Affinage

WNK2

Serine/threonine-protein kinase WNK2 · UniProt Q9Y3S1

Length
2297 aa
Mass
242.7 kDa
Annotated
2026-04-28
24 papers in source corpus 12 papers cited in narrative 12 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

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).

Mechanistic history

Synthesis pass · year-by-year structured walk · 12 steps
  1. 2007 High

    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

    PMID:17667937

    Open questions at the time
    • Direct phosphorylation substrate linking WNK2 catalytic activity to MEK1 inhibition not identified
    • Mechanism by which WNK2 suppresses MEK1 S298 phosphorylation unclear
  2. 2007 Medium

    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

    PMID:17578925

    Open questions at the time
    • Scaffold binding partners mediating kinase-independent suppression not identified
    • Kinase-dependent vs. kinase-independent contributions not quantitatively resolved
  3. 2008 High

    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

    PMID:18593598

    Open questions at the time
    • How WNK2 maintains RhoA-GTP loading is unknown
    • Whether WNK2 directly phosphorylates a RhoGEF or RhoGAP not tested
  4. 2011 High

    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

    PMID:21733846

    Open questions at the time
    • Relative contributions of WNK2 vs. other WNK family members to neuronal Cl⁻ balance in vivo not determined
    • No neuron-specific WNK2 knockout phenotype reported
  5. 2012 High

    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

    PMID:23035050

    Open questions at the time
    • Molecular link between WNK2 and Rac1-specific GEFs/GAPs remains unidentified
    • Contribution of kinase activity vs. scaffolding to invasion suppression not separated
  6. 2015 Medium

    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

    PMID:25596741

    Open questions at the time
    • Direct vs. indirect relationship between WNK2 and JNK not resolved
    • Whether JNK-MMP2 axis operates independently of Rac1/PAK1 not tested
  7. 2019 Medium

    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

    PMID:31349001

    Open questions at the time
    • Mechanism linking WNK2 loss to tumor-associated macrophage recruitment not defined
    • Whether RhoA/Rac1 axis operates identically in HCC not examined
  8. 2020 Medium

    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

    PMID:32093151

    Open questions at the time
    • Target of WNK2 in autophagy pathway not identified
    • Single cell line; generalizability untested
    • Functional consequence for tumor growth not linked to autophagy inhibition specifically
  9. 2020 Medium

    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

    PMID:32768499

    Open questions at the time
    • 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
  10. 2022 Medium

    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

    PMID:36270769

    Open questions at the time
    • Structural basis for variant-induced loss of function not determined
    • In vivo pathogenicity of these variants in animal models not assessed
  11. 2024 Medium

    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

    PMID:39453672

    Open questions at the time
    • Whether WNK2 acts through Rac1/ERK or a distinct pathway in corneal epithelium not resolved
    • No in vivo corneal phenotype reported
  12. 2025 Medium

    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

    PMID:40592720

    Open questions at the time
    • Downstream kinase substrates in chondrocytes not identified
    • Whether SPAK/NKCC1 axis mediates the osmotic response in chondrocytes not tested

Open questions

Synthesis pass · forward-looking unresolved questions
  • 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.
  • 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

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 4 GO:0140096 catalytic activity, acting on a protein 3
Localization
GO:0005829 cytosol 1
Pathway
R-HSA-162582 Signal Transduction 5 R-HSA-382551 Transport of small molecules 1 R-HSA-9612973 Autophagy 1
Partners
PAK1RAC1RHOASLC12A2SLC12A5STK39
Complex memberships
WNK2–SPAK complex

Evidence

Reading pass · 12 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2007 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. RNAi knockdown, kinase-dead mutant expression, phospho-MEK1 S298 immunoblot, cell-cycle analysis Oncogene High 17667937
2007 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. In vitro autophosphorylation assay, hypertonic stimulation, colony formation assay with kinase-dead constructs Proceedings of the National Academy of Sciences of the United States of America Medium 17578925
2008 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. RNAi, GTPase pull-down (active Rac1/RhoA), PAK1 kinase assay, phospho-MEK1 S298 immunoblot Cellular signalling High 18593598
2011 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. ⁸⁶Rb⁺ uptake assay in Xenopus oocytes, TiO₂ enrichment/tandem mass spectrometry, co-immunoprecipitation from brain tissue, immunohistochemistry The Journal of biological chemistry High 21733846
2012 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. Rac1 GTPase pull-down, re-expression and RNAi in glioblastoma cell lines, in vivo xenograft, invasion assay Human molecular genetics High 23035050
2015 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. WNK2 re-expression/depletion, JNK phosphorylation immunoblot, MMP2 zymography Oncotarget Medium 25596741
2019 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. WNK2 loss-of-function (genomic alteration + functional assays), phospho-ERK1/2 immunoblot, in vivo tumor models Journal of hepatology Medium 31349001
2020 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. WNK2 overexpression, bafilomycin A1 and everolimus treatment, LC3A/B and p62 immunoblot and immunofluorescence, mTOR pathway analysis Cells Medium 32093151
2020 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. RNA immunoprecipitation, chromatin immunoprecipitation, RNA pull-down, methylation analysis, WNK2 rescue experiments Experimental cell research Medium 32768499
2022 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. Gene editing (CRISPR), lentiviral variant transfection, immunoblot (phospho-PAK1/2, phospho-ERK1/2, CCND1), clonogenic and adhesion assays Journal of medical genetics Medium 36270769
2024 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. PAX6 shRNA knockdown, RNA-seq, WNK2 shRNA knockdown, immunofluorescence, air-liquid interface differentiation assay Investigative ophthalmology & visual science Medium 39453672
2025 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. WNK2 overexpression and loss-of-function in immortalised/primary chondrocytes, transcriptomic analysis, hyperosmotic stress challenge, immunohistochemistry on human/mouse OA tissue RMD open Medium 40592720

Source papers

Stage 0 corpus · 24 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2011 WNK2 kinase is a novel regulator of essential neuronal cation-chloride cotransporters. The Journal of biological chemistry 76 21733846
2007 Protein kinase WNK2 inhibits cell proliferation by negatively modulating the activation of MEK1/ERK1/2. Oncogene 69 17667937
2007 Epigenome scans and cancer genome sequencing converge on WNK2, a kinase-independent suppressor of cell growth. Proceedings of the National Academy of Sciences of the United States of America 59 17578925
2019 Genomic sequencing identifies WNK2 as a driver in hepatocellular carcinoma and a risk factor for early recurrence. Journal of hepatology 58 31349001
2012 Loss of WNK2 expression by promoter gene methylation occurs in adult gliomas and triggers Rac1-mediated tumour cell invasiveness. Human molecular genetics 46 23035050
2008 Epigenetic silencing of the kinase tumor suppressor WNK2 is tumor-type and tumor-grade specific. Neuro-oncology 45 19001526
2013 Early epigenetic downregulation of WNK2 kinase during pancreatic ductal adenocarcinoma development. Oncogene 33 23912455
2019 Long non-coding RNA LINC00858 exerts a tumor-promoting role in colon cancer via HNF4α and WNK2 regulation. Cellular oncology (Dordrecht, Netherlands) 28 31884577
2015 Silencing of the tumor suppressor gene WNK2 is associated with upregulation of MMP2 and JNK in gliomas. Oncotarget 24 25596741
2008 WNK2 modulates MEK1 activity through the Rho GTPase pathway. Cellular signalling 24 18593598
2020 Long non-coding RNA LINC00858 inhibits colon cancer cell apoptosis, autophagy, and senescence by activating WNK2 promoter methylation. Experimental cell research 22 32768499
2020 Upregulated CBX8 Promotes Cancer Metastasis via the WNK2/MMP2 Pathway. Molecular therapy oncolytics 21 33251331
2019 microRNA-370 Promotes Cell Growth by Targeting WNK2 in Breast Cancer. DNA and cell biology 17 31009242
2021 Circ_0001666 affects miR-620/WNK2 axis to inhibit breast cancer progression. Genes & genomics 13 34061329
2020 LINC00858 knockdown inhibits gastric cancer cell growth and induces apoptosis through reducing WNK2 promoter methylation. Cellular oncology (Dordrecht, Netherlands) 9 32447640
2022 microRNA-324-3p suppresses the aggressive ovarian cancer by targeting WNK2/RAS pathway. Bioengineered 7 35549643
2022 CircRNA-WNK2 Acts as a ceRNA for miR-328a-3p to Promote AANAT Expression in the Male Rat Pineal Gland. Endocrinology 6 34918065
2024 PAX6-WNK2 Axis Governs Corneal Epithelial Homeostasis. Investigative ophthalmology & visual science 5 39453672
2020 WNK2 Inhibits Autophagic Flux in Human Glioblastoma Cell Line. Cells 5 32093151
2022 Germline mutations in WNK2 could be associated with serrated polyposis syndrome. Journal of medical genetics 4 36270769
2023 Regional bias of tumor suppressor gene mutations of STARD8 and WNK2 in colon cancers. Pathology, research and practice 1 38091885
2026 WNK2 may promote ovarian cancer progression by upregulating POU5F1B. PloS one 0 41628111
2025 WNK2 variants associated with familial osteoarthritis alter the chondrocyte response to hyperosmotic stress. RMD open 0 40592720
2024 Correction: Alves et al. WNK2 Inhibits Autophagic Flux in Human Glioblastoma Cell Line. Cells 2020, 9, 485. Cells 0 39056814