{"gene":"ELOVL2","run_date":"2026-06-09T23:54:43","timeline":{"discoveries":[{"year":2010,"finding":"ELOVL2 is required for elongation of very-long-chain n-6 PUFAs (C24–C30) in testis; Elovl2-knockout mice show complete spermatogenesis arrest at the spermatocyte stage, and heterozygous (haploinsufficient) males have reduced C28:5 and C30:5 n-6 PUFAs with impaired spermatid formation, establishing ELOVL2-derived VLC-PUFAs as essential for male fertility.","method":"Elovl2 knockout and heterozygous mouse model; acyl-CoA profiling; histological analysis of seminiferous tubules; dietary DHA supplementation rescue experiment","journal":"Journal of lipid research","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — clean KO and haploinsufficiency demonstrated with multiple biochemical and histological readouts, negative rescue by DHA supplementation providing mechanistic specificity","pmids":["21106902"],"is_preprint":false},{"year":2014,"finding":"ELOVL2 primarily catalyzes elongation of C22 PUFAs (22:5n-3 and 22:4n-6) to C24 precursors for endogenous DHA and DPAn-6 synthesis in liver in vivo; Elovl2-knockout mice accumulate 22:5n-3 and 22:4n-6 and have drastically reduced DHA and DPAn-6 in liver and serum. Loss of hepatic DHA synthesis activates SREBP-1c and downstream lipogenic genes, yet paradoxically protects against hepatic steatosis and diet-induced obesity. DHA dietary supplementation reverses fatty acid and gene-expression changes.","method":"Elovl2 knockout mouse; hepatic lipid composition analysis; gene expression (SREBP-1c and target genes); high-fat diet challenge; DHA supplementation rescue","journal":"Journal of lipid research","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (lipidomics, transcriptomics, dietary rescue) in a well-controlled KO model","pmids":["24489111"],"is_preprint":false},{"year":2013,"finding":"The ability of rat Elovl2 (but not Elovl5) to elongate C22 omega-3 DPA (22:5n-3) to 24:5n-3 is determined by a single cysteine residue at position 217 in transmembrane domains 6–7; substituting this cysteine abolishes the DPA elongation activity, whereas an equivalent tryptophan at the same position in Elovl5 explains its inability to elongate C22 substrates.","method":"Yeast heterologous expression system; Elovl2/Elovl5 chimeric constructs; site-directed point mutagenesis (C217 in Elovl2); fatty acid substrate activity assays","journal":"Journal of lipid research","confidence":"High","confidence_rationale":"Tier 1 / Moderate — reconstitution in yeast with mutagenesis identifying a specific catalytic residue, single lab but multiple chimera/point-mutant constructs providing orthogonal support","pmids":["23873268"],"is_preprint":false},{"year":2020,"finding":"Age-related decrease in Elovl2 expression in mouse retina is associated with increased DNA methylation of its promoter; reversal of promoter hypermethylation by intravitreal 5-Aza-2'-deoxycytidine restores Elovl2 expression and rescues age-related visual function decline. A point mutation C234W that disrupts Elovl2 enzymatic activity causes premature electrophysiological visual decline, early autofluorescent deposits, and sub-RPE deposits resembling human drusen components.","method":"Intravitreal 5-Aza-dc injection in aged mice; electroretinography; Elovl2 C234W enzymatic point mutant knock-in mice; autofluorescence imaging; histological analysis of sub-RPE deposits","journal":"Aging cell","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — enzymatic point mutant combined with pharmacological demethylation rescue, multiple orthogonal functional readouts (ERG, imaging, histology)","pmids":["31943697"],"is_preprint":false},{"year":2007,"finding":"Overexpression of ELOVL2 in preadipocyte cell lines (3T3-L1 and F442A) enhances triacylglycerol synthesis and lipid droplet accumulation by increasing fatty acid (but not glucose) incorporation into TAG, and induces expression of lipogenic genes DGAT2 and FABP4/aP2.","method":"Overexpression of ELOVL2 in preadipocyte cell lines; TAG synthesis assay; [14C]-fatty acid and glucose incorporation; RT-PCR for DGAT2 and FABP4","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — overexpression with biochemical substrate-tracing and gene expression assays in two cell lines, single lab","pmids":["17583696"],"is_preprint":false},{"year":2016,"finding":"Estradiol upregulates Elovl2 expression in MCF7 breast cancer cells via estrogen receptor alpha (ERα); ERα binds a specific estrogen response element (ERE) within the Elovl2 enhancer in a ligand-dependent manner, and tamoxifen or ERα knockdown specifically abolishes Elovl2 (but not Elovl5) upregulation.","method":"Estradiol stimulation of MCF7 cells; tamoxifen treatment; ERα siRNA knockdown; chromatin immunoprecipitation (ChIP) for ERα binding at Elovl2 ERE; RT-PCR","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — ChIP identifying specific ERE binding site combined with siRNA knockdown and pharmacological inhibition, multiple orthogonal methods in one study","pmids":["27788154"],"is_preprint":false},{"year":2017,"finding":"Elovl2 is a network hub gene in pancreatic beta cells; Elovl2 silencing in mouse and human beta cell lines decreases glucose-stimulated insulin secretion (GSIS), placing ELOVL2 as a molecular regulator of normal insulin secretory responses to glucose.","method":"Network-based integration of RNA-Seq and phenotypic data from multi-strain mouse islets; Elovl2 siRNA silencing in mouse and human beta cell lines; GSIS assay","journal":"Molecular metabolism","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown with functional GSIS readout in two cell types, single lab","pmids":["28377873"],"is_preprint":false},{"year":2018,"finding":"ELOVL2/DHA axis protects rodent and human beta cells from glucolipotoxicity-induced apoptosis by promoting palmitate oxidation via a CPT1-dependent mechanism; ELOVL2 downregulation potentiates apoptosis, while adenoviral overexpression or DHA supplementation partially inhibits cell death and reduces ceramide accumulation. The anti-apoptotic effect requires AMPK and CPT1 activity.","method":"ELOVL2 siRNA knockdown and adenoviral overexpression in INS-1 cells and human islets; caspase-3 and PARP cleavage assays; [U-14C]palmitate oxidation and esterification assays; ceramide/DAG measurement; pharmacological inhibition of AMPK and CPT1 (etomoxir); CPT1 siRNA and constitutively active CPT1 construct","journal":"Diabetologia","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal methods (isotope tracing, enzymatic assays, pharmacological and genetic inhibition of pathway components) in rodent and human cells, single lab","pmids":["29754287"],"is_preprint":false},{"year":2019,"finding":"MYCN represses ELOVL2 transcription in neuroblastoma by recruiting Polycomb repressive complex 1 (PRC1), which catalyzes H2AK119 monoubiquitination at the ELOVL2 locus; this suppresses DHA synthesis. Forced ELOVL2 expression in MYCN-amplified cells reduces proliferation and counteracts MYCN's growth-promoting effect in vitro and in vivo.","method":"GC-MS fatty acid profiling; ChIP for MYCN and H2AK119ub at ELOVL2 locus; immunoprecipitation–mass spectrometry (IP-MS) to identify PRC1 as MYCN co-repressor; ELOVL2 overexpression and knockdown; xenograft mouse model; CCK-8, soft agar, flow cytometry assays","journal":"Journal of experimental & clinical cancer research","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — ChIP establishing epigenetic mechanism at ELOVL2 locus, IP-MS identifying co-repressor complex, combined with functional rescue experiments, single lab","pmids":["31856871"],"is_preprint":false},{"year":2020,"finding":"The intronic SNP rs953413 in ELOVL2 lies within a functional FOXA1/FOXA2 and HNF4α cooperative binding site; the G allele increases binding of these transcription factors to an evolutionarily conserved enhancer, conferring allele-specific upregulation of ELOVL2. Knockdown of FOXA1, FOXA2, or HNF4α, and CRISPR/Cas9-mediated disruption of the enhancer element, each significantly downregulate ELOVL2 expression.","method":"FOXA1/FOXA2/HNF4α knockdown; CRISPR/Cas9 enhancer deletion; allele-specific reporter assays; ChIP; GWAS functional annotation","journal":"iScience","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — CRISPR enhancer disruption and TF knockdown with allele-specific gene expression, multiple orthogonal methods in one study","pmids":["31928966"],"is_preprint":false},{"year":2021,"finding":"ADIPOR1 is required for ELOVL2 expression in photoreceptor inner segments; Adipor1 knockout mice show significantly reduced Elovl2 expression and decreased retinal DHA, accompanied by misaligned photoreceptor outer segments and progressive photoreceptor degeneration. The causal relationship between ADIPOR1 deficiency and Elovl2 repression (with upregulation of lipogenic genes) was confirmed in vitro.","method":"Adipor1 knockout mice; electroretinography; electron microscopy; lipid composition analysis; mRNA/protein expression; in vitro ADIPOR1 knockdown confirming Elovl2 downregulation","journal":"Cell death & disease","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vivo KO with functional (ERG) and ultrastructural readouts combined with in vitro confirmation of ADIPOR1→ELOVL2 axis","pmids":["33963174"],"is_preprint":false},{"year":2022,"finding":"Elovl2 ablation in mice causes DHA and DPAn-6 depletion in liver mitochondrial membranes, leading to mitochondrial dysfunction characterized by increased oligomycin-insensitive oxygen consumption, reduced respiratory control coefficients (~50% reduction), and hypersensitivity to fatty acid-induced uncoupling and permeabilization, with ANT2 implicated; mitochondrial volume and peroxisome numbers increase without loss of respiratory chain proteins or oxidative damage.","method":"Elovl2 knockout mice; mitochondrial membrane fatty acid composition analysis; mitochondrial respiration assays (oligomycin, uncoupling agents); oxidative stress biomarkers (MDAL); transmission electron microscopy; Western blot for respiratory chain proteins and VDAC/ANT2","journal":"Nutrients","confidence":"High","confidence_rationale":"Tier 2 / Moderate — KO mouse with multiple orthogonal mitochondrial functional assays and molecular characterization, single lab","pmids":["35276915"],"is_preprint":false},{"year":2024,"finding":"AdipoR2 regulates ELOVL2 both transcriptionally and post-transcriptionally in male meiotic germ cells to synthesize VLC-PUFAs in sphingolipids; depletion of VLC-PUFAs in AdipoR2 knockout testes causes membrane stiffening, nuclear envelope invagination, impaired nuclear peripheral distribution of meiotic telomeres, errors in homologous synapsis and recombination, and disrupted intercellular bridge/syncytium formation.","method":"AdipoR2 knockout mice; lipidomic analysis of testis; meiotic telomere and synapsis analysis; intercellular bridge/syncytium imaging; mechanistic studies of membrane fluidity","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo KO with lipidomics, chromosome biology, and membrane biophysics readouts; multi-method study in Nature Communications","pmids":["38485951"],"is_preprint":false},{"year":2009,"finding":"Atlantic salmon Elovl2 elongates C20 and C22 PUFAs (with lower activity toward C18), distinct from Elovl5b which elongates C18 and C20; heterologous yeast expression confirms that Elovl2 is the elongase enabling DHA biosynthesis via the Sprecher pathway. Hepatic and intestinal Elovl2 expression is significantly upregulated in salmon fed vegetable oil versus fish oil diets.","method":"Cloning of salmon elovl2 cDNA; heterologous yeast expression with fatty acid substrate assays; tissue expression profiling; nutritional regulation experiment (fish oil vs. vegetable oil diets)","journal":"Marine biotechnology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — reconstitution in yeast establishing substrate specificity, complemented by nutritional regulation in vivo, single lab","pmids":["19184219"],"is_preprint":false},{"year":2016,"finding":"Elovl2 evolved from genome duplications in vertebrate ancestry (diverging from the single ancestral Elovl2/5 gene); the ability to efficiently elongate C22 PUFA substrates (enabling DHA synthesis via the Sprecher pathway) emerged specifically in the jawed vertebrate ancestor, as demonstrated by functional characterization of elongases from amphioxus, lamprey, and elephant shark.","method":"Heterologous yeast expression of Elovl2/5 from amphioxus, sea lamprey, and elephant shark; fatty acid substrate activity assays; phylogenetic analysis","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 1 / Moderate — reconstitution in yeast across multiple species with substrate activity assays establishing evolutionary gain of C22 elongation function","pmids":["26856376"],"is_preprint":false},{"year":2021,"finding":"ELOVL2 knockdown (CRISPR/Cas9) in renal cancer cells suppresses elongation of long-chain PUFAs, increases lipid droplet production, inhibits cell proliferation via apoptosis induction in vitro, and attenuates tumor growth in vivo.","method":"CRISPR/Cas9-mediated ELOVL2 knockdown in renal cancer cell lines; fatty acid profiling; lipid droplet staining; cell proliferation and apoptosis assays; in vivo xenograft","journal":"Oncology reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR KD with biochemical and functional readouts in vitro and in vivo, single lab","pmids":["34841437"],"is_preprint":false},{"year":2022,"finding":"ELOVL2 knockdown in prostate cancer cells activates the PI3K/Akt signaling pathway by downregulating INPP4B (a tumor suppressor phosphatase); overexpression of INPP4B rescues the pro-proliferative and pro-invasive phenotype caused by ELOVL2 knockdown, placing ELOVL2 upstream of INPP4B in regulation of PI3K/Akt signaling.","method":"ELOVL2 shRNA knockdown and overexpression in prostate cancer cell lines; INPP4B overexpression rescue; CCK8, colony formation, transwell invasion assays; subcutaneous xenograft; Western blot for PI3K/Akt pathway components","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis (INPP4B rescue of ELOVL2-KD phenotype) with functional assays, single lab","pmids":["35640821"],"is_preprint":false},{"year":2025,"finding":"ELOVL2 facilitates enzalutamide resistance in castration-resistant prostate cancer by impairing the ubiquitin-proteasome system, leading to stabilization (reduced degradation) of androgen receptor (AR) and subsequent AR signaling activation; ELOVL2 inhibition suppresses proliferation and restores enzalutamide sensitivity.","method":"Bioinformatic analysis of LNCaP/enzalutamide-resistant cells; ELOVL2 targeted inhibition; cell proliferation assay; ubiquitin-proteasome pathway assays; AR protein stability/signaling assays","journal":"Frontiers in cell and developmental biology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — abstract describes mechanistic pathway (ubiquitin-proteasome/AR stabilization) but only single method description available from abstract without full biochemical reconstitution details; single lab","pmids":["40552308"],"is_preprint":false},{"year":2019,"finding":"CRISPR/Cas9-mediated elovl2 knockout in Atlantic salmon reduces 22:6n-3 (DHA) and causes accumulation of 20:5n-3 and 22:5n-3 in liver, brain, and white muscle, demonstrating that elovl2 catalyzes two penultimate elongation steps in PUFA synthesis in vivo. Loss of endogenous DHA synthesis induces hepatic expression of srebp-1, fatty acid synthase-b, Δ6fad-a, Δ5fad, and elovl5, identifying Srebp-1 as a main transcriptional regulator of PUFA synthesis.","method":"CRISPR/Cas9 elovl2 partial knockout in Atlantic salmon; tissue fatty acid profiling; hepatic gene expression analysis","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vivo CRISPR KO with multi-tissue lipidomics and transcriptomics establishing both substrate specificity and downstream transcriptional regulation","pmids":["31101849"],"is_preprint":false},{"year":2020,"finding":"Elovl2 (but not Elovl5) is essential for DHA biosynthesis in zebrafish; elovl2 knockout reduces DHA by 67% in adult liver and 92% in embryos. Compensatory upregulation of elovl5 in elovl2 KO (15-fold) cannot rescue DHA deficiency, whereas elovl2 upregulation fully compensates for elovl5 loss, establishing the non-redundant role of Elovl2 in endogenous DHA synthesis.","method":"CRISPR/Cas9 elovl2 and elovl5 single and double knockout zebrafish; fatty acid profiling; gene expression analysis","journal":"Marine biotechnology","confidence":"High","confidence_rationale":"Tier 2 / Strong — comparative KO study with genetic epistasis (compensability of elovl2 by elovl5 and vice versa) establishing irreplaceable enzymatic role of Elovl2 in DHA synthesis","pmids":["32880080"],"is_preprint":false},{"year":2020,"finding":"Elovl2 loss in zebrafish embryos causes changes in retinal lipid composition (especially DHA-containing lipids) and impairs visual behavior (VMR-OFF response), with increased retinal thickness but no gross disruption of retinal architecture. Elovl2 is expressed in Müller glia in embryonic and adult zebrafish retina.","method":"elovl2 CRISPR crispants in zebrafish; whole-mount in situ hybridization; lipidomics; histological analysis; visual motor reflex assay","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo gene disruption with lipidomics and functional visual assay; localization by WISH; single lab","pmids":["33276584"],"is_preprint":false},{"year":2017,"finding":"ELOVL2 hypermethylation is associated with in vitro cell replication (cell divisions) rather than replicative senescence per se, as shown by primary dermal fibroblast cultures from donors of different ages and replication experiments, suggesting the epigenetic clock at this locus is driven by cumulative cell divisions.","method":"Primary dermal fibroblast cultures; in vitro replication vs. senescence experiments; longitudinal cohort methylation analysis (Doetinchem Cohort Study); public epigenomic data analysis across 16 tissues","journal":"The journals of gerontology. Series A","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro cell biology experiments distinguishing replication from senescence, supported by longitudinal cohort data; single lab primary experiments","pmids":["27672102"],"is_preprint":false},{"year":2026,"finding":"POU2F1 transcription factor directly activates ELOVL2 transcription in endometrial cancer, promoting ELOVL2-associated lipid metabolic remodeling; POU2F1-driven proliferation, migration, invasion, and xenograft growth are ELOVL2-dependent.","method":"Bioinformatics; ChIP or reporter assay for POU2F1 binding to ELOVL2 promoter (mechanistic validation described); functional assays with ELOVL2 knockdown rescue; xenograft","journal":"Cancer & metabolism","confidence":"Low","confidence_rationale":"Tier 3 / Weak — mechanistic claim of direct transcriptional activation by POU2F1 stated but full experimental details are limited in the abstract; single lab, single paper","pmids":["41947242"],"is_preprint":false},{"year":2026,"finding":"Co-overexpression of ELOVL2 and ELOVL5 in clear cell renal cell carcinoma promotes invasion and invadopodia formation through a LIMK1-mediated cytoskeletal reorganization pathway; dual siRNA knockdown of ELOVL2/ELOVL5 downregulates actin filament-related processes and LIMK1, and LIMK1 knockdown phenocopies the anti-invasive effects of dual elongase knockdown.","method":"siRNA knockdown of ELOVL2 and ELOVL5 in renal cancer cell lines; transcriptomic profiling; pathway analysis; LIMK1 knockdown; proliferation, invasion, and invadopodia formation assays; TCGA data","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA epistasis (LIMK1 KD phenocopies dual elongase KD) with transcriptomics and functional assays in renal cancer cells, single lab","pmids":["42225919"],"is_preprint":false},{"year":2024,"finding":"Elovl2 enzymatic activity-deficient mice (C234W) show impaired contrast sensitivity and slower rod response recovery after bright light. Intravitreal supplementation with 24:5n-3 (the direct product of ELOVL2) in aged mice improves visual function, reduces accumulation of ApoE, HTRA1, and complement proteins in sub-RPE deposits, and produces a partial transcriptomic rejuvenation signature in retinal gene expression.","method":"Elovl2 C234W enzymatic mutant mice; electroretinography; intravitreal 24:5n-3 supplementation; retinal histology and immunohistochemistry for drusen components; RNA-seq transcriptomic profiling","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — enzymatic point mutant combined with direct product rescue in vivo with multiple functional and molecular readouts; preprint, not yet peer-reviewed","pmids":["bio_10.1101_2024.07.01.601592"],"is_preprint":true},{"year":2024,"finding":"Loss of Elovl2 enzymatic activity in mice causes global downregulation of lymphoid/B cell gene markers in bone marrow and an aging-associated loss of B cell progenitors, suggesting ELOVL2-derived PUFAs are required for normal B cell development. A rare ELOVL2-expressing HSPC subpopulation (<7% of CD34+ cells) is nearly absent in elderly (>60 years) human bone marrow.","method":"RNA-seq of bone marrow from aged Elovl2 mutant vs. wild-type mice; flow cytometry for immune cell markers; lipidomics of bone marrow; single-cell RNA-seq of human HSPCs across age groups","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 3 / Weak — preprint; transcriptomics and flow cytometry describe the phenotype but direct mechanistic link between ELOVL2 lipid products and B cell development is not yet biochemically established","pmids":["bio_10.1101_2024.09.26.614999"],"is_preprint":true}],"current_model":"ELOVL2 is a microsomal fatty acid elongase that catalyzes rate-limiting elongation of C20–C22 polyunsaturated fatty acids to C24 intermediates required for endogenous DHA (and DPAn-6) synthesis; a single cysteine (C217 in rat) in transmembrane domains 6–7 confers C22-substrate specificity, while the C234W mutation abolishes enzymatic activity in vivo. Loss of ELOVL2 disrupts DHA homeostasis in liver, retina, testis, and mitochondria, leading to male infertility (arrest of spermatogenesis via loss of VLC-PUFAs), retinal aging and visual decline (rescued by its direct product 24:5n-3 or by promoter demethylation), impaired mitochondrial respiration, and dysregulated lipid/glucose metabolism including reduced glucose-stimulated insulin secretion; its expression is transcriptionally controlled by ERα (via a specific ERE in the Elovl2 enhancer), by FOXA1/FOXA2 and HNF4α (via an intronic enhancer), by POU2F1, and is epigenetically repressed by MYCN–PRC1-mediated H2AK119 ubiquitination, while AdipoR2 promotes ELOVL2 both transcriptionally and post-transcriptionally to maintain membrane fluidity for meiotic telomere dynamics."},"narrative":{"mechanistic_narrative":"ELOVL2 is a microsomal fatty acid elongase that catalyzes the rate-limiting elongation of C20–C22 polyunsaturated fatty acids, principally converting 22:5n-3 and 22:4n-6 to C24 precursors required for endogenous synthesis of DHA and DPAn-6 via the Sprecher pathway [PMID:24489111, PMID:23873268]. Substrate specificity for C22 acyl chains is conferred by a single cysteine residue (C217 in rat) within transmembrane domains 6–7, a feature whose acquisition in the jawed-vertebrate ancestor enabled DHA biosynthesis and which distinguishes ELOVL2 from the C18/C20-preferring paralog ELOVL5 [PMID:23873268, PMID:26856376]. Genetic ablation across mice, zebrafish, and salmon causes accumulation of C20/C22 substrates and severe depletion of DHA in liver, retina, brain, and germline, establishing a non-redundant role that cannot be rescued by compensatory ELOVL5 upregulation [PMID:31101849, PMID:32880080, PMID:33276584]. Through this control of DHA/VLC-PUFA supply, ELOVL2 supports diverse cellular processes: spermatogenesis, where its very-long-chain PUFA products are required for spermatocyte progression and, via AdipoR2-driven expression, for membrane fluidity governing meiotic telomere dynamics and homologous synapsis [PMID:21106902, PMID:38485951]; retinal photoreceptor maintenance, where age-related promoter hypermethylation lowers ELOVL2 expression and an enzyme-dead C234W mutation drives premature visual decline and sub-RPE drusen-like deposits that are rescued by its direct product 24:5n-3 [PMID:31943697]; hepatic and mitochondrial lipid homeostasis, where loss activates SREBP-1c lipogenic programs yet protects from steatosis while impairing mitochondrial respiratory coupling [PMID:24489111, PMID:35276915]; and pancreatic beta-cell function, where ELOVL2/DHA promotes glucose-stimulated insulin secretion and protects against glucolipotoxic apoptosis through AMPK/CPT1-dependent palmitate oxidation [PMID:28377873, PMID:29754287]. ELOVL2 transcription is governed by multiple inputs including estrogen receptor alpha acting at an enhancer ERE, cooperative FOXA1/FOXA2 and HNF4α binding at an intronic enhancer, and epigenetic repression by MYCN-recruited PRC1-mediated H2AK119 ubiquitination [PMID:27788154, PMID:31928966, PMID:31856871]. In cancer, ELOVL2 displays context-dependent roles, suppressing proliferation in MYCN-amplified neuroblastoma and renal carcinoma while supporting growth and invasion in other contexts [PMID:31856871, PMID:34841437].","teleology":[{"year":2009,"claim":"Whether ELOVL2 was the elongase responsible for the C20/C22 steps of DHA synthesis was unresolved; reconstitution in yeast established it as the enzyme enabling DHA biosynthesis via the Sprecher pathway.","evidence":"Cloning and heterologous yeast expression of salmon Elovl2 with fatty acid substrate assays, plus nutritional regulation in vivo","pmids":["19184219"],"confidence":"High","gaps":["Substrate specificity determinant not yet mapped to a residue","Mammalian in vivo confirmation not provided in this study"]},{"year":2010,"claim":"The physiological requirement for ELOVL2-derived very-long-chain PUFAs was unknown; knockout mice revealed it is essential for elongation of C24–C30 n-6 PUFAs in testis and for completion of spermatogenesis.","evidence":"Elovl2 knockout and haploinsufficient mice with acyl-CoA profiling, seminiferous tubule histology, and DHA dietary rescue","pmids":["21106902"],"confidence":"High","gaps":["Molecular basis for spermatocyte arrest not defined","Lipid species directly required for spermatid formation not pinpointed"]},{"year":2013,"claim":"The structural basis of ELOVL2's distinct C22 substrate preference relative to ELOVL5 was unexplained; mutagenesis identified a single cysteine (C217) in TM6–7 as the specificity determinant.","evidence":"Yeast expression of Elovl2/Elovl5 chimeras and C217 point mutants with substrate activity assays","pmids":["23873268"],"confidence":"High","gaps":["No structural model of the substrate-binding pocket","Whether the residue affects catalysis or only binding not resolved"]},{"year":2014,"claim":"The systemic metabolic consequence of losing hepatic DHA synthesis was unclear; KO mice showed substrate accumulation, SREBP-1c lipogenic activation, yet paradoxical protection from steatosis and diet-induced obesity.","evidence":"Elovl2 knockout mouse hepatic lipidomics, transcriptomics, high-fat diet challenge, and DHA rescue","pmids":["24489111"],"confidence":"High","gaps":["Mechanism linking DHA loss to SREBP-1c activation not defined","Reason for protection against steatosis unexplained"]},{"year":2016,"claim":"Transcriptional regulation of ELOVL2 was uncharacterized; estradiol was shown to upregulate it via ERα binding a specific ERE in the enhancer, and its evolutionary origin in jawed vertebrates was established.","evidence":"ChIP, ERα siRNA and tamoxifen in MCF7 cells; comparative yeast expression of elongases from amphioxus, lamprey, and elephant shark","pmids":["27788154","26856376"],"confidence":"High","gaps":["Physiological role of estrogen regulation outside breast cancer cells unclear","Other regulatory inputs not yet mapped"]},{"year":2017,"claim":"Whether ELOVL2 contributed to beta-cell function and to epigenetic aging was open; silencing impaired glucose-stimulated insulin secretion, and methylation studies linked the ELOVL2 epigenetic clock to cumulative cell divisions.","evidence":"siRNA silencing with GSIS assays in mouse/human beta cells; primary fibroblast replication-vs-senescence experiments and cohort methylation analysis","pmids":["28377873","27672102"],"confidence":"Medium","gaps":["Lipid mediator linking ELOVL2 to insulin secretion not identified","Causal direction of methylation changes for ELOVL2 function unresolved"]},{"year":2018,"claim":"The protective role of ELOVL2/DHA in beta cells was undefined; overexpression and knockdown showed it limits glucolipotoxic apoptosis by promoting CPT1-dependent palmitate oxidation requiring AMPK.","evidence":"siRNA and adenoviral overexpression in INS-1 cells and human islets with isotope tracing, ceramide measurement, and AMPK/CPT1 pharmacological and genetic perturbation","pmids":["29754287"],"confidence":"High","gaps":["Specific DHA-derived signal activating AMPK not identified","In vivo relevance to diabetes not tested"]},{"year":2019,"claim":"How ELOVL2 is silenced in aggressive cancers and whether it has tumor-suppressive function was unknown; MYCN was shown to recruit PRC1 to deposit H2AK119ub at the locus, repressing DHA synthesis and proliferation control.","evidence":"ChIP for MYCN and H2AK119ub, IP-MS identifying PRC1, ELOVL2 gain/loss-of-function, and xenograft assays in neuroblastoma; salmon CRISPR KO confirming dual elongation steps and SREBP-1 regulation in vivo","pmids":["31856871","31101849"],"confidence":"High","gaps":["Whether DHA itself mediates the anti-proliferative effect not fully resolved","Generality of MYCN-PRC1 repression across tumor types untested"]},{"year":2020,"claim":"The basis of ELOVL2 enhancer variation, its non-redundancy with ELOVL5, and its role in retinal aging were addressed; allele-specific FOXA/HNF4α binding controls expression, ELOVL5 cannot compensate for DHA loss, and promoter demethylation rescues age-related visual decline.","evidence":"CRISPR enhancer deletion and TF knockdown with allele-specific reporters; comparative zebrafish elovl2/elovl5 single and double KO; intravitreal 5-Aza-dc and C234W knock-in mice with ERG, imaging, and histology; zebrafish retinal lipidomics and visual assays","pmids":["31928966","32880080","31943697","33276584"],"confidence":"High","gaps":["Mechanism connecting DHA depletion to drusen-like deposits not defined","Cell-type specificity of demethylation rescue unresolved"]},{"year":2021,"claim":"Upstream regulators of retinal ELOVL2 and its role in renal cancer were probed; ADIPOR1 was shown to be required for photoreceptor ELOVL2 expression, and ELOVL2 knockdown suppressed PUFA elongation and renal tumor growth.","evidence":"Adipor1 knockout mice with ERG, EM, and lipid analysis plus in vitro confirmation; CRISPR ELOVL2 knockdown in renal cancer cells with fatty acid profiling and xenografts","pmids":["33963174","34841437"],"confidence":"High","gaps":["Signaling mechanism by which ADIPOR1 controls ELOVL2 not defined","Tumor-context determinants of ELOVL2's pro- vs anti-tumor role unclear"]},{"year":2022,"claim":"Whether ELOVL2 influences signaling pathways and mitochondrial function was tested; loss depleted mitochondrial membrane DHA causing respiratory uncoupling, and in prostate cancer ELOVL2 acted upstream of INPP4B to restrain PI3K/Akt signaling.","evidence":"Elovl2 KO mouse mitochondrial respiration assays, membrane lipidomics, and EM; ELOVL2 knockdown/overexpression with INPP4B rescue and PI3K/Akt Western blots in prostate cancer","pmids":["35276915","35640821"],"confidence":"High","gaps":["Role of ANT2 in uncoupling phenotype not mechanistically resolved","Direct link between ELOVL2 lipids and INPP4B regulation not established"]},{"year":2024,"claim":"The membrane-biophysical and direct-product mechanisms of ELOVL2 were addressed; AdipoR2-driven ELOVL2 generates VLC-PUFA sphingolipids needed for meiotic telomere dynamics, and 24:5n-3 supplementation rescues aged retinal function.","evidence":"AdipoR2 KO mouse testis lipidomics with meiotic chromosome and membrane-fluidity readouts; C234W mutant mice with intravitreal 24:5n-3 supplementation, drusen-component IHC, and retinal RNA-seq (preprint for the retina study)","pmids":["38485951","bio_10.1101_2024.07.01.601592"],"confidence":"High","gaps":["Biophysical mechanism linking VLC-PUFAs to telomere tethering not fully resolved","Durability and translatability of 24:5n-3 rescue unknown"]},{"year":2026,"claim":"Additional transcriptional and cancer-resistance roles were explored; POU2F1 was reported to activate ELOVL2 in endometrial cancer, ELOVL2/ELOVL5 co-overexpression to drive renal cancer invasion via LIMK1, and ELOVL2 to support enzalutamide resistance by stabilizing AR.","evidence":"ChIP/reporter and knockdown-rescue in endometrial cancer; dual siRNA with transcriptomics and LIMK1 epistasis in renal cancer; ubiquitin-proteasome and AR stability assays in castration-resistant prostate cancer","pmids":["41947242","42225919","40552308"],"confidence":"Low","gaps":["AR stabilization mechanism described only at abstract level without full biochemical reconstitution","POU2F1 direct binding validation limited","Whether enzymatic elongase activity is required for these signaling effects untested"]},{"year":null,"claim":"How ELOVL2-derived lipid species are mechanistically read out by distinct downstream processes — membrane biophysics in germ cells, mitochondrial coupling, drusen formation, B-cell development, and oncogenic signaling — remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of the human enzyme or substrate channel","Direct lipid-to-effector links largely inferred from product/substrate manipulation","Tissue-specific determinants of ELOVL2's pro- vs anti-proliferative roles undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[1,2,13,14,18,19]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[1,2,4,18]},{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[0,12]}],"complexes":[],"partners":[],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9NXB9","full_name":"Very long chain fatty acid elongase 2","aliases":["3-keto acyl-CoA synthase ELOVL2","ELOVL fatty acid elongase 2","ELOVL FA elongase 2","Elongation of very long chain fatty acids protein 2","Very long chain 3-ketoacyl-CoA synthase 2","Very long chain 3-oxoacyl-CoA synthase 2"],"length_aa":296,"mass_kda":34.6,"function":"Catalyzes the first and rate-limiting reaction of the four reactions that constitute the long-chain fatty acids elongation cycle. This endoplasmic reticulum-bound enzymatic process allows the addition of 2 carbons to the chain of long- and very long-chain fatty acids (VLCFAs) per cycle. Condensing enzyme that catalyzes the synthesis of polyunsaturated very long chain fatty acid (C20- and C22-PUFA), acting specifically toward polyunsaturated acyl-CoA with the higher activity toward C20:4(n-6) acyl-CoA. May participate in the production of polyunsaturated VLCFAs of different chain lengths that are involved in multiple biological processes as precursors of membrane lipids and lipid mediators","subcellular_location":"Endoplasmic reticulum membrane","url":"https://www.uniprot.org/uniprotkb/Q9NXB9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ELOVL2","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ELOVL2","total_profiled":1310},"omim":[{"mim_id":"612795","title":"POLYUNSATURATED FATTY ACIDS PLASMA LEVEL QUANTITATIVE TRAIT LOCUS 1; PUFAQTL1","url":"https://www.omim.org/entry/612795"},{"mim_id":"611815","title":"ELONGATION OF VERY LONG CHAIN FATTY ACIDS-LIKE 3; ELOVL3","url":"https://www.omim.org/entry/611815"},{"mim_id":"611814","title":"ELONGATION OF VERY LONG CHAIN FATTY ACIDS-LIKE 2; ELOVL2","url":"https://www.omim.org/entry/611814"},{"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":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"brain","ntpm":20.3},{"tissue":"liver","ntpm":49.1},{"tissue":"placenta","ntpm":33.1},{"tissue":"retina","ntpm":25.8}],"url":"https://www.proteinatlas.org/search/ELOVL2"},"hgnc":{"alias_symbol":["Ssc2"],"prev_symbol":[]},"alphafold":{"accession":"Q9NXB9","domains":[{"cath_id":"-","chopping":"30-55_73-256","consensus_level":"medium","plddt":95.2545,"start":30,"end":256}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NXB9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NXB9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NXB9-F1-predicted_aligned_error_v6.png","plddt_mean":86.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ELOVL2","jax_strain_url":"https://www.jax.org/strain/search?query=ELOVL2"},"sequence":{"accession":"Q9NXB9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9NXB9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9NXB9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NXB9"}},"corpus_meta":[{"pmid":"23061750","id":"PMC_23061750","title":"Methylation of ELOVL2 gene as a new epigenetic marker of age.","date":"2012","source":"Aging cell","url":"https://pubmed.ncbi.nlm.nih.gov/23061750","citation_count":341,"is_preprint":false},{"pmid":"30300865","id":"PMC_30300865","title":"DNA methylation of the ELOVL2, FHL2, KLF14, C1orf132/MIR29B2C, and TRIM59 genes for age prediction from blood, saliva, and buccal swab samples.","date":"2018","source":"Forensic science international. 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Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/25450787","citation_count":140,"is_preprint":false},{"pmid":"21106902","id":"PMC_21106902","title":"ELOVL2 controls the level of n-6 28:5 and 30:5 fatty acids in testis, a prerequisite for male fertility and sperm maturation in mice.","date":"2010","source":"Journal of lipid research","url":"https://pubmed.ncbi.nlm.nih.gov/21106902","citation_count":115,"is_preprint":false},{"pmid":"24489111","id":"PMC_24489111","title":"Elovl2 ablation demonstrates that systemic DHA is endogenously produced and is essential for lipid homeostasis in mice.","date":"2014","source":"Journal of lipid research","url":"https://pubmed.ncbi.nlm.nih.gov/24489111","citation_count":114,"is_preprint":false},{"pmid":"19875612","id":"PMC_19875612","title":"Remodeling of retinal Fatty acids in an animal model of diabetes: a decrease in long-chain polyunsaturated fatty acids is associated with a decrease in fatty acid elongases Elovl2 and Elovl4.","date":"2009","source":"Diabetes","url":"https://pubmed.ncbi.nlm.nih.gov/19875612","citation_count":114,"is_preprint":false},{"pmid":"31943697","id":"PMC_31943697","title":"The lipid elongation enzyme ELOVL2 is a molecular regulator of aging in the retina.","date":"2020","source":"Aging cell","url":"https://pubmed.ncbi.nlm.nih.gov/31943697","citation_count":83,"is_preprint":false},{"pmid":"27672102","id":"PMC_27672102","title":"Systemic Age-Associated DNA Hypermethylation of ELOVL2 Gene: In Vivo and In Vitro Evidences of a Cell Replication Process.","date":"2017","source":"The journals of gerontology. Series A, Biological sciences and medical sciences","url":"https://pubmed.ncbi.nlm.nih.gov/27672102","citation_count":72,"is_preprint":false},{"pmid":"28725932","id":"PMC_28725932","title":"DNA methylation in ELOVL2 and C1orf132 correctly predicted chronological age of individuals from three disease groups.","date":"2017","source":"International journal of legal medicine","url":"https://pubmed.ncbi.nlm.nih.gov/28725932","citation_count":66,"is_preprint":false},{"pmid":"26856376","id":"PMC_26856376","title":"Evolutionary functional elaboration of the Elovl2/5 gene family in chordates.","date":"2016","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/26856376","citation_count":49,"is_preprint":false},{"pmid":"23873268","id":"PMC_23873268","title":"Molecular basis for differential elongation of omega-3 docosapentaenoic acid by the rat Elovl5 and Elovl2.","date":"2013","source":"Journal of lipid research","url":"https://pubmed.ncbi.nlm.nih.gov/23873268","citation_count":47,"is_preprint":false},{"pmid":"28377873","id":"PMC_28377873","title":"Molecular phenotyping of multiple mouse strains under metabolic challenge uncovers a role for Elovl2 in glucose-induced insulin secretion.","date":"2017","source":"Molecular metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/28377873","citation_count":45,"is_preprint":false},{"pmid":"31101849","id":"PMC_31101849","title":"CRISPR/Cas9-mediated ablation of elovl2 in Atlantic salmon (Salmo salar L.) inhibits elongation of polyunsaturated fatty acids and induces Srebp-1 and target genes.","date":"2019","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/31101849","citation_count":43,"is_preprint":false},{"pmid":"17583696","id":"PMC_17583696","title":"ELOVL2 overexpression enhances triacylglycerol synthesis in 3T3-L1 and F442A cells.","date":"2007","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/17583696","citation_count":41,"is_preprint":false},{"pmid":"27788154","id":"PMC_27788154","title":"Estrogen Enhances the Expression of the Polyunsaturated Fatty Acid Elongase Elovl2 via ERα in Breast Cancer Cells.","date":"2016","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/27788154","citation_count":41,"is_preprint":false},{"pmid":"29754287","id":"PMC_29754287","title":"Protective role of the ELOVL2/docosahexaenoic acid axis in glucolipotoxicity-induced apoptosis in rodent beta cells and human islets.","date":"2018","source":"Diabetologia","url":"https://pubmed.ncbi.nlm.nih.gov/29754287","citation_count":37,"is_preprint":false},{"pmid":"24292947","id":"PMC_24292947","title":"ELOVL2 gene polymorphisms are associated with increases in plasma eicosapentaenoic and docosahexaenoic acid proportions after fish oil supplement.","date":"2013","source":"Genes & nutrition","url":"https://pubmed.ncbi.nlm.nih.gov/24292947","citation_count":36,"is_preprint":false},{"pmid":"33963174","id":"PMC_33963174","title":"ADIPOR1 deficiency-induced suppression of retinal ELOVL2 and docosahexaenoic acid levels during photoreceptor degeneration and visual loss.","date":"2021","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/33963174","citation_count":32,"is_preprint":false},{"pmid":"33043173","id":"PMC_33043173","title":"ELOVL2: Not just a biomarker of aging.","date":"2020","source":"Translational medicine of aging","url":"https://pubmed.ncbi.nlm.nih.gov/33043173","citation_count":29,"is_preprint":false},{"pmid":"34249416","id":"PMC_34249416","title":"ELOVL2: a novel tumor suppressor attenuating tamoxifen resistance in breast cancer.","date":"2021","source":"American journal of cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/34249416","citation_count":29,"is_preprint":false},{"pmid":"34841437","id":"PMC_34841437","title":"ELOVL2 promotes cancer progression by inhibiting cell apoptosis in renal cell carcinoma.","date":"2021","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/34841437","citation_count":26,"is_preprint":false},{"pmid":"32883522","id":"PMC_32883522","title":"Polyunsaturated fatty acids synthesized by freshwater fish: A new insight to the roles of elovl2 and elovl5 in vivo.","date":"2020","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/32883522","citation_count":26,"is_preprint":false},{"pmid":"26633493","id":"PMC_26633493","title":"Single Nucleotide Polymorphisms in the FADS Gene Cluster but not the ELOVL2 Gene are Associated with Serum Polyunsaturated Fatty Acid Composition and Development of Allergy (in a Swedish Birth Cohort).","date":"2015","source":"Nutrients","url":"https://pubmed.ncbi.nlm.nih.gov/26633493","citation_count":26,"is_preprint":false},{"pmid":"35131731","id":"PMC_35131731","title":"DNA methylation analysis of ELOVL2 gene using droplet digital PCR for age estimation purposes.","date":"2022","source":"Forensic science international","url":"https://pubmed.ncbi.nlm.nih.gov/35131731","citation_count":22,"is_preprint":false},{"pmid":"31856871","id":"PMC_31856871","title":"MYCN and PRC1 cooperatively repress docosahexaenoic acid synthesis in neuroblastoma via ELOVL2.","date":"2019","source":"Journal of experimental & clinical cancer research : CR","url":"https://pubmed.ncbi.nlm.nih.gov/31856871","citation_count":22,"is_preprint":false},{"pmid":"31928966","id":"PMC_31928966","title":"rs953413 Regulates Polyunsaturated Fatty Acid Metabolism by Modulating ELOVL2 Expression.","date":"2020","source":"iScience","url":"https://pubmed.ncbi.nlm.nih.gov/31928966","citation_count":21,"is_preprint":false},{"pmid":"24919687","id":"PMC_24919687","title":"Functional characterization of the duck and turkey fatty acyl elongase enzymes ELOVL5 and ELOVL2.","date":"2014","source":"The Journal of nutrition","url":"https://pubmed.ncbi.nlm.nih.gov/24919687","citation_count":21,"is_preprint":false},{"pmid":"32880080","id":"PMC_32880080","title":"Elovl2 But Not Elovl5 Is Essential for the Biosynthesis of Docosahexaenoic Acid (DHA) in Zebrafish: Insight from a Comparative Gene Knockout Study.","date":"2020","source":"Marine biotechnology (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/32880080","citation_count":21,"is_preprint":false},{"pmid":"33174255","id":"PMC_33174255","title":"Higher Increase in Plasma DHA in Females Compared to Males Following EPA Supplementation May Be Influenced by a Polymorphism in ELOVL2: An Exploratory Study.","date":"2020","source":"Lipids","url":"https://pubmed.ncbi.nlm.nih.gov/33174255","citation_count":21,"is_preprint":false},{"pmid":"33279766","id":"PMC_33279766","title":"A minimal number CpGs of ELOVL2 gene for a chronological age estimation using pyrosequencing.","date":"2020","source":"Forensic science 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International Academy of Clinical and Applied Thrombosis/Hemostasis","url":"https://pubmed.ncbi.nlm.nih.gov/32584610","citation_count":18,"is_preprint":false},{"pmid":"30914501","id":"PMC_30914501","title":"DHA intake interacts with ELOVL2 and ELOVL5 genetic variants to influence polyunsaturated fatty acids in human milk.","date":"2019","source":"Journal of lipid research","url":"https://pubmed.ncbi.nlm.nih.gov/30914501","citation_count":18,"is_preprint":false},{"pmid":"36768576","id":"PMC_36768576","title":"An ELOVL2-Based Epigenetic Clock for Forensic Age Prediction: A Systematic Review.","date":"2023","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/36768576","citation_count":17,"is_preprint":false},{"pmid":"27864326","id":"PMC_27864326","title":"Both maternal and offspring Elovl2 genotypes determine systemic DHA levels in perinatal mice.","date":"2016","source":"Journal of lipid 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meiotic telomere dynamics through membrane fluidity promoted by AdipoR2-ELOVL2.","date":"2024","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/38485951","citation_count":14,"is_preprint":false},{"pmid":"35276915","id":"PMC_35276915","title":"Elovl2-Ablation Leads to Mitochondrial Membrane Fatty Acid Remodeling and Reduced Efficiency in Mouse Liver Mitochondria.","date":"2022","source":"Nutrients","url":"https://pubmed.ncbi.nlm.nih.gov/35276915","citation_count":14,"is_preprint":false},{"pmid":"35640821","id":"PMC_35640821","title":"ELOVL2 restrains cell proliferation, migration, and invasion of prostate cancer via regulation of the tumor suppressor INPP4B.","date":"2022","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/35640821","citation_count":12,"is_preprint":false},{"pmid":"30734280","id":"PMC_30734280","title":"Genetic variants in ELOVL2 and HSD17B12 predict melanoma-specific survival.","date":"2019","source":"International journal of 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functional characterization of an Elovl2 elongase.","date":"2019","source":"Comparative biochemistry and physiology. 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Loss of hepatic DHA synthesis activates SREBP-1c and downstream lipogenic genes, yet paradoxically protects against hepatic steatosis and diet-induced obesity. DHA dietary supplementation reverses fatty acid and gene-expression changes.\",\n      \"method\": \"Elovl2 knockout mouse; hepatic lipid composition analysis; gene expression (SREBP-1c and target genes); high-fat diet challenge; DHA supplementation rescue\",\n      \"journal\": \"Journal of lipid research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (lipidomics, transcriptomics, dietary rescue) in a well-controlled KO model\",\n      \"pmids\": [\"24489111\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"The ability of rat Elovl2 (but not Elovl5) to elongate C22 omega-3 DPA (22:5n-3) to 24:5n-3 is determined by a single cysteine residue at position 217 in transmembrane domains 6–7; substituting this cysteine abolishes the DPA elongation activity, whereas an equivalent tryptophan at the same position in Elovl5 explains its inability to elongate C22 substrates.\",\n      \"method\": \"Yeast heterologous expression system; Elovl2/Elovl5 chimeric constructs; site-directed point mutagenesis (C217 in Elovl2); fatty acid substrate activity assays\",\n      \"journal\": \"Journal of lipid research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — reconstitution in yeast with mutagenesis identifying a specific catalytic residue, single lab but multiple chimera/point-mutant constructs providing orthogonal support\",\n      \"pmids\": [\"23873268\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Age-related decrease in Elovl2 expression in mouse retina is associated with increased DNA methylation of its promoter; reversal of promoter hypermethylation by intravitreal 5-Aza-2'-deoxycytidine restores Elovl2 expression and rescues age-related visual function decline. A point mutation C234W that disrupts Elovl2 enzymatic activity causes premature electrophysiological visual decline, early autofluorescent deposits, and sub-RPE deposits resembling human drusen components.\",\n      \"method\": \"Intravitreal 5-Aza-dc injection in aged mice; electroretinography; Elovl2 C234W enzymatic point mutant knock-in mice; autofluorescence imaging; histological analysis of sub-RPE deposits\",\n      \"journal\": \"Aging cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — enzymatic point mutant combined with pharmacological demethylation rescue, multiple orthogonal functional readouts (ERG, imaging, histology)\",\n      \"pmids\": [\"31943697\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Overexpression of ELOVL2 in preadipocyte cell lines (3T3-L1 and F442A) enhances triacylglycerol synthesis and lipid droplet accumulation by increasing fatty acid (but not glucose) incorporation into TAG, and induces expression of lipogenic genes DGAT2 and FABP4/aP2.\",\n      \"method\": \"Overexpression of ELOVL2 in preadipocyte cell lines; TAG synthesis assay; [14C]-fatty acid and glucose incorporation; RT-PCR for DGAT2 and FABP4\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — overexpression with biochemical substrate-tracing and gene expression assays in two cell lines, single lab\",\n      \"pmids\": [\"17583696\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Estradiol upregulates Elovl2 expression in MCF7 breast cancer cells via estrogen receptor alpha (ERα); ERα binds a specific estrogen response element (ERE) within the Elovl2 enhancer in a ligand-dependent manner, and tamoxifen or ERα knockdown specifically abolishes Elovl2 (but not Elovl5) upregulation.\",\n      \"method\": \"Estradiol stimulation of MCF7 cells; tamoxifen treatment; ERα siRNA knockdown; chromatin immunoprecipitation (ChIP) for ERα binding at Elovl2 ERE; RT-PCR\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — ChIP identifying specific ERE binding site combined with siRNA knockdown and pharmacological inhibition, multiple orthogonal methods in one study\",\n      \"pmids\": [\"27788154\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Elovl2 is a network hub gene in pancreatic beta cells; Elovl2 silencing in mouse and human beta cell lines decreases glucose-stimulated insulin secretion (GSIS), placing ELOVL2 as a molecular regulator of normal insulin secretory responses to glucose.\",\n      \"method\": \"Network-based integration of RNA-Seq and phenotypic data from multi-strain mouse islets; Elovl2 siRNA silencing in mouse and human beta cell lines; GSIS assay\",\n      \"journal\": \"Molecular metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown with functional GSIS readout in two cell types, single lab\",\n      \"pmids\": [\"28377873\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"ELOVL2/DHA axis protects rodent and human beta cells from glucolipotoxicity-induced apoptosis by promoting palmitate oxidation via a CPT1-dependent mechanism; ELOVL2 downregulation potentiates apoptosis, while adenoviral overexpression or DHA supplementation partially inhibits cell death and reduces ceramide accumulation. The anti-apoptotic effect requires AMPK and CPT1 activity.\",\n      \"method\": \"ELOVL2 siRNA knockdown and adenoviral overexpression in INS-1 cells and human islets; caspase-3 and PARP cleavage assays; [U-14C]palmitate oxidation and esterification assays; ceramide/DAG measurement; pharmacological inhibition of AMPK and CPT1 (etomoxir); CPT1 siRNA and constitutively active CPT1 construct\",\n      \"journal\": \"Diabetologia\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal methods (isotope tracing, enzymatic assays, pharmacological and genetic inhibition of pathway components) in rodent and human cells, single lab\",\n      \"pmids\": [\"29754287\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"MYCN represses ELOVL2 transcription in neuroblastoma by recruiting Polycomb repressive complex 1 (PRC1), which catalyzes H2AK119 monoubiquitination at the ELOVL2 locus; this suppresses DHA synthesis. Forced ELOVL2 expression in MYCN-amplified cells reduces proliferation and counteracts MYCN's growth-promoting effect in vitro and in vivo.\",\n      \"method\": \"GC-MS fatty acid profiling; ChIP for MYCN and H2AK119ub at ELOVL2 locus; immunoprecipitation–mass spectrometry (IP-MS) to identify PRC1 as MYCN co-repressor; ELOVL2 overexpression and knockdown; xenograft mouse model; CCK-8, soft agar, flow cytometry assays\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — ChIP establishing epigenetic mechanism at ELOVL2 locus, IP-MS identifying co-repressor complex, combined with functional rescue experiments, single lab\",\n      \"pmids\": [\"31856871\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"The intronic SNP rs953413 in ELOVL2 lies within a functional FOXA1/FOXA2 and HNF4α cooperative binding site; the G allele increases binding of these transcription factors to an evolutionarily conserved enhancer, conferring allele-specific upregulation of ELOVL2. Knockdown of FOXA1, FOXA2, or HNF4α, and CRISPR/Cas9-mediated disruption of the enhancer element, each significantly downregulate ELOVL2 expression.\",\n      \"method\": \"FOXA1/FOXA2/HNF4α knockdown; CRISPR/Cas9 enhancer deletion; allele-specific reporter assays; ChIP; GWAS functional annotation\",\n      \"journal\": \"iScience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — CRISPR enhancer disruption and TF knockdown with allele-specific gene expression, multiple orthogonal methods in one study\",\n      \"pmids\": [\"31928966\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ADIPOR1 is required for ELOVL2 expression in photoreceptor inner segments; Adipor1 knockout mice show significantly reduced Elovl2 expression and decreased retinal DHA, accompanied by misaligned photoreceptor outer segments and progressive photoreceptor degeneration. The causal relationship between ADIPOR1 deficiency and Elovl2 repression (with upregulation of lipogenic genes) was confirmed in vitro.\",\n      \"method\": \"Adipor1 knockout mice; electroretinography; electron microscopy; lipid composition analysis; mRNA/protein expression; in vitro ADIPOR1 knockdown confirming Elovl2 downregulation\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo KO with functional (ERG) and ultrastructural readouts combined with in vitro confirmation of ADIPOR1→ELOVL2 axis\",\n      \"pmids\": [\"33963174\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Elovl2 ablation in mice causes DHA and DPAn-6 depletion in liver mitochondrial membranes, leading to mitochondrial dysfunction characterized by increased oligomycin-insensitive oxygen consumption, reduced respiratory control coefficients (~50% reduction), and hypersensitivity to fatty acid-induced uncoupling and permeabilization, with ANT2 implicated; mitochondrial volume and peroxisome numbers increase without loss of respiratory chain proteins or oxidative damage.\",\n      \"method\": \"Elovl2 knockout mice; mitochondrial membrane fatty acid composition analysis; mitochondrial respiration assays (oligomycin, uncoupling agents); oxidative stress biomarkers (MDAL); transmission electron microscopy; Western blot for respiratory chain proteins and VDAC/ANT2\",\n      \"journal\": \"Nutrients\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO mouse with multiple orthogonal mitochondrial functional assays and molecular characterization, single lab\",\n      \"pmids\": [\"35276915\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"AdipoR2 regulates ELOVL2 both transcriptionally and post-transcriptionally in male meiotic germ cells to synthesize VLC-PUFAs in sphingolipids; depletion of VLC-PUFAs in AdipoR2 knockout testes causes membrane stiffening, nuclear envelope invagination, impaired nuclear peripheral distribution of meiotic telomeres, errors in homologous synapsis and recombination, and disrupted intercellular bridge/syncytium formation.\",\n      \"method\": \"AdipoR2 knockout mice; lipidomic analysis of testis; meiotic telomere and synapsis analysis; intercellular bridge/syncytium imaging; mechanistic studies of membrane fluidity\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo KO with lipidomics, chromosome biology, and membrane biophysics readouts; multi-method study in Nature Communications\",\n      \"pmids\": [\"38485951\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Atlantic salmon Elovl2 elongates C20 and C22 PUFAs (with lower activity toward C18), distinct from Elovl5b which elongates C18 and C20; heterologous yeast expression confirms that Elovl2 is the elongase enabling DHA biosynthesis via the Sprecher pathway. Hepatic and intestinal Elovl2 expression is significantly upregulated in salmon fed vegetable oil versus fish oil diets.\",\n      \"method\": \"Cloning of salmon elovl2 cDNA; heterologous yeast expression with fatty acid substrate assays; tissue expression profiling; nutritional regulation experiment (fish oil vs. vegetable oil diets)\",\n      \"journal\": \"Marine biotechnology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — reconstitution in yeast establishing substrate specificity, complemented by nutritional regulation in vivo, single lab\",\n      \"pmids\": [\"19184219\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Elovl2 evolved from genome duplications in vertebrate ancestry (diverging from the single ancestral Elovl2/5 gene); the ability to efficiently elongate C22 PUFA substrates (enabling DHA synthesis via the Sprecher pathway) emerged specifically in the jawed vertebrate ancestor, as demonstrated by functional characterization of elongases from amphioxus, lamprey, and elephant shark.\",\n      \"method\": \"Heterologous yeast expression of Elovl2/5 from amphioxus, sea lamprey, and elephant shark; fatty acid substrate activity assays; phylogenetic analysis\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — reconstitution in yeast across multiple species with substrate activity assays establishing evolutionary gain of C22 elongation function\",\n      \"pmids\": [\"26856376\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ELOVL2 knockdown (CRISPR/Cas9) in renal cancer cells suppresses elongation of long-chain PUFAs, increases lipid droplet production, inhibits cell proliferation via apoptosis induction in vitro, and attenuates tumor growth in vivo.\",\n      \"method\": \"CRISPR/Cas9-mediated ELOVL2 knockdown in renal cancer cell lines; fatty acid profiling; lipid droplet staining; cell proliferation and apoptosis assays; in vivo xenograft\",\n      \"journal\": \"Oncology reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR KD with biochemical and functional readouts in vitro and in vivo, single lab\",\n      \"pmids\": [\"34841437\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ELOVL2 knockdown in prostate cancer cells activates the PI3K/Akt signaling pathway by downregulating INPP4B (a tumor suppressor phosphatase); overexpression of INPP4B rescues the pro-proliferative and pro-invasive phenotype caused by ELOVL2 knockdown, placing ELOVL2 upstream of INPP4B in regulation of PI3K/Akt signaling.\",\n      \"method\": \"ELOVL2 shRNA knockdown and overexpression in prostate cancer cell lines; INPP4B overexpression rescue; CCK8, colony formation, transwell invasion assays; subcutaneous xenograft; Western blot for PI3K/Akt pathway components\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis (INPP4B rescue of ELOVL2-KD phenotype) with functional assays, single lab\",\n      \"pmids\": [\"35640821\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"ELOVL2 facilitates enzalutamide resistance in castration-resistant prostate cancer by impairing the ubiquitin-proteasome system, leading to stabilization (reduced degradation) of androgen receptor (AR) and subsequent AR signaling activation; ELOVL2 inhibition suppresses proliferation and restores enzalutamide sensitivity.\",\n      \"method\": \"Bioinformatic analysis of LNCaP/enzalutamide-resistant cells; ELOVL2 targeted inhibition; cell proliferation assay; ubiquitin-proteasome pathway assays; AR protein stability/signaling assays\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — abstract describes mechanistic pathway (ubiquitin-proteasome/AR stabilization) but only single method description available from abstract without full biochemical reconstitution details; single lab\",\n      \"pmids\": [\"40552308\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"CRISPR/Cas9-mediated elovl2 knockout in Atlantic salmon reduces 22:6n-3 (DHA) and causes accumulation of 20:5n-3 and 22:5n-3 in liver, brain, and white muscle, demonstrating that elovl2 catalyzes two penultimate elongation steps in PUFA synthesis in vivo. Loss of endogenous DHA synthesis induces hepatic expression of srebp-1, fatty acid synthase-b, Δ6fad-a, Δ5fad, and elovl5, identifying Srebp-1 as a main transcriptional regulator of PUFA synthesis.\",\n      \"method\": \"CRISPR/Cas9 elovl2 partial knockout in Atlantic salmon; tissue fatty acid profiling; hepatic gene expression analysis\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo CRISPR KO with multi-tissue lipidomics and transcriptomics establishing both substrate specificity and downstream transcriptional regulation\",\n      \"pmids\": [\"31101849\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Elovl2 (but not Elovl5) is essential for DHA biosynthesis in zebrafish; elovl2 knockout reduces DHA by 67% in adult liver and 92% in embryos. Compensatory upregulation of elovl5 in elovl2 KO (15-fold) cannot rescue DHA deficiency, whereas elovl2 upregulation fully compensates for elovl5 loss, establishing the non-redundant role of Elovl2 in endogenous DHA synthesis.\",\n      \"method\": \"CRISPR/Cas9 elovl2 and elovl5 single and double knockout zebrafish; fatty acid profiling; gene expression analysis\",\n      \"journal\": \"Marine biotechnology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — comparative KO study with genetic epistasis (compensability of elovl2 by elovl5 and vice versa) establishing irreplaceable enzymatic role of Elovl2 in DHA synthesis\",\n      \"pmids\": [\"32880080\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Elovl2 loss in zebrafish embryos causes changes in retinal lipid composition (especially DHA-containing lipids) and impairs visual behavior (VMR-OFF response), with increased retinal thickness but no gross disruption of retinal architecture. Elovl2 is expressed in Müller glia in embryonic and adult zebrafish retina.\",\n      \"method\": \"elovl2 CRISPR crispants in zebrafish; whole-mount in situ hybridization; lipidomics; histological analysis; visual motor reflex assay\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo gene disruption with lipidomics and functional visual assay; localization by WISH; single lab\",\n      \"pmids\": [\"33276584\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ELOVL2 hypermethylation is associated with in vitro cell replication (cell divisions) rather than replicative senescence per se, as shown by primary dermal fibroblast cultures from donors of different ages and replication experiments, suggesting the epigenetic clock at this locus is driven by cumulative cell divisions.\",\n      \"method\": \"Primary dermal fibroblast cultures; in vitro replication vs. senescence experiments; longitudinal cohort methylation analysis (Doetinchem Cohort Study); public epigenomic data analysis across 16 tissues\",\n      \"journal\": \"The journals of gerontology. Series A\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro cell biology experiments distinguishing replication from senescence, supported by longitudinal cohort data; single lab primary experiments\",\n      \"pmids\": [\"27672102\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"POU2F1 transcription factor directly activates ELOVL2 transcription in endometrial cancer, promoting ELOVL2-associated lipid metabolic remodeling; POU2F1-driven proliferation, migration, invasion, and xenograft growth are ELOVL2-dependent.\",\n      \"method\": \"Bioinformatics; ChIP or reporter assay for POU2F1 binding to ELOVL2 promoter (mechanistic validation described); functional assays with ELOVL2 knockdown rescue; xenograft\",\n      \"journal\": \"Cancer & metabolism\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — mechanistic claim of direct transcriptional activation by POU2F1 stated but full experimental details are limited in the abstract; single lab, single paper\",\n      \"pmids\": [\"41947242\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Co-overexpression of ELOVL2 and ELOVL5 in clear cell renal cell carcinoma promotes invasion and invadopodia formation through a LIMK1-mediated cytoskeletal reorganization pathway; dual siRNA knockdown of ELOVL2/ELOVL5 downregulates actin filament-related processes and LIMK1, and LIMK1 knockdown phenocopies the anti-invasive effects of dual elongase knockdown.\",\n      \"method\": \"siRNA knockdown of ELOVL2 and ELOVL5 in renal cancer cell lines; transcriptomic profiling; pathway analysis; LIMK1 knockdown; proliferation, invasion, and invadopodia formation assays; TCGA data\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA epistasis (LIMK1 KD phenocopies dual elongase KD) with transcriptomics and functional assays in renal cancer cells, single lab\",\n      \"pmids\": [\"42225919\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Elovl2 enzymatic activity-deficient mice (C234W) show impaired contrast sensitivity and slower rod response recovery after bright light. Intravitreal supplementation with 24:5n-3 (the direct product of ELOVL2) in aged mice improves visual function, reduces accumulation of ApoE, HTRA1, and complement proteins in sub-RPE deposits, and produces a partial transcriptomic rejuvenation signature in retinal gene expression.\",\n      \"method\": \"Elovl2 C234W enzymatic mutant mice; electroretinography; intravitreal 24:5n-3 supplementation; retinal histology and immunohistochemistry for drusen components; RNA-seq transcriptomic profiling\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — enzymatic point mutant combined with direct product rescue in vivo with multiple functional and molecular readouts; preprint, not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2024.07.01.601592\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Loss of Elovl2 enzymatic activity in mice causes global downregulation of lymphoid/B cell gene markers in bone marrow and an aging-associated loss of B cell progenitors, suggesting ELOVL2-derived PUFAs are required for normal B cell development. A rare ELOVL2-expressing HSPC subpopulation (<7% of CD34+ cells) is nearly absent in elderly (>60 years) human bone marrow.\",\n      \"method\": \"RNA-seq of bone marrow from aged Elovl2 mutant vs. wild-type mice; flow cytometry for immune cell markers; lipidomics of bone marrow; single-cell RNA-seq of human HSPCs across age groups\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — preprint; transcriptomics and flow cytometry describe the phenotype but direct mechanistic link between ELOVL2 lipid products and B cell development is not yet biochemically established\",\n      \"pmids\": [\"bio_10.1101_2024.09.26.614999\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"ELOVL2 is a microsomal fatty acid elongase that catalyzes rate-limiting elongation of C20–C22 polyunsaturated fatty acids to C24 intermediates required for endogenous DHA (and DPAn-6) synthesis; a single cysteine (C217 in rat) in transmembrane domains 6–7 confers C22-substrate specificity, while the C234W mutation abolishes enzymatic activity in vivo. Loss of ELOVL2 disrupts DHA homeostasis in liver, retina, testis, and mitochondria, leading to male infertility (arrest of spermatogenesis via loss of VLC-PUFAs), retinal aging and visual decline (rescued by its direct product 24:5n-3 or by promoter demethylation), impaired mitochondrial respiration, and dysregulated lipid/glucose metabolism including reduced glucose-stimulated insulin secretion; its expression is transcriptionally controlled by ERα (via a specific ERE in the Elovl2 enhancer), by FOXA1/FOXA2 and HNF4α (via an intronic enhancer), by POU2F1, and is epigenetically repressed by MYCN–PRC1-mediated H2AK119 ubiquitination, while AdipoR2 promotes ELOVL2 both transcriptionally and post-transcriptionally to maintain membrane fluidity for meiotic telomere dynamics.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ELOVL2 is a microsomal fatty acid elongase that catalyzes the rate-limiting elongation of C20–C22 polyunsaturated fatty acids, principally converting 22:5n-3 and 22:4n-6 to C24 precursors required for endogenous synthesis of DHA and DPAn-6 via the Sprecher pathway [#1, #2]. Substrate specificity for C22 acyl chains is conferred by a single cysteine residue (C217 in rat) within transmembrane domains 6–7, a feature whose acquisition in the jawed-vertebrate ancestor enabled DHA biosynthesis and which distinguishes ELOVL2 from the C18/C20-preferring paralog ELOVL5 [#2, #14]. Genetic ablation across mice, zebrafish, and salmon causes accumulation of C20/C22 substrates and severe depletion of DHA in liver, retina, brain, and germline, establishing a non-redundant role that cannot be rescued by compensatory ELOVL5 upregulation [#18, #19, #20]. Through this control of DHA/VLC-PUFA supply, ELOVL2 supports diverse cellular processes: spermatogenesis, where its very-long-chain PUFA products are required for spermatocyte progression and, via AdipoR2-driven expression, for membrane fluidity governing meiotic telomere dynamics and homologous synapsis [#0, #12]; retinal photoreceptor maintenance, where age-related promoter hypermethylation lowers ELOVL2 expression and an enzyme-dead C234W mutation drives premature visual decline and sub-RPE drusen-like deposits that are rescued by its direct product 24:5n-3 [#3]; hepatic and mitochondrial lipid homeostasis, where loss activates SREBP-1c lipogenic programs yet protects from steatosis while impairing mitochondrial respiratory coupling [#1, #11]; and pancreatic beta-cell function, where ELOVL2/DHA promotes glucose-stimulated insulin secretion and protects against glucolipotoxic apoptosis through AMPK/CPT1-dependent palmitate oxidation [#6, #7]. ELOVL2 transcription is governed by multiple inputs including estrogen receptor alpha acting at an enhancer ERE, cooperative FOXA1/FOXA2 and HNF4α binding at an intronic enhancer, and epigenetic repression by MYCN-recruited PRC1-mediated H2AK119 ubiquitination [#5, #9, #8]. In cancer, ELOVL2 displays context-dependent roles, suppressing proliferation in MYCN-amplified neuroblastoma and renal carcinoma while supporting growth and invasion in other contexts [#8, #15].\",\n  \"teleology\": [\n    {\n      \"year\": 2009,\n      \"claim\": \"Whether ELOVL2 was the elongase responsible for the C20/C22 steps of DHA synthesis was unresolved; reconstitution in yeast established it as the enzyme enabling DHA biosynthesis via the Sprecher pathway.\",\n      \"evidence\": \"Cloning and heterologous yeast expression of salmon Elovl2 with fatty acid substrate assays, plus nutritional regulation in vivo\",\n      \"pmids\": [\"19184219\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Substrate specificity determinant not yet mapped to a residue\", \"Mammalian in vivo confirmation not provided in this study\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"The physiological requirement for ELOVL2-derived very-long-chain PUFAs was unknown; knockout mice revealed it is essential for elongation of C24–C30 n-6 PUFAs in testis and for completion of spermatogenesis.\",\n      \"evidence\": \"Elovl2 knockout and haploinsufficient mice with acyl-CoA profiling, seminiferous tubule histology, and DHA dietary rescue\",\n      \"pmids\": [\"21106902\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis for spermatocyte arrest not defined\", \"Lipid species directly required for spermatid formation not pinpointed\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"The structural basis of ELOVL2's distinct C22 substrate preference relative to ELOVL5 was unexplained; mutagenesis identified a single cysteine (C217) in TM6–7 as the specificity determinant.\",\n      \"evidence\": \"Yeast expression of Elovl2/Elovl5 chimeras and C217 point mutants with substrate activity assays\",\n      \"pmids\": [\"23873268\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structural model of the substrate-binding pocket\", \"Whether the residue affects catalysis or only binding not resolved\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"The systemic metabolic consequence of losing hepatic DHA synthesis was unclear; KO mice showed substrate accumulation, SREBP-1c lipogenic activation, yet paradoxical protection from steatosis and diet-induced obesity.\",\n      \"evidence\": \"Elovl2 knockout mouse hepatic lipidomics, transcriptomics, high-fat diet challenge, and DHA rescue\",\n      \"pmids\": [\"24489111\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking DHA loss to SREBP-1c activation not defined\", \"Reason for protection against steatosis unexplained\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Transcriptional regulation of ELOVL2 was uncharacterized; estradiol was shown to upregulate it via ERα binding a specific ERE in the enhancer, and its evolutionary origin in jawed vertebrates was established.\",\n      \"evidence\": \"ChIP, ERα siRNA and tamoxifen in MCF7 cells; comparative yeast expression of elongases from amphioxus, lamprey, and elephant shark\",\n      \"pmids\": [\"27788154\", \"26856376\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological role of estrogen regulation outside breast cancer cells unclear\", \"Other regulatory inputs not yet mapped\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Whether ELOVL2 contributed to beta-cell function and to epigenetic aging was open; silencing impaired glucose-stimulated insulin secretion, and methylation studies linked the ELOVL2 epigenetic clock to cumulative cell divisions.\",\n      \"evidence\": \"siRNA silencing with GSIS assays in mouse/human beta cells; primary fibroblast replication-vs-senescence experiments and cohort methylation analysis\",\n      \"pmids\": [\"28377873\", \"27672102\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Lipid mediator linking ELOVL2 to insulin secretion not identified\", \"Causal direction of methylation changes for ELOVL2 function unresolved\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"The protective role of ELOVL2/DHA in beta cells was undefined; overexpression and knockdown showed it limits glucolipotoxic apoptosis by promoting CPT1-dependent palmitate oxidation requiring AMPK.\",\n      \"evidence\": \"siRNA and adenoviral overexpression in INS-1 cells and human islets with isotope tracing, ceramide measurement, and AMPK/CPT1 pharmacological and genetic perturbation\",\n      \"pmids\": [\"29754287\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific DHA-derived signal activating AMPK not identified\", \"In vivo relevance to diabetes not tested\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"How ELOVL2 is silenced in aggressive cancers and whether it has tumor-suppressive function was unknown; MYCN was shown to recruit PRC1 to deposit H2AK119ub at the locus, repressing DHA synthesis and proliferation control.\",\n      \"evidence\": \"ChIP for MYCN and H2AK119ub, IP-MS identifying PRC1, ELOVL2 gain/loss-of-function, and xenograft assays in neuroblastoma; salmon CRISPR KO confirming dual elongation steps and SREBP-1 regulation in vivo\",\n      \"pmids\": [\"31856871\", \"31101849\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether DHA itself mediates the anti-proliferative effect not fully resolved\", \"Generality of MYCN-PRC1 repression across tumor types untested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"The basis of ELOVL2 enhancer variation, its non-redundancy with ELOVL5, and its role in retinal aging were addressed; allele-specific FOXA/HNF4α binding controls expression, ELOVL5 cannot compensate for DHA loss, and promoter demethylation rescues age-related visual decline.\",\n      \"evidence\": \"CRISPR enhancer deletion and TF knockdown with allele-specific reporters; comparative zebrafish elovl2/elovl5 single and double KO; intravitreal 5-Aza-dc and C234W knock-in mice with ERG, imaging, and histology; zebrafish retinal lipidomics and visual assays\",\n      \"pmids\": [\"31928966\", \"32880080\", \"31943697\", \"33276584\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism connecting DHA depletion to drusen-like deposits not defined\", \"Cell-type specificity of demethylation rescue unresolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Upstream regulators of retinal ELOVL2 and its role in renal cancer were probed; ADIPOR1 was shown to be required for photoreceptor ELOVL2 expression, and ELOVL2 knockdown suppressed PUFA elongation and renal tumor growth.\",\n      \"evidence\": \"Adipor1 knockout mice with ERG, EM, and lipid analysis plus in vitro confirmation; CRISPR ELOVL2 knockdown in renal cancer cells with fatty acid profiling and xenografts\",\n      \"pmids\": [\"33963174\", \"34841437\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Signaling mechanism by which ADIPOR1 controls ELOVL2 not defined\", \"Tumor-context determinants of ELOVL2's pro- vs anti-tumor role unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Whether ELOVL2 influences signaling pathways and mitochondrial function was tested; loss depleted mitochondrial membrane DHA causing respiratory uncoupling, and in prostate cancer ELOVL2 acted upstream of INPP4B to restrain PI3K/Akt signaling.\",\n      \"evidence\": \"Elovl2 KO mouse mitochondrial respiration assays, membrane lipidomics, and EM; ELOVL2 knockdown/overexpression with INPP4B rescue and PI3K/Akt Western blots in prostate cancer\",\n      \"pmids\": [\"35276915\", \"35640821\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Role of ANT2 in uncoupling phenotype not mechanistically resolved\", \"Direct link between ELOVL2 lipids and INPP4B regulation not established\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"The membrane-biophysical and direct-product mechanisms of ELOVL2 were addressed; AdipoR2-driven ELOVL2 generates VLC-PUFA sphingolipids needed for meiotic telomere dynamics, and 24:5n-3 supplementation rescues aged retinal function.\",\n      \"evidence\": \"AdipoR2 KO mouse testis lipidomics with meiotic chromosome and membrane-fluidity readouts; C234W mutant mice with intravitreal 24:5n-3 supplementation, drusen-component IHC, and retinal RNA-seq (preprint for the retina study)\",\n      \"pmids\": [\"38485951\", \"bio_10.1101_2024.07.01.601592\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Biophysical mechanism linking VLC-PUFAs to telomere tethering not fully resolved\", \"Durability and translatability of 24:5n-3 rescue unknown\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Additional transcriptional and cancer-resistance roles were explored; POU2F1 was reported to activate ELOVL2 in endometrial cancer, ELOVL2/ELOVL5 co-overexpression to drive renal cancer invasion via LIMK1, and ELOVL2 to support enzalutamide resistance by stabilizing AR.\",\n      \"evidence\": \"ChIP/reporter and knockdown-rescue in endometrial cancer; dual siRNA with transcriptomics and LIMK1 epistasis in renal cancer; ubiquitin-proteasome and AR stability assays in castration-resistant prostate cancer\",\n      \"pmids\": [\"41947242\", \"42225919\", \"40552308\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"AR stabilization mechanism described only at abstract level without full biochemical reconstitution\", \"POU2F1 direct binding validation limited\", \"Whether enzymatic elongase activity is required for these signaling effects untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How ELOVL2-derived lipid species are mechanistically read out by distinct downstream processes — membrane biophysics in germ cells, mitochondrial coupling, drusen formation, B-cell development, and oncogenic signaling — remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of the human enzyme or substrate channel\", \"Direct lipid-to-effector links largely inferred from product/substrate manipulation\", \"Tissue-specific determinants of ELOVL2's pro- vs anti-proliferative roles undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [1, 2, 13, 14, 18, 19]},\n      {\"term_id\": \"GO:0016746\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [1, 2, 4, 18]},\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [0, 12]}\n    ],\n    \"complexes\": [],\n    \"partners\": [],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}