{"gene":"PPM1A","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":2006,"finding":"PPM1A (PP2Cα) directly dephosphorylates the C-terminal pSXS motif of TGF-β-activated Smad2 and Smad3, promoting their nuclear export and terminating TGF-β transcriptional responses. Ectopic expression abolishes TGF-β-induced antiproliferative and transcriptional responses; depletion enhances TGF-β signaling.","method":"Functional genomic screen, in vitro phosphatase assay, overexpression/RNAi in mammalian cells, zebrafish Nodal signaling epistasis","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro dephosphorylation assay, loss-of-function RNAi, gain-of-function, and in vivo zebrafish epistasis; independently confirmed in multiple subsequent studies","pmids":["16751101"],"is_preprint":false},{"year":2006,"finding":"PPM1A physically interacts with and dephosphorylates Smad1 (BMP-activated R-Smad) both in vitro and in vivo, terminating BMP signaling. Overexpression abolishes BMP-induced transcriptional responses; RNAi knockdown enhances BMP signaling.","method":"Co-immunoprecipitation, in vitro phosphatase assay, overexpression and RNAi in mammalian cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — in vitro phosphatase assay plus reciprocal Co-IP and RNAi with defined transcriptional readout, single lab but multiple orthogonal methods","pmids":["16931515"],"is_preprint":false},{"year":2008,"finding":"PPM1A (and PPM1B) act as IKKβ phosphatases, dephosphorylating IKKβ at Ser177 and Ser181 to terminate TNFα-induced NF-κB activation. PPM1A associates with the phosphorylated form of IKKβ in a TNFα-induced, transient manner; knockdown of PPM1A enhances IKKβ phosphorylation, NF-κB nuclear translocation, and NF-κB-dependent gene expression.","method":"Functional genomic screen, overexpression, Co-immunoprecipitation, RNAi knockdown, NF-κB reporter assay","journal":"Cellular signalling","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, RNAi with defined pathway readout, overexpression rescue, single lab with multiple orthogonal methods","pmids":["18930133"],"is_preprint":false},{"year":2008,"finding":"PPM1A dephosphorylates Thr-186 in the T-loop of Cdk9 (the catalytic subunit of P-TEFb), negatively regulating P-TEFb kinase activity. PPM1A co-immunoprecipitates with Cdk9 in vivo; in vitro, purified PPM1A dephosphorylates Thr-186 in the presence or absence of 7SK RNA.","method":"Phosphatase expression library screen, co-immunoprecipitation, in vitro phosphatase assay, shRNA knockdown, phospho-specific antiserum","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — in vitro reconstitution with purified PPM1A, reciprocal Co-IP, and shRNA with phospho-specific readout; single lab but multiple orthogonal methods","pmids":["18829461"],"is_preprint":false},{"year":2008,"finding":"Nuclear PTEN acts as a co-factor of PPM1A by forming a complex with it (requiring phosphorylation of PTEN's C-terminal serine/threonine residues but not PTEN's lipid phosphatase activity). Complex formation protects PPM1A from TGF-β-induced degradation and enhances Smad2/3 dephosphorylation. dhS1P stimulates this pathway through PTEN nuclear translocation.","method":"Co-immunoprecipitation, overexpression, phospho-mutant analysis, fractionation","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP and overexpression with defined biochemical readout; single lab, mechanistic follow-up on PPM1A-PTEN interaction","pmids":["18482992"],"is_preprint":false},{"year":2011,"finding":"PPM1A directly interacts with and dephosphorylates the nuclear export factor RanBP3 at Ser58 in vitro and in vivo, promoting RanBP3-mediated nuclear export of Smad2/3 and efficient termination of TGF-β signaling. RanBP3 phosphorylation is elevated in PPM1A-null mouse embryonic fibroblasts.","method":"In vitro phosphatase assay, co-immunoprecipitation, RNAi, PPM1A-null MEFs, nuclear export assays","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — in vitro dephosphorylation assay, genetic null MEFs confirming elevated substrate phosphorylation, and functional nuclear export readout; single lab, multiple orthogonal methods","pmids":["21960005"],"is_preprint":false},{"year":2011,"finding":"PPM1A and PPM1B are N-myristoylated, and this modification is essential for their ability to dephosphorylate physiological substrates (including AMPKα) in cells. A non-myristoylated G2A mutant prevents membrane association and shows reduced activity toward AMPKα in cells and in vitro, despite higher activity toward the artificial substrate PNPP.","method":"Mutagenesis (G2A), in vitro phosphatase assay, cell fractionation, AMPKα dephosphorylation assay","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mutagenesis combined with in vitro and cellular phosphatase assays demonstrating substrate-specific requirement; single lab but orthogonal methods","pmids":["23088624"],"is_preprint":false},{"year":2011,"finding":"PPM1A knockout or keratinocyte-specific deletion in mice causes delayed re-epithelialization during cutaneous wound healing due to enhanced Smad2/3 phosphorylation in keratinocytes. Genetic rescue by Smad2 deficiency in PPM1A/Smad2 double-mutant mice restores normal re-epithelialization, placing PPM1A upstream of Smad2 in this pathway.","method":"Ppm1a knockout mice, keratinocyte-specific conditional knockout, Smad2/PPM1A double-mutant epistasis, wound healing assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis in vivo using double-mutant rescue, clean KO with defined cellular phenotype, multiple genetic models","pmids":["21990361"],"is_preprint":false},{"year":2013,"finding":"PPM1A directly dephosphorylates RelA (NF-κB subunit) at Ser536 and Ser276, selectively inhibiting NF-κB transcriptional activity and reducing expression of MCP-1/CCL2 and IL-6. PPM1A depletion enhances NF-κB-dependent cell invasion.","method":"In vitro phosphatase assay, overexpression, RNAi, NF-κB reporter assay, invasion assay","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro dephosphorylation of RelA with site-specific readout plus RNAi/overexpression; single lab, multiple orthogonal methods","pmids":["23812431"],"is_preprint":false},{"year":2013,"finding":"MAN1 (inner nuclear membrane protein) directly binds PPM1A in vitro and recruits it to Smad2/3 at the nuclear envelope, facilitating Smad dephosphorylation and inhibition of TGF-β signaling. MAN1 overexpression promotes Smad2/3 dephosphorylation in a PPM1A-dependent manner.","method":"NMR structure, SAXS, in vitro binding assay (pulldown), in vitro dephosphorylation, cell-based overexpression","journal":"Science signaling","confidence":"High","confidence_rationale":"Tier 1 / Moderate — NMR and SAXS structural data combined with in vitro direct binding and dephosphorylation assays; single lab but multiple orthogonal structural and biochemical methods","pmids":["23779087"],"is_preprint":false},{"year":2015,"finding":"PPM1A negatively regulates antiviral DNA sensing by dephosphorylating both STING and TBK1 in vitro in a phosphatase-activity-dependent manner, antagonizing TBK1-mediated STING phosphorylation and aggregation to dampen innate immune signaling.","method":"In vitro phosphatase assay, overexpression, RNAi, STING aggregation assay","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — in vitro dephosphorylation of STING and TBK1, functional aggregation assay; single lab, multiple substrates tested","pmids":["25815785"],"is_preprint":false},{"year":2016,"finding":"PPM1A silences cytosolic RNA sensing (RLR-IRF3 axis) by directly dephosphorylating both MAVS and TBK1/IKKε. PPM1A is an inherent partner of the TBK1/IKKε complex; high MAVS levels can dissociate the TBK1/PPM1A complex to override inhibition. PPM1A knockout in HEK293 cells and primary macrophages enhances antiviral responses; Ppm1a-/- mice resist RNA virus attack.","method":"In vitro phosphatase assay, Co-immunoprecipitation, PPM1A gene knockout (HEK293 and mouse), primary macrophage assay, transgenic zebrafish, viral infection model","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro reconstitution, Co-IP, gene knockout in multiple cell types and whole organisms; replicated across in vitro and in vivo models","pmids":["27419230"],"is_preprint":false},{"year":2017,"finding":"Mycobacterium tuberculosis exploits PPM1A to suppress host macrophage apoptosis by inactivating JNK. Overproduction of PPM1A suppresses JNK activation in Mtb-infected macrophages; PPM1A depletion (shRNA) or inhibition (sanguinarine) restores JNK activation and apoptosis.","method":"shRNA knockdown, pharmacological inhibition (sanguinarine), JNK activation assay, apoptosis assay in Mtb-infected macrophages","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic (shRNA) and pharmacological loss-of-function with defined JNK/apoptosis readout; single lab, two complementary approaches","pmids":["28176854"],"is_preprint":false},{"year":2018,"finding":"Crystal structure of human PPM1Acat complexed with a cyclic phosphopeptide (c(MpSIpYVA), a cyclized activation loop of p38 MAPK) reveals three metal ions in the active site. The Flap subdomain shows reduced conformational flexibility upon substrate binding. Enzyme kinetics support a random-order bi-substrate mechanism with substantial interaction between bound substrate and the labile third metal ion.","method":"X-ray crystallography, enzyme kinetics, biophysical methods (SAXS, computational docking), active-site mutagenesis (D146E trapping mutant)","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure of enzyme-substrate complex with mutagenesis and detailed kinetic analysis; single study but multiple rigorous orthogonal methods","pmids":["29602904"],"is_preprint":false},{"year":2018,"finding":"TRIM52 E3 ubiquitin ligase interacts with PPM1A via Co-IP and promotes its ubiquitination and proteasomal degradation, thereby activating TGF-β/Smad2/3 signaling and promoting HCC cell proliferation, migration, and invasion.","method":"Co-immunoprecipitation, ubiquitination assay in vitro, overexpression/RNAi, western blot","journal":"Journal of experimental & clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP plus ubiquitination assay with functional rescue; single lab, two complementary biochemical methods","pmids":["29898761"],"is_preprint":false},{"year":2018,"finding":"CSIG (cellular senescence-inhibited gene) facilitates the interaction between NMT1 and PPM1A, promoting PPM1A N-myristoylation. CSIG knockdown disturbs PPM1A myristoylation and reduces PPM1A-mediated dephosphorylation of Smad2, thereby modulating TGF-β signaling.","method":"Co-immunoprecipitation, myristoylation assay, RNAi knockdown, Smad2 phosphorylation readout","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP of three-component complex plus RNAi with biochemical readout; single lab, mechanistic follow-up on myristoylation regulation","pmids":["30201805"],"is_preprint":false},{"year":2018,"finding":"HCV NS3 protein directly interacts with PPM1A (via its protease domain) and promotes PPM1A ubiquitination and proteasomal degradation, thereby enhancing HCC cell migration and invasion. Restoration of PPM1A abrogates NS3-mediated promotion in a phosphatase-activity-dependent manner.","method":"Co-immunoprecipitation, ubiquitination assay, overexpression/RNAi, invasion/migration assay","journal":"Journal of experimental & clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP plus ubiquitination assay with domain mapping and functional rescue; single lab, multiple orthogonal methods","pmids":["28283039"],"is_preprint":false},{"year":2018,"finding":"PPM1A controls monocyte-to-macrophage differentiation: overexpression of PPM1A attenuates the macrophage differentiation program (impairs adherence, reduces M1 markers, inhibits inflammatory cytokines), while knockdown accelerates differentiation. TLR agonists imiquimod and Pam3CSK4 induce PPM1A expression.","method":"Overexpression/knockdown genetic manipulation, flow cytometry, cytokine measurement, differentiation assays","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal genetic manipulation (OE and KD) with defined cellular differentiation phenotype; single lab, multiple readouts","pmids":["29343725"],"is_preprint":false},{"year":2020,"finding":"PPM1A directly dephosphorylates PPARγ at Ser273, a site phosphorylated by CDK5/ERK that drives diabetic gene reprogramming. PPM1A expression decreases in diet-induced obese and db/db mice, negatively correlating with PPARγ pSer273 levels.","method":"In vitro phosphatase assay, overexpression, western blot with phospho-specific antibody, mouse metabolic models","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — in vitro dephosphorylation of PPARγ at specific site; single lab, corroborated in animal models","pmids":["32024237"],"is_preprint":false},{"year":2021,"finding":"PPM1A is the physiological phosphatase for YAP/TAZ, directly eliminating phosphorylation at YAP Ser127 (LATS1 site). PPM1A associates with YAP/TAZ in both cytoplasm and nucleus. Genetic ablation of PPM1A in cells, organoids, and mice causes enhanced YAP/TAZ cytoplasmic retention, diminished proliferation, severe gut regeneration defects in colitis, and impeded liver regeneration; these defects are rescued by LATS1 deficiency or Hippo pathway inhibition.","method":"Phosphatome screen, Co-IP, in vitro phosphatase assay, PPM1A KO mice/organoids, genetic epistasis (LATS1 KO rescue), pharmacological Hippo inhibition","journal":"PLoS biology","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — unbiased phosphatome screen, in vitro reconstitution, Co-IP, genetic KO in multiple in vivo systems, and epistasis rescue; single lab but comprehensive multi-orthogonal approach","pmids":["33630828"],"is_preprint":false},{"year":2022,"finding":"Cytoplasmic NDRG2 binds PPM1A in astrocytes and restricts the dephosphorylation of Smad2/3. After subarachnoid hemorrhage, NDRG2 upregulation sequesters PPM1A, sustaining pSmad2/3 and driving MMP-9 transcription. A blocking peptide (TAT-QFNP12) disrupting NDRG2-PPM1A binding restores Smad2/3 dephosphorylation and reduces MMP-9.","method":"Co-immunoprecipitation, Ndrg2 conditional knockout, peptide competition assay, pSmad2/3 readout, MMP-9 expression/BBB assay","journal":"Science advances","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus conditional KO and peptide disruption with defined biochemical and functional readout; single lab, multiple orthogonal approaches","pmids":["36179025"],"is_preprint":false},{"year":2021,"finding":"Active-site arginines Arg33 and Arg186 of PPM1A are critical for enzymatic dephosphorylation activity. Docking-model analysis suggests Arg186 interacts directly with the substrate phosphate group. The relative importance of each Arg residue depends on the substrate.","method":"Site-directed mutagenesis, in vitro phosphatase assay, docking model analysis","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — mutagenesis and in vitro assay; single lab, single study, computational docking as supporting evidence","pmids":["34637963"],"is_preprint":false},{"year":2022,"finding":"PPM1A inhibition (genetic KO or pharmacological with sanguinarine/BC-21) activates autophagy through a mechanism dependent on phosphorylation of p62-SQSTM1, restricting intracellular Mycobacterium tuberculosis survival in macrophages and mouse lungs. A selective small-molecule PPM1A inhibitor (SMIP-30) was identified.","method":"PPM1A gene knockout (ΔPPM1A), small-molecule inhibitor (SMIP-30), autophagy assay (p62 phosphorylation, LC3B), Mtb survival assay in macrophages and mice","journal":"Cell chemical biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO corroborated by selective pharmacological inhibitor, mechanistic autophagy pathway readout; single lab, two complementary loss-of-function approaches","pmids":["35320734"],"is_preprint":false},{"year":2023,"finding":"PPM1A interacts with phospho-SMAD2 in chondrocytes and its knockout protects mice from cartilage degeneration in the DMM osteoarthritis model by maintaining elevated pSMAD2. The protective phenotype in PPM1A KO mice is abolished by TGF-β/SMAD2 signaling inhibition (SD-208), demonstrating epistasis.","method":"Co-immunoprecipitation, PPM1A KO mice with DMM surgery, genetic epistasis (SD-208 inhibitor rescue), PPM1A inhibitors (sanguinarine, BC-21) in vivo","journal":"JCI insight","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic KO with in vivo phenotype, Co-IP, and pharmacological epistasis rescue; single lab but multiple orthogonal approaches","pmids":["36752205"],"is_preprint":false},{"year":2012,"finding":"Maxacalcitol (vitamin D analog) promotes assembly of a PPM1A/VDR complex that is recruited to phospho-Smad3 (pSmad3), facilitating pSmad3 dephosphorylation and attenuating TGF-β1 autoinduction in kidney fibrosis. Without maxacalcitol, the PPM1A/pSmad3 interaction is insufficient for dephosphorylation.","method":"Co-immunoprecipitation, chromatin immunoprecipitation, nuclear fractionation, in vivo rat model (UUO)","journal":"Laboratory investigation","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP of PPM1A/VDR/pSmad3 complex with in vivo rat model validation; single lab, multiple biochemical and in vivo approaches","pmids":["22926646"],"is_preprint":false},{"year":2013,"finding":"PPM1A is involved in nerve cell survival and differentiation: overexpression in PC6-3 cells causes G2/M cell cycle arrest and apoptosis in naive but not fully differentiated cells, and modulates NGF signaling and neurite outgrowth.","method":"Overexpression, PPM1A knockdown, cell cycle analysis, neurite outgrowth assay in PC6-3 cells","journal":"PloS one","confidence":"Low","confidence_rationale":"Tier 3 / Weak — overexpression/KD with phenotypic readout but no direct substrate identification for neuronal function; single lab, limited mechanistic detail","pmids":["22384250"],"is_preprint":false},{"year":2016,"finding":"HBx (Hepatitis B virus X protein) dose-dependently downregulates PPM1A protein (but not mRNA) in the presence of TGF-β by increasing PPM1A ubiquitination and accelerating proteasomal degradation, thereby amplifying TGF-β/pSmad2/3 signaling and HCC cell motility.","method":"Western blot, ubiquitination assay, overexpression/RNAi, migration/invasion assay","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — ubiquitination assay plus functional rescue by PPM1A restoration; single lab, mechanistic follow-up","pmids":["27121309"],"is_preprint":false},{"year":2022,"finding":"Myoneurin (Mynn) interacts with Smad proteins in the nucleus and competes with Ppm1a for Smad binding, preventing Smad dephosphorylation and sustaining BMP signaling. Loss of mynn reduces BMP signal activity in zebrafish and mammalian cells.","method":"Co-immunoprecipitation, competitive binding assay, zebrafish mynn mutant, mammalian cell knockdown, BMP signaling readout","journal":"iScience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP competitive binding plus genetic loss-of-function in two model systems; single lab, mechanistic epistasis established","pmids":["35712083"],"is_preprint":false},{"year":2020,"finding":"MALAT1 lncRNA regulates TGF-β/Smad signaling by forming a lncRNA-protein complex containing Smads, SETD2, and PPM1A in hepatic cells. This complex facilitates pSmad2/3 dephosphorylation by providing an interaction niche for pSmad2/3 and PPM1A.","method":"RNA immunoprecipitation, Co-IP, RNAi depletion of MALAT1, pSmad2/3 readout, iPS cell differentiation assay","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — RNA-IP and Co-IP demonstrating complex formation with functional dephosphorylation readout; single lab","pmids":["31995604"],"is_preprint":false},{"year":2018,"finding":"TRIM52 promotes PPM1A ubiquitination in hepatic stellate cells (LX-2), leading to PPM1A protein degradation and activation of TGF-β/Smad2/3 pathway. Overexpression of PPM1A reverses TRIM52-mediated fibrogenic effects.","method":"Co-immunoprecipitation, ubiquitination assay, overexpression, siRNA knockdown, fibrosis markers","journal":"Cell biology international","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP plus ubiquitination assay with PPM1A overexpression rescue; single lab","pmids":["31329338"],"is_preprint":false},{"year":2019,"finding":"USP33 deubiquitinates PPM1A, stabilizing it; miR-3591-5p suppresses USP33, leading to PPM1A degradation, sustained Smad2/3 phosphorylation, and radiation-induced EMT in lung cancer cells. Ectopic USP33 or PPM1A expression partially abolishes these effects.","method":"3'UTR luciferase reporter assay, western blot, overexpression rescue, RNAi","journal":"Cellular physiology and biochemistry","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — validated miRNA-target interaction and deubiquitination mechanism with functional rescue; single lab","pmids":["30308513"],"is_preprint":false},{"year":2024,"finding":"TRIM47 acts as an E3 ubiquitin ligase that promotes PPM1A ubiquitination and proteasomal degradation in pulmonary fibrosis. TRIM47 knockdown stabilizes PPM1A, suppressing TGF-β/SMAD3 and NF-κB/NLRP3 signaling. Otilonium bromide (OB) activates PPM1A enzymatically (EC50 = 4.23 μM) and ameliorates bleomycin-induced pulmonary fibrosis in mice in a PPM1A-dependent manner.","method":"Co-immunoprecipitation, ubiquitination assay, PPM1A knockdown mice, in vitro enzymatic activation assay, bleomycin mouse model","journal":"Acta pharmacologica Sinica","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and ubiquitination assay with in vivo PPM1A-specific KD rescue and enzymatic activity data; single lab, multiple approaches","pmids":["39160244"],"is_preprint":false},{"year":2025,"finding":"SLC7A11-AS1 lncRNA interacts with scaffold protein RSL1D1, disrupting the recruitment of PPM1A and NMT1 to RSL1D1, thereby suppressing PPM1A N-myristoylation and prolonging activin A/Smad2/3 signaling in pancreatic cancer cells.","method":"RNA pulldown + LC-MS/MS, co-immunoprecipitation, myristoylation assay, overexpression/knockdown","journal":"British journal of cancer","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — proteomic identification of complex components, Co-IP, and myristoylation assay; single lab, multiple methods","pmids":["40926062"],"is_preprint":false},{"year":2020,"finding":"TRIM59 promotes ubiquitination and proteasomal degradation of PPM1A (at the post-translational level, without altering PPM1A mRNA) in ectopic endometrial stromal cells, activating TGF-β/Smad2/3 signaling and promoting invasion in endometriosis.","method":"Co-immunoprecipitation, ubiquitination assay, overexpression/siRNA, western blot","journal":"American journal of physiology. Cell physiology","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — Co-IP and ubiquitination assay with post-translational specificity demonstrated; single lab","pmids":["32348176"],"is_preprint":false},{"year":2022,"finding":"TRIM65 acts as an E3 ubiquitin ligase targeting PPM1A for ubiquitin-mediated degradation; TRIM65 knockdown increases PPM1A levels and decreases pTBK1 in gastric cancer cells, inhibiting proliferation and invasion.","method":"Co-immunoprecipitation, ubiquitination assay, shRNA knockdown, western blot","journal":"Experimental cell research","confidence":"Low","confidence_rationale":"Tier 3 / Weak — Co-IP and ubiquitination assay, single lab, limited mechanistic detail on TBK1 link","pmids":["35421368"],"is_preprint":false},{"year":2019,"finding":"PPM1A inhibits triple negative breast cancer cell growth by blocking cell cycle progression and reducing CDK and Rb phosphorylation when expressed in TNBC cells.","method":"Induced overexpression, cell cycle analysis, CDK/Rb phosphorylation western blot, in vitro and in vivo tumor growth assay","journal":"NPJ breast cancer","confidence":"Low","confidence_rationale":"Tier 3 / Weak — overexpression with phosphorylation readout but no direct substrate identification for cell cycle; single lab","pmids":["31372497"],"is_preprint":false},{"year":2023,"finding":"Extracellular PPM1A promotes osteoblast differentiation in ankylosing spondylitis by inducing dephosphorylation of FOXO1A at Ser256, enabling FOXO1A nuclear translocation and upregulation of RUNX2.","method":"Exogenous PPM1A treatment, phospho-FOXO1A western blot, RUNX2 promoter luciferase assay, nuclear fractionation","journal":"Journal of cellular and molecular medicine","confidence":"Low","confidence_rationale":"Tier 3 / Weak — exogenous protein treatment with phospho readout; no direct in vitro phosphatase assay shown in abstract; single lab","pmids":["36756789"],"is_preprint":false}],"current_model":"PPM1A (PP2Cα) is a metal-dependent serine/threonine phosphatase whose N-myristoylation is required for physiological substrate recognition; it dephosphorylates a broad set of signaling substrates—including Smad2/3/1 (TGF-β/BMP pathway), YAP/TAZ (Hippo pathway), IKKβ and RelA (NF-κB pathway), TBK1/MAVS/STING (innate antiviral signaling), Cdk9 T-loop (P-TEFb), RanBP3 (nuclear export), AMPKα, and PPARγ pSer273—to terminate or attenuate these pathways, with its own activity regulated by ubiquitin-mediated proteasomal degradation (via TRIM52/59/65/47 E3 ligases) and by co-factor interactions (PTEN, CSIG/NMT1, MAN1, NDRG2) that modulate substrate access to its active site, which contains three metal ions and uses active-site arginines (Arg33 and Arg186) for substrate recognition."},"narrative":{"mechanistic_narrative":"PPM1A (PP2Cα) is a metal-dependent serine/threonine phosphatase that functions as a broad negative regulator of phosphorylation-driven signaling cascades, terminating responses initiated by TGF-β/BMP, Hippo, NF-κB, and innate antiviral pathways [PMID:16751101, PMID:33630828, PMID:18930133, PMID:27419230]. Its best-defined role is to dephosphorylate the C-terminal pSXS motif of TGF-β-activated Smad2/3 and BMP-activated Smad1, driving their nuclear export and shutting down the corresponding transcriptional programs [PMID:16751101, PMID:16931515]; it reinforces TGF-β termination by also dephosphorylating the nuclear export factor RanBP3 at Ser58 [PMID:21960005]. Genetic epistasis in mice places PPM1A directly upstream of Smad2 in cutaneous wound re-epithelialization and upstream of SMAD2 in cartilage homeostasis, where loss of PPM1A sustains pSmad2/3 [PMID:21990361, PMID:36752205]. The same active site terminates additional pathways: it dephosphorylates YAP/TAZ at the LATS1 site (YAP Ser127) to restrain Hippo-controlled proliferation and tissue regeneration [PMID:33630828], IKKβ (Ser177/Ser181) and RelA (Ser536/Ser276) to attenuate NF-κB signaling [PMID:18930133, PMID:23812431], the Cdk9 T-loop (Thr186) to limit P-TEFb activity [PMID:18829461], MAVS, STING and TBK1 to silence cytosolic and DNA antiviral sensing [PMID:27419230, PMID:25815785], and PPARγ at Ser273 in metabolic regulation [PMID:32024237]. Substrate engagement in cells requires N-myristoylation, which directs membrane association and physiological substrate recognition [PMID:23088624]; catalysis proceeds through a three-metal active site engaging the substrate phosphate, with active-site arginines Arg33 and Arg186 contributing to substrate recognition in a random-order bi-substrate mechanism [PMID:29602904, PMID:34637963]. Substrate access is gated by cofactor and scaffold interactions—PTEN, the inner nuclear membrane protein MAN1, NDRG2, and the CSIG/NMT1 myristoylation machinery [PMID:18482992, PMID:23779087, PMID:36179025, PMID:30201805]—and PPM1A abundance is set by ubiquitin-mediated proteasomal degradation through multiple TRIM-family E3 ligases (TRIM52, TRIM59, TRIM47) opposed by the deubiquitinase USP33, a balance frequently subverted in fibrosis and cancer to amplify TGF-β signaling [PMID:29898761, PMID:32348176, PMID:39160244, PMID:30308513].","teleology":[{"year":2006,"claim":"Establishing that a specific phosphatase terminates TGF-β/BMP signaling answered how activated R-Smads are inactivated, identifying PPM1A as the Smad C-terminal phosphatase.","evidence":"Functional genomic screen, in vitro phosphatase assays, RNAi/overexpression, and zebrafish Nodal epistasis for Smad2/3, with reciprocal Co-IP for Smad1/BMP","pmids":["16751101","16931515"],"confidence":"High","gaps":["Did not define how PPM1A is recruited to nuclear Smads","Did not address regulation of PPM1A activity or abundance"]},{"year":2008,"claim":"Identifying PPM1A as a phosphatase for IKKβ and the Cdk9 T-loop extended its role beyond TGF-β, showing it attenuates NF-κB and transcriptional elongation machinery.","evidence":"Phosphatase library screens, reciprocal Co-IP, in vitro dephosphorylation with phospho-specific readouts, and RNAi with reporter assays","pmids":["18930133","18829461"],"confidence":"High","gaps":["Did not establish in vivo physiological relevance of these dephosphorylation events","Did not clarify how substrate selectivity among many targets is achieved"]},{"year":2008,"claim":"Showing that nuclear PTEN forms a complex with PPM1A revealed that cofactor binding can both protect PPM1A from degradation and enhance its Smad-directed activity.","evidence":"Co-IP, phospho-mutant analysis, and fractionation in mammalian cells","pmids":["18482992"],"confidence":"Medium","gaps":["Co-IP/overexpression-based; structural basis of the complex not defined","Generality beyond Smad2/3 substrates not tested"]},{"year":2011,"claim":"Demonstrating that N-myristoylation is required for activity toward physiological substrates explained why an in vitro-competent phosphatase needs lipid modification for cellular function.","evidence":"G2A mutagenesis, cell fractionation, and in vitro/cellular phosphatase assays including AMPKα","pmids":["23088624"],"confidence":"High","gaps":["Did not identify the enzymes setting myristoylation in vivo","Did not map which substrates strictly require membrane targeting"]},{"year":2011,"claim":"Adding RanBP3 dephosphorylation and genetic null MEFs strengthened the model that PPM1A controls Smad nuclear export, while in vivo knockout linked PPM1A loss to enhanced Smad2/3 phosphorylation and a wound-healing phenotype.","evidence":"In vitro phosphatase assay, PPM1A-null MEFs, nuclear export assays, and Ppm1a/Smad2 double-mutant epistasis in mice","pmids":["21960005","21990361"],"confidence":"High","gaps":["Did not resolve relative contributions of direct Smad versus RanBP3 dephosphorylation","Tissue-specific substrate repertoire beyond keratinocytes unexamined"]},{"year":2013,"claim":"Direct dephosphorylation of RelA and recruitment by the inner nuclear membrane protein MAN1 extended PPM1A's NF-κB role and showed scaffold-directed delivery to nuclear-envelope Smads.","evidence":"In vitro phosphatase assays with site-specific RelA readout; NMR/SAXS structure and in vitro binding for MAN1 recruitment","pmids":["23812431","23779087"],"confidence":"Medium","gaps":["MAN1-dependent recruitment not validated in a genetic in vivo model","Whether RelA and Smad dephosphorylation occur at distinct subcellular sites unresolved"]},{"year":2015,"claim":"Identifying STING, TBK1, MAVS, and IKKε as substrates established PPM1A as a brake on innate antiviral signaling, with whole-organism knockouts confirming enhanced antiviral resistance.","evidence":"In vitro phosphatase assays, Co-IP, STING aggregation assays, PPM1A knockout cells/mice, and viral infection models","pmids":["25815785","27419230"],"confidence":"High","gaps":["Mechanism dissociating the TBK1/PPM1A complex at high MAVS levels only partly defined","Crosstalk between antiviral and TGF-β substrate pools not addressed"]},{"year":2018,"claim":"The crystal structure of PPM1Acat with a cyclic phosphopeptide defined the catalytic chemistry, revealing a three-metal active site and a substrate-engaging labile third metal.","evidence":"X-ray crystallography of an enzyme-substrate complex, enzyme kinetics, SAXS, docking, and D146E trapping mutant","pmids":["29602904"],"confidence":"High","gaps":["Structure used a model p38 activation-loop peptide rather than a physiological substrate complex","Did not explain selectivity across the diverse substrate set"]},{"year":2018,"claim":"Discovering that TRIM52 ubiquitinates PPM1A, that CSIG promotes NMT1-dependent myristoylation, and that HCV NS3 drives PPM1A degradation showed that PPM1A levels and modification state are actively controlled to set TGF-β pathway output.","evidence":"Co-IP, ubiquitination assays, myristoylation assays, and overexpression/RNAi with functional readouts in HCC and signaling models","pmids":["29898761","30201805","28283039","27121309"],"confidence":"Medium","gaps":["Largely single-lab Co-IP/ubiquitination evidence per regulator","Substrate specificity of each degradation event not dissected beyond Smad signaling"]},{"year":2021,"claim":"Defining active-site arginines and identifying PPM1A as the physiological YAP/TAZ phosphatase clarified both the catalytic determinants and a new tissue-regeneration role through the Hippo pathway.","evidence":"Site-directed mutagenesis with docking; phosphatome screen, in vitro phosphatase assay, Co-IP, PPM1A KO mice/organoids, and LATS1-deficiency epistasis rescue","pmids":["34637963","33630828"],"confidence":"High","gaps":["How a single active site discriminates YAP versus Smad versus NF-κB substrates remains unresolved","Arg-residue study relied partly on computational docking"]},{"year":2024,"claim":"Mapping additional E3 ligases and deubiquitinases (TRIM47, TRIM59, USP33) and identifying small-molecule activators/inhibitors consolidated PPM1A abundance control as a druggable node in fibrosis and cancer.","evidence":"Co-IP, ubiquitination assays, PPM1A-specific knockdown rescue in vivo, and enzymatic activation assays (otilonium bromide; SMIP-30)","pmids":["39160244","32348176","30308513","35320734"],"confidence":"Medium","gaps":["Pharmacological tools characterized in single-lab settings","Selectivity of activators/inhibitors across PPM1A substrate pathways not established"]},{"year":null,"claim":"How a single shallow PP2C active site achieves selectivity across its many substrates, and how the competing scaffolds, cofactors, and degradation machinery are integrated to direct PPM1A toward a specific pathway in a given cell, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structure of PPM1A bound to a physiological full-length substrate","No systematic comparison of substrate flux under competing cofactor conditions","Spatial partitioning of distinct substrate pools not defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,2,3,5,8,10,11,18,19]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,13]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,2,19,11]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,5,9,24]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[19,20]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[6]},{"term_id":"GO:0005635","term_label":"nuclear envelope","supporting_discovery_ids":[9]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,19,2,8]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[2,10,11]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[22]}],"complexes":[],"partners":["SMAD2","SMAD3","SMAD1","YAP1","RANBP3","IKBKB","PTEN","MAN1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P35813","full_name":"Protein phosphatase 1A","aliases":["Protein phosphatase 2C isoform alpha","PP2C-alpha","Protein phosphatase IA"],"length_aa":382,"mass_kda":42.4,"function":"Enzyme with a broad specificity. Negatively regulates TGF-beta signaling through dephosphorylating SMAD2 and SMAD3, resulting in their dissociation from SMAD4, nuclear export of the SMADs and termination of the TGF-beta-mediated signaling. Dephosphorylates PRKAA1 and PRKAA2. Plays an important role in the termination of TNF-mediated NF-kappa-B activation through dephosphorylating and inactivating IKBKB/IKKB","subcellular_location":"Nucleus; Cytoplasm, cytosol; Membrane","url":"https://www.uniprot.org/uniprotkb/P35813/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PPM1A","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/PPM1A","total_profiled":1310},"omim":[{"mim_id":"616391","title":"RAN-BINDING PROTEIN 3-LIKE; RANBP3L","url":"https://www.omim.org/entry/616391"},{"mim_id":"615932","title":"POTASSIUM CHANNEL TETRAMERIZATION DOMAIN-CONTAINING PROTEIN 20; KCTD20","url":"https://www.omim.org/entry/615932"},{"mim_id":"609668","title":"PROTEIN PHOSPHATASE TARGETING COQ7; PPTC7","url":"https://www.omim.org/entry/609668"},{"mim_id":"606536","title":"CHLORIDE INTRACELLULAR CHANNEL 4; CLIC4","url":"https://www.omim.org/entry/606536"},{"mim_id":"606108","title":"PROTEIN PHOSPHATASE, MAGNESIUM/MANGANESE-DEPENDENT, 1A; PPM1A","url":"https://www.omim.org/entry/606108"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"},{"location":"Plasma membrane","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"bone 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of TGF-β signaling in silico and in vitro, with negative feedback through PPM1A upregulation.","date":"2014","source":"PLoS computational biology","url":"https://pubmed.ncbi.nlm.nih.gov/24901250","citation_count":9,"is_preprint":false},{"pmid":"38958057","id":"PMC_38958057","title":"Small Molecule Targeting PPM1A Activates Autophagy for Mycobacterium tuberculosis Host-Directed Therapy.","date":"2024","source":"Journal of medicinal chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/38958057","citation_count":8,"is_preprint":false},{"pmid":"22669481","id":"PMC_22669481","title":"De novo synthesis of protein phosphatase 1A, magnesium dependent, alpha isoform (PPM1A) during oocyte maturation.","date":"2012","source":"Cellular & molecular biology letters","url":"https://pubmed.ncbi.nlm.nih.gov/22669481","citation_count":8,"is_preprint":false},{"pmid":"39160244","id":"PMC_39160244","title":"Otilonium bromide ameliorates pulmonary fibrosis in mice through activating phosphatase PPM1A.","date":"2024","source":"Acta pharmacologica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/39160244","citation_count":7,"is_preprint":false},{"pmid":"34746000","id":"PMC_34746000","title":"LncRNA PPM1A-AS Regulate Tumor Development Through Multiple Signal Pathways in T-Cell Acute Lymphoblastic Leukemia.","date":"2021","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/34746000","citation_count":7,"is_preprint":false},{"pmid":"34558633","id":"PMC_34558633","title":"PPM1A as a key target of the application of Jiawei‑Maxing‑Shigan decoction for the attenuation of radiation‑induced epithelial‑mesenchymal transition in type II alveolar epithelial cells.","date":"2021","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/34558633","citation_count":7,"is_preprint":false},{"pmid":"36756789","id":"PMC_36756789","title":"Extracellular PPM1A promotes mineralization of osteoblasts differentiation in ankylosing spondylitis via the FOXO1A-RUNX2 pathway.","date":"2023","source":"Journal of cellular and molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/36756789","citation_count":6,"is_preprint":false},{"pmid":"34182082","id":"PMC_34182082","title":"Functional divergence of Brassica napus BnaABI1 paralogs in the structurally conserved PP2CA gene subfamily of Brassicaceae.","date":"2021","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/34182082","citation_count":6,"is_preprint":false},{"pmid":"30201805","id":"PMC_30201805","title":"The Cellular Senescence-Inhibited Gene Is Essential for PPM1A Myristoylation To Modulate Transforming Growth Factor β Signaling.","date":"2018","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/30201805","citation_count":5,"is_preprint":false},{"pmid":"31336763","id":"PMC_31336763","title":"Identification and Total Synthesis of Two Previously Unreported Odd-Chain Bis-Methylene-Interrupted Fatty Acids with a Terminal Olefin that Activate Protein Phosphatase, Mg2+/Mn2+-Dependent 1A (PPM1A) in Ovaries of the Limpet Cellana toreuma.","date":"2019","source":"Marine drugs","url":"https://pubmed.ncbi.nlm.nih.gov/31336763","citation_count":5,"is_preprint":false},{"pmid":"30831200","id":"PMC_30831200","title":"Isolation of a spirolactone norditerpenoid as a yeast Ca2+ signal transduction inhibitor from Kuji amber and evaluation of its effects on PPM1A activity.","date":"2019","source":"Fitoterapia","url":"https://pubmed.ncbi.nlm.nih.gov/30831200","citation_count":5,"is_preprint":false},{"pmid":"36388134","id":"PMC_36388134","title":"Miltefosine as a PPM1A activator improves AD-like pathology in mice by alleviating tauopathy via microglia/neurons crosstalk.","date":"2022","source":"Brain, behavior, & immunity - health","url":"https://pubmed.ncbi.nlm.nih.gov/36388134","citation_count":4,"is_preprint":false},{"pmid":"31933876","id":"PMC_31933876","title":"Effect of miR-135b inhibitor on biological characteristics of osteosarcoma cells through up-regulating PPM1A.","date":"2019","source":"International journal of clinical and experimental pathology","url":"https://pubmed.ncbi.nlm.nih.gov/31933876","citation_count":4,"is_preprint":false},{"pmid":"40435048","id":"PMC_40435048","title":"Knockdown of TRIM47 Overcomes Paclitaxel Resistance in Ovarian Cancer by Suppressing the TGF-β Pathway via PPM1A.","date":"2025","source":"American journal of reproductive immunology (New York, N.Y. : 1989)","url":"https://pubmed.ncbi.nlm.nih.gov/40435048","citation_count":2,"is_preprint":false},{"pmid":"36069235","id":"PMC_36069235","title":"Platyconic acid A‑induced PPM1A upregulation inhibits the proliferation, inflammation and extracellular matrix deposition of TGF‑β1‑induced lung fibroblasts.","date":"2022","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/36069235","citation_count":2,"is_preprint":false},{"pmid":"30463654","id":"PMC_30463654","title":"[Establishment of BV2 cell line with steady knockdown of Mg2+/Mn2+-dependent protein phosphatase 1A(PPM1A)].","date":"2018","source":"Xi bao yu fen zi mian yi xue za zhi = Chinese journal of cellular and molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/30463654","citation_count":1,"is_preprint":false},{"pmid":"38908195","id":"PMC_38908195","title":"Role of TRIM59 in regulating PPM1A in the pathogenesis of silicosis and the intervention effect of tanshinone IIA.","date":"2024","source":"Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie","url":"https://pubmed.ncbi.nlm.nih.gov/38908195","citation_count":1,"is_preprint":false},{"pmid":"22041443","id":"PMC_22041443","title":"[Expression and significance of LMP2 and PPM1A in gestational trophoblastic disease].","date":"2011","source":"Zhonghua fu chan ke za zhi","url":"https://pubmed.ncbi.nlm.nih.gov/22041443","citation_count":1,"is_preprint":false},{"pmid":"34637963","id":"PMC_34637963","title":"Role of active site arginine residues in substrate recognition by PPM1A.","date":"2021","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/34637963","citation_count":1,"is_preprint":false},{"pmid":"38643711","id":"PMC_38643711","title":"Generation of a PPM1A-deficient human induced pluripotent stem cell line using CRISPR-Cas9 technology.","date":"2024","source":"Stem cell research","url":"https://pubmed.ncbi.nlm.nih.gov/38643711","citation_count":0,"is_preprint":false},{"pmid":"40926062","id":"PMC_40926062","title":"SLC7A11-AS1 contributes to prolonged activation of activin A/Smad signaling by suppressing PPM1A myristoylation in pancreatic cancer.","date":"2025","source":"British journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/40926062","citation_count":0,"is_preprint":false},{"pmid":"41501801","id":"PMC_41501801","title":"PPM1A dysfunction aggravates DPN pathology through NF-κB/NLRP3/p-tau axis involving Schwann cell/DRG neuron crosstalk.","date":"2026","source":"Journal of translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/41501801","citation_count":0,"is_preprint":false},{"pmid":"41902461","id":"PMC_41902461","title":"A Bifunctional T3SS-Effector Simultaneously Cleaves Host MAP Kinase and Inhibits PPM1A Phosphatase.","date":"2026","source":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/41902461","citation_count":0,"is_preprint":false},{"pmid":"42098844","id":"PMC_42098844","title":"Otilonium bromide ameliorates paclitaxel-induced peripheral neuropathy by targeting phosphatase PPM1A.","date":"2026","source":"Journal of neuroinflammation","url":"https://pubmed.ncbi.nlm.nih.gov/42098844","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.10.07.680857","title":"Regulation between LRRK2 and PP2A signaling in cellular models of Parkinson’s disease","date":"2025-10-07","source":"bioRxiv","url":"https://doi.org/10.1101/2025.10.07.680857","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":42416,"output_tokens":9221,"usd":0.132781,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":19240,"output_tokens":4470,"usd":0.103975,"stage2_stop_reason":"end_turn"},"total_usd":0.236756,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2006,\n      \"finding\": \"PPM1A (PP2Cα) directly dephosphorylates the C-terminal pSXS motif of TGF-β-activated Smad2 and Smad3, promoting their nuclear export and terminating TGF-β transcriptional responses. Ectopic expression abolishes TGF-β-induced antiproliferative and transcriptional responses; depletion enhances TGF-β signaling.\",\n      \"method\": \"Functional genomic screen, in vitro phosphatase assay, overexpression/RNAi in mammalian cells, zebrafish Nodal signaling epistasis\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro dephosphorylation assay, loss-of-function RNAi, gain-of-function, and in vivo zebrafish epistasis; independently confirmed in multiple subsequent studies\",\n      \"pmids\": [\"16751101\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"PPM1A physically interacts with and dephosphorylates Smad1 (BMP-activated R-Smad) both in vitro and in vivo, terminating BMP signaling. Overexpression abolishes BMP-induced transcriptional responses; RNAi knockdown enhances BMP signaling.\",\n      \"method\": \"Co-immunoprecipitation, in vitro phosphatase assay, overexpression and RNAi in mammalian cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro phosphatase assay plus reciprocal Co-IP and RNAi with defined transcriptional readout, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"16931515\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PPM1A (and PPM1B) act as IKKβ phosphatases, dephosphorylating IKKβ at Ser177 and Ser181 to terminate TNFα-induced NF-κB activation. PPM1A associates with the phosphorylated form of IKKβ in a TNFα-induced, transient manner; knockdown of PPM1A enhances IKKβ phosphorylation, NF-κB nuclear translocation, and NF-κB-dependent gene expression.\",\n      \"method\": \"Functional genomic screen, overexpression, Co-immunoprecipitation, RNAi knockdown, NF-κB reporter assay\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, RNAi with defined pathway readout, overexpression rescue, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"18930133\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PPM1A dephosphorylates Thr-186 in the T-loop of Cdk9 (the catalytic subunit of P-TEFb), negatively regulating P-TEFb kinase activity. PPM1A co-immunoprecipitates with Cdk9 in vivo; in vitro, purified PPM1A dephosphorylates Thr-186 in the presence or absence of 7SK RNA.\",\n      \"method\": \"Phosphatase expression library screen, co-immunoprecipitation, in vitro phosphatase assay, shRNA knockdown, phospho-specific antiserum\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro reconstitution with purified PPM1A, reciprocal Co-IP, and shRNA with phospho-specific readout; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"18829461\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Nuclear PTEN acts as a co-factor of PPM1A by forming a complex with it (requiring phosphorylation of PTEN's C-terminal serine/threonine residues but not PTEN's lipid phosphatase activity). Complex formation protects PPM1A from TGF-β-induced degradation and enhances Smad2/3 dephosphorylation. dhS1P stimulates this pathway through PTEN nuclear translocation.\",\n      \"method\": \"Co-immunoprecipitation, overexpression, phospho-mutant analysis, fractionation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP and overexpression with defined biochemical readout; single lab, mechanistic follow-up on PPM1A-PTEN interaction\",\n      \"pmids\": [\"18482992\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PPM1A directly interacts with and dephosphorylates the nuclear export factor RanBP3 at Ser58 in vitro and in vivo, promoting RanBP3-mediated nuclear export of Smad2/3 and efficient termination of TGF-β signaling. RanBP3 phosphorylation is elevated in PPM1A-null mouse embryonic fibroblasts.\",\n      \"method\": \"In vitro phosphatase assay, co-immunoprecipitation, RNAi, PPM1A-null MEFs, nuclear export assays\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro dephosphorylation assay, genetic null MEFs confirming elevated substrate phosphorylation, and functional nuclear export readout; single lab, multiple orthogonal methods\",\n      \"pmids\": [\"21960005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PPM1A and PPM1B are N-myristoylated, and this modification is essential for their ability to dephosphorylate physiological substrates (including AMPKα) in cells. A non-myristoylated G2A mutant prevents membrane association and shows reduced activity toward AMPKα in cells and in vitro, despite higher activity toward the artificial substrate PNPP.\",\n      \"method\": \"Mutagenesis (G2A), in vitro phosphatase assay, cell fractionation, AMPKα dephosphorylation assay\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis combined with in vitro and cellular phosphatase assays demonstrating substrate-specific requirement; single lab but orthogonal methods\",\n      \"pmids\": [\"23088624\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PPM1A knockout or keratinocyte-specific deletion in mice causes delayed re-epithelialization during cutaneous wound healing due to enhanced Smad2/3 phosphorylation in keratinocytes. Genetic rescue by Smad2 deficiency in PPM1A/Smad2 double-mutant mice restores normal re-epithelialization, placing PPM1A upstream of Smad2 in this pathway.\",\n      \"method\": \"Ppm1a knockout mice, keratinocyte-specific conditional knockout, Smad2/PPM1A double-mutant epistasis, wound healing assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis in vivo using double-mutant rescue, clean KO with defined cellular phenotype, multiple genetic models\",\n      \"pmids\": [\"21990361\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PPM1A directly dephosphorylates RelA (NF-κB subunit) at Ser536 and Ser276, selectively inhibiting NF-κB transcriptional activity and reducing expression of MCP-1/CCL2 and IL-6. PPM1A depletion enhances NF-κB-dependent cell invasion.\",\n      \"method\": \"In vitro phosphatase assay, overexpression, RNAi, NF-κB reporter assay, invasion assay\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro dephosphorylation of RelA with site-specific readout plus RNAi/overexpression; single lab, multiple orthogonal methods\",\n      \"pmids\": [\"23812431\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MAN1 (inner nuclear membrane protein) directly binds PPM1A in vitro and recruits it to Smad2/3 at the nuclear envelope, facilitating Smad dephosphorylation and inhibition of TGF-β signaling. MAN1 overexpression promotes Smad2/3 dephosphorylation in a PPM1A-dependent manner.\",\n      \"method\": \"NMR structure, SAXS, in vitro binding assay (pulldown), in vitro dephosphorylation, cell-based overexpression\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — NMR and SAXS structural data combined with in vitro direct binding and dephosphorylation assays; single lab but multiple orthogonal structural and biochemical methods\",\n      \"pmids\": [\"23779087\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PPM1A negatively regulates antiviral DNA sensing by dephosphorylating both STING and TBK1 in vitro in a phosphatase-activity-dependent manner, antagonizing TBK1-mediated STING phosphorylation and aggregation to dampen innate immune signaling.\",\n      \"method\": \"In vitro phosphatase assay, overexpression, RNAi, STING aggregation assay\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro dephosphorylation of STING and TBK1, functional aggregation assay; single lab, multiple substrates tested\",\n      \"pmids\": [\"25815785\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"PPM1A silences cytosolic RNA sensing (RLR-IRF3 axis) by directly dephosphorylating both MAVS and TBK1/IKKε. PPM1A is an inherent partner of the TBK1/IKKε complex; high MAVS levels can dissociate the TBK1/PPM1A complex to override inhibition. PPM1A knockout in HEK293 cells and primary macrophages enhances antiviral responses; Ppm1a-/- mice resist RNA virus attack.\",\n      \"method\": \"In vitro phosphatase assay, Co-immunoprecipitation, PPM1A gene knockout (HEK293 and mouse), primary macrophage assay, transgenic zebrafish, viral infection model\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro reconstitution, Co-IP, gene knockout in multiple cell types and whole organisms; replicated across in vitro and in vivo models\",\n      \"pmids\": [\"27419230\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Mycobacterium tuberculosis exploits PPM1A to suppress host macrophage apoptosis by inactivating JNK. Overproduction of PPM1A suppresses JNK activation in Mtb-infected macrophages; PPM1A depletion (shRNA) or inhibition (sanguinarine) restores JNK activation and apoptosis.\",\n      \"method\": \"shRNA knockdown, pharmacological inhibition (sanguinarine), JNK activation assay, apoptosis assay in Mtb-infected macrophages\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic (shRNA) and pharmacological loss-of-function with defined JNK/apoptosis readout; single lab, two complementary approaches\",\n      \"pmids\": [\"28176854\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Crystal structure of human PPM1Acat complexed with a cyclic phosphopeptide (c(MpSIpYVA), a cyclized activation loop of p38 MAPK) reveals three metal ions in the active site. The Flap subdomain shows reduced conformational flexibility upon substrate binding. Enzyme kinetics support a random-order bi-substrate mechanism with substantial interaction between bound substrate and the labile third metal ion.\",\n      \"method\": \"X-ray crystallography, enzyme kinetics, biophysical methods (SAXS, computational docking), active-site mutagenesis (D146E trapping mutant)\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure of enzyme-substrate complex with mutagenesis and detailed kinetic analysis; single study but multiple rigorous orthogonal methods\",\n      \"pmids\": [\"29602904\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"TRIM52 E3 ubiquitin ligase interacts with PPM1A via Co-IP and promotes its ubiquitination and proteasomal degradation, thereby activating TGF-β/Smad2/3 signaling and promoting HCC cell proliferation, migration, and invasion.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay in vitro, overexpression/RNAi, western blot\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP plus ubiquitination assay with functional rescue; single lab, two complementary biochemical methods\",\n      \"pmids\": [\"29898761\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"CSIG (cellular senescence-inhibited gene) facilitates the interaction between NMT1 and PPM1A, promoting PPM1A N-myristoylation. CSIG knockdown disturbs PPM1A myristoylation and reduces PPM1A-mediated dephosphorylation of Smad2, thereby modulating TGF-β signaling.\",\n      \"method\": \"Co-immunoprecipitation, myristoylation assay, RNAi knockdown, Smad2 phosphorylation readout\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP of three-component complex plus RNAi with biochemical readout; single lab, mechanistic follow-up on myristoylation regulation\",\n      \"pmids\": [\"30201805\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"HCV NS3 protein directly interacts with PPM1A (via its protease domain) and promotes PPM1A ubiquitination and proteasomal degradation, thereby enhancing HCC cell migration and invasion. Restoration of PPM1A abrogates NS3-mediated promotion in a phosphatase-activity-dependent manner.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, overexpression/RNAi, invasion/migration assay\",\n      \"journal\": \"Journal of experimental & clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP plus ubiquitination assay with domain mapping and functional rescue; single lab, multiple orthogonal methods\",\n      \"pmids\": [\"28283039\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PPM1A controls monocyte-to-macrophage differentiation: overexpression of PPM1A attenuates the macrophage differentiation program (impairs adherence, reduces M1 markers, inhibits inflammatory cytokines), while knockdown accelerates differentiation. TLR agonists imiquimod and Pam3CSK4 induce PPM1A expression.\",\n      \"method\": \"Overexpression/knockdown genetic manipulation, flow cytometry, cytokine measurement, differentiation assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal genetic manipulation (OE and KD) with defined cellular differentiation phenotype; single lab, multiple readouts\",\n      \"pmids\": [\"29343725\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PPM1A directly dephosphorylates PPARγ at Ser273, a site phosphorylated by CDK5/ERK that drives diabetic gene reprogramming. PPM1A expression decreases in diet-induced obese and db/db mice, negatively correlating with PPARγ pSer273 levels.\",\n      \"method\": \"In vitro phosphatase assay, overexpression, western blot with phospho-specific antibody, mouse metabolic models\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — in vitro dephosphorylation of PPARγ at specific site; single lab, corroborated in animal models\",\n      \"pmids\": [\"32024237\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PPM1A is the physiological phosphatase for YAP/TAZ, directly eliminating phosphorylation at YAP Ser127 (LATS1 site). PPM1A associates with YAP/TAZ in both cytoplasm and nucleus. Genetic ablation of PPM1A in cells, organoids, and mice causes enhanced YAP/TAZ cytoplasmic retention, diminished proliferation, severe gut regeneration defects in colitis, and impeded liver regeneration; these defects are rescued by LATS1 deficiency or Hippo pathway inhibition.\",\n      \"method\": \"Phosphatome screen, Co-IP, in vitro phosphatase assay, PPM1A KO mice/organoids, genetic epistasis (LATS1 KO rescue), pharmacological Hippo inhibition\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — unbiased phosphatome screen, in vitro reconstitution, Co-IP, genetic KO in multiple in vivo systems, and epistasis rescue; single lab but comprehensive multi-orthogonal approach\",\n      \"pmids\": [\"33630828\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cytoplasmic NDRG2 binds PPM1A in astrocytes and restricts the dephosphorylation of Smad2/3. After subarachnoid hemorrhage, NDRG2 upregulation sequesters PPM1A, sustaining pSmad2/3 and driving MMP-9 transcription. A blocking peptide (TAT-QFNP12) disrupting NDRG2-PPM1A binding restores Smad2/3 dephosphorylation and reduces MMP-9.\",\n      \"method\": \"Co-immunoprecipitation, Ndrg2 conditional knockout, peptide competition assay, pSmad2/3 readout, MMP-9 expression/BBB assay\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus conditional KO and peptide disruption with defined biochemical and functional readout; single lab, multiple orthogonal approaches\",\n      \"pmids\": [\"36179025\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Active-site arginines Arg33 and Arg186 of PPM1A are critical for enzymatic dephosphorylation activity. Docking-model analysis suggests Arg186 interacts directly with the substrate phosphate group. The relative importance of each Arg residue depends on the substrate.\",\n      \"method\": \"Site-directed mutagenesis, in vitro phosphatase assay, docking model analysis\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — mutagenesis and in vitro assay; single lab, single study, computational docking as supporting evidence\",\n      \"pmids\": [\"34637963\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PPM1A inhibition (genetic KO or pharmacological with sanguinarine/BC-21) activates autophagy through a mechanism dependent on phosphorylation of p62-SQSTM1, restricting intracellular Mycobacterium tuberculosis survival in macrophages and mouse lungs. A selective small-molecule PPM1A inhibitor (SMIP-30) was identified.\",\n      \"method\": \"PPM1A gene knockout (ΔPPM1A), small-molecule inhibitor (SMIP-30), autophagy assay (p62 phosphorylation, LC3B), Mtb survival assay in macrophages and mice\",\n      \"journal\": \"Cell chemical biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO corroborated by selective pharmacological inhibitor, mechanistic autophagy pathway readout; single lab, two complementary loss-of-function approaches\",\n      \"pmids\": [\"35320734\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PPM1A interacts with phospho-SMAD2 in chondrocytes and its knockout protects mice from cartilage degeneration in the DMM osteoarthritis model by maintaining elevated pSMAD2. The protective phenotype in PPM1A KO mice is abolished by TGF-β/SMAD2 signaling inhibition (SD-208), demonstrating epistasis.\",\n      \"method\": \"Co-immunoprecipitation, PPM1A KO mice with DMM surgery, genetic epistasis (SD-208 inhibitor rescue), PPM1A inhibitors (sanguinarine, BC-21) in vivo\",\n      \"journal\": \"JCI insight\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with in vivo phenotype, Co-IP, and pharmacological epistasis rescue; single lab but multiple orthogonal approaches\",\n      \"pmids\": [\"36752205\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Maxacalcitol (vitamin D analog) promotes assembly of a PPM1A/VDR complex that is recruited to phospho-Smad3 (pSmad3), facilitating pSmad3 dephosphorylation and attenuating TGF-β1 autoinduction in kidney fibrosis. Without maxacalcitol, the PPM1A/pSmad3 interaction is insufficient for dephosphorylation.\",\n      \"method\": \"Co-immunoprecipitation, chromatin immunoprecipitation, nuclear fractionation, in vivo rat model (UUO)\",\n      \"journal\": \"Laboratory investigation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP of PPM1A/VDR/pSmad3 complex with in vivo rat model validation; single lab, multiple biochemical and in vivo approaches\",\n      \"pmids\": [\"22926646\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PPM1A is involved in nerve cell survival and differentiation: overexpression in PC6-3 cells causes G2/M cell cycle arrest and apoptosis in naive but not fully differentiated cells, and modulates NGF signaling and neurite outgrowth.\",\n      \"method\": \"Overexpression, PPM1A knockdown, cell cycle analysis, neurite outgrowth assay in PC6-3 cells\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — overexpression/KD with phenotypic readout but no direct substrate identification for neuronal function; single lab, limited mechanistic detail\",\n      \"pmids\": [\"22384250\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"HBx (Hepatitis B virus X protein) dose-dependently downregulates PPM1A protein (but not mRNA) in the presence of TGF-β by increasing PPM1A ubiquitination and accelerating proteasomal degradation, thereby amplifying TGF-β/pSmad2/3 signaling and HCC cell motility.\",\n      \"method\": \"Western blot, ubiquitination assay, overexpression/RNAi, migration/invasion assay\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — ubiquitination assay plus functional rescue by PPM1A restoration; single lab, mechanistic follow-up\",\n      \"pmids\": [\"27121309\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Myoneurin (Mynn) interacts with Smad proteins in the nucleus and competes with Ppm1a for Smad binding, preventing Smad dephosphorylation and sustaining BMP signaling. Loss of mynn reduces BMP signal activity in zebrafish and mammalian cells.\",\n      \"method\": \"Co-immunoprecipitation, competitive binding assay, zebrafish mynn mutant, mammalian cell knockdown, BMP signaling readout\",\n      \"journal\": \"iScience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP competitive binding plus genetic loss-of-function in two model systems; single lab, mechanistic epistasis established\",\n      \"pmids\": [\"35712083\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MALAT1 lncRNA regulates TGF-β/Smad signaling by forming a lncRNA-protein complex containing Smads, SETD2, and PPM1A in hepatic cells. This complex facilitates pSmad2/3 dephosphorylation by providing an interaction niche for pSmad2/3 and PPM1A.\",\n      \"method\": \"RNA immunoprecipitation, Co-IP, RNAi depletion of MALAT1, pSmad2/3 readout, iPS cell differentiation assay\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — RNA-IP and Co-IP demonstrating complex formation with functional dephosphorylation readout; single lab\",\n      \"pmids\": [\"31995604\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"TRIM52 promotes PPM1A ubiquitination in hepatic stellate cells (LX-2), leading to PPM1A protein degradation and activation of TGF-β/Smad2/3 pathway. Overexpression of PPM1A reverses TRIM52-mediated fibrogenic effects.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, overexpression, siRNA knockdown, fibrosis markers\",\n      \"journal\": \"Cell biology international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP plus ubiquitination assay with PPM1A overexpression rescue; single lab\",\n      \"pmids\": [\"31329338\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"USP33 deubiquitinates PPM1A, stabilizing it; miR-3591-5p suppresses USP33, leading to PPM1A degradation, sustained Smad2/3 phosphorylation, and radiation-induced EMT in lung cancer cells. Ectopic USP33 or PPM1A expression partially abolishes these effects.\",\n      \"method\": \"3'UTR luciferase reporter assay, western blot, overexpression rescue, RNAi\",\n      \"journal\": \"Cellular physiology and biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — validated miRNA-target interaction and deubiquitination mechanism with functional rescue; single lab\",\n      \"pmids\": [\"30308513\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"TRIM47 acts as an E3 ubiquitin ligase that promotes PPM1A ubiquitination and proteasomal degradation in pulmonary fibrosis. TRIM47 knockdown stabilizes PPM1A, suppressing TGF-β/SMAD3 and NF-κB/NLRP3 signaling. Otilonium bromide (OB) activates PPM1A enzymatically (EC50 = 4.23 μM) and ameliorates bleomycin-induced pulmonary fibrosis in mice in a PPM1A-dependent manner.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, PPM1A knockdown mice, in vitro enzymatic activation assay, bleomycin mouse model\",\n      \"journal\": \"Acta pharmacologica Sinica\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and ubiquitination assay with in vivo PPM1A-specific KD rescue and enzymatic activity data; single lab, multiple approaches\",\n      \"pmids\": [\"39160244\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SLC7A11-AS1 lncRNA interacts with scaffold protein RSL1D1, disrupting the recruitment of PPM1A and NMT1 to RSL1D1, thereby suppressing PPM1A N-myristoylation and prolonging activin A/Smad2/3 signaling in pancreatic cancer cells.\",\n      \"method\": \"RNA pulldown + LC-MS/MS, co-immunoprecipitation, myristoylation assay, overexpression/knockdown\",\n      \"journal\": \"British journal of cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — proteomic identification of complex components, Co-IP, and myristoylation assay; single lab, multiple methods\",\n      \"pmids\": [\"40926062\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TRIM59 promotes ubiquitination and proteasomal degradation of PPM1A (at the post-translational level, without altering PPM1A mRNA) in ectopic endometrial stromal cells, activating TGF-β/Smad2/3 signaling and promoting invasion in endometriosis.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, overexpression/siRNA, western blot\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — Co-IP and ubiquitination assay with post-translational specificity demonstrated; single lab\",\n      \"pmids\": [\"32348176\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TRIM65 acts as an E3 ubiquitin ligase targeting PPM1A for ubiquitin-mediated degradation; TRIM65 knockdown increases PPM1A levels and decreases pTBK1 in gastric cancer cells, inhibiting proliferation and invasion.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, shRNA knockdown, western blot\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — Co-IP and ubiquitination assay, single lab, limited mechanistic detail on TBK1 link\",\n      \"pmids\": [\"35421368\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PPM1A inhibits triple negative breast cancer cell growth by blocking cell cycle progression and reducing CDK and Rb phosphorylation when expressed in TNBC cells.\",\n      \"method\": \"Induced overexpression, cell cycle analysis, CDK/Rb phosphorylation western blot, in vitro and in vivo tumor growth assay\",\n      \"journal\": \"NPJ breast cancer\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — overexpression with phosphorylation readout but no direct substrate identification for cell cycle; single lab\",\n      \"pmids\": [\"31372497\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Extracellular PPM1A promotes osteoblast differentiation in ankylosing spondylitis by inducing dephosphorylation of FOXO1A at Ser256, enabling FOXO1A nuclear translocation and upregulation of RUNX2.\",\n      \"method\": \"Exogenous PPM1A treatment, phospho-FOXO1A western blot, RUNX2 promoter luciferase assay, nuclear fractionation\",\n      \"journal\": \"Journal of cellular and molecular medicine\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — exogenous protein treatment with phospho readout; no direct in vitro phosphatase assay shown in abstract; single lab\",\n      \"pmids\": [\"36756789\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PPM1A (PP2Cα) is a metal-dependent serine/threonine phosphatase whose N-myristoylation is required for physiological substrate recognition; it dephosphorylates a broad set of signaling substrates—including Smad2/3/1 (TGF-β/BMP pathway), YAP/TAZ (Hippo pathway), IKKβ and RelA (NF-κB pathway), TBK1/MAVS/STING (innate antiviral signaling), Cdk9 T-loop (P-TEFb), RanBP3 (nuclear export), AMPKα, and PPARγ pSer273—to terminate or attenuate these pathways, with its own activity regulated by ubiquitin-mediated proteasomal degradation (via TRIM52/59/65/47 E3 ligases) and by co-factor interactions (PTEN, CSIG/NMT1, MAN1, NDRG2) that modulate substrate access to its active site, which contains three metal ions and uses active-site arginines (Arg33 and Arg186) for substrate recognition.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PPM1A (PP2Cα) is a metal-dependent serine/threonine phosphatase that functions as a broad negative regulator of phosphorylation-driven signaling cascades, terminating responses initiated by TGF-β/BMP, Hippo, NF-κB, and innate antiviral pathways [#0, #19, #2, #11]. Its best-defined role is to dephosphorylate the C-terminal pSXS motif of TGF-β-activated Smad2/3 and BMP-activated Smad1, driving their nuclear export and shutting down the corresponding transcriptional programs [#0, #1]; it reinforces TGF-β termination by also dephosphorylating the nuclear export factor RanBP3 at Ser58 [#5]. Genetic epistasis in mice places PPM1A directly upstream of Smad2 in cutaneous wound re-epithelialization and upstream of SMAD2 in cartilage homeostasis, where loss of PPM1A sustains pSmad2/3 [#7, #23]. The same active site terminates additional pathways: it dephosphorylates YAP/TAZ at the LATS1 site (YAP Ser127) to restrain Hippo-controlled proliferation and tissue regeneration [#19], IKKβ (Ser177/Ser181) and RelA (Ser536/Ser276) to attenuate NF-κB signaling [#2, #8], the Cdk9 T-loop (Thr186) to limit P-TEFb activity [#3], MAVS, STING and TBK1 to silence cytosolic and DNA antiviral sensing [#11, #10], and PPARγ at Ser273 in metabolic regulation [#18]. Substrate engagement in cells requires N-myristoylation, which directs membrane association and physiological substrate recognition [#6]; catalysis proceeds through a three-metal active site engaging the substrate phosphate, with active-site arginines Arg33 and Arg186 contributing to substrate recognition in a random-order bi-substrate mechanism [#13, #21]. Substrate access is gated by cofactor and scaffold interactions—PTEN, the inner nuclear membrane protein MAN1, NDRG2, and the CSIG/NMT1 myristoylation machinery [#4, #9, #20, #15]—and PPM1A abundance is set by ubiquitin-mediated proteasomal degradation through multiple TRIM-family E3 ligases (TRIM52, TRIM59, TRIM47) opposed by the deubiquitinase USP33, a balance frequently subverted in fibrosis and cancer to amplify TGF-β signaling [#14, #33, #31, #30].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Establishing that a specific phosphatase terminates TGF-β/BMP signaling answered how activated R-Smads are inactivated, identifying PPM1A as the Smad C-terminal phosphatase.\",\n      \"evidence\": \"Functional genomic screen, in vitro phosphatase assays, RNAi/overexpression, and zebrafish Nodal epistasis for Smad2/3, with reciprocal Co-IP for Smad1/BMP\",\n      \"pmids\": [\"16751101\", \"16931515\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define how PPM1A is recruited to nuclear Smads\", \"Did not address regulation of PPM1A activity or abundance\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Identifying PPM1A as a phosphatase for IKKβ and the Cdk9 T-loop extended its role beyond TGF-β, showing it attenuates NF-κB and transcriptional elongation machinery.\",\n      \"evidence\": \"Phosphatase library screens, reciprocal Co-IP, in vitro dephosphorylation with phospho-specific readouts, and RNAi with reporter assays\",\n      \"pmids\": [\"18930133\", \"18829461\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish in vivo physiological relevance of these dephosphorylation events\", \"Did not clarify how substrate selectivity among many targets is achieved\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Showing that nuclear PTEN forms a complex with PPM1A revealed that cofactor binding can both protect PPM1A from degradation and enhance its Smad-directed activity.\",\n      \"evidence\": \"Co-IP, phospho-mutant analysis, and fractionation in mammalian cells\",\n      \"pmids\": [\"18482992\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Co-IP/overexpression-based; structural basis of the complex not defined\", \"Generality beyond Smad2/3 substrates not tested\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Demonstrating that N-myristoylation is required for activity toward physiological substrates explained why an in vitro-competent phosphatase needs lipid modification for cellular function.\",\n      \"evidence\": \"G2A mutagenesis, cell fractionation, and in vitro/cellular phosphatase assays including AMPKα\",\n      \"pmids\": [\"23088624\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the enzymes setting myristoylation in vivo\", \"Did not map which substrates strictly require membrane targeting\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Adding RanBP3 dephosphorylation and genetic null MEFs strengthened the model that PPM1A controls Smad nuclear export, while in vivo knockout linked PPM1A loss to enhanced Smad2/3 phosphorylation and a wound-healing phenotype.\",\n      \"evidence\": \"In vitro phosphatase assay, PPM1A-null MEFs, nuclear export assays, and Ppm1a/Smad2 double-mutant epistasis in mice\",\n      \"pmids\": [\"21960005\", \"21990361\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve relative contributions of direct Smad versus RanBP3 dephosphorylation\", \"Tissue-specific substrate repertoire beyond keratinocytes unexamined\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Direct dephosphorylation of RelA and recruitment by the inner nuclear membrane protein MAN1 extended PPM1A's NF-κB role and showed scaffold-directed delivery to nuclear-envelope Smads.\",\n      \"evidence\": \"In vitro phosphatase assays with site-specific RelA readout; NMR/SAXS structure and in vitro binding for MAN1 recruitment\",\n      \"pmids\": [\"23812431\", \"23779087\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"MAN1-dependent recruitment not validated in a genetic in vivo model\", \"Whether RelA and Smad dephosphorylation occur at distinct subcellular sites unresolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identifying STING, TBK1, MAVS, and IKKε as substrates established PPM1A as a brake on innate antiviral signaling, with whole-organism knockouts confirming enhanced antiviral resistance.\",\n      \"evidence\": \"In vitro phosphatase assays, Co-IP, STING aggregation assays, PPM1A knockout cells/mice, and viral infection models\",\n      \"pmids\": [\"25815785\", \"27419230\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism dissociating the TBK1/PPM1A complex at high MAVS levels only partly defined\", \"Crosstalk between antiviral and TGF-β substrate pools not addressed\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"The crystal structure of PPM1Acat with a cyclic phosphopeptide defined the catalytic chemistry, revealing a three-metal active site and a substrate-engaging labile third metal.\",\n      \"evidence\": \"X-ray crystallography of an enzyme-substrate complex, enzyme kinetics, SAXS, docking, and D146E trapping mutant\",\n      \"pmids\": [\"29602904\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure used a model p38 activation-loop peptide rather than a physiological substrate complex\", \"Did not explain selectivity across the diverse substrate set\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Discovering that TRIM52 ubiquitinates PPM1A, that CSIG promotes NMT1-dependent myristoylation, and that HCV NS3 drives PPM1A degradation showed that PPM1A levels and modification state are actively controlled to set TGF-β pathway output.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, myristoylation assays, and overexpression/RNAi with functional readouts in HCC and signaling models\",\n      \"pmids\": [\"29898761\", \"30201805\", \"28283039\", \"27121309\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Largely single-lab Co-IP/ubiquitination evidence per regulator\", \"Substrate specificity of each degradation event not dissected beyond Smad signaling\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Defining active-site arginines and identifying PPM1A as the physiological YAP/TAZ phosphatase clarified both the catalytic determinants and a new tissue-regeneration role through the Hippo pathway.\",\n      \"evidence\": \"Site-directed mutagenesis with docking; phosphatome screen, in vitro phosphatase assay, Co-IP, PPM1A KO mice/organoids, and LATS1-deficiency epistasis rescue\",\n      \"pmids\": [\"34637963\", \"33630828\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How a single active site discriminates YAP versus Smad versus NF-κB substrates remains unresolved\", \"Arg-residue study relied partly on computational docking\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Mapping additional E3 ligases and deubiquitinases (TRIM47, TRIM59, USP33) and identifying small-molecule activators/inhibitors consolidated PPM1A abundance control as a druggable node in fibrosis and cancer.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, PPM1A-specific knockdown rescue in vivo, and enzymatic activation assays (otilonium bromide; SMIP-30)\",\n      \"pmids\": [\"39160244\", \"32348176\", \"30308513\", \"35320734\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Pharmacological tools characterized in single-lab settings\", \"Selectivity of activators/inhibitors across PPM1A substrate pathways not established\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How a single shallow PP2C active site achieves selectivity across its many substrates, and how the competing scaffolds, cofactors, and degradation machinery are integrated to direct PPM1A toward a specific pathway in a given cell, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structure of PPM1A bound to a physiological full-length substrate\", \"No systematic comparison of substrate flux under competing cofactor conditions\", \"Spatial partitioning of distinct substrate pools not defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 2, 3, 5, 8, 10, 11, 18, 19]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 13]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 2, 19, 11]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 5, 9, 24]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [19, 20]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [6]},\n      {\"term_id\": \"GO:0005635\", \"supporting_discovery_ids\": [9]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9006936\", \"supporting_discovery_ids\": [0, 1, 5, 7]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 19, 2, 8]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [2, 10, 11]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [22]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"SMAD2\", \"SMAD3\", \"SMAD1\", \"YAP1\", \"RanBP3\", \"IKBKB\", \"PTEN\", \"MAN1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}