validation in single lab","pmids":["33852174"],"is_preprint":false},{"year":2024,"finding":"LASS2 (CERS2) directly interacts with transferrin receptor (TFRC) as identified by co-IP LC-MS in thyroid, breast, and liver cancer cells; LASS2 overexpression regulates iron homeostasis and ferroptosis status, inhibiting tumor cell migration, invasion and EMT through this TFRC interaction.","method":"Co-IP coupled LC-MS, protein-protein docking, co-immunoprecipitation western blot, immunofluorescence, proximity ligation assay, transcriptomics/proteomics/metabolomics, ferroptosis pathway assays","journal":"Cancer cell international","confidence":"Medium","confidence_rationale":"Tier 2 — reciprocal Co-IP plus proximity ligation plus multi-omics in single lab","pmids":["38419028"],"is_preprint":false},{"year":2024,"finding":"LASS2 inhibits PP2A activity and physically dissociates PP2A from β-catenin in bladder cancer stem cells, preventing β-catenin dephosphorylation and accumulating cytosolic phospho-β-catenin, which decreases transcription of ABCC2 and CD44, thereby reducing stem-like properties and restoring cisplatin sensitivity.","method":"Co-immunoprecipitation, LC-MS, luciferase reporter assay, chromatin immunoprecipitation, pathway reporter array, gain/loss-of-function, cell- and patient-derived xenograft models","journal":"BMC medicine","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal mechanistic methods including Co-IP, ChIP, and in vivo validation in single lab","pmids":["38191448"],"is_preprint":false},{"year":2018,"finding":"LASS2 overexpression inhibits ERK phosphorylation, which acts upstream of Drp1 phosphorylation, to promote mitochondrial fusion over fission; LASS2 depletion increases p-Drp1, causing mitochondrial fission and increased cancer cell invasion and chemoresistance in bladder cancer cells.","method":"Plasmid transfection and siRNA knockdown, MitoTracker staining, JC-1 staining, ERK inhibitor (PD98059), Drp1 inhibitor (Mdivi), western blot","journal":"Journal of Cancer","confidence":"Medium","confidence_rationale":"Tier 2 — pharmacological epistasis plus gain/loss-of-function with defined pathway placement","pmids":["29581781"],"is_preprint":false},{"year":2021,"finding":"Nrf2 transcriptionally activates LASS2 (CERS2) by binding antioxidant response elements (AREs) in the LASS2 promoter, as demonstrated by luciferase reporter assays; elevated Nrf2/LASS2 expression promotes progestin resistance in endometrial cancer cells.","method":"Luciferase reporter assay (ARE-containing LASS2 promoter), siRNA knockdown, western blot, flow cytometry","journal":"American journal of translational research","confidence":"Medium","confidence_rationale":"Tier 2 — direct promoter assay demonstrating Nrf2 as transcriptional activator of CERS2","pmids":["33841656"],"is_preprint":false},{"year":2023,"finding":"LASS2 interacts directly with MDM2 and MDMX, disrupting p53 degradation; LASS2 overexpression also promotes p53 phosphorylation at Ser15 and acetylation at Lys373, facilitating nuclear translocation of p53, thereby exerting tumor-suppressive effects in a p53-dependent manner in liver cancer cells.","method":"Co-immunoprecipitation, gene set enrichment analysis, western blot for p53 modifications, overexpression/knockdown functional assays","journal":"Cell death discovery","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP demonstrating direct interaction, with downstream p53 modification assays in single lab","pmids":["37963859"],"is_preprint":false},{"year":2020,"finding":"LASS2 interacts with NDUFS2 (complex I subunit) as identified by co-IP and LC-MS; this interaction promotes mitochondrial ROS production, activates AMPK phosphorylation, and inhibits lipogenesis, reducing hepatocyte lipid accumulation.","method":"Co-IP, LC-MS, siRNA knockdown and overexpression, western blot for AMPK/ACC phosphorylation, lipid content assays","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP plus LC-MS identification of interaction partner plus functional AMPK readout in single lab","pmids":["32279995"],"is_preprint":false},{"year":2017,"finding":"LASS2 knockdown in liver-specific knockout mice delayed liver regeneration after partial hepatectomy, with reduced PCNA, Ki67, cyclin A, CDK2, p-Rb, and CDK4/cyclin D1 complex formation; co-immunoprecipitation confirmed decreased CDK4/cyclin D1 interaction in LASS2-deficient livers.","method":"Liver-specific conditional Cre-LoxP knockout, partial hepatectomy model, co-immunoprecipitation (CDK4/cyclin D1), IHC, western blot","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 — clean liver-specific KO with defined molecular phenotype and Co-IP in single lab","pmids":["28958935"],"is_preprint":false},{"year":2021,"finding":"The rs267738 SNP in CERS2 (encoding an E115A substitution) is a partial loss-of-function variant: homozygous knock-in mice generated by CRISPR show reduced liver CERS2 ceramide synthase activity, worsened diet-induced glucose intolerance, and hepatic steatosis.","method":"CRISPR knock-in mouse model, in vitro ceramide synthase activity assay, lipidomics, metabolic phenotyping (glucose tolerance test)","journal":"The Journal of clinical endocrinology and metabolism","confidence":"High","confidence_rationale":"Tier 1 — CRISPR knock-in with direct enzymatic activity measurement and metabolic phenotyping","pmids":["33705551"],"is_preprint":false},{"year":2025,"finding":"Whole-body Cers2 knockout and rs267738 knock-in mice exhibit glucose intolerance and impaired insulin secretion in vivo; islets isolated from these mice show reduced β-cell function with decreased glucose-stimulated insulin secretion ex vivo, linking CERS2 activity and very-long-chain sphingolipid biosynthesis to β-cell function.","method":"Cers2 knockout and CRISPR knock-in mouse models, glucose tolerance tests, ex vivo islet insulin secretion assays, metabolomics","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 1–2 — two genetic mouse models with ex vivo islet functional validation","pmids":["39792658"],"is_preprint":false},{"year":2025,"finding":"CERS2 physically interacts with the ER calcium channel IP3R1; the small-molecule CerS2 agonist DH20931 promotes this interaction, enhancing ER-mitochondria proximity and facilitating Ca2+ flux into mitochondria, triggering mitochondrial dysfunction and apoptosis. Additionally, VLCC accumulation from CerS2 activation induces ER stress via ATF4/CHOP/PUMA pathway.","method":"Co-immunoprecipitation, Ca2+ flux measurements, ER-mitochondria proximity assays, small-molecule agonist (DH20931), LC-MS ceramide quantification, fluorescence-coupled enzymatic assays, xenograft models","journal":"Molecular cancer therapeutics","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP demonstrating novel interaction, pharmacological validation with direct enzymatic measurement, multiple in vivo models","pmids":["42012500"],"is_preprint":false},{"year":2025,"finding":"Phosphorylation of LASS2 at serine-348 (identified by mass spectrometry) is essential for regulation of V-ATPase activity; the LASS2 S348A dephosphorylation mutant fails to suppress V-ATPase activity, increases extracellular H+ and active MMP-2, and significantly enhances prostate cancer cell invasion and migration. Protein phosphatase inhibitor calyculin A reduced growth and invasion of metastatic prostate cancer cells.","method":"Mass spectrometry phospho-site mapping, site-directed mutagenesis (S348A), V-ATPase activity assay, MMP-2 zymography, invasion assays, calyculin A pharmacological inhibition","journal":"Beijing da xue xue bao. Yi xue ban","confidence":"Medium","confidence_rationale":"Tier 1–2 — MS-identified phosphosite validated by mutagenesis with direct enzymatic and functional readouts","pmids":["41399074"],"is_preprint":false},{"year":2014,"finding":"CerS2 deletion in mice results in bulk loss of sulfatides containing C23/C24 acyl chains in the kidney, with compensatory upregulation of C16–C20 acyl chain sulfatides; phytosphingosine-containing cortical sulfatides are completely depleted without compensation, establishing CerS2 as uniquely required for these species.","method":"CerS2 knockout mice, imaging mass spectrometry (IMS), LC-MS/MS lipid profiling, regional mRNA expression analysis","journal":"Journal of lipid research","confidence":"Medium","confidence_rationale":"Tier 2 — clean KO with direct lipid profiling by multiple MS methods","pmids":["25267995"],"is_preprint":false}],"current_model":"CERS2 is an ER-resident ceramide synthase with substrate specificity for very-long-chain fatty acyl-CoAs (C22–C24), whose catalytic activity is positively regulated by CK2-mediated phosphorylation at C-terminal serine residues; it maintains myelin sphingolipids in oligodendrocytes and Schwann cells, regulates β-cell insulin secretion, inhibits tumor cell invasion by directly interacting with V-ATPase subunit ATP6V0C (via its homeodomain) to suppress V-ATPase activity and extracellular acidification, interacts with TFRC to modulate iron homeostasis and ferroptosis, stabilizes p53 by binding MDM2/MDMX, promotes β-catenin degradation via STK38/SCYL2/ATP6V0C interactions dependent on Ser248 phosphorylation, and interacts with IP3R1 to modulate ER-mitochondrial calcium flux and apoptosis."},"narrative":{"teleology":[{"year":2007,"claim":"Identifying where CERS2 is expressed established it as the myelinating-cell ceramide synthase, predicting a role in myelin sphingolipid production before any loss-of-function data existed.","evidence":"In situ hybridization and RT-PCR in mouse brain showing oligodendrocyte- and Schwann-cell-specific expression peaking during active myelination","pmids":["17901973"],"confidence":"High","gaps":["No functional loss-of-function data at this point","Expression pattern alone does not prove requirement"]},{"year":2009,"claim":"Gene-trap knockout mice demonstrated that CERS2 is non-redundantly required for C24 ceramide synthesis, myelin compaction, and hepatic tumor suppression, converting expression data into a causal framework.","evidence":"CERS2 knockout mice with loss of C24:1 ceramide synthase activity, 50% myelin loss, MBP reduction, cerebellar degeneration, and hepatocarcinoma","pmids":["19801672"],"confidence":"High","gaps":["Mechanism linking ceramide loss to hepatocarcinogenesis unknown","Whether myelin loss is cell-autonomous was not tested"]},{"year":2009,"claim":"CERS2 knockdown revealed a sphingolipid rheostat: loss of very-long-chain ceramides paradoxically elevates long-chain ceramides and triggers ER stress, showing that CERS2 depletion remodels the entire ceramide landscape.","evidence":"siRNA knockdown with mass spectrometry lipidomics and UPR marker western blots in cultured cells","pmids":["19728861"],"confidence":"High","gaps":["Mechanism of compensatory C16 ceramide increase not resolved","In vivo ER stress consequence not tested"]},{"year":2010,"claim":"Overexpression studies in hepatocellular carcinoma cells first linked CERS2's tumor-suppressive action to V-ATPase-dependent intracellular acidification and mitochondrial apoptosis, opening a non-enzymatic interaction axis.","evidence":"pH-sensitive fluorescence probes and Annexin-V/PI flow cytometry after LASS2 overexpression in HCCLM3 cells","pmids":["20571735"],"confidence":"Medium","gaps":["Direct physical interaction with V-ATPase not yet mapped","Ceramide-dependent vs. -independent contribution not delineated"]},{"year":2012,"claim":"Demonstrating that CERS2 directly binds and inhibits V-ATPase subunit ATP6V0C established a ceramide synthase-independent protein-interaction mechanism for tumor suppression via extracellular pH control and MMP-2 reduction.","evidence":"Co-IP, V-ATPase activity assays, pH measurements, invasion assays, and xenograft models in breast cancer cells","pmids":["22580606"],"confidence":"High","gaps":["Whether ceramide synthesis is dispensable for V-ATPase regulation not formally separated","Structural basis of interaction unknown"]},{"year":2013,"claim":"Domain-deletion mapping pinpointed the CERS2 homeodomain as the required interface for ATP6V0C binding, linking a specific structural element to V-ATPase inhibition and apoptosis induction.","evidence":"Co-IP with domain-deletion constructs, immuno-electron microscopy, and BCECF pH probes","pmids":["22991218"],"confidence":"High","gaps":["No atomic-resolution structure of the homeodomain–ATP6V0C complex","Homeodomain contribution to ceramide synthase activity not assessed"]},{"year":2014,"claim":"Loss-of-function studies extended the V-ATPase axis to prostate cancer metastasis, showing CERS2 silencing activates MMP-2/9 and promotes lymph node metastasis in vivo, reinforcing generality across cancer types.","evidence":"shRNA stable knockdown, MMP zymography, and lymph node metastasis xenograft model in PC-3M-2B4 cells","pmids":["24453046"],"confidence":"High","gaps":["Relative contribution of ceramide product changes vs. V-ATPase interaction to metastasis unclear"]},{"year":2014,"claim":"Lipidomic analysis of CERS2 knockout kidneys revealed that phytosphingosine-based cortical sulfatides are entirely CERS2-dependent and cannot be compensated by other CerS isoforms, defining a unique lipid niche.","evidence":"Imaging mass spectrometry and LC-MS/MS in CerS2 knockout mouse kidneys","pmids":["25267995"],"confidence":"Medium","gaps":["Functional consequence of phytosphingosine sulfatide loss in kidney not characterized","Single lab study"]},{"year":2016,"claim":"Identification of CK2-mediated phosphorylation as a Vmax regulator of CERS2 catalytic activity established the first post-translational control mechanism for this enzyme.","evidence":"CK2 inhibitor CX-4945, in vitro ceramide synthase activity assays, and phosphorylation site mapping in mouse brain","pmids":["26887952"],"confidence":"High","gaps":["Specific phosphorylated residues not fully resolved","In vivo phosphosite mutant mice not generated"]},{"year":2017,"claim":"Liver-specific CERS2 knockout showed impaired hepatocyte cell cycle progression after partial hepatectomy, demonstrating a non-tumor-suppressive proliferative role for CERS2 in regenerating tissue.","evidence":"Cre-LoxP liver-specific knockout, partial hepatectomy, Co-IP for CDK4/cyclin D1","pmids":["28958935"],"confidence":"Medium","gaps":["Whether the effect is ceramide-dependent or interaction-dependent unknown","Single lab observation"]},{"year":2018,"claim":"Placing CERS2 upstream of ERK–Drp1 signaling showed it controls mitochondrial dynamics: depletion shifts the fission–fusion balance toward fission, increasing invasion and chemoresistance.","evidence":"Gain/loss-of-function with ERK and Drp1 inhibitors, MitoTracker and JC-1 staining in bladder cancer cells","pmids":["29581781"],"confidence":"Medium","gaps":["Mechanism connecting CERS2 to ERK inhibition not identified","No direct binding partner for ERK regulation shown"]},{"year":2020,"claim":"Discovery of the CERS2–NDUFS2 interaction linked CERS2 to mitochondrial complex I ROS production and downstream AMPK-mediated lipogenesis inhibition, revealing a metabolic regulatory arm.","evidence":"Co-IP and LC-MS identification of NDUFS2, AMPK/ACC phosphorylation western blots, lipid content assays","pmids":["32279995"],"confidence":"Medium","gaps":["Interaction validated in single lab only","Whether CERS2 catalytic product or physical interaction drives ROS is unresolved"]},{"year":2021,"claim":"CRISPR knock-in of the human E115A variant (rs267738) in mice confirmed it as a partial loss-of-function allele causing metabolic syndrome features, bridging a common human polymorphism to CERS2 enzymatic insufficiency.","evidence":"CRISPR knock-in mouse, in vitro ceramide synthase activity, lipidomics, glucose tolerance testing","pmids":["33705551"],"confidence":"High","gaps":["Human clinical phenotype data for homozygous carriers still limited","Tissue-specific consequences beyond liver not characterized"]},{"year":2021,"claim":"Epistasis experiments positioned CERS2-derived VLC ceramides as effectors of oncogene-induced senescence downstream of sphingosine kinase 1, providing a defined sphingolipid-to-cell-fate signaling axis.","evidence":"siRNA epistasis of CerS2 and SK1, lipidomics, p21/SA-β-gal assays in K-Ras-transformed MCF10A cells","pmids":["33414460"],"confidence":"Medium","gaps":["Direct ceramide species responsible for p21 induction not identified","In vivo validation lacking"]},{"year":2021,"claim":"Ser248 phosphorylation was shown to be required for CERS2's ability to promote β-catenin ubiquitin-proteasomal degradation via a STK38/SCYL2/ATP6V0C complex, connecting V-ATPase interactions to Wnt pathway suppression.","evidence":"Co-IP, S248A mutagenesis, ubiquitin-proteasome assays, and xenograft models in prostate cancer","pmids":["33852174"],"confidence":"Medium","gaps":["Kinase responsible for Ser248 phosphorylation not identified","Single lab, not independently replicated"]},{"year":2021,"claim":"Identification of Nrf2 as a direct transcriptional activator of the CERS2 promoter via ARE elements established the first defined transcription factor–CERS2 regulatory relationship.","evidence":"Luciferase reporter assays with ARE-containing CERS2 promoter, siRNA knockdown in endometrial cancer cells","pmids":["33841656"],"confidence":"Medium","gaps":["Other transcription factors regulating CERS2 not surveyed","Functional impact on ceramide levels not measured"]},{"year":2023,"claim":"Demonstrating that CERS2 binds MDM2 and MDMX to stabilize p53 (promoting Ser15 phosphorylation and Lys373 acetylation) added a p53-dependent tumor-suppressive mechanism independent of the V-ATPase axis.","evidence":"Co-IP for MDM2/MDMX, western blots for p53 modifications, overexpression/knockdown in liver cancer cells","pmids":["37963859"],"confidence":"Medium","gaps":["Not independently replicated","Whether ceramide synthase activity is required for MDM2 binding unknown","Structural basis of CERS2–MDM2 interaction not resolved"]},{"year":2024,"claim":"Discovery of the CERS2–TFRC interaction linked CERS2 to iron homeostasis and ferroptosis regulation, opening a new functional axis beyond sphingolipid metabolism and V-ATPase.","evidence":"Co-IP LC-MS, proximity ligation assay, multi-omics, ferroptosis assays across thyroid, breast, and liver cancer lines","pmids":["38419028"],"confidence":"Medium","gaps":["Mechanism by which CERS2 alters TFRC function not defined","Single lab","Ceramide dependence not tested"]},{"year":2024,"claim":"Showing that CERS2 inhibits PP2A to maintain phospho-β-catenin and reduce stemness markers (CD44, ABCC2) provided a mechanistic basis for cisplatin resensitization in bladder cancer stem cells.","evidence":"Co-IP, LC-MS, ChIP, luciferase reporters, patient-derived xenografts in bladder cancer","pmids":["38191448"],"confidence":"Medium","gaps":["PP2A subunit specificity not determined","Independent replication needed"]},{"year":2025,"claim":"Ex vivo islet studies from both CERS2 knockout and E115A knock-in mice established that CERS2-derived VLC sphingolipids are required for glucose-stimulated insulin secretion, translating whole-body metabolic phenotypes to a defined β-cell mechanism.","evidence":"Two genetic mouse models with ex vivo islet glucose-stimulated insulin secretion assays and metabolomics","pmids":["39792658"],"confidence":"High","gaps":["Specific sphingolipid species mediating β-cell exocytosis not identified","Human islet validation not performed"]},{"year":2025,"claim":"Identification of CERS2–IP3R1 interaction and pharmacological activation by DH20931 demonstrated that CERS2 modulates ER-mitochondrial calcium transfer and apoptosis, providing both a novel interactor and a tool compound.","evidence":"Co-IP, calcium flux measurements, ER-mitochondria proximity assays, DH20931 agonist treatment, xenograft models","pmids":["42012500"],"confidence":"Medium","gaps":["DH20931 selectivity for CERS2 vs. other CerS not fully characterized","Whether IP3R1 interaction is ceramide-dependent unclear"]},{"year":2025,"claim":"Phospho-site mapping identified Ser348 as required for V-ATPase suppression and anti-invasive function, adding a second regulatory phosphosite (alongside Ser248) to the growing picture of CERS2 post-translational control.","evidence":"Mass spectrometry phosphosite mapping, S348A mutagenesis, V-ATPase and MMP-2 assays in prostate cancer cells","pmids":["41399074"],"confidence":"Medium","gaps":["Kinase phosphorylating Ser348 not identified","Relationship between Ser348 and CK2-regulated C-terminal sites not clarified"]},{"year":null,"claim":"A central unresolved question is whether CERS2's numerous protein–protein interactions (ATP6V0C, MDM2, TFRC, IP3R1, NDUFS2, PP2A) operate independently of its ceramide synthase catalytic activity, and how its multiple phosphosites are coordinately regulated to direct these distinct functions.","evidence":"","pmids":[],"confidence":"Low","gaps":["No catalytic-dead separation-of-function mutant tested across interaction partners","No structural model of full-length CERS2","Interplay between CK2 phosphorylation and Ser248/Ser348 phosphorylation unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,2,3,17,21]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[4,5,7,11,20]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[0,3,21]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[0,19]},{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[6,15,19]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0,2,3,17,21]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[6,19]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[9,11,14]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[4,7,8,10]}],"complexes":[],"partners":["ATP6V0C","MDM2","MDMX","TFRC","ITPR1","NDUFS2","STK38","SCYL2"],"other_free_text":[]},"mechanistic_narrative":"CERS2 is an endoplasmic reticulum-resident ceramide synthase that generates very-long-chain ceramides (C22–C24) essential for myelin sphingolipid maintenance, pancreatic β-cell insulin secretion, and hepatic lipid homeostasis. Its catalytic activity toward C22:0/C24:0-CoA substrates is positively regulated by CK2-mediated phosphorylation at C-terminal serine residues, and the common E115A variant (rs267738) is a partial loss-of-function allele that causes glucose intolerance and hepatic steatosis in knock-in mice [PMID:26887952, PMID:33705551, PMID:39792658]. Beyond its enzymatic role, CERS2 functions as a tumor suppressor through multiple protein–protein interactions: its homeodomain binds the V-ATPase V0 c-subunit (ATP6V0C) to inhibit proton pump activity, suppress extracellular acidification, and reduce MMP-dependent invasion; it stabilizes p53 by disrupting MDM2/MDMX-mediated degradation; it promotes phospho-β-catenin accumulation by inhibiting PP2A and engaging STK38/SCYL2; and it interacts with IP3R1 to modulate ER-to-mitochondria calcium flux and apoptosis [PMID:22580606, PMID:22991218, PMID:37963859, PMID:38191448, PMID:42012500]. CERS2 knockout mice exhibit loss of compacted myelin, cerebellar degeneration, hepatocarcinoma, and impaired liver regeneration, underscoring its non-redundant roles in neural, hepatic, and metabolic tissue homeostasis [PMID:19801672, PMID:28958935]."},"prefetch_data":{"uniprot":{"accession":"Q96G23","full_name":"Ceramide synthase 2","aliases":["LAG1 longevity assurance homolog 2","SP260","Sphingosine N-acyltransferase CERS2","Tumor metastasis-suppressor gene 1 protein","Very-long-chain ceramide synthase CERS2"],"length_aa":380,"mass_kda":44.9,"function":"Ceramide synthase that catalyzes the transfer of the acyl chain from acyl-CoA to a sphingoid base, with high selectivity toward very-long-chain fatty acyl-CoA (chain length C22-C27) (PubMed:17977534, PubMed:18165233, PubMed:18541923, PubMed:19728861, PubMed:20937905, PubMed:22144673, PubMed:22661289, PubMed:26887952, PubMed:29632068). N-acylates sphinganine and sphingosine bases to form dihydroceramides and ceramides in de novo synthesis and salvage pathways, respectively (By similarity) (PubMed:17977534, PubMed:18165233, PubMed:18541923, PubMed:19728861, PubMed:20937905, PubMed:22144673, PubMed:22661289, PubMed:26887952, PubMed:29632068). Plays a non-redundant role in the synthesis of ceramides with very-long-chain fatty acids in kidney, liver and brain. Regulates the abundance of myelin-specific sphingolipids galactosylceramide and sulfatide that affects myelin sheath architecture and motor neuron functions (By similarity)","subcellular_location":"Endoplasmic reticulum membrane","url":"https://www.uniprot.org/uniprotkb/Q96G23/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CERS2","classification":"Not Classified","n_dependent_lines":316,"n_total_lines":1208,"dependency_fraction":0.26158940397350994},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CANX","stoichiometry":0.2},{"gene":"CSNK2B","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/CERS2","total_profiled":1310},"omim":[{"mim_id":"619822","title":"BCL2-LIKE 13; BCL2L13","url":"https://www.omim.org/entry/619822"},{"mim_id":"615336","title":"CERAMIDE SYNTHASE 6; CERS6","url":"https://www.omim.org/entry/615336"},{"mim_id":"615335","title":"CERAMIDE SYNTHASE 5; CERS5","url":"https://www.omim.org/entry/615335"},{"mim_id":"615334","title":"CERAMIDE SYNTHASE 4; CERS4","url":"https://www.omim.org/entry/615334"},{"mim_id":"611813","title":"ELONGATION OF VERY LONG CHAIN FATTY ACIDS-LIKE 1; ELOVL1","url":"https://www.omim.org/entry/611813"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nuclear membrane","reliability":"Supported"},{"location":"Endoplasmic reticulum","reliability":"Supported"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"liver","ntpm":683.9}],"url":"https://www.proteinatlas.org/search/CERS2"},"hgnc":{"alias_symbol":["SP260","FLJ10243"],"prev_symbol":["LASS2"]},"alphafold":{"accession":"Q96G23","domains":[{"cath_id":"1.10.10.60","chopping":"81-124","consensus_level":"high","plddt":92.9423,"start":81,"end":124},{"cath_id":"-","chopping":"127-331","consensus_level":"high","plddt":94.714,"start":127,"end":331}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96G23","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96G23-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96G23-F1-predicted_aligned_error_v6.png","plddt_mean":86.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CERS2","jax_strain_url":"https://www.jax.org/strain/search?query=CERS2"},"sequence":{"accession":"Q96G23","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96G23.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96G23/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96G23"}},"corpus_meta":[{"pmid":"19801672","id":"PMC_19801672","title":"Adult 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cancer.","date":"2015","source":"Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine","url":"https://pubmed.ncbi.nlm.nih.gov/26150338","citation_count":59,"is_preprint":false},{"pmid":"25213553","id":"PMC_25213553","title":"CERS2 suppresses tumor cell invasion and is associated with decreased V-ATPase and MMP-2/MMP-9 activities in breast cancer.","date":"2015","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/25213553","citation_count":56,"is_preprint":false},{"pmid":"24453046","id":"PMC_24453046","title":"Silencing of LASS2/TMSG1 enhances invasion and metastasis capacity of prostate cancer cell.","date":"2014","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/24453046","citation_count":39,"is_preprint":false},{"pmid":"27241665","id":"PMC_27241665","title":"The asialoglycoprotein receptor suppresses the metastasis of hepatocellular carcinoma via LASS2-mediated inhibition of V-ATPase activity.","date":"2016","source":"Cancer letters","url":"https://pubmed.ncbi.nlm.nih.gov/27241665","citation_count":36,"is_preprint":false},{"pmid":"22573553","id":"PMC_22573553","title":"Silencing of a novel tumor metastasis suppressor gene LASS2/TMSG1 promotes invasion of prostate cancer cell in vitro through increase of vacuolar ATPase activity.","date":"2012","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22573553","citation_count":36,"is_preprint":false},{"pmid":"30463687","id":"PMC_30463687","title":"MicroRNA-98 promotes drug resistance and regulates mitochondrial dynamics by targeting LASS2 in bladder cancer cells.","date":"2018","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/30463687","citation_count":35,"is_preprint":false},{"pmid":"25238615","id":"PMC_25238615","title":"A gene variant in CERS2 is associated with rate of increase in albuminuria in patients with diabetes from ONTARGET and TRANSCEND.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25238615","citation_count":32,"is_preprint":false},{"pmid":"26110566","id":"PMC_26110566","title":"AGPAT9 suppresses cell growth, invasion and metastasis by counteracting acidic tumor microenvironment through KLF4/LASS2/V-ATPase signaling pathway in breast cancer.","date":"2015","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/26110566","citation_count":30,"is_preprint":false},{"pmid":"22991218","id":"PMC_22991218","title":"A novel tumor metastasis suppressor gene LASS2/TMSG1 interacts with vacuolar ATPase through its homeodomain.","date":"2013","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22991218","citation_count":28,"is_preprint":false},{"pmid":"27099514","id":"PMC_27099514","title":"Repression of the miR-93-enhanced sensitivity of bladder carcinoma to chemotherapy involves the regulation of LASS2.","date":"2016","source":"OncoTargets and 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Sinica]","url":"https://pubmed.ncbi.nlm.nih.gov/20571735","citation_count":17,"is_preprint":false},{"pmid":"23407876","id":"PMC_23407876","title":"Expression of a tumor-associated gene, LASS2, in the human bladder carcinoma cell lines BIU-87, T24, EJ and EJ-M3.","date":"2013","source":"Experimental and therapeutic medicine","url":"https://pubmed.ncbi.nlm.nih.gov/23407876","citation_count":17,"is_preprint":false},{"pmid":"30898713","id":"PMC_30898713","title":"miR-3622a promotes proliferation and invasion of bladder cancer cells by downregulating LASS2.","date":"2019","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/30898713","citation_count":16,"is_preprint":false},{"pmid":"28088541","id":"PMC_28088541","title":"Secretory pathway optimization of CHO producer cells by co-engineering of the mitosRNA-1978 target genes CerS2 and Tbc1D20.","date":"2017","source":"Metabolic 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bing li xue za zhi = Chinese journal of pathology","url":"https://pubmed.ncbi.nlm.nih.gov/24842017","citation_count":2,"is_preprint":false},{"pmid":"39233348","id":"PMC_39233348","title":"Downregulation of CerS4 Instead of CerS2 in Liver Effectively Alleviates Hepatic Insulin Resistance in HFD Male Mice.","date":"2024","source":"Endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/39233348","citation_count":2,"is_preprint":false},{"pmid":"30996356","id":"PMC_30996356","title":"[Novel tumor metastasis suppressorgene LASS2/TMSG1 S248A mutant promotes invasion of prostate cancer cells through increasing ATP6V0C expression].","date":"2019","source":"Beijing da xue xue bao. Yi xue ban = Journal of Peking University. Health sciences","url":"https://pubmed.ncbi.nlm.nih.gov/30996356","citation_count":1,"is_preprint":false},{"pmid":"36946034","id":"PMC_36946034","title":"[LASS2/TMSG1 overexpression inhibits proliferation and promotes apoptosis of human lung cancer A549 cells possibly by upregulating ceramide and p38 MAPK to activate a signaling cascade].","date":"2023","source":"Nan fang yi ke da xue xue bao = Journal of Southern Medical University","url":"https://pubmed.ncbi.nlm.nih.gov/36946034","citation_count":0,"is_preprint":false},{"pmid":"15969039","id":"PMC_15969039","title":"[Study of the expression membrane protein LASS2].","date":"2003","source":"Sheng wu gong cheng xue bao = Chinese journal of biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/15969039","citation_count":0,"is_preprint":false},{"pmid":"41399074","id":"PMC_41399074","title":"[Effect of dephosphorylation of tumor metastasis suppressor gene LASS2 on vacuolar ATPase activity and invasiveness of prostate cancer].","date":"2025","source":"Beijing da xue xue bao. Yi xue ban = Journal of Peking University. Health sciences","url":"https://pubmed.ncbi.nlm.nih.gov/41399074","citation_count":0,"is_preprint":false},{"pmid":"41483315","id":"PMC_41483315","title":"Discovery of a potential CERS2 inhibitor: hit compound identification via structure-based virtual screening and molecular dynamics simulations.","date":"2026","source":"Molecular diversity","url":"https://pubmed.ncbi.nlm.nih.gov/41483315","citation_count":0,"is_preprint":false},{"pmid":"38757331","id":"PMC_38757331","title":"Expression of LASS2 Can be Regulated by Dihydroartemisinin to Regulate Cisplatin Chemosensitivity in Bladder Cancer Cells.","date":"2025","source":"Current pharmaceutical biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/38757331","citation_count":0,"is_preprint":false},{"pmid":"40894709","id":"PMC_40894709","title":"CerS2 is a druggable target in triple-negative breast cancer.","date":"2025","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/40894709","citation_count":0,"is_preprint":false},{"pmid":"42012500","id":"PMC_42012500","title":"CerS2 is a druggable target in triple-negative breast cancer.","date":"2026","source":"Molecular cancer therapeutics","url":"https://pubmed.ncbi.nlm.nih.gov/42012500","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.11.28.691118","title":"Uncoupling of nutrient sensing and cell size control by specific defects in ceramide structure","date":"2025-12-01","source":"bioRxiv","url":"https://doi.org/10.1101/2025.11.28.691118","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.05.13.653734","title":"Very long chain fatty acids drive 1-deoxy-Sphingolipid toxicity","date":"2025-05-16","source":"bioRxiv","url":"https://doi.org/10.1101/2025.05.13.653734","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.05.14.653935","title":"Serine palmitoyltransferase-mediated de novo sphingolipid biosynthesis is required for normal insulin production and glucose tolerance","date":"2025-05-17","source":"bioRxiv","url":"https://doi.org/10.1101/2025.05.14.653935","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.08.23.609447","title":"BCL2L13 Influences Autophagy and Ceramide Metabolism without Affecting Temozolomide Resistance in Glioblastoma","date":"2024-08-26","source":"bioRxiv","url":"https://doi.org/10.1101/2024.08.23.609447","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":36136,"output_tokens":5439,"usd":0.094996},"stage2":{"model":"claude-opus-4-6","input_tokens":9021,"output_tokens":4752,"usd":0.245858},"total_usd":0.340854,"stage1_batch_id":"msgbatch_011kfMfE81o6CTcyhVUqumuW","stage2_batch_id":"msgbatch_01DTputS6WNkH745x1nVSoBo","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2009,\n      \"finding\": \"CERS2 (CerS2/LASS2) is the predominant ceramide synthase in oligodendrocytes and Schwann cells, with substrate specificity for very long-chain fatty acid residues (C22–C24). Knockout mice lacking CERS2 show strongly reduced C24:1 ceramide synthase activity in brain and liver, ~50% loss of compacted myelin, 80% loss of myelin basic protein, cerebellar degeneration, and hepatocarcinoma development, establishing CERS2 as required for myelin maintenance and hepatic tumor suppression.\",\n      \"method\": \"Gene-trap knockout mice (loss-of-function), biochemical ceramide synthase activity assays, lipid profiling, histology, lacZ reporter\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with multiple defined cellular and biochemical phenotypes, replicated across tissues\",\n      \"pmids\": [\"19801672\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"CerS2 expression in mouse brain is specifically localized to oligodendrocytes in white matter tracts and is the predominant CerS in Schwann cells of sciatic nerves; its expression peaks transiently during active myelination, consistent with a role in synthesizing very-long-chain dihydroceramides for myelin sphingolipids.\",\n      \"method\": \"Northern blot, real-time RT-PCR, in situ hybridization\",\n      \"journal\": \"Histochemistry and cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct localization by in situ hybridization across brain regions with functional context; replicated by KO study\",\n      \"pmids\": [\"17901973\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"CerS2 knockdown by siRNA reduces very-long-chain ceramides (C24, C24:1) and paradoxically increases long-chain ceramides (C14, C16) through a ceramide synthase-independent mechanism, leading to growth arrest, autophagy induction, and activation of PERK and IRE1 unfolded protein response pathways.\",\n      \"method\": \"siRNA knockdown, mass spectrometry lipid profiling, cell viability assays, western blot for UPR markers\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods in single study demonstrating pathway placement\",\n      \"pmids\": [\"19728861\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CERS2 enzymatic activity is regulated by phosphorylation at cytoplasmic C-terminal residues conforming to a CK2 consensus motif; CK2 inhibition (CX-4945) reduced CERS2 phosphorylation and drastically lowered CERS2 catalytic activity (primarily by reducing Vmax) toward C22:0/C24:0-CoA substrates in mouse brain.\",\n      \"method\": \"Pharmacological CK2 inhibition, in vitro ceramide synthase activity assays, phosphorylation site mapping, mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro enzymatic assay with pharmacological perturbation and mechanistic follow-up across multiple CERS isoforms\",\n      \"pmids\": [\"26887952\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"LASS2 (CERS2) directly interacts with the C subunit of vacuolar H+-ATPase (V-ATPase, ATP6V0C) and inhibits V-ATPase activity, thereby increasing intracellular H+ concentration, raising extracellular pH, reducing MMP-2 secretion, and suppressing breast cancer cell invasion; LASS2 overexpression increases chemosensitivity to doxorubicin.\",\n      \"method\": \"Overexpression and knockdown (siRNA), V-ATPase activity assay, pH measurement, invasion assays, co-immunoprecipitation (referenced from prior work), xenograft model\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal functional assays with gain- and loss-of-function, in vitro and in vivo, across multiple labs\",\n      \"pmids\": [\"22580606\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"The homeodomain of LASS2/TMSG1 directly mediates physical interaction with the C subunit of V-ATPase (ATP6V0C); domain-deletion variants lacking the homeodomain fail to regulate V-ATPase activity and intracellular pH, and lose apoptosis-inducing function.\",\n      \"method\": \"Immunoprecipitation, immunofluorescence, immuno-electron microscopy, domain deletion constructs, pH fluorescence probe (BCECF/AM), apoptosis assay\",\n      \"journal\": \"Journal of cellular biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal methods (Co-IP, immuno-EM, fluorescence) demonstrating direct interaction and functional domain\",\n      \"pmids\": [\"22991218\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"LASS2 overexpression in hepatocellular carcinoma cells (HCCLM3) increases intracellular H+ and decreases extracellular H+ via interaction with V-ATPase, induces cytochrome c release from mitochondria, reduces pro-caspase-3, and enhances apoptosis through the mitochondrial pathway.\",\n      \"method\": \"Transient transfection, pH-sensitive fluorescence probes (BCECF/BCECF-AM), Annexin-V/PI flow cytometry, western blot for cytochrome c and caspase-3\",\n      \"journal\": \"Sheng li xue bao : [Acta physiologica Sinica]\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple functional assays in single lab; direct mechanistic link established\",\n      \"pmids\": [\"20571735\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Silencing LASS2/TMSG1 in prostate cancer cell line PC-3M-2B4 increases V-ATPase activity and extracellular H+ concentration, activates secreted MMP-2 and MMP-9, and enhances cell proliferation, invasion in vitro, and lymph node metastasis in vivo.\",\n      \"method\": \"shRNA stable knockdown, V-ATPase activity assay, MMP gelatin zymography, xenograft/lymph node metastasis model\",\n      \"journal\": \"Journal of cellular biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO/KD with defined mechanistic readouts in vitro and in vivo, replicated across multiple labs\",\n      \"pmids\": [\"24453046\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"CerS2-derived very-long-chain ceramides (C24, C24:1, C26:1) mediate oncogene-induced senescence downstream of SK1 knockdown in MCF10A cells expressing oncogenic K-Ras; siRNA knockdown of CerS2 blocks the increase of VLC ceramides induced by SK1 knockdown and reverses p21 induction.\",\n      \"method\": \"siRNA knockdown (CerS2 and SK1), lipidomic mass spectrometry, p21/SA-β-gal senescence assays, fumonisin B1 inhibition\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with multiple readouts in single lab study\",\n      \"pmids\": [\"33414460\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"LASS2 phosphorylation at serine-248 is essential for promoting β-catenin degradation; LASS2 interacts physically with STK38, SCYL2, and ATP6V0C to promote ubiquitin-proteasome-dependent degradation of β-catenin. The S248A dephosphorylation mutant fails to suppress Wnt/β-catenin signaling and enhances prostate cancer growth and metastasis in vivo.\",\n      \"method\": \"Co-immunoprecipitation, site-directed mutagenesis (S248A), ubiquitin-proteasome pathway assays, xenograft in vivo model\",\n      \"journal\": \"Journal of cellular biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus mutagenesis plus in vivo validation in single lab\",\n      \"pmids\": [\"33852174\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LASS2 (CERS2) directly interacts with transferrin receptor (TFRC) as identified by co-IP LC-MS in thyroid, breast, and liver cancer cells; LASS2 overexpression regulates iron homeostasis and ferroptosis status, inhibiting tumor cell migration, invasion and EMT through this TFRC interaction.\",\n      \"method\": \"Co-IP coupled LC-MS, protein-protein docking, co-immunoprecipitation western blot, immunofluorescence, proximity ligation assay, transcriptomics/proteomics/metabolomics, ferroptosis pathway assays\",\n      \"journal\": \"Cancer cell international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP plus proximity ligation plus multi-omics in single lab\",\n      \"pmids\": [\"38419028\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LASS2 inhibits PP2A activity and physically dissociates PP2A from β-catenin in bladder cancer stem cells, preventing β-catenin dephosphorylation and accumulating cytosolic phospho-β-catenin, which decreases transcription of ABCC2 and CD44, thereby reducing stem-like properties and restoring cisplatin sensitivity.\",\n      \"method\": \"Co-immunoprecipitation, LC-MS, luciferase reporter assay, chromatin immunoprecipitation, pathway reporter array, gain/loss-of-function, cell- and patient-derived xenograft models\",\n      \"journal\": \"BMC medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal mechanistic methods including Co-IP, ChIP, and in vivo validation in single lab\",\n      \"pmids\": [\"38191448\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"LASS2 overexpression inhibits ERK phosphorylation, which acts upstream of Drp1 phosphorylation, to promote mitochondrial fusion over fission; LASS2 depletion increases p-Drp1, causing mitochondrial fission and increased cancer cell invasion and chemoresistance in bladder cancer cells.\",\n      \"method\": \"Plasmid transfection and siRNA knockdown, MitoTracker staining, JC-1 staining, ERK inhibitor (PD98059), Drp1 inhibitor (Mdivi), western blot\",\n      \"journal\": \"Journal of Cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — pharmacological epistasis plus gain/loss-of-function with defined pathway placement\",\n      \"pmids\": [\"29581781\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Nrf2 transcriptionally activates LASS2 (CERS2) by binding antioxidant response elements (AREs) in the LASS2 promoter, as demonstrated by luciferase reporter assays; elevated Nrf2/LASS2 expression promotes progestin resistance in endometrial cancer cells.\",\n      \"method\": \"Luciferase reporter assay (ARE-containing LASS2 promoter), siRNA knockdown, western blot, flow cytometry\",\n      \"journal\": \"American journal of translational research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct promoter assay demonstrating Nrf2 as transcriptional activator of CERS2\",\n      \"pmids\": [\"33841656\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"LASS2 interacts directly with MDM2 and MDMX, disrupting p53 degradation; LASS2 overexpression also promotes p53 phosphorylation at Ser15 and acetylation at Lys373, facilitating nuclear translocation of p53, thereby exerting tumor-suppressive effects in a p53-dependent manner in liver cancer cells.\",\n      \"method\": \"Co-immunoprecipitation, gene set enrichment analysis, western blot for p53 modifications, overexpression/knockdown functional assays\",\n      \"journal\": \"Cell death discovery\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP demonstrating direct interaction, with downstream p53 modification assays in single lab\",\n      \"pmids\": [\"37963859\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"LASS2 interacts with NDUFS2 (complex I subunit) as identified by co-IP and LC-MS; this interaction promotes mitochondrial ROS production, activates AMPK phosphorylation, and inhibits lipogenesis, reducing hepatocyte lipid accumulation.\",\n      \"method\": \"Co-IP, LC-MS, siRNA knockdown and overexpression, western blot for AMPK/ACC phosphorylation, lipid content assays\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus LC-MS identification of interaction partner plus functional AMPK readout in single lab\",\n      \"pmids\": [\"32279995\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"LASS2 knockdown in liver-specific knockout mice delayed liver regeneration after partial hepatectomy, with reduced PCNA, Ki67, cyclin A, CDK2, p-Rb, and CDK4/cyclin D1 complex formation; co-immunoprecipitation confirmed decreased CDK4/cyclin D1 interaction in LASS2-deficient livers.\",\n      \"method\": \"Liver-specific conditional Cre-LoxP knockout, partial hepatectomy model, co-immunoprecipitation (CDK4/cyclin D1), IHC, western blot\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean liver-specific KO with defined molecular phenotype and Co-IP in single lab\",\n      \"pmids\": [\"28958935\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"The rs267738 SNP in CERS2 (encoding an E115A substitution) is a partial loss-of-function variant: homozygous knock-in mice generated by CRISPR show reduced liver CERS2 ceramide synthase activity, worsened diet-induced glucose intolerance, and hepatic steatosis.\",\n      \"method\": \"CRISPR knock-in mouse model, in vitro ceramide synthase activity assay, lipidomics, metabolic phenotyping (glucose tolerance test)\",\n      \"journal\": \"The Journal of clinical endocrinology and metabolism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — CRISPR knock-in with direct enzymatic activity measurement and metabolic phenotyping\",\n      \"pmids\": [\"33705551\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Whole-body Cers2 knockout and rs267738 knock-in mice exhibit glucose intolerance and impaired insulin secretion in vivo; islets isolated from these mice show reduced β-cell function with decreased glucose-stimulated insulin secretion ex vivo, linking CERS2 activity and very-long-chain sphingolipid biosynthesis to β-cell function.\",\n      \"method\": \"Cers2 knockout and CRISPR knock-in mouse models, glucose tolerance tests, ex vivo islet insulin secretion assays, metabolomics\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — two genetic mouse models with ex vivo islet functional validation\",\n      \"pmids\": [\"39792658\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CERS2 physically interacts with the ER calcium channel IP3R1; the small-molecule CerS2 agonist DH20931 promotes this interaction, enhancing ER-mitochondria proximity and facilitating Ca2+ flux into mitochondria, triggering mitochondrial dysfunction and apoptosis. Additionally, VLCC accumulation from CerS2 activation induces ER stress via ATF4/CHOP/PUMA pathway.\",\n      \"method\": \"Co-immunoprecipitation, Ca2+ flux measurements, ER-mitochondria proximity assays, small-molecule agonist (DH20931), LC-MS ceramide quantification, fluorescence-coupled enzymatic assays, xenograft models\",\n      \"journal\": \"Molecular cancer therapeutics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP demonstrating novel interaction, pharmacological validation with direct enzymatic measurement, multiple in vivo models\",\n      \"pmids\": [\"42012500\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Phosphorylation of LASS2 at serine-348 (identified by mass spectrometry) is essential for regulation of V-ATPase activity; the LASS2 S348A dephosphorylation mutant fails to suppress V-ATPase activity, increases extracellular H+ and active MMP-2, and significantly enhances prostate cancer cell invasion and migration. Protein phosphatase inhibitor calyculin A reduced growth and invasion of metastatic prostate cancer cells.\",\n      \"method\": \"Mass spectrometry phospho-site mapping, site-directed mutagenesis (S348A), V-ATPase activity assay, MMP-2 zymography, invasion assays, calyculin A pharmacological inhibition\",\n      \"journal\": \"Beijing da xue xue bao. Yi xue ban\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 — MS-identified phosphosite validated by mutagenesis with direct enzymatic and functional readouts\",\n      \"pmids\": [\"41399074\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"CerS2 deletion in mice results in bulk loss of sulfatides containing C23/C24 acyl chains in the kidney, with compensatory upregulation of C16–C20 acyl chain sulfatides; phytosphingosine-containing cortical sulfatides are completely depleted without compensation, establishing CerS2 as uniquely required for these species.\",\n      \"method\": \"CerS2 knockout mice, imaging mass spectrometry (IMS), LC-MS/MS lipid profiling, regional mRNA expression analysis\",\n      \"journal\": \"Journal of lipid research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with direct lipid profiling by multiple MS methods\",\n      \"pmids\": [\"25267995\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CERS2 is an ER-resident ceramide synthase with substrate specificity for very-long-chain fatty acyl-CoAs (C22–C24), whose catalytic activity is positively regulated by CK2-mediated phosphorylation at C-terminal serine residues; it maintains myelin sphingolipids in oligodendrocytes and Schwann cells, regulates β-cell insulin secretion, inhibits tumor cell invasion by directly interacting with V-ATPase subunit ATP6V0C (via its homeodomain) to suppress V-ATPase activity and extracellular acidification, interacts with TFRC to modulate iron homeostasis and ferroptosis, stabilizes p53 by binding MDM2/MDMX, promotes β-catenin degradation via STK38/SCYL2/ATP6V0C interactions dependent on Ser248 phosphorylation, and interacts with IP3R1 to modulate ER-mitochondrial calcium flux and apoptosis.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"CERS2 is an endoplasmic reticulum-resident ceramide synthase that generates very-long-chain ceramides (C22–C24) essential for myelin sphingolipid maintenance, pancreatic β-cell insulin secretion, and hepatic lipid homeostasis. Its catalytic activity toward C22:0/C24:0-CoA substrates is positively regulated by CK2-mediated phosphorylation at C-terminal serine residues, and the common E115A variant (rs267738) is a partial loss-of-function allele that causes glucose intolerance and hepatic steatosis in knock-in mice [PMID:26887952, PMID:33705551, PMID:39792658]. Beyond its enzymatic role, CERS2 functions as a tumor suppressor through multiple protein–protein interactions: its homeodomain binds the V-ATPase V0 c-subunit (ATP6V0C) to inhibit proton pump activity, suppress extracellular acidification, and reduce MMP-dependent invasion; it stabilizes p53 by disrupting MDM2/MDMX-mediated degradation; it promotes phospho-β-catenin accumulation by inhibiting PP2A and engaging STK38/SCYL2; and it interacts with IP3R1 to modulate ER-to-mitochondria calcium flux and apoptosis [PMID:22580606, PMID:22991218, PMID:37963859, PMID:38191448, PMID:42012500]. CERS2 knockout mice exhibit loss of compacted myelin, cerebellar degeneration, hepatocarcinoma, and impaired liver regeneration, underscoring its non-redundant roles in neural, hepatic, and metabolic tissue homeostasis [PMID:19801672, PMID:28958935].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Identifying where CERS2 is expressed established it as the myelinating-cell ceramide synthase, predicting a role in myelin sphingolipid production before any loss-of-function data existed.\",\n      \"evidence\": \"In situ hybridization and RT-PCR in mouse brain showing oligodendrocyte- and Schwann-cell-specific expression peaking during active myelination\",\n      \"pmids\": [\"17901973\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No functional loss-of-function data at this point\", \"Expression pattern alone does not prove requirement\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Gene-trap knockout mice demonstrated that CERS2 is non-redundantly required for C24 ceramide synthesis, myelin compaction, and hepatic tumor suppression, converting expression data into a causal framework.\",\n      \"evidence\": \"CERS2 knockout mice with loss of C24:1 ceramide synthase activity, 50% myelin loss, MBP reduction, cerebellar degeneration, and hepatocarcinoma\",\n      \"pmids\": [\"19801672\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking ceramide loss to hepatocarcinogenesis unknown\", \"Whether myelin loss is cell-autonomous was not tested\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"CERS2 knockdown revealed a sphingolipid rheostat: loss of very-long-chain ceramides paradoxically elevates long-chain ceramides and triggers ER stress, showing that CERS2 depletion remodels the entire ceramide landscape.\",\n      \"evidence\": \"siRNA knockdown with mass spectrometry lipidomics and UPR marker western blots in cultured cells\",\n      \"pmids\": [\"19728861\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of compensatory C16 ceramide increase not resolved\", \"In vivo ER stress consequence not tested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Overexpression studies in hepatocellular carcinoma cells first linked CERS2's tumor-suppressive action to V-ATPase-dependent intracellular acidification and mitochondrial apoptosis, opening a non-enzymatic interaction axis.\",\n      \"evidence\": \"pH-sensitive fluorescence probes and Annexin-V/PI flow cytometry after LASS2 overexpression in HCCLM3 cells\",\n      \"pmids\": [\"20571735\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct physical interaction with V-ATPase not yet mapped\", \"Ceramide-dependent vs. -independent contribution not delineated\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Demonstrating that CERS2 directly binds and inhibits V-ATPase subunit ATP6V0C established a ceramide synthase-independent protein-interaction mechanism for tumor suppression via extracellular pH control and MMP-2 reduction.\",\n      \"evidence\": \"Co-IP, V-ATPase activity assays, pH measurements, invasion assays, and xenograft models in breast cancer cells\",\n      \"pmids\": [\"22580606\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether ceramide synthesis is dispensable for V-ATPase regulation not formally separated\", \"Structural basis of interaction unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Domain-deletion mapping pinpointed the CERS2 homeodomain as the required interface for ATP6V0C binding, linking a specific structural element to V-ATPase inhibition and apoptosis induction.\",\n      \"evidence\": \"Co-IP with domain-deletion constructs, immuno-electron microscopy, and BCECF pH probes\",\n      \"pmids\": [\"22991218\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No atomic-resolution structure of the homeodomain–ATP6V0C complex\", \"Homeodomain contribution to ceramide synthase activity not assessed\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Loss-of-function studies extended the V-ATPase axis to prostate cancer metastasis, showing CERS2 silencing activates MMP-2/9 and promotes lymph node metastasis in vivo, reinforcing generality across cancer types.\",\n      \"evidence\": \"shRNA stable knockdown, MMP zymography, and lymph node metastasis xenograft model in PC-3M-2B4 cells\",\n      \"pmids\": [\"24453046\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contribution of ceramide product changes vs. V-ATPase interaction to metastasis unclear\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Lipidomic analysis of CERS2 knockout kidneys revealed that phytosphingosine-based cortical sulfatides are entirely CERS2-dependent and cannot be compensated by other CerS isoforms, defining a unique lipid niche.\",\n      \"evidence\": \"Imaging mass spectrometry and LC-MS/MS in CerS2 knockout mouse kidneys\",\n      \"pmids\": [\"25267995\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of phytosphingosine sulfatide loss in kidney not characterized\", \"Single lab study\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identification of CK2-mediated phosphorylation as a Vmax regulator of CERS2 catalytic activity established the first post-translational control mechanism for this enzyme.\",\n      \"evidence\": \"CK2 inhibitor CX-4945, in vitro ceramide synthase activity assays, and phosphorylation site mapping in mouse brain\",\n      \"pmids\": [\"26887952\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific phosphorylated residues not fully resolved\", \"In vivo phosphosite mutant mice not generated\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Liver-specific CERS2 knockout showed impaired hepatocyte cell cycle progression after partial hepatectomy, demonstrating a non-tumor-suppressive proliferative role for CERS2 in regenerating tissue.\",\n      \"evidence\": \"Cre-LoxP liver-specific knockout, partial hepatectomy, Co-IP for CDK4/cyclin D1\",\n      \"pmids\": [\"28958935\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether the effect is ceramide-dependent or interaction-dependent unknown\", \"Single lab observation\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Placing CERS2 upstream of ERK–Drp1 signaling showed it controls mitochondrial dynamics: depletion shifts the fission–fusion balance toward fission, increasing invasion and chemoresistance.\",\n      \"evidence\": \"Gain/loss-of-function with ERK and Drp1 inhibitors, MitoTracker and JC-1 staining in bladder cancer cells\",\n      \"pmids\": [\"29581781\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism connecting CERS2 to ERK inhibition not identified\", \"No direct binding partner for ERK regulation shown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Discovery of the CERS2–NDUFS2 interaction linked CERS2 to mitochondrial complex I ROS production and downstream AMPK-mediated lipogenesis inhibition, revealing a metabolic regulatory arm.\",\n      \"evidence\": \"Co-IP and LC-MS identification of NDUFS2, AMPK/ACC phosphorylation western blots, lipid content assays\",\n      \"pmids\": [\"32279995\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Interaction validated in single lab only\", \"Whether CERS2 catalytic product or physical interaction drives ROS is unresolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"CRISPR knock-in of the human E115A variant (rs267738) in mice confirmed it as a partial loss-of-function allele causing metabolic syndrome features, bridging a common human polymorphism to CERS2 enzymatic insufficiency.\",\n      \"evidence\": \"CRISPR knock-in mouse, in vitro ceramide synthase activity, lipidomics, glucose tolerance testing\",\n      \"pmids\": [\"33705551\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Human clinical phenotype data for homozygous carriers still limited\", \"Tissue-specific consequences beyond liver not characterized\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Epistasis experiments positioned CERS2-derived VLC ceramides as effectors of oncogene-induced senescence downstream of sphingosine kinase 1, providing a defined sphingolipid-to-cell-fate signaling axis.\",\n      \"evidence\": \"siRNA epistasis of CerS2 and SK1, lipidomics, p21/SA-β-gal assays in K-Ras-transformed MCF10A cells\",\n      \"pmids\": [\"33414460\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct ceramide species responsible for p21 induction not identified\", \"In vivo validation lacking\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Ser248 phosphorylation was shown to be required for CERS2's ability to promote β-catenin ubiquitin-proteasomal degradation via a STK38/SCYL2/ATP6V0C complex, connecting V-ATPase interactions to Wnt pathway suppression.\",\n      \"evidence\": \"Co-IP, S248A mutagenesis, ubiquitin-proteasome assays, and xenograft models in prostate cancer\",\n      \"pmids\": [\"33852174\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Kinase responsible for Ser248 phosphorylation not identified\", \"Single lab, not independently replicated\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identification of Nrf2 as a direct transcriptional activator of the CERS2 promoter via ARE elements established the first defined transcription factor–CERS2 regulatory relationship.\",\n      \"evidence\": \"Luciferase reporter assays with ARE-containing CERS2 promoter, siRNA knockdown in endometrial cancer cells\",\n      \"pmids\": [\"33841656\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Other transcription factors regulating CERS2 not surveyed\", \"Functional impact on ceramide levels not measured\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Demonstrating that CERS2 binds MDM2 and MDMX to stabilize p53 (promoting Ser15 phosphorylation and Lys373 acetylation) added a p53-dependent tumor-suppressive mechanism independent of the V-ATPase axis.\",\n      \"evidence\": \"Co-IP for MDM2/MDMX, western blots for p53 modifications, overexpression/knockdown in liver cancer cells\",\n      \"pmids\": [\"37963859\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Not independently replicated\", \"Whether ceramide synthase activity is required for MDM2 binding unknown\", \"Structural basis of CERS2–MDM2 interaction not resolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Discovery of the CERS2–TFRC interaction linked CERS2 to iron homeostasis and ferroptosis regulation, opening a new functional axis beyond sphingolipid metabolism and V-ATPase.\",\n      \"evidence\": \"Co-IP LC-MS, proximity ligation assay, multi-omics, ferroptosis assays across thyroid, breast, and liver cancer lines\",\n      \"pmids\": [\"38419028\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which CERS2 alters TFRC function not defined\", \"Single lab\", \"Ceramide dependence not tested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Showing that CERS2 inhibits PP2A to maintain phospho-β-catenin and reduce stemness markers (CD44, ABCC2) provided a mechanistic basis for cisplatin resensitization in bladder cancer stem cells.\",\n      \"evidence\": \"Co-IP, LC-MS, ChIP, luciferase reporters, patient-derived xenografts in bladder cancer\",\n      \"pmids\": [\"38191448\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"PP2A subunit specificity not determined\", \"Independent replication needed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Ex vivo islet studies from both CERS2 knockout and E115A knock-in mice established that CERS2-derived VLC sphingolipids are required for glucose-stimulated insulin secretion, translating whole-body metabolic phenotypes to a defined β-cell mechanism.\",\n      \"evidence\": \"Two genetic mouse models with ex vivo islet glucose-stimulated insulin secretion assays and metabolomics\",\n      \"pmids\": [\"39792658\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific sphingolipid species mediating β-cell exocytosis not identified\", \"Human islet validation not performed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identification of CERS2–IP3R1 interaction and pharmacological activation by DH20931 demonstrated that CERS2 modulates ER-mitochondrial calcium transfer and apoptosis, providing both a novel interactor and a tool compound.\",\n      \"evidence\": \"Co-IP, calcium flux measurements, ER-mitochondria proximity assays, DH20931 agonist treatment, xenograft models\",\n      \"pmids\": [\"42012500\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"DH20931 selectivity for CERS2 vs. other CerS not fully characterized\", \"Whether IP3R1 interaction is ceramide-dependent unclear\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Phospho-site mapping identified Ser348 as required for V-ATPase suppression and anti-invasive function, adding a second regulatory phosphosite (alongside Ser248) to the growing picture of CERS2 post-translational control.\",\n      \"evidence\": \"Mass spectrometry phosphosite mapping, S348A mutagenesis, V-ATPase and MMP-2 assays in prostate cancer cells\",\n      \"pmids\": [\"41399074\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Kinase phosphorylating Ser348 not identified\", \"Relationship between Ser348 and CK2-regulated C-terminal sites not clarified\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A central unresolved question is whether CERS2's numerous protein–protein interactions (ATP6V0C, MDM2, TFRC, IP3R1, NDUFS2, PP2A) operate independently of its ceramide synthase catalytic activity, and how its multiple phosphosites are coordinately regulated to direct these distinct functions.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No catalytic-dead separation-of-function mutant tested across interaction partners\", \"No structural model of full-length CERS2\", \"Interplay between CK2 phosphorylation and Ser248/Ser348 phosphorylation unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 2, 3, 17, 21]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [4, 5, 7, 11, 20]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [0, 3, 21]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [0, 19]},\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [6, 15, 19]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 2, 3, 17, 21]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [6, 19]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [9, 11, 14]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [4, 7, 8, 10]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"ATP6V0C\",\n      \"MDM2\",\n      \"MDMX\",\n      \"TFRC\",\n      \"ITPR1\",\n      \"NDUFS2\",\n      \"STK38\",\n      \"SCYL2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}