{"gene":"WNK2","run_date":"2026-04-28T23:00:23","timeline":{"discoveries":[{"year":2007,"finding":"WNK2 depletion by RNAi in HeLa cells activates ERK1/2 via MEK1 phosphorylation at serine 298, and kinase-dead WNK2-K207M also activates ERK1/2, indicating WNK2 catalytic activity is required to suppress MEK1/ERK1/2 signaling; WNK2 depletion increased G1/S progression and potentiated EGF response.","method":"RNAi knockdown, kinase-dead mutant expression, phospho-MEK1 S298 immunoblot, cell-cycle analysis","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 — reciprocal RNAi + kinase-dead mutant, replicated in two cancer cell lines (HeLa, HT29)","pmids":["17667937"],"is_preprint":false},{"year":2007,"finding":"WNK2 exhibits autophosphorylation and protein kinase activity enhanced by hypertonic conditions; WNK2 inhibits glioma colony formation in a kinase-independent manner, suggesting a scaffolding/regulatory function distinct from catalytic activity.","method":"In vitro autophosphorylation assay, hypertonic stimulation, colony formation assay with kinase-dead constructs","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 1/2 — in vitro kinase assay plus kinase-independence functional test, single study","pmids":["17578925"],"is_preprint":false},{"year":2008,"finding":"WNK2 controls a RhoA/Rac1 cross-talk mechanism: WNK2 depletion decreases RhoA activation, promotes GTP-loading of Rac1, stimulates the Rac1-effector PAK1, and PAK1 then phosphorylates MEK1 at serine 298 to increase MEK1 activity toward ERK1/2.","method":"RNAi, GTPase pull-down (active Rac1/RhoA), PAK1 kinase assay, phospho-MEK1 S298 immunoblot","journal":"Cellular signalling","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal assays (GTPase pull-down, kinase assay, phospho-immunoblot) in a single study defining the pathway order","pmids":["18593598"],"is_preprint":false},{"year":2011,"finding":"WNK2 is a neuron-enriched kinase (not expressed in kidney) that reciprocally activates NKCC1 and inhibits KCC2 in a kinase-dependent manner in Xenopus oocytes, promoting Cl⁻ accumulation independent of tonicity; WNK2 forms a protein complex with SPAK in the mammalian brain, in which SPAK is phosphorylated at Ser-383.","method":"⁸⁶Rb⁺ uptake assay in Xenopus oocytes, TiO₂ enrichment/tandem mass spectrometry, co-immunoprecipitation from brain tissue, immunohistochemistry","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1/2 — functional reconstitution in oocytes plus MS-validated protein complex with phosphosite identification, strong mechanistic detail","pmids":["21733846"],"is_preprint":false},{"year":2012,"finding":"WNK2 re-expression in WNK2-silenced glioblastoma cells reduces Rac1 GTP-loading; conversely, WNK2 depletion in cells with unmethylated WNK2 increases Rac1 activation, cell morphology changes, and invasion, establishing WNK2 as a negative regulator of Rac1-driven tumor invasion.","method":"Rac1 GTPase pull-down, re-expression and RNAi in glioblastoma cell lines, in vivo xenograft, invasion assay","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 — bidirectional genetic manipulation (re-expression + knockdown) with active-Rac1 pull-down and in vivo validation","pmids":["23035050"],"is_preprint":false},{"year":2015,"finding":"WNK2 silencing in glioma cells is associated with elevated JNK activation and increased MMP2 expression and activity; WNK2 suppresses JNK, which in turn reduces MMP2 levels, linking WNK2 to an invasion-relevant protease pathway.","method":"WNK2 re-expression/depletion, JNK phosphorylation immunoblot, MMP2 zymography","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2/3 — clear pathway placement (WNK2→JNK→MMP2) but mechanistic detail of direct vs. indirect connection not fully resolved","pmids":["25596741"],"is_preprint":false},{"year":2019,"finding":"WNK2 inactivation in HCC cells leads to ERK1/2 signaling activation, tumor-associated macrophage infiltration, and increased tumor growth and metastasis, positioning WNK2 as a suppressor of ERK1/2 signaling in liver cancer.","method":"WNK2 loss-of-function (genomic alteration + functional assays), phospho-ERK1/2 immunoblot, in vivo tumor models","journal":"Journal of hepatology","confidence":"Medium","confidence_rationale":"Tier 2 — defined cellular phenotype and pathway placement (WNK2→ERK1/2) in HCC, single study","pmids":["31349001"],"is_preprint":false},{"year":2020,"finding":"WNK2 overexpression in A172 glioblastoma cells inhibits autophagic flux (decreased LC3B, p62 levels and LC3A/B ratio under bafilomycin A1 + everolimus) through an mTOR-independent pathway.","method":"WNK2 overexpression, bafilomycin A1 and everolimus treatment, LC3A/B and p62 immunoblot and immunofluorescence, mTOR pathway analysis","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2/3 — clean overexpression with multiple autophagic markers and pharmacological probes; mTOR independence established, single lab","pmids":["32093151"],"is_preprint":false},{"year":2020,"finding":"LINC00858 recruits DNA methyltransferases to the WNK2 promoter, enhancing its methylation and silencing WNK2 expression, thereby activating the MAPK/ERK pathway in colon cancer cells.","method":"RNA immunoprecipitation, chromatin immunoprecipitation, RNA pull-down, methylation analysis, WNK2 rescue experiments","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 2 — multiple biochemical assays (RIP, ChIP, RNA pull-down) establishing LINC00858-DNMT-WNK2 promoter mechanism","pmids":["32768499"],"is_preprint":false},{"year":2022,"finding":"WNK2 germline variants (p.Pro702Leu, p.Ala1607Val, p.Val2053Ile) display elevated phospho-PAK1/2, phospho-ERK1/2, and CCND1 levels in HT-29 cells, demonstrating that loss-of-function WNK2 variants deregulate the MAPK pathway via PAK1.","method":"Gene editing (CRISPR), lentiviral variant transfection, immunoblot (phospho-PAK1/2, phospho-ERK1/2, CCND1), clonogenic and adhesion assays","journal":"Journal of medical genetics","confidence":"Medium","confidence_rationale":"Tier 2 — functional characterization of specific variants with defined pathway readout, single lab","pmids":["36270769"],"is_preprint":false},{"year":2024,"finding":"WNK2 is a downstream transcriptional target of PAX6 in corneal epithelial cells; WNK2 knockdown impairs expression of corneal differentiation markers (KRT12, ALDH3A1, CLU) and activates keratinization, inflammation, and proliferation pathways, establishing WNK2 as required for corneal epithelial homeostasis.","method":"PAX6 shRNA knockdown, RNA-seq, WNK2 shRNA knockdown, immunofluorescence, air-liquid interface differentiation assay","journal":"Investigative ophthalmology & visual science","confidence":"Medium","confidence_rationale":"Tier 2 — epistasis (PAX6→WNK2) plus loss-of-function phenotype with defined differentiation markers, single study","pmids":["39453672"],"is_preprint":false},{"year":2025,"finding":"WNK2 coding variants associated with familial osteoarthritis alter the chondrocyte transcriptional response to hyperosmotic stress; elevated WNK2 signalling combined with hyperosmotic stress drives an OA-associated catabolic/anabolic gene expression program in chondrocytes.","method":"WNK2 overexpression and loss-of-function in immortalised/primary chondrocytes, transcriptomic analysis, hyperosmotic stress challenge, immunohistochemistry on human/mouse OA tissue","journal":"RMD open","confidence":"Medium","confidence_rationale":"Tier 2 — bidirectional genetic manipulation with transcriptomic readout under defined osmotic stress, single study","pmids":["40592720"],"is_preprint":false}],"current_model":"WNK2 is a neuron-enriched serine-threonine kinase that suppresses cell growth and invasion by: (1) phosphorylating and activating NKCC1 while inhibiting KCC2 via a SPAK complex to regulate neuronal chloride homeostasis; (2) maintaining RhoA activity to prevent Rac1-GTP loading, thereby blocking PAK1-mediated phosphorylation of MEK1-S298 and downstream ERK1/2 activation; (3) suppressing JNK and MMP2-driven invasion; and (4) inhibiting autophagic flux in glioblastoma through an mTOR-independent pathway — collectively positioning WNK2 as a tumor suppressor whose loss, via promoter hypermethylation or mutation, derepresses ERK/MAPK, Rac1, and MMP2 signaling to promote cancer cell proliferation and invasion."},"narrative":{"teleology":[{"year":2007,"claim":"Establishing that WNK2 catalytic activity suppresses MEK1/ERK1/2 signaling and cell-cycle progression resolved the question of whether WNK2 acts on the MAPK cascade and defined it as a growth-inhibitory kinase.","evidence":"RNAi knockdown and kinase-dead mutant expression with phospho-MEK1 S298 immunoblot and cell-cycle analysis in HeLa/HT29 cells","pmids":["17667937"],"confidence":"High","gaps":["Direct phosphorylation substrate linking WNK2 catalytic activity to MEK1 inhibition not identified","Mechanism by which WNK2 suppresses MEK1 S298 phosphorylation unclear"]},{"year":2007,"claim":"Demonstration that WNK2 suppresses glioma colony formation independently of its kinase activity revealed a dual-mode (catalytic and scaffolding) mechanism of tumor suppression.","evidence":"In vitro autophosphorylation assay and colony formation assay with kinase-dead WNK2 in glioma cells","pmids":["17578925"],"confidence":"Medium","gaps":["Scaffold binding partners mediating kinase-independent suppression not identified","Kinase-dependent vs. kinase-independent contributions not quantitatively resolved"]},{"year":2008,"claim":"Defining the RhoA→Rac1→PAK1→MEK1-S298 axis downstream of WNK2 resolved how WNK2 loss activates ERK1/2 — through cross-talk between Rho-family GTPases rather than direct kinase action on MEK1.","evidence":"GTPase pull-down assays for active RhoA and Rac1, PAK1 kinase assay, and phospho-MEK1 S298 immunoblot after WNK2 RNAi","pmids":["18593598"],"confidence":"High","gaps":["How WNK2 maintains RhoA-GTP loading is unknown","Whether WNK2 directly phosphorylates a RhoGEF or RhoGAP not tested"]},{"year":2011,"claim":"Reconstitution of WNK2-dependent NKCC1 activation and KCC2 inhibition, and identification of the WNK2–SPAK complex in brain, established WNK2's physiological role in neuronal chloride homeostasis distinct from its tumor-suppressive function.","evidence":"⁸⁶Rb⁺ uptake in Xenopus oocytes, co-immunoprecipitation and mass spectrometry of SPAK phospho-Ser-383 from brain tissue","pmids":["21733846"],"confidence":"High","gaps":["Relative contributions of WNK2 vs. other WNK family members to neuronal Cl⁻ balance in vivo not determined","No neuron-specific WNK2 knockout phenotype reported"]},{"year":2012,"claim":"Bidirectional manipulation (re-expression and knockdown) confirmed WNK2 as a negative regulator of Rac1 GTP-loading and tumor invasion in glioblastoma, extending the RhoA/Rac1 mechanism to a disease-relevant invasion phenotype.","evidence":"Rac1 pull-down, invasion assays, and in vivo xenograft after WNK2 re-expression and RNAi in glioblastoma cell lines","pmids":["23035050"],"confidence":"High","gaps":["Molecular link between WNK2 and Rac1-specific GEFs/GAPs remains unidentified","Contribution of kinase activity vs. scaffolding to invasion suppression not separated"]},{"year":2015,"claim":"Linking WNK2 loss to JNK activation and MMP2 upregulation identified a second invasion-promoting axis parallel to Rac1/PAK1.","evidence":"WNK2 re-expression/depletion with JNK phosphorylation immunoblot and MMP2 zymography in glioma cells","pmids":["25596741"],"confidence":"Medium","gaps":["Direct vs. indirect relationship between WNK2 and JNK not resolved","Whether JNK-MMP2 axis operates independently of Rac1/PAK1 not tested"]},{"year":2019,"claim":"Extension of the WNK2-ERK1/2 tumor-suppressor axis to hepatocellular carcinoma, with evidence for macrophage infiltration, generalized WNK2's growth-suppressive role across cancer types.","evidence":"WNK2 loss-of-function, phospho-ERK1/2 immunoblot, and in vivo tumor models in HCC","pmids":["31349001"],"confidence":"Medium","gaps":["Mechanism linking WNK2 loss to tumor-associated macrophage recruitment not defined","Whether RhoA/Rac1 axis operates identically in HCC not examined"]},{"year":2020,"claim":"Discovery that WNK2 inhibits autophagic flux through an mTOR-independent pathway added a new cellular process to WNK2's tumor-suppressive repertoire.","evidence":"WNK2 overexpression with bafilomycin A1/everolimus treatment, LC3A/B and p62 immunoblot/immunofluorescence in A172 glioblastoma cells","pmids":["32093151"],"confidence":"Medium","gaps":["Target of WNK2 in autophagy pathway not identified","Single cell line; generalizability untested","Functional consequence for tumor growth not linked to autophagy inhibition specifically"]},{"year":2020,"claim":"Identification of LINC00858-mediated recruitment of DNA methyltransferases to the WNK2 promoter revealed an upstream epigenetic mechanism for WNK2 silencing in colon cancer.","evidence":"RNA immunoprecipitation, ChIP, RNA pull-down, methylation analysis, and WNK2 rescue experiments in colon cancer cells","pmids":["32768499"],"confidence":"Medium","gaps":["Whether this lncRNA-mediated silencing mechanism operates in glioma or HCC not tested","Specificity of LINC00858 for the WNK2 locus vs. other targets not clarified"]},{"year":2022,"claim":"Functional characterization of germline WNK2 coding variants showing elevated phospho-PAK1/2 and phospho-ERK1/2 demonstrated that specific missense variants are loss-of-function and deregulate the same PAK1-MEK1-ERK axis.","evidence":"CRISPR gene editing, lentiviral variant expression, phospho-PAK1/2 and phospho-ERK1/2 immunoblot, clonogenic assays in HT-29 cells","pmids":["36270769"],"confidence":"Medium","gaps":["Structural basis for variant-induced loss of function not determined","In vivo pathogenicity of these variants in animal models not assessed"]},{"year":2024,"claim":"Placing WNK2 downstream of PAX6 and showing its requirement for corneal epithelial differentiation extended WNK2's physiological role beyond neurons and cancer to epithelial homeostasis.","evidence":"PAX6 and WNK2 shRNA knockdown, RNA-seq, immunofluorescence, air-liquid interface differentiation in corneal epithelial cells","pmids":["39453672"],"confidence":"Medium","gaps":["Whether WNK2 acts through Rac1/ERK or a distinct pathway in corneal epithelium not resolved","No in vivo corneal phenotype reported"]},{"year":2025,"claim":"Association of WNK2 coding variants with familial osteoarthritis and demonstration that elevated WNK2 signaling under hyperosmotic stress drives a catabolic chondrocyte program linked WNK2 to cartilage pathophysiology.","evidence":"WNK2 overexpression/loss-of-function in chondrocytes with transcriptomic analysis under hyperosmotic stress, immunohistochemistry on human/mouse OA tissue","pmids":["40592720"],"confidence":"Medium","gaps":["Downstream kinase substrates in chondrocytes not identified","Whether SPAK/NKCC1 axis mediates the osmotic response in chondrocytes not tested"]},{"year":null,"claim":"The direct phosphorylation substrates through which WNK2 maintains RhoA activity and suppresses Rac1 remain unknown, and no structural model explains how disease-associated variants impair function.","evidence":"","pmids":[],"confidence":"High","gaps":["No RhoGEF or RhoGAP identified as direct WNK2 substrate","No crystal or cryo-EM structure of WNK2","Relative contributions of kinase-dependent vs. kinase-independent functions in vivo not resolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,3]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,2,4,5]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[3]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,2,4,6,9]},{"term_id":"R-HSA-382551","term_label":"Transport of small molecules","supporting_discovery_ids":[3]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[7]}],"complexes":["WNK2–SPAK complex"],"partners":["STK39","SLC12A2","SLC12A5","RAC1","RHOA","PAK1"],"other_free_text":[]},"mechanistic_narrative":"WNK2 is a serine-threonine kinase that functions as a tumor suppressor and regulator of ion homeostasis by restraining MAPK/ERK signaling, Rac1-driven invasion, and cation-chloride cotransporter activity. WNK2 maintains RhoA activation to prevent Rac1 GTP-loading, thereby blocking PAK1-mediated phosphorylation of MEK1 at Ser-298 and downstream ERK1/2 activation; loss of WNK2 through promoter hypermethylation or coding variants derepresses this cascade, promoting cell proliferation and invasion in glioblastoma, colon cancer, and hepatocellular carcinoma [PMID:18593598, PMID:17667937, PMID:23035050, PMID:31349001]. In neurons, WNK2 forms a complex with SPAK to reciprocally activate NKCC1 and inhibit KCC2 in a kinase-dependent manner, regulating intracellular chloride homeostasis [PMID:21733846]. WNK2 also suppresses JNK-MMP2-mediated invasion, inhibits autophagic flux through an mTOR-independent pathway, is a transcriptional target of PAX6 required for corneal epithelial differentiation, and modulates chondrocyte responses to hyperosmotic stress [PMID:25596741, PMID:32093151, PMID:39453672, PMID:40592720]."},"prefetch_data":{"uniprot":{"accession":"Q9Y3S1","full_name":"Serine/threonine-protein kinase WNK2","aliases":["Antigen NY-CO-43","Protein kinase lysine-deficient 2","Protein kinase with no lysine 2","Serologically defined colon cancer antigen 43"],"length_aa":2297,"mass_kda":242.7,"function":"Serine/threonine-protein kinase component of the WNK2-SPAK/OSR1 kinase cascade, which plays an important role in the regulation of electrolyte homeostasis, cell signaling, survival, and proliferation (PubMed:17667937, PubMed:18593598, PubMed:21733846). The WNK2-SPAK/OSR1 kinase cascade is composed of WNK2, which mediates phosphorylation and activation of downstream kinases OXSR1/OSR1 and STK39/SPAK (By similarity). Following activation, OXSR1/OSR1 and STK39/SPAK catalyze phosphorylation of ion cotransporters, regulating their activity (By similarity). Acts as an activator and inhibitor of sodium-coupled chloride cotransporters and potassium-coupled chloride cotransporters respectively (PubMed:21733846). Activates SLC12A2, SCNN1A, SCNN1B, SCNN1D and SGK1 and inhibits SLC12A5 (PubMed:21733846). Negatively regulates the EGF-induced activation of the ERK/MAPK-pathway and the downstream cell cycle progression (PubMed:17667937, PubMed:18593598). Affects MAPK3/MAPK1 activity by modulating the activity of MAP2K1 and this modulation depends on phosphorylation of MAP2K1 by PAK1 (PubMed:17667937, PubMed:18593598). WNK2 acts by interfering with the activity of PAK1 by controlling the balance of the activity of upstream regulators of PAK1 activity, RHOA and RAC1, which display reciprocal activity (PubMed:17667937, PubMed:18593598)","subcellular_location":"Cytoplasm; Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q9Y3S1/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/WNK2","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":77,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"WNK1","stoichiometry":4.0},{"gene":"OXSR1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/WNK2","total_profiled":1310},"omim":[{"mim_id":"606249","title":"PROTEIN KINASE, LYSINE-DEFICIENT 2; WNK2","url":"https://www.omim.org/entry/606249"},{"mim_id":"605232","title":"PROTEIN KINASE, LYSINE-DEFICIENT 1; WNK1","url":"https://www.omim.org/entry/605232"},{"mim_id":"300358","title":"PROTEIN KINASE, LYSINE-DEFICIENT 3; WNK3","url":"https://www.omim.org/entry/300358"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"heart muscle","ntpm":63.5}],"url":"https://www.proteinatlas.org/search/WNK2"},"hgnc":{"alias_symbol":["NY-CO-43","KIAA1760"],"prev_symbol":["SDCCAG43","PRKWNK2"]},"alphafold":{"accession":"Q9Y3S1","domains":[{"cath_id":"3.30.200.20","chopping":"183-278","consensus_level":"medium","plddt":86.2956,"start":183,"end":278},{"cath_id":"1.10.510.10","chopping":"281-454","consensus_level":"medium","plddt":88.0979,"start":281,"end":454},{"cath_id":"3.10.20.90","chopping":"457-548","consensus_level":"medium","plddt":85.9466,"start":457,"end":548},{"cath_id":"3.10.20.90","chopping":"1185-1261_1303-1320","consensus_level":"medium","plddt":77.7414,"start":1185,"end":1320}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y3S1","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y3S1-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y3S1-F1-predicted_aligned_error_v6.png","plddt_mean":43.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=WNK2","jax_strain_url":"https://www.jax.org/strain/search?query=WNK2"},"sequence":{"accession":"Q9Y3S1","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9Y3S1.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9Y3S1/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y3S1"}},"corpus_meta":[{"pmid":"21733846","id":"PMC_21733846","title":"WNK2 kinase is a novel regulator of essential neuronal cation-chloride cotransporters.","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21733846","citation_count":76,"is_preprint":false},{"pmid":"17667937","id":"PMC_17667937","title":"Protein kinase WNK2 inhibits cell proliferation by negatively modulating the activation of MEK1/ERK1/2.","date":"2007","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/17667937","citation_count":69,"is_preprint":false},{"pmid":"17578925","id":"PMC_17578925","title":"Epigenome scans and cancer genome sequencing converge on WNK2, a kinase-independent suppressor of cell growth.","date":"2007","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/17578925","citation_count":59,"is_preprint":false},{"pmid":"31349001","id":"PMC_31349001","title":"Genomic sequencing identifies WNK2 as a driver in hepatocellular carcinoma and a risk factor for early recurrence.","date":"2019","source":"Journal of hepatology","url":"https://pubmed.ncbi.nlm.nih.gov/31349001","citation_count":58,"is_preprint":false},{"pmid":"23035050","id":"PMC_23035050","title":"Loss of WNK2 expression by promoter gene methylation occurs in adult gliomas and triggers Rac1-mediated tumour cell invasiveness.","date":"2012","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/23035050","citation_count":46,"is_preprint":false},{"pmid":"19001526","id":"PMC_19001526","title":"Epigenetic silencing of the kinase tumor suppressor WNK2 is tumor-type and tumor-grade specific.","date":"2008","source":"Neuro-oncology","url":"https://pubmed.ncbi.nlm.nih.gov/19001526","citation_count":45,"is_preprint":false},{"pmid":"23912455","id":"PMC_23912455","title":"Early epigenetic downregulation of WNK2 kinase during pancreatic ductal adenocarcinoma development.","date":"2013","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/23912455","citation_count":33,"is_preprint":false},{"pmid":"31884577","id":"PMC_31884577","title":"Long non-coding RNA LINC00858 exerts a tumor-promoting role in colon cancer via HNF4α and WNK2 regulation.","date":"2019","source":"Cellular oncology (Dordrecht, Netherlands)","url":"https://pubmed.ncbi.nlm.nih.gov/31884577","citation_count":28,"is_preprint":false},{"pmid":"25596741","id":"PMC_25596741","title":"Silencing of the tumor suppressor gene WNK2 is associated with upregulation of MMP2 and JNK in gliomas.","date":"2015","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/25596741","citation_count":24,"is_preprint":false},{"pmid":"18593598","id":"PMC_18593598","title":"WNK2 modulates MEK1 activity through the Rho GTPase pathway.","date":"2008","source":"Cellular 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pathway.","date":"2022","source":"Bioengineered","url":"https://pubmed.ncbi.nlm.nih.gov/35549643","citation_count":7,"is_preprint":false},{"pmid":"34918065","id":"PMC_34918065","title":"CircRNA-WNK2 Acts as a ceRNA for miR-328a-3p to Promote AANAT Expression in the Male Rat Pineal Gland.","date":"2022","source":"Endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/34918065","citation_count":6,"is_preprint":false},{"pmid":"32093151","id":"PMC_32093151","title":"WNK2 Inhibits Autophagic Flux in Human Glioblastoma Cell Line.","date":"2020","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/32093151","citation_count":5,"is_preprint":false},{"pmid":"39453672","id":"PMC_39453672","title":"PAX6-WNK2 Axis Governs Corneal Epithelial Homeostasis.","date":"2024","source":"Investigative ophthalmology & visual science","url":"https://pubmed.ncbi.nlm.nih.gov/39453672","citation_count":5,"is_preprint":false},{"pmid":"36270769","id":"PMC_36270769","title":"Germline mutations in WNK2 could be associated with serrated polyposis syndrome.","date":"2022","source":"Journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/36270769","citation_count":4,"is_preprint":false},{"pmid":"38091885","id":"PMC_38091885","title":"Regional bias of tumor suppressor gene mutations of STARD8 and WNK2 in colon cancers.","date":"2023","source":"Pathology, research and practice","url":"https://pubmed.ncbi.nlm.nih.gov/38091885","citation_count":1,"is_preprint":false},{"pmid":"39056814","id":"PMC_39056814","title":"Correction: Alves et al. WNK2 Inhibits Autophagic Flux in Human Glioblastoma Cell Line. Cells 2020, 9, 485.","date":"2024","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/39056814","citation_count":0,"is_preprint":false},{"pmid":"41628111","id":"PMC_41628111","title":"WNK2 may promote ovarian cancer progression by upregulating POU5F1B.","date":"2026","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/41628111","citation_count":0,"is_preprint":false},{"pmid":"40592720","id":"PMC_40592720","title":"WNK2 variants associated with familial osteoarthritis alter the chondrocyte response to hyperosmotic stress.","date":"2025","source":"RMD open","url":"https://pubmed.ncbi.nlm.nih.gov/40592720","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.08.26.25334517","title":"WNK2 facilitates ovarian cancer progression by upregulating POU5F1B","date":"2025-08-29","source":"bioRxiv","url":"https://doi.org/10.1101/2025.08.26.25334517","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.03.25.645260","title":"A Phenotype-Driven Multi-Omic Atlas of Glioblastoma Invasion","date":"2025-03-28","source":"bioRxiv","url":"https://doi.org/10.1101/2025.03.25.645260","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":14173,"output_tokens":3033,"usd":0.044007},"stage2":{"model":"claude-opus-4-6","input_tokens":6395,"output_tokens":3152,"usd":0.166162},"total_usd":0.210169,"stage1_batch_id":"msgbatch_01BparvgRZ9S2LMidvaoo86K","stage2_batch_id":"msgbatch_01NkBfv9SVZWthhS7j6mU6G3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2007,\n      \"finding\": \"WNK2 depletion by RNAi in HeLa cells activates ERK1/2 via MEK1 phosphorylation at serine 298, and kinase-dead WNK2-K207M also activates ERK1/2, indicating WNK2 catalytic activity is required to suppress MEK1/ERK1/2 signaling; WNK2 depletion increased G1/S progression and potentiated EGF response.\",\n      \"method\": \"RNAi knockdown, kinase-dead mutant expression, phospho-MEK1 S298 immunoblot, cell-cycle analysis\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal RNAi + kinase-dead mutant, replicated in two cancer cell lines (HeLa, HT29)\",\n      \"pmids\": [\"17667937\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"WNK2 exhibits autophosphorylation and protein kinase activity enhanced by hypertonic conditions; WNK2 inhibits glioma colony formation in a kinase-independent manner, suggesting a scaffolding/regulatory function distinct from catalytic activity.\",\n      \"method\": \"In vitro autophosphorylation assay, hypertonic stimulation, colony formation assay with kinase-dead constructs\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1/2 — in vitro kinase assay plus kinase-independence functional test, single study\",\n      \"pmids\": [\"17578925\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"WNK2 controls a RhoA/Rac1 cross-talk mechanism: WNK2 depletion decreases RhoA activation, promotes GTP-loading of Rac1, stimulates the Rac1-effector PAK1, and PAK1 then phosphorylates MEK1 at serine 298 to increase MEK1 activity toward ERK1/2.\",\n      \"method\": \"RNAi, GTPase pull-down (active Rac1/RhoA), PAK1 kinase assay, phospho-MEK1 S298 immunoblot\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal assays (GTPase pull-down, kinase assay, phospho-immunoblot) in a single study defining the pathway order\",\n      \"pmids\": [\"18593598\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"WNK2 is a neuron-enriched kinase (not expressed in kidney) that reciprocally activates NKCC1 and inhibits KCC2 in a kinase-dependent manner in Xenopus oocytes, promoting Cl⁻ accumulation independent of tonicity; WNK2 forms a protein complex with SPAK in the mammalian brain, in which SPAK is phosphorylated at Ser-383.\",\n      \"method\": \"⁸⁶Rb⁺ uptake assay in Xenopus oocytes, TiO₂ enrichment/tandem mass spectrometry, co-immunoprecipitation from brain tissue, immunohistochemistry\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1/2 — functional reconstitution in oocytes plus MS-validated protein complex with phosphosite identification, strong mechanistic detail\",\n      \"pmids\": [\"21733846\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"WNK2 re-expression in WNK2-silenced glioblastoma cells reduces Rac1 GTP-loading; conversely, WNK2 depletion in cells with unmethylated WNK2 increases Rac1 activation, cell morphology changes, and invasion, establishing WNK2 as a negative regulator of Rac1-driven tumor invasion.\",\n      \"method\": \"Rac1 GTPase pull-down, re-expression and RNAi in glioblastoma cell lines, in vivo xenograft, invasion assay\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — bidirectional genetic manipulation (re-expression + knockdown) with active-Rac1 pull-down and in vivo validation\",\n      \"pmids\": [\"23035050\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"WNK2 silencing in glioma cells is associated with elevated JNK activation and increased MMP2 expression and activity; WNK2 suppresses JNK, which in turn reduces MMP2 levels, linking WNK2 to an invasion-relevant protease pathway.\",\n      \"method\": \"WNK2 re-expression/depletion, JNK phosphorylation immunoblot, MMP2 zymography\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2/3 — clear pathway placement (WNK2→JNK→MMP2) but mechanistic detail of direct vs. indirect connection not fully resolved\",\n      \"pmids\": [\"25596741\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"WNK2 inactivation in HCC cells leads to ERK1/2 signaling activation, tumor-associated macrophage infiltration, and increased tumor growth and metastasis, positioning WNK2 as a suppressor of ERK1/2 signaling in liver cancer.\",\n      \"method\": \"WNK2 loss-of-function (genomic alteration + functional assays), phospho-ERK1/2 immunoblot, in vivo tumor models\",\n      \"journal\": \"Journal of hepatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — defined cellular phenotype and pathway placement (WNK2→ERK1/2) in HCC, single study\",\n      \"pmids\": [\"31349001\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"WNK2 overexpression in A172 glioblastoma cells inhibits autophagic flux (decreased LC3B, p62 levels and LC3A/B ratio under bafilomycin A1 + everolimus) through an mTOR-independent pathway.\",\n      \"method\": \"WNK2 overexpression, bafilomycin A1 and everolimus treatment, LC3A/B and p62 immunoblot and immunofluorescence, mTOR pathway analysis\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2/3 — clean overexpression with multiple autophagic markers and pharmacological probes; mTOR independence established, single lab\",\n      \"pmids\": [\"32093151\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"LINC00858 recruits DNA methyltransferases to the WNK2 promoter, enhancing its methylation and silencing WNK2 expression, thereby activating the MAPK/ERK pathway in colon cancer cells.\",\n      \"method\": \"RNA immunoprecipitation, chromatin immunoprecipitation, RNA pull-down, methylation analysis, WNK2 rescue experiments\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple biochemical assays (RIP, ChIP, RNA pull-down) establishing LINC00858-DNMT-WNK2 promoter mechanism\",\n      \"pmids\": [\"32768499\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"WNK2 germline variants (p.Pro702Leu, p.Ala1607Val, p.Val2053Ile) display elevated phospho-PAK1/2, phospho-ERK1/2, and CCND1 levels in HT-29 cells, demonstrating that loss-of-function WNK2 variants deregulate the MAPK pathway via PAK1.\",\n      \"method\": \"Gene editing (CRISPR), lentiviral variant transfection, immunoblot (phospho-PAK1/2, phospho-ERK1/2, CCND1), clonogenic and adhesion assays\",\n      \"journal\": \"Journal of medical genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional characterization of specific variants with defined pathway readout, single lab\",\n      \"pmids\": [\"36270769\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"WNK2 is a downstream transcriptional target of PAX6 in corneal epithelial cells; WNK2 knockdown impairs expression of corneal differentiation markers (KRT12, ALDH3A1, CLU) and activates keratinization, inflammation, and proliferation pathways, establishing WNK2 as required for corneal epithelial homeostasis.\",\n      \"method\": \"PAX6 shRNA knockdown, RNA-seq, WNK2 shRNA knockdown, immunofluorescence, air-liquid interface differentiation assay\",\n      \"journal\": \"Investigative ophthalmology & visual science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — epistasis (PAX6→WNK2) plus loss-of-function phenotype with defined differentiation markers, single study\",\n      \"pmids\": [\"39453672\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"WNK2 coding variants associated with familial osteoarthritis alter the chondrocyte transcriptional response to hyperosmotic stress; elevated WNK2 signalling combined with hyperosmotic stress drives an OA-associated catabolic/anabolic gene expression program in chondrocytes.\",\n      \"method\": \"WNK2 overexpression and loss-of-function in immortalised/primary chondrocytes, transcriptomic analysis, hyperosmotic stress challenge, immunohistochemistry on human/mouse OA tissue\",\n      \"journal\": \"RMD open\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — bidirectional genetic manipulation with transcriptomic readout under defined osmotic stress, single study\",\n      \"pmids\": [\"40592720\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"WNK2 is a neuron-enriched serine-threonine kinase that suppresses cell growth and invasion by: (1) phosphorylating and activating NKCC1 while inhibiting KCC2 via a SPAK complex to regulate neuronal chloride homeostasis; (2) maintaining RhoA activity to prevent Rac1-GTP loading, thereby blocking PAK1-mediated phosphorylation of MEK1-S298 and downstream ERK1/2 activation; (3) suppressing JNK and MMP2-driven invasion; and (4) inhibiting autophagic flux in glioblastoma through an mTOR-independent pathway — collectively positioning WNK2 as a tumor suppressor whose loss, via promoter hypermethylation or mutation, derepresses ERK/MAPK, Rac1, and MMP2 signaling to promote cancer cell proliferation and invasion.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"WNK2 is a serine-threonine kinase that functions as a tumor suppressor and regulator of ion homeostasis by restraining MAPK/ERK signaling, Rac1-driven invasion, and cation-chloride cotransporter activity. WNK2 maintains RhoA activation to prevent Rac1 GTP-loading, thereby blocking PAK1-mediated phosphorylation of MEK1 at Ser-298 and downstream ERK1/2 activation; loss of WNK2 through promoter hypermethylation or coding variants derepresses this cascade, promoting cell proliferation and invasion in glioblastoma, colon cancer, and hepatocellular carcinoma [PMID:18593598, PMID:17667937, PMID:23035050, PMID:31349001]. In neurons, WNK2 forms a complex with SPAK to reciprocally activate NKCC1 and inhibit KCC2 in a kinase-dependent manner, regulating intracellular chloride homeostasis [PMID:21733846]. WNK2 also suppresses JNK-MMP2-mediated invasion, inhibits autophagic flux through an mTOR-independent pathway, is a transcriptional target of PAX6 required for corneal epithelial differentiation, and modulates chondrocyte responses to hyperosmotic stress [PMID:25596741, PMID:32093151, PMID:39453672, PMID:40592720].\",\n  \"teleology\": [\n    {\n      \"year\": 2007,\n      \"claim\": \"Establishing that WNK2 catalytic activity suppresses MEK1/ERK1/2 signaling and cell-cycle progression resolved the question of whether WNK2 acts on the MAPK cascade and defined it as a growth-inhibitory kinase.\",\n      \"evidence\": \"RNAi knockdown and kinase-dead mutant expression with phospho-MEK1 S298 immunoblot and cell-cycle analysis in HeLa/HT29 cells\",\n      \"pmids\": [\"17667937\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct phosphorylation substrate linking WNK2 catalytic activity to MEK1 inhibition not identified\", \"Mechanism by which WNK2 suppresses MEK1 S298 phosphorylation unclear\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Demonstration that WNK2 suppresses glioma colony formation independently of its kinase activity revealed a dual-mode (catalytic and scaffolding) mechanism of tumor suppression.\",\n      \"evidence\": \"In vitro autophosphorylation assay and colony formation assay with kinase-dead WNK2 in glioma cells\",\n      \"pmids\": [\"17578925\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Scaffold binding partners mediating kinase-independent suppression not identified\", \"Kinase-dependent vs. kinase-independent contributions not quantitatively resolved\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Defining the RhoA→Rac1→PAK1→MEK1-S298 axis downstream of WNK2 resolved how WNK2 loss activates ERK1/2 — through cross-talk between Rho-family GTPases rather than direct kinase action on MEK1.\",\n      \"evidence\": \"GTPase pull-down assays for active RhoA and Rac1, PAK1 kinase assay, and phospho-MEK1 S298 immunoblot after WNK2 RNAi\",\n      \"pmids\": [\"18593598\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How WNK2 maintains RhoA-GTP loading is unknown\", \"Whether WNK2 directly phosphorylates a RhoGEF or RhoGAP not tested\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Reconstitution of WNK2-dependent NKCC1 activation and KCC2 inhibition, and identification of the WNK2–SPAK complex in brain, established WNK2's physiological role in neuronal chloride homeostasis distinct from its tumor-suppressive function.\",\n      \"evidence\": \"⁸⁶Rb⁺ uptake in Xenopus oocytes, co-immunoprecipitation and mass spectrometry of SPAK phospho-Ser-383 from brain tissue\",\n      \"pmids\": [\"21733846\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative contributions of WNK2 vs. other WNK family members to neuronal Cl⁻ balance in vivo not determined\", \"No neuron-specific WNK2 knockout phenotype reported\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Bidirectional manipulation (re-expression and knockdown) confirmed WNK2 as a negative regulator of Rac1 GTP-loading and tumor invasion in glioblastoma, extending the RhoA/Rac1 mechanism to a disease-relevant invasion phenotype.\",\n      \"evidence\": \"Rac1 pull-down, invasion assays, and in vivo xenograft after WNK2 re-expression and RNAi in glioblastoma cell lines\",\n      \"pmids\": [\"23035050\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular link between WNK2 and Rac1-specific GEFs/GAPs remains unidentified\", \"Contribution of kinase activity vs. scaffolding to invasion suppression not separated\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Linking WNK2 loss to JNK activation and MMP2 upregulation identified a second invasion-promoting axis parallel to Rac1/PAK1.\",\n      \"evidence\": \"WNK2 re-expression/depletion with JNK phosphorylation immunoblot and MMP2 zymography in glioma cells\",\n      \"pmids\": [\"25596741\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs. indirect relationship between WNK2 and JNK not resolved\", \"Whether JNK-MMP2 axis operates independently of Rac1/PAK1 not tested\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Extension of the WNK2-ERK1/2 tumor-suppressor axis to hepatocellular carcinoma, with evidence for macrophage infiltration, generalized WNK2's growth-suppressive role across cancer types.\",\n      \"evidence\": \"WNK2 loss-of-function, phospho-ERK1/2 immunoblot, and in vivo tumor models in HCC\",\n      \"pmids\": [\"31349001\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism linking WNK2 loss to tumor-associated macrophage recruitment not defined\", \"Whether RhoA/Rac1 axis operates identically in HCC not examined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Discovery that WNK2 inhibits autophagic flux through an mTOR-independent pathway added a new cellular process to WNK2's tumor-suppressive repertoire.\",\n      \"evidence\": \"WNK2 overexpression with bafilomycin A1/everolimus treatment, LC3A/B and p62 immunoblot/immunofluorescence in A172 glioblastoma cells\",\n      \"pmids\": [\"32093151\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Target of WNK2 in autophagy pathway not identified\", \"Single cell line; generalizability untested\", \"Functional consequence for tumor growth not linked to autophagy inhibition specifically\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identification of LINC00858-mediated recruitment of DNA methyltransferases to the WNK2 promoter revealed an upstream epigenetic mechanism for WNK2 silencing in colon cancer.\",\n      \"evidence\": \"RNA immunoprecipitation, ChIP, RNA pull-down, methylation analysis, and WNK2 rescue experiments in colon cancer cells\",\n      \"pmids\": [\"32768499\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether this lncRNA-mediated silencing mechanism operates in glioma or HCC not tested\", \"Specificity of LINC00858 for the WNK2 locus vs. other targets not clarified\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Functional characterization of germline WNK2 coding variants showing elevated phospho-PAK1/2 and phospho-ERK1/2 demonstrated that specific missense variants are loss-of-function and deregulate the same PAK1-MEK1-ERK axis.\",\n      \"evidence\": \"CRISPR gene editing, lentiviral variant expression, phospho-PAK1/2 and phospho-ERK1/2 immunoblot, clonogenic assays in HT-29 cells\",\n      \"pmids\": [\"36270769\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis for variant-induced loss of function not determined\", \"In vivo pathogenicity of these variants in animal models not assessed\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Placing WNK2 downstream of PAX6 and showing its requirement for corneal epithelial differentiation extended WNK2's physiological role beyond neurons and cancer to epithelial homeostasis.\",\n      \"evidence\": \"PAX6 and WNK2 shRNA knockdown, RNA-seq, immunofluorescence, air-liquid interface differentiation in corneal epithelial cells\",\n      \"pmids\": [\"39453672\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether WNK2 acts through Rac1/ERK or a distinct pathway in corneal epithelium not resolved\", \"No in vivo corneal phenotype reported\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Association of WNK2 coding variants with familial osteoarthritis and demonstration that elevated WNK2 signaling under hyperosmotic stress drives a catabolic chondrocyte program linked WNK2 to cartilage pathophysiology.\",\n      \"evidence\": \"WNK2 overexpression/loss-of-function in chondrocytes with transcriptomic analysis under hyperosmotic stress, immunohistochemistry on human/mouse OA tissue\",\n      \"pmids\": [\"40592720\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Downstream kinase substrates in chondrocytes not identified\", \"Whether SPAK/NKCC1 axis mediates the osmotic response in chondrocytes not tested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The direct phosphorylation substrates through which WNK2 maintains RhoA activity and suppresses Rac1 remain unknown, and no structural model explains how disease-associated variants impair function.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No RhoGEF or RhoGAP identified as direct WNK2 substrate\", \"No crystal or cryo-EM structure of WNK2\", \"Relative contributions of kinase-dependent vs. kinase-independent functions in vivo not resolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 3]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 2, 4, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 2, 4, 6, 9]},\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [7]}\n    ],\n    \"complexes\": [\n      \"WNK2–SPAK complex\"\n    ],\n    \"partners\": [\n      \"STK39\",\n      \"SLC12A2\",\n      \"SLC12A5\",\n      \"RAC1\",\n      \"RHOA\",\n      \"PAK1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}