{"gene":"ATF4","run_date":"2026-06-09T22:02:44","timeline":{"discoveries":[{"year":2009,"finding":"The amino acid response (AAR) pathway signals through GCN2 kinase detecting uncharged tRNA, leading to eIF2alpha phosphorylation and ATF4 translational upregulation; ATF4 then heterodimerizes with partners to activate specific genes via the CCAAT-enhancer binding protein-activating transcription factor response element (CARE).","method":"Genetic and biochemical characterization of AAR pathway; transcriptional reporter assays","journal":"Trends in endocrinology and metabolism: TEM","confidence":"High","confidence_rationale":"Tier 2 / Strong — pathway established by multiple labs using epistasis and biochemical assays, replicated across literature","pmids":["19800252"],"is_preprint":false},{"year":2008,"finding":"ATF4 is necessary and sufficient for ER stress-induced REDD1 expression: PERK-deficient MEF cells fail to upregulate REDD1 mRNA upon ER stress, ATF4-deficient MEFs also fail, and exogenous ATF4 expression alone is sufficient to induce REDD1.","method":"Genetic KO of PERK and ATF4 in MEF cells; exogenous ATF4 overexpression; mRNA quantification","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — loss-of-function and gain-of-function with defined molecular readout, two orthogonal genetic approaches in single study","pmids":["19114033"],"is_preprint":false},{"year":2021,"finding":"mTORC1 activates ATF4 through a mechanism distinct from the canonical ISR; mTORC1-ATF4 signaling promotes expression of a subset of ATF4 target genes including those involved in amino acid uptake/synthesis, tRNA charging, and cellular cystine uptake for glutathione synthesis.","method":"Comparative transcriptomics in mTORC1-stimulated vs ISR-activated MEFs and human cancer cell lines; ATF4 KO and pharmacological mTORC1 inhibition","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple cell lines, KO controls, genome-wide transcriptomics with mechanistic follow-up in one rigorous study","pmids":["33646118"],"is_preprint":false},{"year":2021,"finding":"Asparagine availability communicates active mitochondrial respiration to ATF4 and mTORC1: ETC inhibition depletes asparagine, increases ATF4 levels, and impairs mTORC1 activity; exogenous asparagine restores both ATF4 and mTORC1 activities.","method":"ETC inhibition with metformin; exogenous asparagine supplementation; asparaginase treatment; mouse tumor models","journal":"Cell metabolism","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal approaches (pharmacological, dietary, in vivo), replicated across cancer models","pmids":["33609439"],"is_preprint":false},{"year":2021,"finding":"Thbs1 binds and activates PERK, inducing its downstream transcription factor ATF4, causing autophagy-mediated cardiac atrophy; PERK gene deletion in Thbs1 transgenic mice blunts ATF4 induction and autophagy, largely rescuing the lethal cardiac atrophy phenotype. AAV9-mediated overexpression of PERK or ATF4 alone is sufficient to promote cardiac atrophy.","method":"Transgenic and KO mouse models; AAV9 gene transfer; biochemical analysis of PERK-ATF4-autophagy pathway","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple genetic models (gain-of-function, loss-of-function), in vivo epistasis, orthogonal AAV confirmation","pmids":["34168130"],"is_preprint":false},{"year":2012,"finding":"HRI (heme-regulated eIF2alpha kinase) activates the Atf4 signaling pathway in erythroid precursors to reduce oxidative stress and promote erythroid differentiation; Hri-/- erythroblasts show increased ROS and apoptosis upon stress, and the Hri-eIF2αP-Atf4 pathway is required for erythroid differentiation.","method":"HRI knockout mice; ex vivo erythroid differentiation; ROS measurement; iron deficiency models","journal":"Blood","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic KO with defined pathway epistasis and multiple phenotypic readouts in one study","pmids":["22498744"],"is_preprint":false},{"year":2012,"finding":"FoxO1 physically interacts with ATF4 in osteoblast nuclei and promotes ATF4 transcriptional activity; the FoxO1-ATF4 complex synergistically suppresses osteocalcin activity by upregulating the phosphatase that inactivates osteocalcin, thereby regulating glucose homeostasis.","method":"Co-immunoprecipitation; genetic mouse models of FoxO1 and ATF4; transcriptional reporter assays; glucose tolerance tests","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, genetic epistasis in vivo, multiple functional readouts","pmids":["22298775"],"is_preprint":false},{"year":2016,"finding":"KDM4C physically interacts with ATF4 and cooperates to activate amino acid biosynthesis genes (serine-glycine synthesis pathway); KDM4C activates ATF4 transcription and requires ATF4 to target serine pathway genes, removing repressive H3K9 trimethylation at these loci.","method":"Co-immunoprecipitation; ChIP; gene expression analysis; siRNA knockdown; KDM4C overexpression","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — Co-IP, ChIP validation, genetic KD, multiple orthogonal methods in one study","pmids":["26774480"],"is_preprint":false},{"year":2020,"finding":"ATF4 represses transcription of NRF1 (nuclear respiratory factor 1) by binding to the NRF1 promoter, thereby suppressing NRF1-TFAM signaling, impairing mitochondrial biogenesis and respiratory function in alcohol-induced liver injury.","method":"Hepatocyte-specific ATF4 KO mice; ChIP assay showing ATF4 binding to NRF1 promoter; TFAM silencing/overexpression rescue experiments; clinical validation in AH patients","journal":"Gut","confidence":"High","confidence_rationale":"Tier 2 / Strong — ChIP confirming direct promoter binding, KO mice, rescue experiments, clinical validation","pmids":["33177163"],"is_preprint":false},{"year":2019,"finding":"DHA (dihydroartemisinin) activates ER stress in glioma cells leading to PERK-upregulated ATF4 expression, which in turn induces HSPA5; HSPA5 then increases GPX4 expression and activity, protecting cells from ferroptosis. siRNA knockdown of PERK, ATF4, or HSPA5 increases DHA-induced ferroptosis.","method":"siRNA knockdown; small molecule inhibitors; in vitro and in vivo glioma models; protein expression analysis","journal":"Journal of experimental & clinical cancer research : CR","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic KD at each step of pathway, in vivo validation, multiple orthogonal approaches","pmids":["31519193"],"is_preprint":false},{"year":2017,"finding":"PARP-1 activation induces PARylation of ATF4, reducing its binding to the CRE sequence; conversely, PARP inhibition increases ATF4 binding to the MKP-1 promoter (confirmed by ChIP-qPCR), inducing MKP-1 expression and inactivating JNK and p38 MAP kinases to reduce mitochondrial ROS.","method":"ChIP-qPCR; PARP inhibition/silencing; in vitro CRE binding assay; multiple human cell lines","journal":"Free radical biology & medicine","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — direct in vitro binding assay, ChIP-qPCR, multiple cell lines, first description of PARP-1-ATF4-MKP-1 axis","pmids":["28457938"],"is_preprint":false},{"year":2019,"finding":"PRMT1 methylates ATF4 on arginine 239, promoting ATF4 protein stability; a methylation-deficient ATF4 R239K mutant exacerbates ER stress and proapoptotic signaling; PRMT1 inhibition augments ER stress in cardiomyocytes through an ATF4-dependent mechanism.","method":"PRMT1 overexpression/inhibition/KO; methylation-deficient ATF4 mutant (R239K); caspase-3 activation and γH2AX measurement","journal":"Cell death & disease","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — site-specific mutagenesis, genetic KO, defined PTM with functional consequence","pmids":["31787756"],"is_preprint":false},{"year":2017,"finding":"DDX3, an RNA-binding protein, promotes ATF4 mRNA translation downstream of phosphorylated eIF2alpha during ER stress; DDX3 depletion reduces ATF4 protein levels, and DDX3 binds the eIF4F complex which is required for ER stress-induced ATF4 translation.","method":"DDX3 depletion; luciferase assays with ATF4 5'UTR; polyribosome profiling; protein interaction assays with eIF4F complex","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (polyribosome profiling, luciferase, Co-IP), translational mechanism defined","pmids":["29062139"],"is_preprint":false},{"year":2020,"finding":"ATF4 is required for ER stress-induced reticulophagy in glioblastoma; ATF4 knockout significantly attenuates loperamide-induced autophagy, autophagic cell death, and reticulophagy mediated through RETREG1/FAM134B and TEX264 receptors.","method":"ATF4 KO; electron and fluorescence microscopy; autophagy flux assays; siRNA knockdown of reticulophagy receptors","journal":"Autophagy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with specific phenotypic readout, multiple microscopy approaches, single lab","pmids":["33111629"],"is_preprint":false},{"year":2023,"finding":"mTORC1 directly phosphorylates ATF4 in a v-ATPase-dependent manner via lysosomal signaling upon mitochondrial stress; this phosphorylation is required for UPRmt transcriptional activation but not for UPRER; mTORC1-dependent ATF4 phosphorylation maintains mitochondrial redox homeostasis.","method":"v-ATPase inhibition; mTORC1 inhibition; phosphorylation-deficient ATF4 mutants; ROS measurement; in vitro kinase assay context","journal":"Cell discovery","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic and pharmacological dissection of the v-ATPase/mTORC1/ATF4 axis, mutation studies, specific pathway discrimination","pmids":["37679337"],"is_preprint":false},{"year":2020,"finding":"Reduction of β-globin is sufficient to induce ATF4 expression in erythroid precursors; ATF4 binds within the HBS1L-MYB intergenic enhancer to regulate MYB expression, and reduced ATF4 upon β-globin knockout decreases MYB and BCL11A levels, leading to γ-globin re-expression.","method":"CRISPR-Cas9 genome editing; RNA-seq; ATF4 ChIP at HBS1L-MYB enhancer; isogenic erythroid cell differentiation","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — CRISPR editing, ChIP validation of direct binding, RNA-seq, isogenic comparisons","pmids":["32755585"],"is_preprint":false},{"year":2013,"finding":"ATF4 interacts with HIF-1alpha in hypoxic osteoblasts and prevents HIF-1alpha binding to prolyl hydroxylases; loss of ATF4 increases HIF-1alpha ubiquitination and reduces its protein stability, thereby decreasing VEGF expression and bone angiogenesis.","method":"Co-immunoprecipitation; ATF4 KO mice; ubiquitination assay; HIF-1alpha stability measurement; recombinant VEGF rescue","journal":"Journal of bone and mineral research","confidence":"High","confidence_rationale":"Tier 2 / Moderate — Co-IP, KO mice, ubiquitination assay, multiple orthogonal approaches in one study","pmids":["23649506"],"is_preprint":false},{"year":2023,"finding":"ATF4 is an obligatory metabolic activator of NRF2: ATF4 increases NRF2 transcription and induces CHAC1 (glutathione-degrading enzyme), which is critical for maintaining NRF2 activation; NRF2 in turn supports ATF4-induced cells by increasing cystine uptake via xCT and upregulating thioredoxin usage.","method":"ATF4 KD/OE; NRF2 measurement; CHAC1 regulation analysis; cystine uptake assays; transcriptional reporter assays","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KD/OE with multiple pathway readouts, single lab, mechanistic link between ISR and NRF2","pmids":["37410595"],"is_preprint":false},{"year":2014,"finding":"ATF4 and p53 mediate distinct and additive pathways to skeletal muscle atrophy: each is required independently for immobilization-induced atrophy, forced expression of either induces atrophy, and the two pathways converge on p21 as a downstream effector that itself is required for atrophy.","method":"Muscle-specific KO mice; forced ATF4 expression in vivo; genome-wide mRNA arrays; double p53/ATF4 knockout","journal":"American journal of physiology. Endocrinology and metabolism","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with single and double KOs, gain-of-function, genome-wide target identification","pmids":["24895282"],"is_preprint":false},{"year":2023,"finding":"Muscle-specific ATF4 knockout mice are protected from age-related muscle atrophy, weakness, and transcriptional changes of aging (repression of anabolic mRNAs, induction of senescence-associated mRNAs), identifying ATF4 as an essential mediator of skeletal muscle aging.","method":"Muscle-specific ATF4 KO mice at 6 and 22 months; transcriptomics; exercise capacity and strength testing; proteomics","journal":"GeroScience","confidence":"High","confidence_rationale":"Tier 2 / Moderate — tissue-specific KO with longitudinal phenotyping, transcriptomics and proteomics","pmids":["37014538"],"is_preprint":false},{"year":2018,"finding":"ATF4 regulates a coordinated gene network in CD4+ T cells driving amino acid uptake, mTORC1 activation, protein translation, de novo synthesis of amino acids and glutathione, glycolysis, glutaminolysis, and oxidative phosphorylation; ATF4-deficient mice mount reduced Th1 but elevated Th17 responses.","method":"Atf4-deficient CD4+ T cells; gene expression analysis; mTORC1 activity measurement; cytokine production assays; EAE model","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic KO with multiple metabolic and immunological readouts, in vivo disease model","pmids":["29742431"],"is_preprint":false},{"year":2020,"finding":"ATF4 is required for ER stress-dependent UPRmt induction in alveolar epithelial cells: ER stress (UPRER) leads to ATF4-dependent UPRmt and mitochondrial dysfunction, but not the reverse; inducible ATF4 expression in mouse alveolar epithelial cells aggravates pulmonary UPRmt and lung injury.","method":"ATF4 KD/OE; mitochondrial stress assays; inducible ATF4 transgenic mice; bleomycin lung injury model","journal":"American journal of respiratory cell and molecular biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — directional epistasis established, genetic gain/loss of function, in vivo mouse model","pmids":["32551949"],"is_preprint":false},{"year":2022,"finding":"ATF4 controls expression of NADPH-generating enzymes in both the pentose phosphate pathway and mitochondrial serine/glycine/folate metabolic pathways; cardiomyocyte-specific ATF4 KO reduces NADPH, lowers reduced glutathione, exacerbates cardiomyopathy under pressure overload; ATF4 overexpression augments metabolic flux in these pathways.","method":"Cardiomyocyte-specific ATF4 KO mice; stable isotope tracer experiments; RNA-seq; metabolomics; transverse aortic constriction model","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — stable isotope tracing (metabolic flux), KO mice, transcriptomics and metabolomics combined","pmids":["35574856"],"is_preprint":false},{"year":2020,"finding":"ATF4 directly regulates LAMP3 (lysosomal-associated membrane protein 3) transcription during the integrated stress response: siRNA knockdown of ATF4 reduces LAMP3 mRNA, exogenous ATF4 upregulates LAMP3, and ChIP assays verified an ATF4-binding site in the LAMP3 promoter confirmed by dual-luciferase assay.","method":"siRNA knockdown; ATF4 overexpression; ChIP assay; dual-luciferase promoter assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — direct ChIP validation, luciferase reporter, loss/gain-of-function, multiple orthogonal methods","pmids":["32312748"],"is_preprint":false},{"year":2020,"finding":"In long-term synaptic plasticity (cLTP), ATF4 (also known as CREB-2, a transcriptional repressor of CREB-mediated gene expression) is phosphorylated at serine-219 by cAMP-dependent protein kinase, then degraded via ubiquitin-proteasome-mediated proteolysis; proteasome inhibitor β-lactone prevents this decrease; β-TrCP may serve as the ubiquitin E3 ligase.","method":"Chemically-induced LTP; proteasome inhibitor treatment; phospho-ATF4 immunoblotting; PKA pharmacology","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple biochemical approaches, defined phosphorylation site and kinase, but E3 ligase identification is preliminary","pmids":["33198401"],"is_preprint":false},{"year":2019,"finding":"Hop2 physically interacts with ATF4 via the Zip domain and enhances ATF4-dependent transcription; Hop2-deficient mice display an osteopenic phenotype similar to Atf4-/- mice with decreased osteocalcin mRNA, and Atf4+/-:Hop2+/- compound heterozygous mice exhibit identical skeletal defects.","method":"Yeast two-hybrid; deletional mapping; Hop2-/- mice; compound heterozygous mice; osteoblast differentiation assays","journal":"Journal of bone and mineral research","confidence":"High","confidence_rationale":"Tier 2 / Strong — yeast two-hybrid, domain mapping, genetic epistasis in vivo with compound heterozygotes","pmids":["31433867"],"is_preprint":false},{"year":2018,"finding":"Oncogenic BRAF ensures ATF4 induction during nutrient stress by activating GCN2 kinase; BRAF utilizes mTOR and eIF4B as downstream regulators of ATF4 translation, a pathway distinct from MEK-ERK that remains transiently active even during BRAF inhibitor treatment.","method":"BRAF inhibitors; GCN2 activator/inhibitor; mTOR inhibitors; eIF4B knockdown; ATF4 protein measurement under nutrient stress","journal":"iScience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological and genetic dissection of pathway, single lab, multiple approaches","pmids":["32283529"],"is_preprint":false},{"year":2017,"finding":"ATF4 transcriptionally targets SLC7A11/xCT (glutamate/cystine antiporter), elevating xCT expression; ATF4-dependent tumor-promoting effects including proliferation and angiogenesis are attenuated by pharmacological or genetic xCT inhibition, and forced xCT expression rescues growth in ATF4 knockdown cells.","method":"ATF4 siRNA knockdown; xCT inhibition/overexpression; ferroptosis inducer treatment; in vivo tumor models","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 / Moderate — loss/gain of function for both ATF4 and xCT with rescue experiments, multiple functional readouts","pmids":["28553953"],"is_preprint":false},{"year":2023,"finding":"Hepatocyte ATF4 protects against ferroptosis by maintaining SLC7A11/xCT expression for glutathione synthesis; hepatocyte-specific ATF4 deletion increases ferroptosis susceptibility and accelerates HCC development, reversed by ectopic SLC7A11 expression; ATF4 and SLC7A11 are positively correlated in human HCC and NASH.","method":"Hepatocyte-specific ATF4 KO mice; SLC7A11 reconstitution in ATF4-deficient livers; RNA-seq; ferroptosis inhibitor experiments; DEN carcinogen model","journal":"Journal of hepatology","confidence":"High","confidence_rationale":"Tier 2 / Strong — tissue-specific KO, rescue by single target reconstitution, multiple HCC models, human correlation","pmids":["36996941"],"is_preprint":false},{"year":2021,"finding":"YAP/TAZ sustain ATF4 protein stability, nuclear localization, and transcriptional activity in a TEAD-dependent manner; ATF4 cooperates with YAP/TAZ to induce SLC7A11 expression, enabling HCC cells to overcome ferroptosis and develop Sorafenib resistance.","method":"shRNA screening; transcriptomic analysis; ATF4 localization and stability assays; SLC7A11 reporter assays; TEAD inhibition","journal":"EMBO molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mechanistic follow-up with defined pathway, single lab, functional validation of ATF4 protein stability","pmids":["34664408"],"is_preprint":false},{"year":2022,"finding":"PRMT5 controls ATF4 mRNA splicing; PRMT5 inhibition causes intron-retaining ATF4 mRNA that is detained in the nucleus, reducing cytoplasmic ATF4 mRNA and protein, and downregulating ATF4 target genes involved in oxidative stress defense.","method":"PRMT5 inhibition; RNA-seq; nuclear/cytoplasmic ATF4 mRNA fractionation; ATF4 target gene expression; ROS measurement","journal":"Redox biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — transcriptomic analysis, pharmacological inhibition, single lab","pmids":["35305370"],"is_preprint":false},{"year":2022,"finding":"ATF4 interacts with CHOP and this interaction is essential for IOP elevation in glaucoma; ATF4-CHOP-GADD34 pathway promotes aberrant protein synthesis and ER client protein load in trabecular meshwork cells, causing TM dysfunction, IOP elevation, and glaucomatous neurodegeneration.","method":"ATF4-CHOP interaction assay; genetic depletion of pathway components; mouse glaucoma models; pharmacological GADD34 inhibition; protein synthesis measurement","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic and pharmacological pathway dissection, multiple glaucoma models, defined molecular interaction","pmids":["33154371"],"is_preprint":false},{"year":2023,"finding":"RGC-specific deletion of ATF4 and/or CHOP synergistically promotes retinal ganglion cell and optic nerve survival and preserves visual function; CRISPR-mediated knockdown of the ATF4 downstream effector Gadd45a also delivers neuroprotection in glaucoma models.","method":"RGC-specific Cre-mediated ATF4/CHOP deletion; optic nerve crush and ocular hypertension models; CRISPR knockdown; ISRIB pharmacological inhibition; visual function testing","journal":"Molecular therapy. Nucleic acids","confidence":"High","confidence_rationale":"Tier 2 / Moderate — cell-type-specific KO, multiple genetic and pharmacological approaches, two disease models","pmids":["37547290"],"is_preprint":false},{"year":2024,"finding":"ATF4 is preferentially translated within stress granules (SGs) and delivered from fibroblasts to tumor cells via migracytosis; pharmacological disassembly of SGs with PT-129 (a PROTAC targeting G3BP1/2 NTF2L domain) disrupts ATF4 delivery and prevents cancer cell proliferation.","method":"PROTAC degrader (PT-129); SG formation/disassembly assays; ATF4 localization and transfer assays; in vitro and in vivo tumor growth assays","journal":"Journal of the American Chemical Society","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — novel mechanistic finding with PROTAC tool compound, functional in vitro and in vivo validation, single lab","pmids":["39710983"],"is_preprint":false},{"year":2021,"finding":"ATF4 transcriptionally upregulates DDIT4 (REDD1) to suppress mTOR, inducing pro-survival autophagy during glutaminolysis inhibition; glutaminolysis inhibition promotes ATF4 mRNA expression by abrogating m6A modification and YTHDF2-mediated RNA decay.","method":"RNA-seq; luciferase reporter assays; ChIP; m6A modification analysis; mRNA half-life assays; RNA immunoprecipitation; in vivo CRC model","journal":"Theranostics","confidence":"High","confidence_rationale":"Tier 2 / Moderate — ChIP of ATF4 on DDIT4 promoter, m6A mechanism, multiple orthogonal methods, in vivo validation","pmids":["34373753"],"is_preprint":false},{"year":2018,"finding":"EIF1AX-A113splice mutations stabilize the translation preinitiation complex (PIC) and induce ATF4; ATF4 co-opts to suppress EIF2alpha phosphorylation, enabling a general increase in protein synthesis, and ATF4 cooperates with c-MYC to enhance mTOR sensitivity to amino acids.","method":"Isogenic cell lines expressing EIF1AX-A113splice; EIF2alpha phosphorylation assays; ATF4 expression measurement; mTOR activity assays; mouse thyroid cancer models","journal":"Cancer discovery","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — isogenic cell line models, mechanistic pathway dissection, in vivo validation","pmids":["30305285"],"is_preprint":false},{"year":2023,"finding":"VDR (Vitamin D receptor) suppresses ATF4 transcription by binding to the ATF4 promoter region, as confirmed by ChIP-qPCR and dual-luciferase reporter assay; VDR overexpression or agonist (paricalcitol) reduces ATF4-dependent ER stress in ischemia-reperfusion kidney injury.","method":"VDR KO/overexpression mice; paricalcitol treatment; ChIP-qPCR; dual-luciferase reporter assay; ATF4 overexpression rescue","journal":"Cell death discovery","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct promoter binding confirmed by ChIP and luciferase, genetic models, rescue experiment","pmids":["37173347"],"is_preprint":false},{"year":2024,"finding":"ATF4 directly binds the SLC7A11 promoter and increases its transcription; DHA inhibits ATF4 expression, thereby reducing SLC7A11, promoting lipid peroxidation and ferroptosis; ATF4 overexpression rescues DHA-induced ferroptosis.","method":"ATF4 promoter ChIP; ATF4/SLC7A11 lentiviral overexpression rescue; lipid peroxidation measurement; xenograft model","journal":"Journal of cellular and molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP of ATF4 on SLC7A11 promoter, gain-of-function rescue, in vivo validation, single lab","pmids":["38652216"],"is_preprint":false},{"year":2022,"finding":"ATF4-mediated CD36 upregulation contributes to hepatic lipotoxicity: genetic inhibition of ATF4 attenuates palmitate- or ER stress-induced CD36 upregulation; hepatocyte-specific ATF4 KO mice have lower CD36 expression; CD36 knockdown blunts ATF4 activation in a feedforward mechanism.","method":"Hepatocyte-specific ATF4 KO mice; siRNA knockdown; ER stress induction; CD36 and ATF4 expression analysis","journal":"American journal of physiology. Gastrointestinal and liver physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — tissue-specific KO, siRNA approaches, feedforward mechanism identified, single lab","pmids":["36852918"],"is_preprint":false},{"year":2022,"finding":"ATF4 directly regulated CTCF expression and interacted with CTCF in 3T3-L1 cells; ATF4 co-localizes with CTCF at promoters of key adipogenic genes including Cebpd and PPARg, cooperating to drive their transactivation and promote adipogenesis.","method":"ChIP-seq; RNA-seq; Co-IP of ATF4 and CTCF; ATF4 KD in vivo; CTCF KD/OE","journal":"Cell biology and toxicology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP-seq, Co-IP, loss/gain-of-function, in vivo confirmation, single lab","pmids":["33950334"],"is_preprint":false},{"year":2024,"finding":"Thbs1 activates TGFβ-Smad2/3 signaling in skeletal muscle, which induces ATF4 expression; ATF4 then modulates the autophagy-lysosomal pathway and ubiquitin-proteasome system to facilitate muscle atrophy; myofiber-specific Smad2/3 or ATF4 deletion antagonizes Thbs1-induced muscle atrophy.","method":"Skeletal muscle-specific transgenic and KO mice; TGFβ receptor inhibition; Smad2/3 KO; ATF4 KO; ALP and UPS activity assays","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple tissue-specific KO models, clear epistasis (Thbs1→TGFβ→Smad2/3→ATF4→atrophy), in vivo validation","pmids":["38678560"],"is_preprint":false},{"year":2017,"finding":"ATF4 knockdown in glioma cells attenuates autophagy induced by FLT3-ITD; FLT3-ITD activity controls cellular ATF4 levels; ATF4 is an essential mediator of FLT3-ITD-induced autophagy-dependent AML cell proliferation.","method":"FLT3 inhibitor treatment; ATF4 knockdown; autophagy measurement; xenograft mouse model; conditional shRNA","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KD with defined phenotype, in vivo validation, single lab","pmids":["29059168"],"is_preprint":false},{"year":2021,"finding":"Brown adipocyte-specific ATF4 activation (genetically via overexpression or physiologically via low-protein diet) improves cold tolerance and systemic metabolism in a Ucp1-independent manner, revealing a diet-dependent thermogenic mechanism in brown adipocytes.","method":"BA-specific ATF4 overexpression; Ucp1 KO mice; low-protein diet feeding; cold tolerance tests; proteome analysis","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — tissue-specific gain-of-function, Ucp1 KO epistasis, dietary intervention, single lab","pmids":["34551310"],"is_preprint":false},{"year":2023,"finding":"O-GlcNAcylation regulates ATF4 during the mitochondrial integrated stress response: OGT (O-GlcNAc transferase) knockdown increases ATF4 protein and mRNA, while Thiamet-G (OGT activator) elevates ATF4 protein upon mitochondrial stress; ATF4 occupancy at the ATF5 promoter increases in TMG-treated mouse brains.","method":"OGT KD; Thiamet-G treatment; ATF4 ChIP at ATF5 promoter; iPSC-derived neurons; AD mouse model","journal":"Frontiers in aging neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP confirming ATF4 occupancy, genetic KD, multiple model systems, single lab","pmids":["38192280"],"is_preprint":false},{"year":2022,"finding":"ATF4 cooperates with FOXO1 and C/EBPδ to regulate the transcriptional program of skeletal muscle atrophy during fasting; ATF4 enhances promoter activity of target atrophy genes in cooperation with C/EBPδ.","method":"FOXO1-transgenic and FOXO1,3a,4-/- mice; C/EBPδ KD/OE; gene expression arrays; promoter activity assays","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic models, promoter assays, cooperative transcription factor evidence, single lab","pmids":["35061305"],"is_preprint":false},{"year":2022,"finding":"ATF4 transcriptionally activates GLUT5 and ALDOB expression in GBM cells in response to glucose deprivation, switching energy supply from glycolysis to fructolysis; disruption of ATF4-dependent fructolysis inhibits GBM growth in vitro and in vivo.","method":"ATF4 KD/KO; GLUT5 and ALDOB expression analysis; genetic/pharmacological disruption of fructolysis; xenograft models; patient specimen correlation","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic loss-of-function, in vivo validation, defined transcriptional targets, single lab","pmids":["36245009"],"is_preprint":false},{"year":2020,"finding":"ATF4 in Drosophila (ortholog): Notch signaling combined with ETC attenuation activates the PERK-ATF4 pathway, which drives expression of metabolic enzymes, nutrient transporters, and mitochondrial chaperones; this ATF4-mediated Warburg metabolism promotes cell proliferation, pH changes mediate over-proliferation.","method":"Drosophila genetic models (COX7a KD, Notch activation); PERK and ATF4 genetic manipulation; metabolic profiling; pH measurement","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Drosophila ortholog, genetic epistasis, metabolic mechanistic follow-up, single lab","pmids":["32433968"],"is_preprint":false}],"current_model":"ATF4 is a stress-induced bZIP transcription factor whose translation is selectively upregulated by eIF2alpha phosphorylation (via GCN2, PERK, HRI, or PKR kinases) and, paradoxically, by mTORC1 signaling; once translated, ATF4 acts as a transcriptional activator (heterodimerizing with partners including CHOP, FoxO1, KDM4C, Hop2, and CTCF) to drive expression of target genes governing amino acid uptake/synthesis, glutathione biosynthesis (via SLC7A11/xCT), NADPH production, autophagy, UPRmt, and VEGF/angiogenesis, while its activity and stability are regulated by post-translational modifications including PRMT1-mediated arginine methylation (promoting stability), PARP-1-mediated PARylation (reducing CRE binding), mTORC1-mediated phosphorylation (activating UPRmt), and O-GlcNAcylation, as well as ubiquitin-proteasome-mediated degradation downstream of PKA phosphorylation at serine-219; collectively ATF4 coordinates cellular adaptation to metabolic, ER, and mitochondrial stress, but can also drive pathological outcomes including cardiac atrophy (via PERK-ATF4-autophagy), muscle atrophy (cooperating with p53 and Thbs1-TGFβ-Smad2/3 pathways), and glaucoma (via ATF4-CHOP-GADD34-dependent protein synthesis overload)."},"narrative":{"mechanistic_narrative":"ATF4 is a stress-induced bZIP transcription factor that serves as the master effector of the integrated stress response (ISR), coupling diverse upstream signals to a transcriptional program governing amino acid metabolism, redox homeostasis, autophagy, and mitochondrial adaptation [PMID:19800252, PMID:33646118]. Its expression is controlled chiefly at the level of translation: phosphorylation of eIF2alpha by stress-sensing kinases—GCN2 detecting uncharged tRNA in the amino acid response [PMID:19800252], PERK during ER stress [PMID:19114033], and HRI in erythroid precursors [PMID:22498744]—selectively upregulates ATF4 synthesis, a step requiring the RNA helicase DDX3 acting through the eIF4F complex [PMID:29062139]. mTORC1 provides a parallel, ISR-distinct route to ATF4 induction and, upon mitochondrial stress, directly phosphorylates ATF4 in a v-ATPase/lysosome-dependent manner to drive the mitochondrial unfolded protein response (UPRmt) [PMID:33646118, PMID:37679337]. Once active, ATF4 heterodimerizes and cooperates with partners including CHOP, FoxO1, KDM4C, Hop2, and CTCF to bind target promoters and CARE/CRE elements [PMID:22298775, PMID:26774480, PMID:31433867, PMID:33154371, PMID:33950334], and directly transactivates genes for cystine uptake and glutathione synthesis (SLC7A11/xCT) [PMID:28553953, PMID:36996941], NADPH-generating pentose-phosphate and serine/glycine/folate enzymes [PMID:35574856], the mTOR repressor REDD1/DDIT4 [PMID:19114033, PMID:34373753], and the NRF2 antioxidant axis via CHAC1 [PMID:37410595], thereby protecting cells from oxidative stress and ferroptosis. ATF4 activity is further tuned post-translationally by PRMT1-mediated arginine-239 methylation that stabilizes the protein [PMID:31787756], PARP-1-mediated PARylation that reduces CRE binding [PMID:28457938], O-GlcNAcylation [PMID:38192280], and PKA-triggered phosphorylation at serine-219 leading to ubiquitin-proteasome degradation [PMID:33198401]. Through these outputs ATF4 coordinates adaptation to metabolic, ER, and mitochondrial stress across many tissues, but its sustained activity drives pathology including PERK-ATF4-autophagy-mediated cardiac atrophy [PMID:34168130], skeletal muscle atrophy and aging in cooperation with p53, FOXO1/C/EBPdelta, and Thbs1-TGFbeta-Smad2/3 signaling [PMID:24895282, PMID:37014538, PMID:38678560, PMID:35061305], and ATF4-CHOP-GADD34-dependent protein-synthesis overload in glaucoma [PMID:33154371, PMID:37547290].","teleology":[{"year":2008,"claim":"Established ATF4 as the necessary and sufficient transcriptional output of the PERK arm of ER stress, linking eIF2alpha phosphorylation to a defined target gene (REDD1).","evidence":"Genetic KO of PERK and ATF4 in MEFs plus ATF4 overexpression with mRNA readout","pmids":["19114033"],"confidence":"High","gaps":["Did not address non-ER stress inputs","Direct vs indirect promoter binding at REDD1 not resolved here"]},{"year":2009,"claim":"Defined the upstream logic of ATF4 induction in the amino acid response, showing GCN2 sensing of uncharged tRNA feeds eIF2alpha-ATF4 to activate CARE-containing genes.","evidence":"Genetic/biochemical characterization of the AAR pathway with transcriptional reporters","pmids":["19800252"],"confidence":"High","gaps":["Did not enumerate the full ATF4 target set","Heterodimer partner identities at CARE elements not defined"]},{"year":2012,"claim":"Identified physiological ATF4 partner proteins and kinase inputs, showing FoxO1 binds ATF4 to control glucose homeostasis and HRI drives the erythroid ATF4 program.","evidence":"Co-IP and genetic mouse models (FoxO1/ATF4); HRI KO mice with ROS and differentiation readouts","pmids":["22298775","22498744"],"confidence":"High","gaps":["Tissue specificity of FoxO1-ATF4 complex not generalized","Direct ATF4 target genes in erythroid context not fully mapped"]},{"year":2013,"claim":"Revealed a non-transcriptional protein-protein function of ATF4: stabilizing HIF-1alpha to promote VEGF-driven angiogenesis.","evidence":"Co-IP, ATF4 KO mice, ubiquitination and HIF-1alpha stability assays, VEGF rescue","pmids":["23649506"],"confidence":"High","gaps":["Structural basis of ATF4-HIF-1alpha interaction unknown","Generality beyond osteoblasts untested"]},{"year":2016,"claim":"Connected ATF4 to chromatin-modifying machinery, showing KDM4C cooperates with ATF4 to derepress serine-glycine biosynthesis genes via H3K9me3 removal.","evidence":"Co-IP, ChIP, siRNA knockdown and KDM4C overexpression","pmids":["26774480"],"confidence":"High","gaps":["Whether KDM4C is a general ATF4 cofactor unknown","Recruitment order of ATF4 vs KDM4C not resolved"]},{"year":2017,"claim":"Showed ATF4 activity and stability are post-translationally controlled (PARP-1 PARylation reducing CRE binding) and that DDX3 governs its stress-induced translation, while xCT/SLC7A11 emerged as a key pro-tumor ATF4 target.","evidence":"ChIP-qPCR, in vitro CRE binding assay, polyribosome profiling/luciferase, xCT inhibition/overexpression rescue","pmids":["28457938","29062139","28553953"],"confidence":"High","gaps":["PARylation site on ATF4 not mapped","Interplay between translational and PTM control not integrated"]},{"year":2018,"claim":"Defined ATF4 as a metabolic master regulator in adaptive immunity and a node co-opted by oncogenes, coordinating amino acid/glutathione metabolism and additive muscle atrophy with p53.","evidence":"Atf4-deficient CD4+ T cells with EAE model; BRAF/GCN2 pharmacology; muscle-specific and double p53/ATF4 KO mice","pmids":["29742431","32283529","24895282"],"confidence":"High","gaps":["Direct ATF4 targets in T cells not all validated by ChIP","p53-ATF4 convergence point upstream of p21 unresolved"]},{"year":2019,"claim":"Established arginine methylation as a stability switch (PRMT1 at R239) and embedded ATF4 in ER-stress ferroptosis defense and skeletal partnerships (Hop2).","evidence":"R239K mutant, PRMT1 KO; siRNA pathway dissection (PERK-ATF4-HSPA5-GPX4); yeast two-hybrid and compound heterozygous mice (Hop2)","pmids":["31787756","31519193","31433867"],"confidence":"High","gaps":["Enzyme(s) reversing R239 methylation unknown","Whether Hop2-ATF4 acts outside bone untested"]},{"year":2020,"claim":"Expanded ATF4 outputs to organelle quality control and direct transcriptional targets, including reticulophagy, UPRmt induction, NRF1 repression, LAMP3, and the HBS1L-MYB enhancer governing globin switching.","evidence":"ATF4 KO with reticulophagy imaging; directional UPRER-to-UPRmt epistasis; ChIP at NRF1, LAMP3, and HBS1L-MYB; CRISPR isogenic erythroid cells","pmids":["33111629","32551949","33177163","32312748","32755585"],"confidence":"High","gaps":["Direct vs indirect status of some targets varies","Determinants of activating vs repressive ATF4 promoter occupancy unclear"]},{"year":2021,"claim":"Distinguished mTORC1 from canonical ISR control of ATF4, linked mitochondrial respiration to ATF4 via asparagine, and demonstrated PERK-ATF4-autophagy as a driver of cardiac atrophy and tumor ferroptosis resistance.","evidence":"Comparative transcriptomics in mTORC1- vs ISR-activated cells; metformin/asparagine in tumor models; Thbs1 transgenic/PERK KO hearts; YAP/TAZ-ATF4-SLC7A11 in HCC; DDIT4 m6A/YTHDF2 mechanism","pmids":["33646118","33609439","34168130","34664408","34373753"],"confidence":"High","gaps":["How mTORC1 selects a subset of ATF4 targets unresolved","Crosstalk between transcriptional and translational mTORC1 inputs to ATF4 unclear"]},{"year":2022,"claim":"Detailed ATF4's redox/metabolic effector network and additional partners, showing control of NADPH-generating pathways, fructolysis genes, CD36 lipotoxicity, and cooperation with CTCF and FOXO1/C/EBPdelta.","evidence":"Cardiomyocyte-specific ATF4 KO with isotope tracing/metabolomics; ATF4 KD/KO for GLUT5/ALDOB; hepatocyte ATF4 KO for CD36; ChIP-seq/Co-IP with CTCF; promoter assays with C/EBPdelta","pmids":["35574856","36245009","36852918","33950334","35061305"],"confidence":"High","gaps":["Tissue-specific partner combinations not unified into a single model","PRMT5 splicing control of ATF4 mRNA needs orthogonal confirmation"]},{"year":2023,"claim":"Resolved direct mTORC1 phosphorylation of ATF4 driving UPRmt selectivity and positioned ATF4 as a therapeutic node in glaucoma, HCC ferroptosis, NRF2 activation, and O-GlcNAc/VDR regulation.","evidence":"v-ATPase/mTORC1 inhibition with phospho-deficient ATF4 mutants; RGC-specific ATF4/CHOP deletion and ISRIB; hepatocyte ATF4 KO with SLC7A11 rescue; ATF4-NRF2-CHAC1 KD/OE; OGT/Thiamet-G ChIP; VDR promoter ChIP","pmids":["37679337","37547290","36996941","37410595","38192280","37173347"],"confidence":"High","gaps":["mTORC1 phosphorylation site(s) on ATF4 not fully mapped","Several upstream regulators validated in single labs only"]},{"year":2024,"claim":"Uncovered non-cell-autonomous ATF4 biology and additional atrophy circuitry, showing stress-granule-localized ATF4 transfer between cells via migracytosis and Thbs1-TGFbeta-Smad2/3 induction of ATF4 driving muscle atrophy.","evidence":"G3BP1/2 PROTAC (PT-129) disrupting SG-dependent ATF4 delivery; muscle-specific Smad2/3 and ATF4 KO mice","pmids":["39710983","38678560"],"confidence":"Medium","gaps":["Migracytosis-mediated ATF4 transfer awaits independent replication","Physiological scope of intercellular ATF4 transfer unknown"]},{"year":null,"claim":"How the full repertoire of ATF4 heterodimer partners, post-translational modifications, and upstream kinase/mTORC1 inputs are integrated to select context-specific target gene programs—and to switch between adaptive and pathological outcomes—remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model explaining target-gene selectivity across stress inputs","Genome-wide partner-dependent ATF4 occupancy maps lacking across tissues","Determinants of activating vs repressive ATF4 binding undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[0,1,8,15,23,27,34,37]},{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[8,15,23,36,37]},{"term_id":"GO:0140097","term_label":"catalytic activity, acting on DNA","supporting_discovery_ids":[0,27,34]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[6,16,29]},{"term_id":"GO:0005654","term_label":"nucleoplasm","supporting_discovery_ids":[6,7,39]}],"pathway":[{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[0,1,2,14]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[0,8,23,27,34,39]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[2,20,22,27,45]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[4,13,34,41]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[9,27,28,37]}],"complexes":[],"partners":["CHOP","FOXO1","KDM4C","HOP2","CTCF","HIF1A","CEBPD","DDX3X"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P18848","full_name":"Cyclic AMP-dependent transcription factor ATF-4","aliases":["Activating transcription factor 4","Cyclic AMP-responsive element-binding protein 2","CREB-2","cAMP-responsive element-binding protein 2","Tax-responsive enhancer element-binding protein 67","TaxREB67"],"length_aa":351,"mass_kda":38.6,"function":"Transcription factor that binds the cAMP response element (CRE) (consensus: 5'-GTGACGT[AC][AG]-3') and displays two biological functions, as regulator of metabolic and redox processes under normal cellular conditions, and as master transcription factor during integrated stress response (ISR) (PubMed:16682973, PubMed:17684156, PubMed:31023583, PubMed:31444471, PubMed:32132707). Binds to asymmetric CRE's as a heterodimer and to palindromic CRE's as a homodimer (By similarity). Core effector of the ISR, which is required for adaptation to various stress such as endoplasmic reticulum (ER) stress, amino acid starvation, mitochondrial stress or oxidative stress (PubMed:31023583, PubMed:32132707). During ISR, ATF4 translation is induced via an alternative ribosome translation re-initiation mechanism in response to EIF2S1/eIF-2-alpha phosphorylation, and stress-induced ATF4 acts as a master transcription factor of stress-responsive genes in order to promote cell recovery (PubMed:31023583, PubMed:32132706, PubMed:32132707). Promotes the transcription of genes linked to amino acid sufficiency and resistance to oxidative stress to protect cells against metabolic consequences of ER oxidation (By similarity). Activates the transcription of NLRP1, possibly in concert with other factors in response to ER stress (PubMed:26086088). Activates the transcription of asparagine synthetase (ASNS) in response to amino acid deprivation or ER stress (PubMed:11960987). However, when associated with DDIT3/CHOP, the transcriptional activation of the ASNS gene is inhibited in response to amino acid deprivation (PubMed:18940792). Together with DDIT3/CHOP, mediates programmed cell death by promoting the expression of genes involved in cellular amino acid metabolic processes, mRNA translation and the terminal unfolded protein response (terminal UPR), a cellular response that elicits programmed cell death when ER stress is prolonged and unresolved (By similarity). Activates the expression of COX7A2L/SCAF1 downstream of the EIF2AK3/PERK-mediated unfolded protein response, thereby promoting formation of respiratory chain supercomplexes and increasing mitochondrial oxidative phosphorylation (PubMed:31023583). Together with DDIT3/CHOP, activates the transcription of the IRS-regulator TRIB3 and promotes ER stress-induced neuronal cell death by regulating the expression of BBC3/PUMA in response to ER stress (PubMed:15775988). May cooperate with the UPR transcriptional regulator QRICH1 to regulate ER protein homeostasis which is critical for cell viability in response to ER stress (PubMed:33384352). In the absence of stress, ATF4 translation is at low levels and it is required for normal metabolic processes such as embryonic lens formation, fetal liver hematopoiesis, bone development and synaptic plasticity (By similarity). Acts as a regulator of osteoblast differentiation in response to phosphorylation by RPS6KA3/RSK2: phosphorylation in osteoblasts enhances transactivation activity and promotes expression of osteoblast-specific genes and post-transcriptionally regulates the synthesis of Type I collagen, the main constituent of the bone matrix (PubMed:15109498). Cooperates with FOXO1 in osteoblasts to regulate glucose homeostasis through suppression of beta-cell production and decrease in insulin production (By similarity). Activates transcription of SIRT4 (By similarity). Regulates the circadian expression of the core clock component PER2 and the serotonin transporter SLC6A4 (By similarity). Binds in a circadian time-dependent manner to the cAMP response elements (CRE) in the SLC6A4 and PER2 promoters and periodically activates the transcription of these genes (By similarity). Mainly acts as a transcriptional activator in cellular stress adaptation, but it can also act as a transcriptional repressor: acts as a regulator of synaptic plasticity by repressing transcription, thereby inhibiting induction and maintenance of long-term memory (By similarity). Regulates synaptic functions via interaction with DISC1 in neurons, which inhibits ATF4 transcription factor activity by disrupting ATF4 dimerization and DNA-binding (PubMed:31444471) (Microbial infection) Binds to a Tax-responsive enhancer element in the long terminal repeat of HTLV-I","subcellular_location":"Nucleus; Nucleus speckle; Cytoplasm; Cell membrane; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome","url":"https://www.uniprot.org/uniprotkb/P18848/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/ATF4","classification":"Common Essential","n_dependent_lines":927,"n_total_lines":1208,"dependency_fraction":0.7673841059602649},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ATF4","total_profiled":1310},"omim":[{"mim_id":"620670","title":"IMMUNODEFICIENCY, COMMON VARIABLE, 15; CVID15","url":"https://www.omim.org/entry/620670"},{"mim_id":"620521","title":"KELCH DOMAIN-CONTAINING PROTEIN 7B; KLHDC7B","url":"https://www.omim.org/entry/620521"},{"mim_id":"619275","title":"BASIC LEUCINE ZIPPER DOMAIN- AND W2 DOMAIN-CONTAINING PROTEIN 2; BZW2","url":"https://www.omim.org/entry/619275"},{"mim_id":"619252","title":"BASIC LEUCINE ZIPPER DOMAIN- AND W2 DOMAIN-CONTAINING PROTEIN 1; BZW1","url":"https://www.omim.org/entry/619252"},{"mim_id":"618877","title":"LEUKOENCEPHALOPATHY, DEVELOPMENTAL DELAY, AND EPISODIC NEUROLOGIC REGRESSION SYNDROME; LEUDEN","url":"https://www.omim.org/entry/618877"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/ATF4"},"hgnc":{"alias_symbol":["TAXREB67","CREB-2"],"prev_symbol":["TXREB"]},"alphafold":{"accession":"P18848","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P18848","model_url":"https://alphafold.ebi.ac.uk/files/AF-P18848-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P18848-F1-predicted_aligned_error_v6.png","plddt_mean":62.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ATF4","jax_strain_url":"https://www.jax.org/strain/search?query=ATF4"},"sequence":{"accession":"P18848","fasta_url":"https://rest.uniprot.org/uniprotkb/P18848.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P18848/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P18848"}},"corpus_meta":[{"pmid":"19800252","id":"PMC_19800252","title":"ATF4-dependent transcription mediates signaling of amino acid limitation.","date":"2009","source":"Trends in endocrinology and 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ATF4 then heterodimerizes with partners to activate specific genes via the CCAAT-enhancer binding protein-activating transcription factor response element (CARE).\",\n      \"method\": \"Genetic and biochemical characterization of AAR pathway; transcriptional reporter assays\",\n      \"journal\": \"Trends in endocrinology and metabolism: TEM\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — pathway established by multiple labs using epistasis and biochemical assays, replicated across literature\",\n      \"pmids\": [\"19800252\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"ATF4 is necessary and sufficient for ER stress-induced REDD1 expression: PERK-deficient MEF cells fail to upregulate REDD1 mRNA upon ER stress, ATF4-deficient MEFs also fail, and exogenous ATF4 expression alone is sufficient to induce REDD1.\",\n      \"method\": \"Genetic KO of PERK and ATF4 in MEF cells; exogenous ATF4 overexpression; mRNA quantification\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function and gain-of-function with defined molecular readout, two orthogonal genetic approaches in single study\",\n      \"pmids\": [\"19114033\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"mTORC1 activates ATF4 through a mechanism distinct from the canonical ISR; mTORC1-ATF4 signaling promotes expression of a subset of ATF4 target genes including those involved in amino acid uptake/synthesis, tRNA charging, and cellular cystine uptake for glutathione synthesis.\",\n      \"method\": \"Comparative transcriptomics in mTORC1-stimulated vs ISR-activated MEFs and human cancer cell lines; ATF4 KO and pharmacological mTORC1 inhibition\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple cell lines, KO controls, genome-wide transcriptomics with mechanistic follow-up in one rigorous study\",\n      \"pmids\": [\"33646118\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Asparagine availability communicates active mitochondrial respiration to ATF4 and mTORC1: ETC inhibition depletes asparagine, increases ATF4 levels, and impairs mTORC1 activity; exogenous asparagine restores both ATF4 and mTORC1 activities.\",\n      \"method\": \"ETC inhibition with metformin; exogenous asparagine supplementation; asparaginase treatment; mouse tumor models\",\n      \"journal\": \"Cell metabolism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal approaches (pharmacological, dietary, in vivo), replicated across cancer models\",\n      \"pmids\": [\"33609439\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Thbs1 binds and activates PERK, inducing its downstream transcription factor ATF4, causing autophagy-mediated cardiac atrophy; PERK gene deletion in Thbs1 transgenic mice blunts ATF4 induction and autophagy, largely rescuing the lethal cardiac atrophy phenotype. AAV9-mediated overexpression of PERK or ATF4 alone is sufficient to promote cardiac atrophy.\",\n      \"method\": \"Transgenic and KO mouse models; AAV9 gene transfer; biochemical analysis of PERK-ATF4-autophagy pathway\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple genetic models (gain-of-function, loss-of-function), in vivo epistasis, orthogonal AAV confirmation\",\n      \"pmids\": [\"34168130\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"HRI (heme-regulated eIF2alpha kinase) activates the Atf4 signaling pathway in erythroid precursors to reduce oxidative stress and promote erythroid differentiation; Hri-/- erythroblasts show increased ROS and apoptosis upon stress, and the Hri-eIF2αP-Atf4 pathway is required for erythroid differentiation.\",\n      \"method\": \"HRI knockout mice; ex vivo erythroid differentiation; ROS measurement; iron deficiency models\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with defined pathway epistasis and multiple phenotypic readouts in one study\",\n      \"pmids\": [\"22498744\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"FoxO1 physically interacts with ATF4 in osteoblast nuclei and promotes ATF4 transcriptional activity; the FoxO1-ATF4 complex synergistically suppresses osteocalcin activity by upregulating the phosphatase that inactivates osteocalcin, thereby regulating glucose homeostasis.\",\n      \"method\": \"Co-immunoprecipitation; genetic mouse models of FoxO1 and ATF4; transcriptional reporter assays; glucose tolerance tests\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, genetic epistasis in vivo, multiple functional readouts\",\n      \"pmids\": [\"22298775\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"KDM4C physically interacts with ATF4 and cooperates to activate amino acid biosynthesis genes (serine-glycine synthesis pathway); KDM4C activates ATF4 transcription and requires ATF4 to target serine pathway genes, removing repressive H3K9 trimethylation at these loci.\",\n      \"method\": \"Co-immunoprecipitation; ChIP; gene expression analysis; siRNA knockdown; KDM4C overexpression\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ChIP validation, genetic KD, multiple orthogonal methods in one study\",\n      \"pmids\": [\"26774480\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"ATF4 represses transcription of NRF1 (nuclear respiratory factor 1) by binding to the NRF1 promoter, thereby suppressing NRF1-TFAM signaling, impairing mitochondrial biogenesis and respiratory function in alcohol-induced liver injury.\",\n      \"method\": \"Hepatocyte-specific ATF4 KO mice; ChIP assay showing ATF4 binding to NRF1 promoter; TFAM silencing/overexpression rescue experiments; clinical validation in AH patients\",\n      \"journal\": \"Gut\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ChIP confirming direct promoter binding, KO mice, rescue experiments, clinical validation\",\n      \"pmids\": [\"33177163\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"DHA (dihydroartemisinin) activates ER stress in glioma cells leading to PERK-upregulated ATF4 expression, which in turn induces HSPA5; HSPA5 then increases GPX4 expression and activity, protecting cells from ferroptosis. siRNA knockdown of PERK, ATF4, or HSPA5 increases DHA-induced ferroptosis.\",\n      \"method\": \"siRNA knockdown; small molecule inhibitors; in vitro and in vivo glioma models; protein expression analysis\",\n      \"journal\": \"Journal of experimental & clinical cancer research : CR\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KD at each step of pathway, in vivo validation, multiple orthogonal approaches\",\n      \"pmids\": [\"31519193\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"PARP-1 activation induces PARylation of ATF4, reducing its binding to the CRE sequence; conversely, PARP inhibition increases ATF4 binding to the MKP-1 promoter (confirmed by ChIP-qPCR), inducing MKP-1 expression and inactivating JNK and p38 MAP kinases to reduce mitochondrial ROS.\",\n      \"method\": \"ChIP-qPCR; PARP inhibition/silencing; in vitro CRE binding assay; multiple human cell lines\",\n      \"journal\": \"Free radical biology & medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — direct in vitro binding assay, ChIP-qPCR, multiple cell lines, first description of PARP-1-ATF4-MKP-1 axis\",\n      \"pmids\": [\"28457938\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PRMT1 methylates ATF4 on arginine 239, promoting ATF4 protein stability; a methylation-deficient ATF4 R239K mutant exacerbates ER stress and proapoptotic signaling; PRMT1 inhibition augments ER stress in cardiomyocytes through an ATF4-dependent mechanism.\",\n      \"method\": \"PRMT1 overexpression/inhibition/KO; methylation-deficient ATF4 mutant (R239K); caspase-3 activation and γH2AX measurement\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — site-specific mutagenesis, genetic KO, defined PTM with functional consequence\",\n      \"pmids\": [\"31787756\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"DDX3, an RNA-binding protein, promotes ATF4 mRNA translation downstream of phosphorylated eIF2alpha during ER stress; DDX3 depletion reduces ATF4 protein levels, and DDX3 binds the eIF4F complex which is required for ER stress-induced ATF4 translation.\",\n      \"method\": \"DDX3 depletion; luciferase assays with ATF4 5'UTR; polyribosome profiling; protein interaction assays with eIF4F complex\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (polyribosome profiling, luciferase, Co-IP), translational mechanism defined\",\n      \"pmids\": [\"29062139\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"ATF4 is required for ER stress-induced reticulophagy in glioblastoma; ATF4 knockout significantly attenuates loperamide-induced autophagy, autophagic cell death, and reticulophagy mediated through RETREG1/FAM134B and TEX264 receptors.\",\n      \"method\": \"ATF4 KO; electron and fluorescence microscopy; autophagy flux assays; siRNA knockdown of reticulophagy receptors\",\n      \"journal\": \"Autophagy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with specific phenotypic readout, multiple microscopy approaches, single lab\",\n      \"pmids\": [\"33111629\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"mTORC1 directly phosphorylates ATF4 in a v-ATPase-dependent manner via lysosomal signaling upon mitochondrial stress; this phosphorylation is required for UPRmt transcriptional activation but not for UPRER; mTORC1-dependent ATF4 phosphorylation maintains mitochondrial redox homeostasis.\",\n      \"method\": \"v-ATPase inhibition; mTORC1 inhibition; phosphorylation-deficient ATF4 mutants; ROS measurement; in vitro kinase assay context\",\n      \"journal\": \"Cell discovery\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic and pharmacological dissection of the v-ATPase/mTORC1/ATF4 axis, mutation studies, specific pathway discrimination\",\n      \"pmids\": [\"37679337\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Reduction of β-globin is sufficient to induce ATF4 expression in erythroid precursors; ATF4 binds within the HBS1L-MYB intergenic enhancer to regulate MYB expression, and reduced ATF4 upon β-globin knockout decreases MYB and BCL11A levels, leading to γ-globin re-expression.\",\n      \"method\": \"CRISPR-Cas9 genome editing; RNA-seq; ATF4 ChIP at HBS1L-MYB enhancer; isogenic erythroid cell differentiation\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR editing, ChIP validation of direct binding, RNA-seq, isogenic comparisons\",\n      \"pmids\": [\"32755585\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"ATF4 interacts with HIF-1alpha in hypoxic osteoblasts and prevents HIF-1alpha binding to prolyl hydroxylases; loss of ATF4 increases HIF-1alpha ubiquitination and reduces its protein stability, thereby decreasing VEGF expression and bone angiogenesis.\",\n      \"method\": \"Co-immunoprecipitation; ATF4 KO mice; ubiquitination assay; HIF-1alpha stability measurement; recombinant VEGF rescue\",\n      \"journal\": \"Journal of bone and mineral research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, KO mice, ubiquitination assay, multiple orthogonal approaches in one study\",\n      \"pmids\": [\"23649506\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ATF4 is an obligatory metabolic activator of NRF2: ATF4 increases NRF2 transcription and induces CHAC1 (glutathione-degrading enzyme), which is critical for maintaining NRF2 activation; NRF2 in turn supports ATF4-induced cells by increasing cystine uptake via xCT and upregulating thioredoxin usage.\",\n      \"method\": \"ATF4 KD/OE; NRF2 measurement; CHAC1 regulation analysis; cystine uptake assays; transcriptional reporter assays\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KD/OE with multiple pathway readouts, single lab, mechanistic link between ISR and NRF2\",\n      \"pmids\": [\"37410595\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"ATF4 and p53 mediate distinct and additive pathways to skeletal muscle atrophy: each is required independently for immobilization-induced atrophy, forced expression of either induces atrophy, and the two pathways converge on p21 as a downstream effector that itself is required for atrophy.\",\n      \"method\": \"Muscle-specific KO mice; forced ATF4 expression in vivo; genome-wide mRNA arrays; double p53/ATF4 knockout\",\n      \"journal\": \"American journal of physiology. Endocrinology and metabolism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with single and double KOs, gain-of-function, genome-wide target identification\",\n      \"pmids\": [\"24895282\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Muscle-specific ATF4 knockout mice are protected from age-related muscle atrophy, weakness, and transcriptional changes of aging (repression of anabolic mRNAs, induction of senescence-associated mRNAs), identifying ATF4 as an essential mediator of skeletal muscle aging.\",\n      \"method\": \"Muscle-specific ATF4 KO mice at 6 and 22 months; transcriptomics; exercise capacity and strength testing; proteomics\",\n      \"journal\": \"GeroScience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — tissue-specific KO with longitudinal phenotyping, transcriptomics and proteomics\",\n      \"pmids\": [\"37014538\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"ATF4 regulates a coordinated gene network in CD4+ T cells driving amino acid uptake, mTORC1 activation, protein translation, de novo synthesis of amino acids and glutathione, glycolysis, glutaminolysis, and oxidative phosphorylation; ATF4-deficient mice mount reduced Th1 but elevated Th17 responses.\",\n      \"method\": \"Atf4-deficient CD4+ T cells; gene expression analysis; mTORC1 activity measurement; cytokine production assays; EAE model\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with multiple metabolic and immunological readouts, in vivo disease model\",\n      \"pmids\": [\"29742431\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"ATF4 is required for ER stress-dependent UPRmt induction in alveolar epithelial cells: ER stress (UPRER) leads to ATF4-dependent UPRmt and mitochondrial dysfunction, but not the reverse; inducible ATF4 expression in mouse alveolar epithelial cells aggravates pulmonary UPRmt and lung injury.\",\n      \"method\": \"ATF4 KD/OE; mitochondrial stress assays; inducible ATF4 transgenic mice; bleomycin lung injury model\",\n      \"journal\": \"American journal of respiratory cell and molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — directional epistasis established, genetic gain/loss of function, in vivo mouse model\",\n      \"pmids\": [\"32551949\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ATF4 controls expression of NADPH-generating enzymes in both the pentose phosphate pathway and mitochondrial serine/glycine/folate metabolic pathways; cardiomyocyte-specific ATF4 KO reduces NADPH, lowers reduced glutathione, exacerbates cardiomyopathy under pressure overload; ATF4 overexpression augments metabolic flux in these pathways.\",\n      \"method\": \"Cardiomyocyte-specific ATF4 KO mice; stable isotope tracer experiments; RNA-seq; metabolomics; transverse aortic constriction model\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — stable isotope tracing (metabolic flux), KO mice, transcriptomics and metabolomics combined\",\n      \"pmids\": [\"35574856\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"ATF4 directly regulates LAMP3 (lysosomal-associated membrane protein 3) transcription during the integrated stress response: siRNA knockdown of ATF4 reduces LAMP3 mRNA, exogenous ATF4 upregulates LAMP3, and ChIP assays verified an ATF4-binding site in the LAMP3 promoter confirmed by dual-luciferase assay.\",\n      \"method\": \"siRNA knockdown; ATF4 overexpression; ChIP assay; dual-luciferase promoter assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — direct ChIP validation, luciferase reporter, loss/gain-of-function, multiple orthogonal methods\",\n      \"pmids\": [\"32312748\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"In long-term synaptic plasticity (cLTP), ATF4 (also known as CREB-2, a transcriptional repressor of CREB-mediated gene expression) is phosphorylated at serine-219 by cAMP-dependent protein kinase, then degraded via ubiquitin-proteasome-mediated proteolysis; proteasome inhibitor β-lactone prevents this decrease; β-TrCP may serve as the ubiquitin E3 ligase.\",\n      \"method\": \"Chemically-induced LTP; proteasome inhibitor treatment; phospho-ATF4 immunoblotting; PKA pharmacology\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple biochemical approaches, defined phosphorylation site and kinase, but E3 ligase identification is preliminary\",\n      \"pmids\": [\"33198401\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Hop2 physically interacts with ATF4 via the Zip domain and enhances ATF4-dependent transcription; Hop2-deficient mice display an osteopenic phenotype similar to Atf4-/- mice with decreased osteocalcin mRNA, and Atf4+/-:Hop2+/- compound heterozygous mice exhibit identical skeletal defects.\",\n      \"method\": \"Yeast two-hybrid; deletional mapping; Hop2-/- mice; compound heterozygous mice; osteoblast differentiation assays\",\n      \"journal\": \"Journal of bone and mineral research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — yeast two-hybrid, domain mapping, genetic epistasis in vivo with compound heterozygotes\",\n      \"pmids\": [\"31433867\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Oncogenic BRAF ensures ATF4 induction during nutrient stress by activating GCN2 kinase; BRAF utilizes mTOR and eIF4B as downstream regulators of ATF4 translation, a pathway distinct from MEK-ERK that remains transiently active even during BRAF inhibitor treatment.\",\n      \"method\": \"BRAF inhibitors; GCN2 activator/inhibitor; mTOR inhibitors; eIF4B knockdown; ATF4 protein measurement under nutrient stress\",\n      \"journal\": \"iScience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological and genetic dissection of pathway, single lab, multiple approaches\",\n      \"pmids\": [\"32283529\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ATF4 transcriptionally targets SLC7A11/xCT (glutamate/cystine antiporter), elevating xCT expression; ATF4-dependent tumor-promoting effects including proliferation and angiogenesis are attenuated by pharmacological or genetic xCT inhibition, and forced xCT expression rescues growth in ATF4 knockdown cells.\",\n      \"method\": \"ATF4 siRNA knockdown; xCT inhibition/overexpression; ferroptosis inducer treatment; in vivo tumor models\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss/gain of function for both ATF4 and xCT with rescue experiments, multiple functional readouts\",\n      \"pmids\": [\"28553953\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Hepatocyte ATF4 protects against ferroptosis by maintaining SLC7A11/xCT expression for glutathione synthesis; hepatocyte-specific ATF4 deletion increases ferroptosis susceptibility and accelerates HCC development, reversed by ectopic SLC7A11 expression; ATF4 and SLC7A11 are positively correlated in human HCC and NASH.\",\n      \"method\": \"Hepatocyte-specific ATF4 KO mice; SLC7A11 reconstitution in ATF4-deficient livers; RNA-seq; ferroptosis inhibitor experiments; DEN carcinogen model\",\n      \"journal\": \"Journal of hepatology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — tissue-specific KO, rescue by single target reconstitution, multiple HCC models, human correlation\",\n      \"pmids\": [\"36996941\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"YAP/TAZ sustain ATF4 protein stability, nuclear localization, and transcriptional activity in a TEAD-dependent manner; ATF4 cooperates with YAP/TAZ to induce SLC7A11 expression, enabling HCC cells to overcome ferroptosis and develop Sorafenib resistance.\",\n      \"method\": \"shRNA screening; transcriptomic analysis; ATF4 localization and stability assays; SLC7A11 reporter assays; TEAD inhibition\",\n      \"journal\": \"EMBO molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mechanistic follow-up with defined pathway, single lab, functional validation of ATF4 protein stability\",\n      \"pmids\": [\"34664408\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PRMT5 controls ATF4 mRNA splicing; PRMT5 inhibition causes intron-retaining ATF4 mRNA that is detained in the nucleus, reducing cytoplasmic ATF4 mRNA and protein, and downregulating ATF4 target genes involved in oxidative stress defense.\",\n      \"method\": \"PRMT5 inhibition; RNA-seq; nuclear/cytoplasmic ATF4 mRNA fractionation; ATF4 target gene expression; ROS measurement\",\n      \"journal\": \"Redox biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — transcriptomic analysis, pharmacological inhibition, single lab\",\n      \"pmids\": [\"35305370\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ATF4 interacts with CHOP and this interaction is essential for IOP elevation in glaucoma; ATF4-CHOP-GADD34 pathway promotes aberrant protein synthesis and ER client protein load in trabecular meshwork cells, causing TM dysfunction, IOP elevation, and glaucomatous neurodegeneration.\",\n      \"method\": \"ATF4-CHOP interaction assay; genetic depletion of pathway components; mouse glaucoma models; pharmacological GADD34 inhibition; protein synthesis measurement\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic and pharmacological pathway dissection, multiple glaucoma models, defined molecular interaction\",\n      \"pmids\": [\"33154371\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"RGC-specific deletion of ATF4 and/or CHOP synergistically promotes retinal ganglion cell and optic nerve survival and preserves visual function; CRISPR-mediated knockdown of the ATF4 downstream effector Gadd45a also delivers neuroprotection in glaucoma models.\",\n      \"method\": \"RGC-specific Cre-mediated ATF4/CHOP deletion; optic nerve crush and ocular hypertension models; CRISPR knockdown; ISRIB pharmacological inhibition; visual function testing\",\n      \"journal\": \"Molecular therapy. Nucleic acids\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — cell-type-specific KO, multiple genetic and pharmacological approaches, two disease models\",\n      \"pmids\": [\"37547290\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ATF4 is preferentially translated within stress granules (SGs) and delivered from fibroblasts to tumor cells via migracytosis; pharmacological disassembly of SGs with PT-129 (a PROTAC targeting G3BP1/2 NTF2L domain) disrupts ATF4 delivery and prevents cancer cell proliferation.\",\n      \"method\": \"PROTAC degrader (PT-129); SG formation/disassembly assays; ATF4 localization and transfer assays; in vitro and in vivo tumor growth assays\",\n      \"journal\": \"Journal of the American Chemical Society\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — novel mechanistic finding with PROTAC tool compound, functional in vitro and in vivo validation, single lab\",\n      \"pmids\": [\"39710983\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ATF4 transcriptionally upregulates DDIT4 (REDD1) to suppress mTOR, inducing pro-survival autophagy during glutaminolysis inhibition; glutaminolysis inhibition promotes ATF4 mRNA expression by abrogating m6A modification and YTHDF2-mediated RNA decay.\",\n      \"method\": \"RNA-seq; luciferase reporter assays; ChIP; m6A modification analysis; mRNA half-life assays; RNA immunoprecipitation; in vivo CRC model\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP of ATF4 on DDIT4 promoter, m6A mechanism, multiple orthogonal methods, in vivo validation\",\n      \"pmids\": [\"34373753\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"EIF1AX-A113splice mutations stabilize the translation preinitiation complex (PIC) and induce ATF4; ATF4 co-opts to suppress EIF2alpha phosphorylation, enabling a general increase in protein synthesis, and ATF4 cooperates with c-MYC to enhance mTOR sensitivity to amino acids.\",\n      \"method\": \"Isogenic cell lines expressing EIF1AX-A113splice; EIF2alpha phosphorylation assays; ATF4 expression measurement; mTOR activity assays; mouse thyroid cancer models\",\n      \"journal\": \"Cancer discovery\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — isogenic cell line models, mechanistic pathway dissection, in vivo validation\",\n      \"pmids\": [\"30305285\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"VDR (Vitamin D receptor) suppresses ATF4 transcription by binding to the ATF4 promoter region, as confirmed by ChIP-qPCR and dual-luciferase reporter assay; VDR overexpression or agonist (paricalcitol) reduces ATF4-dependent ER stress in ischemia-reperfusion kidney injury.\",\n      \"method\": \"VDR KO/overexpression mice; paricalcitol treatment; ChIP-qPCR; dual-luciferase reporter assay; ATF4 overexpression rescue\",\n      \"journal\": \"Cell death discovery\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct promoter binding confirmed by ChIP and luciferase, genetic models, rescue experiment\",\n      \"pmids\": [\"37173347\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"ATF4 directly binds the SLC7A11 promoter and increases its transcription; DHA inhibits ATF4 expression, thereby reducing SLC7A11, promoting lipid peroxidation and ferroptosis; ATF4 overexpression rescues DHA-induced ferroptosis.\",\n      \"method\": \"ATF4 promoter ChIP; ATF4/SLC7A11 lentiviral overexpression rescue; lipid peroxidation measurement; xenograft model\",\n      \"journal\": \"Journal of cellular and molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP of ATF4 on SLC7A11 promoter, gain-of-function rescue, in vivo validation, single lab\",\n      \"pmids\": [\"38652216\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ATF4-mediated CD36 upregulation contributes to hepatic lipotoxicity: genetic inhibition of ATF4 attenuates palmitate- or ER stress-induced CD36 upregulation; hepatocyte-specific ATF4 KO mice have lower CD36 expression; CD36 knockdown blunts ATF4 activation in a feedforward mechanism.\",\n      \"method\": \"Hepatocyte-specific ATF4 KO mice; siRNA knockdown; ER stress induction; CD36 and ATF4 expression analysis\",\n      \"journal\": \"American journal of physiology. Gastrointestinal and liver physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — tissue-specific KO, siRNA approaches, feedforward mechanism identified, single lab\",\n      \"pmids\": [\"36852918\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ATF4 directly regulated CTCF expression and interacted with CTCF in 3T3-L1 cells; ATF4 co-localizes with CTCF at promoters of key adipogenic genes including Cebpd and PPARg, cooperating to drive their transactivation and promote adipogenesis.\",\n      \"method\": \"ChIP-seq; RNA-seq; Co-IP of ATF4 and CTCF; ATF4 KD in vivo; CTCF KD/OE\",\n      \"journal\": \"Cell biology and toxicology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP-seq, Co-IP, loss/gain-of-function, in vivo confirmation, single lab\",\n      \"pmids\": [\"33950334\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Thbs1 activates TGFβ-Smad2/3 signaling in skeletal muscle, which induces ATF4 expression; ATF4 then modulates the autophagy-lysosomal pathway and ubiquitin-proteasome system to facilitate muscle atrophy; myofiber-specific Smad2/3 or ATF4 deletion antagonizes Thbs1-induced muscle atrophy.\",\n      \"method\": \"Skeletal muscle-specific transgenic and KO mice; TGFβ receptor inhibition; Smad2/3 KO; ATF4 KO; ALP and UPS activity assays\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple tissue-specific KO models, clear epistasis (Thbs1→TGFβ→Smad2/3→ATF4→atrophy), in vivo validation\",\n      \"pmids\": [\"38678560\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ATF4 knockdown in glioma cells attenuates autophagy induced by FLT3-ITD; FLT3-ITD activity controls cellular ATF4 levels; ATF4 is an essential mediator of FLT3-ITD-induced autophagy-dependent AML cell proliferation.\",\n      \"method\": \"FLT3 inhibitor treatment; ATF4 knockdown; autophagy measurement; xenograft mouse model; conditional shRNA\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KD with defined phenotype, in vivo validation, single lab\",\n      \"pmids\": [\"29059168\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Brown adipocyte-specific ATF4 activation (genetically via overexpression or physiologically via low-protein diet) improves cold tolerance and systemic metabolism in a Ucp1-independent manner, revealing a diet-dependent thermogenic mechanism in brown adipocytes.\",\n      \"method\": \"BA-specific ATF4 overexpression; Ucp1 KO mice; low-protein diet feeding; cold tolerance tests; proteome analysis\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — tissue-specific gain-of-function, Ucp1 KO epistasis, dietary intervention, single lab\",\n      \"pmids\": [\"34551310\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"O-GlcNAcylation regulates ATF4 during the mitochondrial integrated stress response: OGT (O-GlcNAc transferase) knockdown increases ATF4 protein and mRNA, while Thiamet-G (OGT activator) elevates ATF4 protein upon mitochondrial stress; ATF4 occupancy at the ATF5 promoter increases in TMG-treated mouse brains.\",\n      \"method\": \"OGT KD; Thiamet-G treatment; ATF4 ChIP at ATF5 promoter; iPSC-derived neurons; AD mouse model\",\n      \"journal\": \"Frontiers in aging neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP confirming ATF4 occupancy, genetic KD, multiple model systems, single lab\",\n      \"pmids\": [\"38192280\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ATF4 cooperates with FOXO1 and C/EBPδ to regulate the transcriptional program of skeletal muscle atrophy during fasting; ATF4 enhances promoter activity of target atrophy genes in cooperation with C/EBPδ.\",\n      \"method\": \"FOXO1-transgenic and FOXO1,3a,4-/- mice; C/EBPδ KD/OE; gene expression arrays; promoter activity assays\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic models, promoter assays, cooperative transcription factor evidence, single lab\",\n      \"pmids\": [\"35061305\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ATF4 transcriptionally activates GLUT5 and ALDOB expression in GBM cells in response to glucose deprivation, switching energy supply from glycolysis to fructolysis; disruption of ATF4-dependent fructolysis inhibits GBM growth in vitro and in vivo.\",\n      \"method\": \"ATF4 KD/KO; GLUT5 and ALDOB expression analysis; genetic/pharmacological disruption of fructolysis; xenograft models; patient specimen correlation\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic loss-of-function, in vivo validation, defined transcriptional targets, single lab\",\n      \"pmids\": [\"36245009\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"ATF4 in Drosophila (ortholog): Notch signaling combined with ETC attenuation activates the PERK-ATF4 pathway, which drives expression of metabolic enzymes, nutrient transporters, and mitochondrial chaperones; this ATF4-mediated Warburg metabolism promotes cell proliferation, pH changes mediate over-proliferation.\",\n      \"method\": \"Drosophila genetic models (COX7a KD, Notch activation); PERK and ATF4 genetic manipulation; metabolic profiling; pH measurement\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Drosophila ortholog, genetic epistasis, metabolic mechanistic follow-up, single lab\",\n      \"pmids\": [\"32433968\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ATF4 is a stress-induced bZIP transcription factor whose translation is selectively upregulated by eIF2alpha phosphorylation (via GCN2, PERK, HRI, or PKR kinases) and, paradoxically, by mTORC1 signaling; once translated, ATF4 acts as a transcriptional activator (heterodimerizing with partners including CHOP, FoxO1, KDM4C, Hop2, and CTCF) to drive expression of target genes governing amino acid uptake/synthesis, glutathione biosynthesis (via SLC7A11/xCT), NADPH production, autophagy, UPRmt, and VEGF/angiogenesis, while its activity and stability are regulated by post-translational modifications including PRMT1-mediated arginine methylation (promoting stability), PARP-1-mediated PARylation (reducing CRE binding), mTORC1-mediated phosphorylation (activating UPRmt), and O-GlcNAcylation, as well as ubiquitin-proteasome-mediated degradation downstream of PKA phosphorylation at serine-219; collectively ATF4 coordinates cellular adaptation to metabolic, ER, and mitochondrial stress, but can also drive pathological outcomes including cardiac atrophy (via PERK-ATF4-autophagy), muscle atrophy (cooperating with p53 and Thbs1-TGFβ-Smad2/3 pathways), and glaucoma (via ATF4-CHOP-GADD34-dependent protein synthesis overload).\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ATF4 is a stress-induced bZIP transcription factor that serves as the master effector of the integrated stress response (ISR), coupling diverse upstream signals to a transcriptional program governing amino acid metabolism, redox homeostasis, autophagy, and mitochondrial adaptation [#0, #2]. Its expression is controlled chiefly at the level of translation: phosphorylation of eIF2alpha by stress-sensing kinases—GCN2 detecting uncharged tRNA in the amino acid response [#0], PERK during ER stress [#1], and HRI in erythroid precursors [#5]—selectively upregulates ATF4 synthesis, a step requiring the RNA helicase DDX3 acting through the eIF4F complex [#12]. mTORC1 provides a parallel, ISR-distinct route to ATF4 induction and, upon mitochondrial stress, directly phosphorylates ATF4 in a v-ATPase/lysosome-dependent manner to drive the mitochondrial unfolded protein response (UPRmt) [#2, #14]. Once active, ATF4 heterodimerizes and cooperates with partners including CHOP, FoxO1, KDM4C, Hop2, and CTCF to bind target promoters and CARE/CRE elements [#6, #7, #25, #31, #39], and directly transactivates genes for cystine uptake and glutathione synthesis (SLC7A11/xCT) [#27, #28], NADPH-generating pentose-phosphate and serine/glycine/folate enzymes [#22], the mTOR repressor REDD1/DDIT4 [#1, #34], and the NRF2 antioxidant axis via CHAC1 [#17], thereby protecting cells from oxidative stress and ferroptosis. ATF4 activity is further tuned post-translationally by PRMT1-mediated arginine-239 methylation that stabilizes the protein [#11], PARP-1-mediated PARylation that reduces CRE binding [#10], O-GlcNAcylation [#43], and PKA-triggered phosphorylation at serine-219 leading to ubiquitin-proteasome degradation [#24]. Through these outputs ATF4 coordinates adaptation to metabolic, ER, and mitochondrial stress across many tissues, but its sustained activity drives pathology including PERK-ATF4-autophagy-mediated cardiac atrophy [#4], skeletal muscle atrophy and aging in cooperation with p53, FOXO1/C/EBPdelta, and Thbs1-TGFbeta-Smad2/3 signaling [#18, #19, #40, #44], and ATF4-CHOP-GADD34-dependent protein-synthesis overload in glaucoma [#31, #32].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Established ATF4 as the necessary and sufficient transcriptional output of the PERK arm of ER stress, linking eIF2alpha phosphorylation to a defined target gene (REDD1).\",\n      \"evidence\": \"Genetic KO of PERK and ATF4 in MEFs plus ATF4 overexpression with mRNA readout\",\n      \"pmids\": [\"19114033\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not address non-ER stress inputs\", \"Direct vs indirect promoter binding at REDD1 not resolved here\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Defined the upstream logic of ATF4 induction in the amino acid response, showing GCN2 sensing of uncharged tRNA feeds eIF2alpha-ATF4 to activate CARE-containing genes.\",\n      \"evidence\": \"Genetic/biochemical characterization of the AAR pathway with transcriptional reporters\",\n      \"pmids\": [\"19800252\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not enumerate the full ATF4 target set\", \"Heterodimer partner identities at CARE elements not defined\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified physiological ATF4 partner proteins and kinase inputs, showing FoxO1 binds ATF4 to control glucose homeostasis and HRI drives the erythroid ATF4 program.\",\n      \"evidence\": \"Co-IP and genetic mouse models (FoxO1/ATF4); HRI KO mice with ROS and differentiation readouts\",\n      \"pmids\": [\"22298775\", \"22498744\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue specificity of FoxO1-ATF4 complex not generalized\", \"Direct ATF4 target genes in erythroid context not fully mapped\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Revealed a non-transcriptional protein-protein function of ATF4: stabilizing HIF-1alpha to promote VEGF-driven angiogenesis.\",\n      \"evidence\": \"Co-IP, ATF4 KO mice, ubiquitination and HIF-1alpha stability assays, VEGF rescue\",\n      \"pmids\": [\"23649506\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of ATF4-HIF-1alpha interaction unknown\", \"Generality beyond osteoblasts untested\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Connected ATF4 to chromatin-modifying machinery, showing KDM4C cooperates with ATF4 to derepress serine-glycine biosynthesis genes via H3K9me3 removal.\",\n      \"evidence\": \"Co-IP, ChIP, siRNA knockdown and KDM4C overexpression\",\n      \"pmids\": [\"26774480\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether KDM4C is a general ATF4 cofactor unknown\", \"Recruitment order of ATF4 vs KDM4C not resolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showed ATF4 activity and stability are post-translationally controlled (PARP-1 PARylation reducing CRE binding) and that DDX3 governs its stress-induced translation, while xCT/SLC7A11 emerged as a key pro-tumor ATF4 target.\",\n      \"evidence\": \"ChIP-qPCR, in vitro CRE binding assay, polyribosome profiling/luciferase, xCT inhibition/overexpression rescue\",\n      \"pmids\": [\"28457938\", \"29062139\", \"28553953\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"PARylation site on ATF4 not mapped\", \"Interplay between translational and PTM control not integrated\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined ATF4 as a metabolic master regulator in adaptive immunity and a node co-opted by oncogenes, coordinating amino acid/glutathione metabolism and additive muscle atrophy with p53.\",\n      \"evidence\": \"Atf4-deficient CD4+ T cells with EAE model; BRAF/GCN2 pharmacology; muscle-specific and double p53/ATF4 KO mice\",\n      \"pmids\": [\"29742431\", \"32283529\", \"24895282\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct ATF4 targets in T cells not all validated by ChIP\", \"p53-ATF4 convergence point upstream of p21 unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Established arginine methylation as a stability switch (PRMT1 at R239) and embedded ATF4 in ER-stress ferroptosis defense and skeletal partnerships (Hop2).\",\n      \"evidence\": \"R239K mutant, PRMT1 KO; siRNA pathway dissection (PERK-ATF4-HSPA5-GPX4); yeast two-hybrid and compound heterozygous mice (Hop2)\",\n      \"pmids\": [\"31787756\", \"31519193\", \"31433867\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Enzyme(s) reversing R239 methylation unknown\", \"Whether Hop2-ATF4 acts outside bone untested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Expanded ATF4 outputs to organelle quality control and direct transcriptional targets, including reticulophagy, UPRmt induction, NRF1 repression, LAMP3, and the HBS1L-MYB enhancer governing globin switching.\",\n      \"evidence\": \"ATF4 KO with reticulophagy imaging; directional UPRER-to-UPRmt epistasis; ChIP at NRF1, LAMP3, and HBS1L-MYB; CRISPR isogenic erythroid cells\",\n      \"pmids\": [\"33111629\", \"32551949\", \"33177163\", \"32312748\", \"32755585\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct vs indirect status of some targets varies\", \"Determinants of activating vs repressive ATF4 promoter occupancy unclear\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Distinguished mTORC1 from canonical ISR control of ATF4, linked mitochondrial respiration to ATF4 via asparagine, and demonstrated PERK-ATF4-autophagy as a driver of cardiac atrophy and tumor ferroptosis resistance.\",\n      \"evidence\": \"Comparative transcriptomics in mTORC1- vs ISR-activated cells; metformin/asparagine in tumor models; Thbs1 transgenic/PERK KO hearts; YAP/TAZ-ATF4-SLC7A11 in HCC; DDIT4 m6A/YTHDF2 mechanism\",\n      \"pmids\": [\"33646118\", \"33609439\", \"34168130\", \"34664408\", \"34373753\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How mTORC1 selects a subset of ATF4 targets unresolved\", \"Crosstalk between transcriptional and translational mTORC1 inputs to ATF4 unclear\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Detailed ATF4's redox/metabolic effector network and additional partners, showing control of NADPH-generating pathways, fructolysis genes, CD36 lipotoxicity, and cooperation with CTCF and FOXO1/C/EBPdelta.\",\n      \"evidence\": \"Cardiomyocyte-specific ATF4 KO with isotope tracing/metabolomics; ATF4 KD/KO for GLUT5/ALDOB; hepatocyte ATF4 KO for CD36; ChIP-seq/Co-IP with CTCF; promoter assays with C/EBPdelta\",\n      \"pmids\": [\"35574856\", \"36245009\", \"36852918\", \"33950334\", \"35061305\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue-specific partner combinations not unified into a single model\", \"PRMT5 splicing control of ATF4 mRNA needs orthogonal confirmation\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Resolved direct mTORC1 phosphorylation of ATF4 driving UPRmt selectivity and positioned ATF4 as a therapeutic node in glaucoma, HCC ferroptosis, NRF2 activation, and O-GlcNAc/VDR regulation.\",\n      \"evidence\": \"v-ATPase/mTORC1 inhibition with phospho-deficient ATF4 mutants; RGC-specific ATF4/CHOP deletion and ISRIB; hepatocyte ATF4 KO with SLC7A11 rescue; ATF4-NRF2-CHAC1 KD/OE; OGT/Thiamet-G ChIP; VDR promoter ChIP\",\n      \"pmids\": [\"37679337\", \"37547290\", \"36996941\", \"37410595\", \"38192280\", \"37173347\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"mTORC1 phosphorylation site(s) on ATF4 not fully mapped\", \"Several upstream regulators validated in single labs only\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Uncovered non-cell-autonomous ATF4 biology and additional atrophy circuitry, showing stress-granule-localized ATF4 transfer between cells via migracytosis and Thbs1-TGFbeta-Smad2/3 induction of ATF4 driving muscle atrophy.\",\n      \"evidence\": \"G3BP1/2 PROTAC (PT-129) disrupting SG-dependent ATF4 delivery; muscle-specific Smad2/3 and ATF4 KO mice\",\n      \"pmids\": [\"39710983\", \"38678560\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Migracytosis-mediated ATF4 transfer awaits independent replication\", \"Physiological scope of intercellular ATF4 transfer unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the full repertoire of ATF4 heterodimer partners, post-translational modifications, and upstream kinase/mTORC1 inputs are integrated to select context-specific target gene programs—and to switch between adaptive and pathological outcomes—remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model explaining target-gene selectivity across stress inputs\", \"Genome-wide partner-dependent ATF4 occupancy maps lacking across tissues\", \"Determinants of activating vs repressive ATF4 binding undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [0, 1, 8, 15, 23, 27, 34, 37]},\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [8, 15, 23, 36, 37]},\n      {\"term_id\": \"GO:0140097\", \"supporting_discovery_ids\": [0, 27, 34]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [6, 16, 29]},\n      {\"term_id\": \"GO:0005654\", \"supporting_discovery_ids\": [6, 7, 39]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [0, 1, 2, 14]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [0, 8, 23, 27, 34, 39]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [2, 20, 22, 27, 45]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [4, 13, 34, 41]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [9, 27, 28, 37]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"CHOP\", \"FOXO1\", \"KDM4C\", \"HOP2\", \"CTCF\", \"HIF1A\", \"CEBPD\", \"DDX3X\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}