{"gene":"MAPKAPK3","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":1996,"finding":"3pK (MAPKAPK3) is a serine-threonine kinase activated downstream of ERK; it was demonstrated in vitro that recombinant ERK phosphorylates and activates 3pK, and in vivo activation occurs after serum or TPA stimulation in a Raf-dependent manner through the Raf/MEK/ERK cascade.","method":"In vitro kinase assays with recombinant proteins; co-transfection with dominant pathway components; specific MEK/p38 inhibitors; in vivo stimulation assays in HL60 and HEK293 cells","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro reconstitution with recombinant proteins plus in vivo epistasis, replicated across two independent labs (PMID:8622688 and PMID:8943323)","pmids":["8943323","8622688"],"is_preprint":false},{"year":1996,"finding":"In addition to ERK, p38RK (p38 MAPK) and JNK/SAPK can also phosphorylate and activate 3pK in vitro and in vivo, making 3pK the first kinase shown to be activated through all three MAPK cascades and a convergence point of mitogen and stress signaling.","method":"In vitro kinase assays with recombinant p38RK and JNK; co-transfection epistasis experiments; SB203580 (p38 inhibitor) pharmacological blockade","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro reconstitution plus pharmacological and genetic epistasis in vivo, multiple orthogonal methods in one study","pmids":["8943323"],"is_preprint":false},{"year":2000,"finding":"MAPKAPK3 (3pK) physically interacts with and phosphorylates the bHLH transcription factor E47 in vitro, and overexpression of 3pK represses E47 transcriptional activity on an E-box-containing promoter.","method":"In vitro kinase assay; co-immunoprecipitation; luciferase reporter transcription assay with E47 overexpression","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — in vitro kinase assay and co-IP with reporter assay, single lab, two orthogonal methods","pmids":["10781029"],"is_preprint":false},{"year":2004,"finding":"MAPKAPK3 (3pK) directly phosphorylates the Polycomb group protein Bmi1 and other PcG complex members, causing their dissociation from chromatin; this leads to de-repression of the Cdkn2a/INK4A locus target p14ARF. 3pK was identified as a physical interaction partner of PcG proteins by yeast two-hybrid and co-immunoprecipitation.","method":"Yeast two-hybrid; co-immunoprecipitation; in vitro and in vivo phosphorylation assays; chromatin fractionation; gene expression analysis of p14ARF upon 3pK overexpression","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — yeast two-hybrid, reciprocal Co-IP, in vitro kinase assay, and chromatin fractionation with functional readout, multiple orthogonal methods in one study","pmids":["15563468"],"is_preprint":false},{"year":2015,"finding":"MAPKAPK2 and MAPKAPK3 positively regulate starvation-induced autophagy by directly phosphorylating Beclin 1 at serine 90; this phosphorylation is essential for autophagy induction and for the tumor suppressor function of Beclin 1. BCL2 blocks MK2/MK3-dependent Beclin 1 S90 phosphorylation both in vitro and in vivo, providing a mechanism by which BCL2 inhibits autophagy.","method":"In vitro kinase assays; site-directed mutagenesis of Beclin 1 S90; genetic knockout of MK2/MK3; in vivo autophagy assays; BCL2 overexpression/inhibition experiments","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro kinase assay with mutagenesis, genetic KO, in vivo validation, multiple orthogonal methods","pmids":["25693418"],"is_preprint":false},{"year":2009,"finding":"Overexpression of MAPKAPK3 inhibits IFN-alpha-induced gene transcription via ISRE and GAS elements, as shown by luciferase reporter assay, suggesting MAPKAPK3 negatively regulates IFN signaling.","method":"Luciferase reporter assay (ISRE- and GAS-driven); allele-specific transcript quantification in liver biopsy","journal":"Gastroenterology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — functional reporter assay and allele-specific expression data, single lab, two orthogonal methods but no direct biochemical mechanism defined","pmids":["19208361"],"is_preprint":false},{"year":2016,"finding":"A dominant MAPKAPK3 mutation (p.Leu173Pro) causes mislocalization of the protein to the cytoplasm (rather than its normal localization), leading to cytoskeleton alteration and inhibition of cytodieresis (cell division) in HEK cells. In Mapkapk3-/- mice, Bruch's membrane shows abnormal thickening and thinning, establishing a role for MAPKAPK3 in RPE/Bruch's membrane physiology.","method":"Mutant protein expression in HEK cells with subcellular localization imaging; cytoskeletal staining; cytodieresis assay; Mapkapk3 knockout mouse histology; crystal structure analysis (bioinformatic) of mutant","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — live cell imaging with functional readout plus KO mouse phenotype, single lab, two orthogonal approaches","pmids":["26744326"],"is_preprint":false},{"year":2025,"finding":"MAPKAPK3 directly interacts with and phosphorylates Bax; downregulation of MAPKAPK3 leads to reduced Bax phosphorylation and increased Bax mitochondrial translocation, promoting apoptosis in neuroblastoma cells.","method":"Co-immunoprecipitation confirming MAPKAPK3-Bax interaction; phosphorylation assay; Western blot for Bax mitochondrial fractionation; MAPKAPK3 knockdown with functional apoptosis readout","journal":"Nanomedicine : nanotechnology, biology, and medicine","confidence":"Medium","confidence_rationale":"Tier 2-3 / Weak — Co-IP and fractionation with KD phenotype, single lab, single study, not yet replicated","pmids":["40976474"],"is_preprint":false},{"year":2020,"finding":"3PK (MAPKAPK3) physically associates with EZH2 protein and its promoter region (-1107 to -1002), and 3PK inhibition leads to proteasomal-mediated degradation of EZH2 and reduced PcG-mediated epigenetic repression in oral squamous cell carcinoma cells.","method":"Co-immunoprecipitation; ChIP-qPCR; Western blotting; immunofluorescence; pharmacological 3PK inhibition","journal":"Phytomedicine","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, Co-IP and ChIP data but mechanistic link between 3PK and EZH2 proteasomal degradation is not biochemically reconstituted, and results are embedded in a drug-treatment study","pmids":["33113500"],"is_preprint":false}],"current_model":"MAPKAPK3 (3pK) is a serine/threonine kinase activated downstream of all three MAPK cascades (ERK, p38, JNK) that promotes starvation-induced autophagy by phosphorylating Beclin 1 at S90, antagonizes Polycomb-mediated silencing by phosphorylating Bmi1 and dissociating PcG complexes from chromatin, represses E47-dependent transcription, regulates Bax mitochondrial translocation via direct phosphorylation, and inhibits IFN-alpha signaling; proper nuclear localization is required for its role in cell division and RPE/Bruch's membrane integrity."},"narrative":{"mechanistic_narrative":"MAPKAPK3 (3pK) is a serine/threonine protein kinase that functions as a convergence point of mitogen and stress signaling, being phosphorylated and activated downstream of the ERK, p38, and JNK MAPK cascades [PMID:8943323, PMID:8622688]. Through its kinase activity it acts on multiple substrates to regulate chromatin state, autophagy, and apoptosis: it directly phosphorylates the Polycomb group protein Bmi1 and other PcG members, driving their dissociation from chromatin and de-repression of the Cdkn2a/INK4A locus product p14ARF [PMID:15563468], and it phosphorylates the bHLH transcription factor E47 to repress E-box-dependent transcription [PMID:10781029]. Together with MAPKAPK2, it promotes starvation-induced autophagy by phosphorylating Beclin 1 at serine 90, an event antagonized by BCL2 [PMID:25693418]. It also directly phosphorylates Bax, restraining its mitochondrial translocation and thereby limiting apoptosis [PMID:40976474]. A dominant p.Leu173Pro mutation that mislocalizes the protein to the cytoplasm disrupts the cytoskeleton and cytodieresis, and Mapkapk3-knockout mice show Bruch's membrane abnormalities, establishing a role in cell division and RPE/Bruch's membrane integrity [PMID:26744326].","teleology":[{"year":1996,"claim":"Established 3pK as a bona fide MAPK substrate kinase, placing it downstream of the Raf/MEK/ERK mitogenic cascade.","evidence":"In vitro kinase assays with recombinant ERK plus in vivo serum/TPA stimulation with pathway inhibitors in HL60 and HEK293 cells","pmids":["8943323","8622688"],"confidence":"High","gaps":["Physiological substrates of activated 3pK not identified at this stage","Activation kinetics relative to other MAPKAPKs not defined"]},{"year":1996,"claim":"Showed 3pK is also activated by p38 and JNK, defining it as the first kinase integrating signals from all three MAPK cascades and a node where mitogen and stress inputs converge.","evidence":"In vitro kinase assays with recombinant p38RK and JNK, co-transfection epistasis, and SB203580 blockade","pmids":["8943323"],"confidence":"High","gaps":["Whether the three cascades activate 3pK in distinct cellular contexts unresolved","Downstream consequences of each input not distinguished"]},{"year":2000,"claim":"Identified the first transcriptional substrate of 3pK, linking its kinase activity to repression of E-box-dependent gene expression.","evidence":"In vitro kinase assay, co-immunoprecipitation, and E-box luciferase reporter assay with 3pK overexpression","pmids":["10781029"],"confidence":"Medium","gaps":["Phosphosite on E47 not mapped","Single lab, overexpression-based; endogenous relevance not established"]},{"year":2004,"claim":"Connected 3pK to epigenetic control by showing it phosphorylates Bmi1/PcG proteins to evict them from chromatin and de-repress the INK4A/p14ARF locus.","evidence":"Yeast two-hybrid, reciprocal Co-IP, in vitro/in vivo phosphorylation, chromatin fractionation, and p14ARF expression analysis","pmids":["15563468"],"confidence":"High","gaps":["Specific Bmi1 phosphosites and their stoichiometry not fully defined","Upstream MAPK input driving this event in vivo not identified"]},{"year":2009,"claim":"Linked MAPKAPK3 to negative regulation of type I interferon signaling output.","evidence":"ISRE- and GAS-driven luciferase reporter assays and allele-specific transcript quantification in liver biopsy","pmids":["19208361"],"confidence":"Medium","gaps":["Direct biochemical substrate in the IFN pathway not defined","Effect shown by overexpression; endogenous kinase requirement untested"]},{"year":2015,"claim":"Defined a direct mechanistic role in autophagy by identifying Beclin 1 S90 as a MK2/MK3 phosphosite required for starvation-induced autophagy and Beclin 1 tumor suppressor function.","evidence":"In vitro kinase assays, Beclin 1 S90 mutagenesis, MK2/MK3 genetic knockout, in vivo autophagy assays, and BCL2 manipulation","pmids":["25693418"],"confidence":"High","gaps":["Relative contributions of MK2 versus MK3 not separated","Which MAPK cascade triggers this phosphorylation during starvation unresolved"]},{"year":2016,"claim":"Demonstrated that correct nuclear localization of MAPKAPK3 is required for cell division and tissue integrity, via a mislocalizing dominant mutation and a knockout mouse.","evidence":"p.Leu173Pro mutant localization imaging and cytodieresis assays in HEK cells plus Mapkapk3-/- mouse Bruch's membrane histology","pmids":["26744326"],"confidence":"Medium","gaps":["Substrates underlying the cytoskeletal/cytodieresis defect not identified","Mechanism linking kinase to Bruch's membrane physiology unknown"]},{"year":2020,"claim":"Associated 3PK with EZH2 stability and PcG-mediated repression in oral squamous carcinoma cells.","evidence":"Co-IP, ChIP-qPCR, Western blot, and immunofluorescence under pharmacological 3PK inhibition","pmids":["33113500"],"confidence":"Low","gaps":["Mechanistic link between 3PK and EZH2 proteasomal degradation not biochemically reconstituted","Findings embedded in a drug-treatment study; direct phosphorylation of EZH2 not demonstrated"]},{"year":2025,"claim":"Identified Bax as a direct MAPKAPK3 substrate, positioning the kinase as a brake on intrinsic apoptosis.","evidence":"Co-IP, phosphorylation assay, Bax mitochondrial fractionation, and MAPKAPK3 knockdown apoptosis readouts in neuroblastoma cells","pmids":["40976474"],"confidence":"Medium","gaps":["Bax phosphosite not mapped","Single lab, not yet replicated; reciprocal validation lacking"]},{"year":null,"claim":"How distinct upstream MAPK inputs are routed to specific substrates (chromatin, autophagy, apoptosis) to produce context-specific outputs remains unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No unifying model linking activating cascade to substrate choice","In vivo substrate hierarchy under physiological stress unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,2,3,4,7]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,4]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[2,3]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[6]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[6]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,1]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[4]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[3]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[7]}],"complexes":[],"partners":["BECN1","BMI1","BAX","E47","EZH2","BCL2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q16644","full_name":"MAP kinase-activated protein kinase 3","aliases":["Chromosome 3p kinase","3pK"],"length_aa":382,"mass_kda":43.0,"function":"Stress-activated serine/threonine-protein kinase involved in cytokines production, endocytosis, cell migration, chromatin remodeling and transcriptional regulation. Following stress, it is phosphorylated and activated by MAP kinase p38-alpha/MAPK14, leading to phosphorylation of substrates. Phosphorylates serine in the peptide sequence, Hyd-X-R-X(2)-S, where Hyd is a large hydrophobic residue. MAPKAPK2 and MAPKAPK3, share the same function and substrate specificity, but MAPKAPK3 kinase activity and level in protein expression are lower compared to MAPKAPK2. Phosphorylates HSP27/HSPB1, KRT18, KRT20, RCSD1, RPS6KA3, TAB3 and TTP/ZFP36. Mediates phosphorylation of HSP27/HSPB1 in response to stress, leading to dissociate HSP27/HSPB1 from large small heat-shock protein (sHsps) oligomers and impair their chaperone activities and ability to protect against oxidative stress effectively. Involved in inflammatory response by regulating tumor necrosis factor (TNF) and IL6 production post-transcriptionally: acts by phosphorylating AU-rich elements (AREs)-binding proteins, such as TTP/ZFP36, leading to regulate the stability and translation of TNF and IL6 mRNAs. Phosphorylation of TTP/ZFP36, a major post-transcriptional regulator of TNF, promotes its binding to 14-3-3 proteins and reduces its ARE mRNA affinity leading to inhibition of dependent degradation of ARE-containing transcript. Involved in toll-like receptor signaling pathway (TLR) in dendritic cells: required for acute TLR-induced macropinocytosis by phosphorylating and activating RPS6KA3. Also acts as a modulator of Polycomb-mediated repression","subcellular_location":"Nucleus; Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q16644/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MAPKAPK3","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000114738","cell_line_id":"CID001210","localizations":[{"compartment":"cytoplasmic","grade":3},{"compartment":"nucleoplasm","grade":3}],"interactors":[{"gene":"MAPK14","stoichiometry":10.0},{"gene":"DIEXF","stoichiometry":0.2},{"gene":"MAPK11","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID001210","total_profiled":1310},"omim":[{"mim_id":"617111","title":"MACULAR DYSTROPHY, PATTERNED, 3; MDPT3","url":"https://www.omim.org/entry/617111"},{"mim_id":"616175","title":"UBIQUITIN-CONJUGATING ENZYME E2 J1; UBE2J1","url":"https://www.omim.org/entry/616175"},{"mim_id":"610579","title":"RCSD DOMAIN-CONTAINING PROTEIN 1; RCSD1","url":"https://www.omim.org/entry/610579"},{"mim_id":"606724","title":"MITOGEN-ACTIVATED PROTEIN KINASE-INTERACTING SERINE/THREONINE KINASE 1; MKNK1","url":"https://www.omim.org/entry/606724"},{"mim_id":"602130","title":"MITOGEN-ACTIVATED PROTEIN KINASE-ACTIVATED PROTEIN KINASE 3; MAPKAPK3","url":"https://www.omim.org/entry/602130"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"heart muscle","ntpm":241.8},{"tissue":"skeletal muscle","ntpm":213.3},{"tissue":"tongue","ntpm":265.2}],"url":"https://www.proteinatlas.org/search/MAPKAPK3"},"hgnc":{"alias_symbol":["3pK","MAPKAP3","3PK","MK-3","MK3"],"prev_symbol":[]},"alphafold":{"accession":"Q16644","domains":[{"cath_id":"3.30.200.20","chopping":"38-118","consensus_level":"high","plddt":94.4998,"start":38,"end":118},{"cath_id":"1.10.510.10","chopping":"123-197_212-341","consensus_level":"high","plddt":87.7201,"start":123,"end":341}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q16644","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q16644-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q16644-F1-predicted_aligned_error_v6.png","plddt_mean":81.94},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MAPKAPK3","jax_strain_url":"https://www.jax.org/strain/search?query=MAPKAPK3"},"sequence":{"accession":"Q16644","fasta_url":"https://rest.uniprot.org/uniprotkb/Q16644.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q16644/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q16644"}},"corpus_meta":[{"pmid":"25693418","id":"PMC_25693418","title":"The stress-responsive kinases MAPKAPK2/MAPKAPK3 activate starvation-induced autophagy through Beclin 1 phosphorylation.","date":"2015","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/25693418","citation_count":157,"is_preprint":false},{"pmid":"8943323","id":"PMC_8943323","title":"3pK, a novel mitogen-activated protein (MAP) kinase-activated protein kinase, is targeted by three MAP kinase pathways.","date":"1996","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/8943323","citation_count":156,"is_preprint":false},{"pmid":"15563468","id":"PMC_15563468","title":"MAPKAP kinase 3pK phosphorylates and regulates chromatin association of the polycomb group protein Bmi1.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15563468","citation_count":136,"is_preprint":false},{"pmid":"8622688","id":"PMC_8622688","title":"3pK, a new mitogen-activated protein kinase-activated protein kinase located in the small cell lung cancer tumor suppressor gene region.","date":"1996","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/8622688","citation_count":81,"is_preprint":false},{"pmid":"10781029","id":"PMC_10781029","title":"Serine/Threonine kinases 3pK and MAPK-activated protein kinase 2 interact with the basic helix-loop-helix transcription factor E47 and repress its transcriptional activity.","date":"2000","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10781029","citation_count":53,"is_preprint":false},{"pmid":"19208361","id":"PMC_19208361","title":"A polymorphism in MAPKAPK3 affects response to interferon therapy for chronic hepatitis C.","date":"2009","source":"Gastroenterology","url":"https://pubmed.ncbi.nlm.nih.gov/19208361","citation_count":40,"is_preprint":false},{"pmid":"33113500","id":"PMC_33113500","title":"Genistein nanoformulation promotes selective apoptosis in oral squamous cell carcinoma through repression of 3PK-EZH2 signalling pathway.","date":"2020","source":"Phytomedicine : international journal of phytotherapy and phytopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/33113500","citation_count":34,"is_preprint":false},{"pmid":"26744326","id":"PMC_26744326","title":"A dominant mutation in MAPKAPK3, an actor of p38 signaling pathway, causes a new retinal dystrophy involving Bruch's membrane and retinal pigment epithelium.","date":"2016","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/26744326","citation_count":13,"is_preprint":false},{"pmid":"8817073","id":"PMC_8817073","title":"Mapping of a new MAP kinase activated protein kinase gene (3PK) to human chromosome band 3p21.2 and ordering of 3PK and two cosmid markers in the 3p22-p21 tumour-suppressor region by two-colour fluorescence in situ hybridization.","date":"1996","source":"Chromosome research : an international journal on the molecular, supramolecular and evolutionary aspects of chromosome biology","url":"https://pubmed.ncbi.nlm.nih.gov/8817073","citation_count":11,"is_preprint":false},{"pmid":"19921547","id":"PMC_19921547","title":"A novel porcine gene, MAPKAPK3, is differentially expressed in the pituitary gland from mini-type Diannan small-ear pigs and large-type Diannan small-ear pigs.","date":"2009","source":"Molecular biology reports","url":"https://pubmed.ncbi.nlm.nih.gov/19921547","citation_count":9,"is_preprint":false},{"pmid":"28258406","id":"PMC_28258406","title":"Biotransformation of menadione to its prenylated derivative MK-3 using recombinant Pichia pastoris.","date":"2017","source":"Journal of industrial microbiology & biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/28258406","citation_count":9,"is_preprint":false},{"pmid":"16367997","id":"PMC_16367997","title":"Absence of mutations in the coding sequence of the potential tumor suppressor 3pK in metastatic melanoma.","date":"2005","source":"Journal of carcinogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/16367997","citation_count":3,"is_preprint":false},{"pmid":"40976474","id":"PMC_40976474","title":"4HPR nanoformulation regulates MAPKAPK3/3pK signaling to control Bax phosphorylation and mitochondrial translocation to execute apoptosis in neuroblastoma.","date":"2025","source":"Nanomedicine : nanotechnology, biology, and medicine","url":"https://pubmed.ncbi.nlm.nih.gov/40976474","citation_count":0,"is_preprint":false},{"pmid":"41778012","id":"PMC_41778012","title":"A Newborn With Down-Klinefelter Syndrome and Bilateral Congenital Cataracts Harboring a Novel MAPKAPK3 Mutation.","date":"2026","source":"Journal of vitreoretinal diseases","url":"https://pubmed.ncbi.nlm.nih.gov/41778012","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9293,"output_tokens":2451,"usd":0.032322,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9497,"output_tokens":3069,"usd":0.062105,"stage2_stop_reason":"end_turn"},"total_usd":0.094427,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1996,\n      \"finding\": \"3pK (MAPKAPK3) is a serine-threonine kinase activated downstream of ERK; it was demonstrated in vitro that recombinant ERK phosphorylates and activates 3pK, and in vivo activation occurs after serum or TPA stimulation in a Raf-dependent manner through the Raf/MEK/ERK cascade.\",\n      \"method\": \"In vitro kinase assays with recombinant proteins; co-transfection with dominant pathway components; specific MEK/p38 inhibitors; in vivo stimulation assays in HL60 and HEK293 cells\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro reconstitution with recombinant proteins plus in vivo epistasis, replicated across two independent labs (PMID:8622688 and PMID:8943323)\",\n      \"pmids\": [\"8943323\", \"8622688\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"In addition to ERK, p38RK (p38 MAPK) and JNK/SAPK can also phosphorylate and activate 3pK in vitro and in vivo, making 3pK the first kinase shown to be activated through all three MAPK cascades and a convergence point of mitogen and stress signaling.\",\n      \"method\": \"In vitro kinase assays with recombinant p38RK and JNK; co-transfection epistasis experiments; SB203580 (p38 inhibitor) pharmacological blockade\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro reconstitution plus pharmacological and genetic epistasis in vivo, multiple orthogonal methods in one study\",\n      \"pmids\": [\"8943323\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"MAPKAPK3 (3pK) physically interacts with and phosphorylates the bHLH transcription factor E47 in vitro, and overexpression of 3pK represses E47 transcriptional activity on an E-box-containing promoter.\",\n      \"method\": \"In vitro kinase assay; co-immunoprecipitation; luciferase reporter transcription assay with E47 overexpression\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — in vitro kinase assay and co-IP with reporter assay, single lab, two orthogonal methods\",\n      \"pmids\": [\"10781029\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"MAPKAPK3 (3pK) directly phosphorylates the Polycomb group protein Bmi1 and other PcG complex members, causing their dissociation from chromatin; this leads to de-repression of the Cdkn2a/INK4A locus target p14ARF. 3pK was identified as a physical interaction partner of PcG proteins by yeast two-hybrid and co-immunoprecipitation.\",\n      \"method\": \"Yeast two-hybrid; co-immunoprecipitation; in vitro and in vivo phosphorylation assays; chromatin fractionation; gene expression analysis of p14ARF upon 3pK overexpression\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — yeast two-hybrid, reciprocal Co-IP, in vitro kinase assay, and chromatin fractionation with functional readout, multiple orthogonal methods in one study\",\n      \"pmids\": [\"15563468\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"MAPKAPK2 and MAPKAPK3 positively regulate starvation-induced autophagy by directly phosphorylating Beclin 1 at serine 90; this phosphorylation is essential for autophagy induction and for the tumor suppressor function of Beclin 1. BCL2 blocks MK2/MK3-dependent Beclin 1 S90 phosphorylation both in vitro and in vivo, providing a mechanism by which BCL2 inhibits autophagy.\",\n      \"method\": \"In vitro kinase assays; site-directed mutagenesis of Beclin 1 S90; genetic knockout of MK2/MK3; in vivo autophagy assays; BCL2 overexpression/inhibition experiments\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro kinase assay with mutagenesis, genetic KO, in vivo validation, multiple orthogonal methods\",\n      \"pmids\": [\"25693418\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Overexpression of MAPKAPK3 inhibits IFN-alpha-induced gene transcription via ISRE and GAS elements, as shown by luciferase reporter assay, suggesting MAPKAPK3 negatively regulates IFN signaling.\",\n      \"method\": \"Luciferase reporter assay (ISRE- and GAS-driven); allele-specific transcript quantification in liver biopsy\",\n      \"journal\": \"Gastroenterology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — functional reporter assay and allele-specific expression data, single lab, two orthogonal methods but no direct biochemical mechanism defined\",\n      \"pmids\": [\"19208361\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"A dominant MAPKAPK3 mutation (p.Leu173Pro) causes mislocalization of the protein to the cytoplasm (rather than its normal localization), leading to cytoskeleton alteration and inhibition of cytodieresis (cell division) in HEK cells. In Mapkapk3-/- mice, Bruch's membrane shows abnormal thickening and thinning, establishing a role for MAPKAPK3 in RPE/Bruch's membrane physiology.\",\n      \"method\": \"Mutant protein expression in HEK cells with subcellular localization imaging; cytoskeletal staining; cytodieresis assay; Mapkapk3 knockout mouse histology; crystal structure analysis (bioinformatic) of mutant\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — live cell imaging with functional readout plus KO mouse phenotype, single lab, two orthogonal approaches\",\n      \"pmids\": [\"26744326\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"MAPKAPK3 directly interacts with and phosphorylates Bax; downregulation of MAPKAPK3 leads to reduced Bax phosphorylation and increased Bax mitochondrial translocation, promoting apoptosis in neuroblastoma cells.\",\n      \"method\": \"Co-immunoprecipitation confirming MAPKAPK3-Bax interaction; phosphorylation assay; Western blot for Bax mitochondrial fractionation; MAPKAPK3 knockdown with functional apoptosis readout\",\n      \"journal\": \"Nanomedicine : nanotechnology, biology, and medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Weak — Co-IP and fractionation with KD phenotype, single lab, single study, not yet replicated\",\n      \"pmids\": [\"40976474\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"3PK (MAPKAPK3) physically associates with EZH2 protein and its promoter region (-1107 to -1002), and 3PK inhibition leads to proteasomal-mediated degradation of EZH2 and reduced PcG-mediated epigenetic repression in oral squamous cell carcinoma cells.\",\n      \"method\": \"Co-immunoprecipitation; ChIP-qPCR; Western blotting; immunofluorescence; pharmacological 3PK inhibition\",\n      \"journal\": \"Phytomedicine\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, Co-IP and ChIP data but mechanistic link between 3PK and EZH2 proteasomal degradation is not biochemically reconstituted, and results are embedded in a drug-treatment study\",\n      \"pmids\": [\"33113500\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MAPKAPK3 (3pK) is a serine/threonine kinase activated downstream of all three MAPK cascades (ERK, p38, JNK) that promotes starvation-induced autophagy by phosphorylating Beclin 1 at S90, antagonizes Polycomb-mediated silencing by phosphorylating Bmi1 and dissociating PcG complexes from chromatin, represses E47-dependent transcription, regulates Bax mitochondrial translocation via direct phosphorylation, and inhibits IFN-alpha signaling; proper nuclear localization is required for its role in cell division and RPE/Bruch's membrane integrity.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MAPKAPK3 (3pK) is a serine/threonine protein kinase that functions as a convergence point of mitogen and stress signaling, being phosphorylated and activated downstream of the ERK, p38, and JNK MAPK cascades [#0, #1]. Through its kinase activity it acts on multiple substrates to regulate chromatin state, autophagy, and apoptosis: it directly phosphorylates the Polycomb group protein Bmi1 and other PcG members, driving their dissociation from chromatin and de-repression of the Cdkn2a/INK4A locus product p14ARF [#3], and it phosphorylates the bHLH transcription factor E47 to repress E-box-dependent transcription [#2]. Together with MAPKAPK2, it promotes starvation-induced autophagy by phosphorylating Beclin 1 at serine 90, an event antagonized by BCL2 [#4]. It also directly phosphorylates Bax, restraining its mitochondrial translocation and thereby limiting apoptosis [#7]. A dominant p.Leu173Pro mutation that mislocalizes the protein to the cytoplasm disrupts the cytoskeleton and cytodieresis, and Mapkapk3-knockout mice show Bruch's membrane abnormalities, establishing a role in cell division and RPE/Bruch's membrane integrity [#6].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Established 3pK as a bona fide MAPK substrate kinase, placing it downstream of the Raf/MEK/ERK mitogenic cascade.\",\n      \"evidence\": \"In vitro kinase assays with recombinant ERK plus in vivo serum/TPA stimulation with pathway inhibitors in HL60 and HEK293 cells\",\n      \"pmids\": [\"8943323\", \"8622688\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological substrates of activated 3pK not identified at this stage\", \"Activation kinetics relative to other MAPKAPKs not defined\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Showed 3pK is also activated by p38 and JNK, defining it as the first kinase integrating signals from all three MAPK cascades and a node where mitogen and stress inputs converge.\",\n      \"evidence\": \"In vitro kinase assays with recombinant p38RK and JNK, co-transfection epistasis, and SB203580 blockade\",\n      \"pmids\": [\"8943323\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the three cascades activate 3pK in distinct cellular contexts unresolved\", \"Downstream consequences of each input not distinguished\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Identified the first transcriptional substrate of 3pK, linking its kinase activity to repression of E-box-dependent gene expression.\",\n      \"evidence\": \"In vitro kinase assay, co-immunoprecipitation, and E-box luciferase reporter assay with 3pK overexpression\",\n      \"pmids\": [\"10781029\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Phosphosite on E47 not mapped\", \"Single lab, overexpression-based; endogenous relevance not established\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Connected 3pK to epigenetic control by showing it phosphorylates Bmi1/PcG proteins to evict them from chromatin and de-repress the INK4A/p14ARF locus.\",\n      \"evidence\": \"Yeast two-hybrid, reciprocal Co-IP, in vitro/in vivo phosphorylation, chromatin fractionation, and p14ARF expression analysis\",\n      \"pmids\": [\"15563468\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specific Bmi1 phosphosites and their stoichiometry not fully defined\", \"Upstream MAPK input driving this event in vivo not identified\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Linked MAPKAPK3 to negative regulation of type I interferon signaling output.\",\n      \"evidence\": \"ISRE- and GAS-driven luciferase reporter assays and allele-specific transcript quantification in liver biopsy\",\n      \"pmids\": [\"19208361\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct biochemical substrate in the IFN pathway not defined\", \"Effect shown by overexpression; endogenous kinase requirement untested\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Defined a direct mechanistic role in autophagy by identifying Beclin 1 S90 as a MK2/MK3 phosphosite required for starvation-induced autophagy and Beclin 1 tumor suppressor function.\",\n      \"evidence\": \"In vitro kinase assays, Beclin 1 S90 mutagenesis, MK2/MK3 genetic knockout, in vivo autophagy assays, and BCL2 manipulation\",\n      \"pmids\": [\"25693418\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contributions of MK2 versus MK3 not separated\", \"Which MAPK cascade triggers this phosphorylation during starvation unresolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Demonstrated that correct nuclear localization of MAPKAPK3 is required for cell division and tissue integrity, via a mislocalizing dominant mutation and a knockout mouse.\",\n      \"evidence\": \"p.Leu173Pro mutant localization imaging and cytodieresis assays in HEK cells plus Mapkapk3-/- mouse Bruch's membrane histology\",\n      \"pmids\": [\"26744326\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Substrates underlying the cytoskeletal/cytodieresis defect not identified\", \"Mechanism linking kinase to Bruch's membrane physiology unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Associated 3PK with EZH2 stability and PcG-mediated repression in oral squamous carcinoma cells.\",\n      \"evidence\": \"Co-IP, ChIP-qPCR, Western blot, and immunofluorescence under pharmacological 3PK inhibition\",\n      \"pmids\": [\"33113500\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Mechanistic link between 3PK and EZH2 proteasomal degradation not biochemically reconstituted\", \"Findings embedded in a drug-treatment study; direct phosphorylation of EZH2 not demonstrated\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified Bax as a direct MAPKAPK3 substrate, positioning the kinase as a brake on intrinsic apoptosis.\",\n      \"evidence\": \"Co-IP, phosphorylation assay, Bax mitochondrial fractionation, and MAPKAPK3 knockdown apoptosis readouts in neuroblastoma cells\",\n      \"pmids\": [\"40976474\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Bax phosphosite not mapped\", \"Single lab, not yet replicated; reciprocal validation lacking\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How distinct upstream MAPK inputs are routed to specific substrates (chromatin, autophagy, apoptosis) to produce context-specific outputs remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No unifying model linking activating cascade to substrate choice\", \"In vivo substrate hierarchy under physiological stress unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 2, 3, 4, 7]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 4]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [2, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [6]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [7]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"BECN1\", \"BMI1\", \"BAX\", \"E47\", \"EZH2\", \"BCL2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}