{"gene":"PKN2","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":1997,"finding":"PRK2/PKN2 is a Rho- and Rac-associated serine/threonine kinase (p140); unlike other Rho-binding kinases it associates with both RhoA and Rac1. Interaction with Rho is nucleotide-independent, whereas interaction with Rac is GTP-dependent. Association with either GTPase stimulates PRK2 kinase activity. Expression of kinase-deficient PRK2 in microinjected fibroblasts disrupts actin stress fibers, establishing PRK2 as a downstream effector of Rho/Rac that regulates actin cytoskeletal organization.","method":"Biochemical purification of p140 from tissues, peptide microsequencing, in vitro binding/nucleotide-dependence assays, in vitro kinase assays with activated GTPases, dominant-negative microinjection into fibroblasts with actin staining","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding assays, in vitro kinase activity, and dominant-negative cellular phenotype in a single focused study; replicated conceptually by multiple subsequent papers","pmids":["9121475"],"is_preprint":false},{"year":1996,"finding":"PRK2 specifically binds to the middle SH3 domain of the NCK adapter protein and interacts with Rho in a GTP-dependent manner. PRK2 cooperates with Rho family proteins to activate serum response factor (SRF)-dependent transcription, suggesting it bridges receptor tyrosine kinase signals (via NCK) with Rho-dependent transcriptional outputs.","method":"Bacterial expression library screen with NCK SH3 domains, in vitro GST pulldown, GTP-dependence binding assays, SRF luciferase reporter assays, mouse chromosome mapping by interspecific backcross","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding assays and functional reporter assay in a single lab","pmids":["8910519"],"is_preprint":false},{"year":1997,"finding":"Rat PRK2 (isolated as PAK-2/PRK2 from liver) is a 130-kDa cytosolic serine/threonine kinase activated by acidic phospholipids (especially cardiolipin) and unsaturated fatty acids. Its catalytic properties — substrate preferences, sensitivity to PKC pseudosubstrate inhibitors — are distinct from but overlapping with PKN/PRK1.","method":"Protein purification to homogeneity, tryptic peptide sequencing, RT-PCR cDNA analysis, in vitro kinase assays with lipid activators and peptide substrates","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro biochemical characterization with purified enzyme, single lab","pmids":["9092545"],"is_preprint":false},{"year":1999,"finding":"The C-terminal PDK1-interacting fragment (PIF) of PRK2 docks to PDK1 via a conserved hydrophobic motif; this interaction converts PDK1 from an enzyme that phosphorylates only PKBα Thr308 to one that also phosphorylates Ser473 in a PtdIns(3,4,5)P3-dependent manner, and activates PDK1 ~3-fold by PtdIns(3,4,5)P3. Mutation of conserved PIF residues abolishes the interaction. PRK2 is identified as a probable PDK1 substrate.","method":"In vitro kinase assays, PDK1–PIF peptide binding assays, mutagenesis of PIF motif, partial purification of brain PDK2 activity and immunoprecipitation with PDK1 antibodies","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstituted in vitro with mutagenesis, replicated across subsequent AGC kinase studies","pmids":["10226025"],"is_preprint":false},{"year":1998,"finding":"PRK2 is expressed as the predominant PKC-like maternal transcript in starfish oocytes, localizes to the cytoplasm in immature oocytes, and redistributes partially to the disintegrating germinal vesicle during meiotic maturation. PRK2 is phosphorylated in vivo in response to 1-methyladenine stimulus, preceding MPF activation, placing it as an early regulator during meiotic re-entry.","method":"RT-PCR cloning, subcellular fractionation/immunolocalization, in vivo 32P-labeling after 1-methyladenine stimulation","journal":"Developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization and in vivo phosphorylation with functional context, single lab","pmids":["9466886"],"is_preprint":false},{"year":2000,"finding":"During TNF-induced apoptosis, caspase cleavage of PRK2 generates a C-terminal fragment (aa 862–908) that specifically binds Akt (identified by yeast two-hybrid and confirmed in mammalian cells) and inhibits Akt kinase activity by blocking phosphorylation at Thr308 and Ser473, leading to inhibition of downstream Akt signaling including BAD phosphorylation and anti-apoptotic activity.","method":"Yeast two-hybrid screen, co-immunoprecipitation in mammalian cells, in vitro and in vivo kinase assays, apoptosis assays","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — yeast two-hybrid confirmed by co-IP, functional kinase inhibition shown, single lab","pmids":["10926925"],"is_preprint":false},{"year":2001,"finding":"PRK2 interacts with the PDZ3 domain of the protein tyrosine phosphatase PTP-BL via the extreme C-terminal cysteine of PRK2 (a novel PDZ-binding motif). This interaction was demonstrated by yeast two-hybrid and co-immunoprecipitation from transfected HeLa cells, with co-localization of both proteins in lamellipodia-like structures.","method":"Yeast two-hybrid, co-immunoprecipitation from transfected HeLa cells, site-directed mutagenesis of C-terminal cysteine, immunofluorescence co-localization","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal yeast two-hybrid and co-IP with mutagenesis, single lab","pmids":["11356191"],"is_preprint":false},{"year":2002,"finding":"Rho–PRK2 signaling promotes keratinocyte cell-cell adhesion via activation of the Fyn tyrosine kinase. An activated Rho mutant defective in PRK2/PKN binding fails to induce cell-cell adhesion. Increased endogenous PRK2 kinase activity during keratinocyte differentiation is sufficient to promote cell-cell adhesion, induce tyrosine phosphorylation of β- and γ-catenin and p120ctn, and activate Fyn, placing PRK2 as a Rho effector upstream of Fyn in this pathway.","method":"Dominant-negative and constitutively active Rho mutants, Rho mutants with defective PRK2 binding, PRK2 overexpression, kinase activity assays, co-immunoprecipitation, tyrosine phosphorylation assays","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — epistasis defined by Rho mutant defective in PRK2 binding, kinase activity assays, and cellular phenotype; multiple orthogonal approaches","pmids":["11777936"],"is_preprint":false},{"year":2002,"finding":"A caspase-3-generated C-terminal PRK2 fragment inhibits PDK1 autophosphorylation by >90% and blocks PDK1-mediated phosphorylation of PKC-ζ and PKC-δ in vitro and in vivo. The C-terminal tail of PKC is required for PKC-ζ/δ phosphorylation by PDK1. This establishes that the apoptotic PRK2 cleavage product acts as a potent negative regulator of PDK1.","method":"Yeast two-hybrid PDK1 bait screen, co-precipitation from mammalian cells, in vitro PDK1 kinase assays, in vivo phosphorylation assays with PRK2 fragment expression","journal":"Biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro and in vivo kinase inhibition assays, single lab, consistent with prior PDK1–PRK2 interaction data","pmids":["11781095"],"is_preprint":false},{"year":2007,"finding":"PRK2 is required for entry into mitosis and exit from cytokinesis in HeLa cells. Specifically, PRK2 is required for abscission at the midbody at the end of cell division, and for phosphorylation and activation of Cdc25B, the phosphatase that activates mitotic cyclin/Cdk1 at the G2/M transition. This links Rho GTPase signaling through PRK2 to cell cycle control.","method":"siRNA depletion of PRK2 in HeLa S3 cells, live-cell imaging, immunofluorescence for mitotic markers, Cdc25B phosphorylation assays","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — siRNA loss-of-function with specific mitotic and cytokinetic phenotypes and defined molecular substrate (Cdc25B), single rigorous study","pmids":["17332740"],"is_preprint":false},{"year":2008,"finding":"The extreme C-terminal segment of PRK2 is critical for full activation by RhoA in cells in a GTP-dependent manner, although it is dispensable for in vitro activation by RhoA. Two conserved threonines in the activation loop and turn motif are essential for catalytic activity; the phosphomimetic Asp-978 at the hydrophobic motif is dispensable. The PRK2-Δ958 mutant (turn motif truncated) still interacts with PDK1, indicating the hydrophobic and turn motifs are dispensable for PDK1 docking.","method":"Structure-function mutagenesis, in vitro kinase assays, in vivo RhoA activation assays, PDK1 co-immunoprecipitation","journal":"Archives of biochemistry and biophysics","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — mutagenesis with in vitro and in vivo kinase assays, single lab","pmids":["18835241"],"is_preprint":false},{"year":2008,"finding":"Both ROCK and PRK2 kinases promote polyglutamine (huntingtin and androgen receptor) aggregation in cultured cells. Overexpression of either increases aggregation; RNAi knockdown of either reduces aggregation; and the inhibitory effect of Y-27632 on aggregation requires both kinases (epistasis by RNAi).","method":"Overexpression and RNAi knockdown in cell-based aggregation assays with ROCK-specific inhibitors","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function and gain-of-function with pharmacological validation, single lab","pmids":["18423405"],"is_preprint":false},{"year":2009,"finding":"PDK1 phosphorylates the activation loop of PRK2. In-vivo 32P labeling identified two PRK2 phosphorylation sites: the activation loop and the zipper/turn-motif (Z/TM) in the C-terminal extension. Phosphorylation of the Z/TM site negatively regulates PRK2 docking to PDK1, providing a self-limiting regulatory mechanism where PRK2 activation inhibits further PDK1 interaction.","method":"In vivo 32P labeling of recombinant PRK2, phosphopeptide mapping/mass spectrometry, PDK1 docking interaction assays with phospho-site mutants","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vivo phosphorylation site mapping combined with mechanistic docking assays, multiple orthogonal methods, single lab","pmids":["19723632"],"is_preprint":false},{"year":2010,"finding":"The Yersinia effector YopM interacts with PRK2 via an internal leucine-rich repeat region (LRR6–LRR15). Both the PRK2-binding domain and the RSK1-binding domain of YopM are required for IL-10 induction in vivo and for virulence, establishing that PRK2 is co-opted by a bacterial effector as part of a signaling complex that suppresses host immunity.","method":"In vitro binding assays with truncated YopM proteins, murine infection models, serum cytokine measurements, orogastric infection virulence assays","journal":"Infection and immunity","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro domain mapping combined with in vivo genetic requirement, single lab","pmids":["20515922"],"is_preprint":false},{"year":2010,"finding":"PRK2 is required for maturation of primordial junctions into apical junctions in human bronchial epithelial cells. PRK2 is recruited to nascent cell-cell contacts via its C2-like domain; Rho binding facilitates this recruitment and is essential for PRK2 function. Kinase-dead PRK2 acts as a dominant-negative, and RhoA binding-deficient PRK2 fails to rescue junction formation, establishing that Rho-activated PRK2 kinase activity is required downstream of Rho for apical junction maturation.","method":"siRNA library screen targeting 28 Rho effectors, PRK2 depletion by siRNA, domain-mapping with C2-like and Rho-binding mutants, kinase-dead dominant-negative, immunofluorescence localization","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — siRNA screen identification followed by domain dissection with multiple mutants and cellular phenotype, single rigorous study","pmids":["20974804"],"is_preprint":false},{"year":2012,"finding":"PRK2 regulation is mediated in trans by an intermolecular PRK2–PRK2 dimerization through its N-terminal region, which prevents interaction with upstream kinase PDK1. Amino acids 487–501 in the linker between N-terminal domains and the catalytic domain contribute to dimer formation. The C-terminal region intramolecularly activates PRK2, and the catalytic domain mediates cross-talk between inhibitory N-terminal and activating C-terminal regions.","method":"In vitro kinase assays with N-terminal and C-terminal domain constructs, PDK1 interaction assays, mutagenesis of linker region","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro biochemical dissection with domain mutants, single lab","pmids":["22511787"],"is_preprint":false},{"year":2012,"finding":"PRK2 phosphorylates the HCV NS5B RNA-dependent RNA polymerase, and this phosphorylation is required for HCV replication. Hsp90 inhibition destabilizes PDK1 (via proteasomal degradation), reducing active PRK2 levels and thereby decreasing NS5B phosphorylation and HCV genome replication.","method":"Pharmacological Hsp90 inhibition (17-DMAG), Western blotting of phospho-NS5B, HCV replicon replication assays in Huh7 cells, HCV-infected cell assays","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — defined phosphorylation substrate (NS5B) with pathway epistasis through PDK1-PRK2, single lab; confirmed by siRNA-based follow-up","pmids":["22490666"],"is_preprint":false},{"year":2013,"finding":"PRK2 HR1a and HR1b domains bind RhoA, RhoB, and RhoC with distinct affinities; RhoB binds more tightly than RhoA or RhoC to PRK isoforms. The PRK1 HR1ab didomain shows similar affinities for RhoA and RhoC as HR1a alone, but RhoB additionally recruits the HR1b domain. PRK2 HR1 domains bind all Rho isoforms less well than PRK1 domains. The PRK2 HR1a domain has the highest thermal stability among PRK HR1 domains.","method":"Quantitative binding affinity measurements (biophysical assays), thermal stability analysis, domain-specific HR1a and HR1ab constructs","journal":"Biochemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — quantitative in vitro binding assays with purified domains, single lab","pmids":["24128008"],"is_preprint":false},{"year":2015,"finding":"H. pylori CagA toxin interacts directly with PRK2 and inhibits its kinase activity. This interaction disrupts PRK2-dependent cytoskeletal rearrangements and cell polarity pathways in host epithelial cells.","method":"Co-immunoprecipitation, in vitro kinase activity assay with CagA","journal":"Cellular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct co-IP and kinase inhibition assay, single lab","pmids":["26041307"],"is_preprint":false},{"year":2016,"finding":"Constitutive PKN2 knockout in mice results in embryonic lethality at E10 with cardiovascular and morphogenetic defects. The lethal phenotype is not recapitulated by endothelial- or cardiac-specific deletion but is reproduced by inducible systemic deletion after E7, causing collapse of the embryonic mesoderm. Mouse embryonic fibroblasts from PKN2-null embryos are defective in proliferation and motility, and neural crest migration is impaired in vivo, establishing PKN2 as a non-redundant, cell-autonomous regulator of mesoderm expansion and mesodermal-cell function.","method":"Constitutive and conditional PKN2 knockout mice, inducible systemic deletion (tamoxifen-inducible), tissue-specific Cre deletions, MEF proliferation/motility assays, in vivo neural crest migration analysis","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple independent genetic models with specific cellular phenotypes, replicated by independent PKN2 knockout study (PMID:28102564)","pmids":["26774483"],"is_preprint":false},{"year":2016,"finding":"PKN2 forms a complex with Cdo, APPL1, and AKT via its C-terminal region during myoblast differentiation, and this interaction promotes AKT activation and myoblast differentiation. PKN2 overexpression enhances C2C12 differentiation; PKN2 depletion impairs it. PKN2 also mediates recruitment of BAF60c and MyoD to the myogenin promoter, promoting MyoD-responsive transcription.","method":"Co-immunoprecipitation, shRNA knockdown, overexpression in C2C12 myoblasts, MyoD-responsive luciferase reporter assay, ChIP for BAF60c and MyoD at myogenin promoter, differentiation marker assays","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, ChIP, and loss/gain-of-function with multiple cellular phenotypes, single lab","pmids":["27763641"],"is_preprint":false},{"year":2017,"finding":"PKN2 knockout MEFs fail to proliferate, and Cre-mediated ablation of PKN2 in floxed MEFs causes impaired cell proliferation with a decrease in S-phase population by cell cycle analysis. PKN2 knockout mouse embryos fail to undergo axial turning and show insufficient neural tube closure, confirming non-redundant in vivo functions distinct from PKN1 and PKN3.","method":"Constitutive PKN2 knockout mice, Cre-mediated conditional deletion in MEFs, cell cycle analysis (flow cytometry), proliferation assays","journal":"Genes to cells","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout confirmed in two cell systems with defined cell cycle phenotype; independently replicates PMID:26774483","pmids":["28102564"],"is_preprint":false},{"year":2018,"finding":"PKN2 in colon cancer cells directly associates with and phosphorylates/activates DUSP6, a dual-specificity phosphatase that dephosphorylates/inactivates ERK1/2. This suppresses ERK1/2 phosphorylation, reducing CREB/Elk-1 binding to IL-4 and IL-10 promoters, thereby inhibiting M2 macrophage polarization.","method":"Co-immunoprecipitation (Co-IP) of PKN2 and DUSP6, kinase activity assay for PKN2 on DUSP6, ChIP-qPCR for CREB/Elk-1, luciferase promoter assays, PKN2 siRNA, xenograft models","journal":"Molecular cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct Co-IP, kinase activity assay, and ChIP-qPCR, single lab","pmids":["29368606"],"is_preprint":false},{"year":2020,"finding":"Muscle-specific genetic ablation of PAK2/PKN2 (note: this paper uses 'PAK2' to refer to the p21-activated kinase PAK2, NOT PKN2/PRK2; the gene symbol collision must be assessed). Assessment: The paper describes PAK2 (group I PAK family, activated by Rac/Cdc42) in insulin-stimulated glucose uptake in skeletal muscle — this is PAK2 (gene: PAK2), NOT PKN2/PRK2. EXCLUDED as alias collision.","method":"N/A","journal":"The Journal of physiology","confidence":"Low","confidence_rationale":"Excluded — alias collision (PAK2 = p21-activated kinase 2, different gene from PKN2/PRK2)","pmids":["32844438"],"is_preprint":false},{"year":2020,"finding":"PKN2 localizes to the transition zone of primary cilia upon serum withdrawal (where activating pPRK2 signal is detected), and co-depletion of PRK1 and PRK2 results in reduced cilia length, impaired planar polarity, and impaired cilia-associated signaling. PRK2 depletion also reduces spheroid growth.","method":"Immunofluorescence localization of phospho-PRK1/2, siRNA co-depletion, cilia length measurement, planar polarity assays, spheroid growth assays, proteomic identification of PRK2 binding partners","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization and loss-of-function with defined cilia phenotype, single lab","pmids":["32127582"],"is_preprint":false},{"year":2021,"finding":"PKN2 depletion in fibroblasts reduces cell motility velocity and delays recovery of N-cadherin expression (both protein and mRNA) after trypsin dissociation, impairing cell aggregate compaction and spheroid formation in suspension culture. This establishes PKN2 as a regulator of N-cadherin transcription and cell motility required for spheroid formation.","method":"Cre-mediated PKN2 deletion in floxed fibroblasts, time-lapse microscopy, immunoblot for N-cadherin, RT-qPCR for N-cadherin mRNA, spheroid formation assays in low-attachment plates","journal":"Biochemistry and biophysics reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional KO with multiple phenotypic readouts and mRNA analysis, single lab","pmids":["33437883"],"is_preprint":false},{"year":2022,"finding":"PKN2 promotes cardiac hypertrophy downstream of angiotensin II: cardiomyocyte-specific PKN2 knockout causes developmental myocardial defects (clefts, ventricular septal defects) and PKN2 haploinsufficiency in adults attenuates angiotensin II-induced cardiac hypertrophy, cardiomyocyte hypertrophy, and fibrosis.","method":"Cardiomyocyte-specific conditional PKN2 knockout, global PKN2 haploinsufficiency, angiotensin II infusion model, high-resolution episcopic microscopy, MRI, micro-CT, echocardiography, histology, RNAseq","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple independent genetic models with detailed cardiac phenotyping using multiple imaging modalities","pmids":["35730579"],"is_preprint":false},{"year":2024,"finding":"PKN2 allosteric regulation involves a PIF-pocket that communicates with both the ATP-binding site and the pseudosubstrate PKL-binding site. A small compound binding to the PIF-pocket can act as either an allosteric activator (displacing the PKL pseudosubstrate from the active site) or an allosteric inhibitor of PRK2 catalytic activity. PIFtide peptide binding to the PIF-pocket similarly activates PRK2 allosterically. At least two distinct complexes between PRK2 and PDK1 were identified.","method":"Chemical biology with small compound PIF-pocket ligands, in vitro kinase assays, allosteric activation/inhibition assays, binding interaction studies with PDK1","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution with chemical tools and mechanistic interpretation, single lab","pmids":["39002682"],"is_preprint":false},{"year":2025,"finding":"PKN2 promotes mesenchymal-like cancer cell growth through a PKN2–SAV1–TAZ signaling mechanism, identifying PKN2 as a core regulator of the Hippo tumor suppressor pathway. Biochemical experiments demonstrated the PKN2-SAV1-TAZ interaction, and genetic PKN2 inhibition suppresses drug-tolerant persister cells driven by the mesenchymal-like state.","method":"Genome-wide essentiality analysis (~800 cancer cell lines), co-essentiality mapping, biochemical interaction experiments (Co-IP/pulldown), genomic analysis of patient tumors, genetic PKN2 inhibition combined with targeted therapies","journal":"Cancer discovery","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — biochemical interaction confirmed with functional genetic validation, single lab; novel pathway placement","pmids":["39560431"],"is_preprint":false},{"year":2025,"finding":"PKN2 directly interacts with HIF-1α protein, phosphorylates it, and induces ubiquitination-dependent degradation of HIF-1α, thereby suppressing HIF-1α nuclear accumulation and transcription of VEGFA and bFGF. This inhibits tumor angiogenesis in colon cancer.","method":"Co-immunoprecipitation of PKN2 and HIF-1α, in vitro phosphorylation assay, ubiquitination assay, HIF-1α nuclear localization by fractionation/immunofluorescence, VEGFA/bFGF promoter assays, in vitro and in vivo tumor angiogenesis models","journal":"The Kaohsiung journal of medical sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct biochemical interaction, phosphorylation, and ubiquitination assays with functional angiogenesis phenotype, single lab","pmids":["40515512"],"is_preprint":false},{"year":2025,"finding":"PKN2 promotes immunosuppressive activity of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) in esophageal cancer by upregulating STAT3 phosphorylation, which drives CPT1B transcription and fatty acid oxidation (FAO) in PMN-MDSCs.","method":"PKN2 overexpression in PMN-MDSCs, co-culture with T cells and organoids, Western blotting for phospho-STAT3 and CPT1B, FAO measurement assays","journal":"Molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — gain-of-function with defined downstream signaling (STAT3-CPT1B) and functional immunosuppression readout, single lab","pmids":["40069590"],"is_preprint":false},{"year":2025,"finding":"Upon wound healing, PKN2 relocalizes from cytoplasm to lateral cell-cell junctions in MCF10A epithelial monolayers, where it stabilizes adherens junctions and maintains coordinated collective migration. PKN2 CRISPR KO reduces collective migration due to destabilization of adherens junctions.","method":"CRISPR/Cas9 PKN2 knockout, wound healing assay, live-cell imaging, immunofluorescence for junction markers, PKN2 relocalization imaging","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR KO with defined junction phenotype and direct relocalization imaging, single lab","pmids":["41276909"],"is_preprint":false},{"year":2026,"finding":"The E3 ubiquitin ligase TRIM40 binds PKN2 via its B-box domain and promotes K63-linked ubiquitination of PKN2 in an E3 ligase activity-dependent manner, enhancing PKN2 phosphorylation at Ser815 and activating downstream pro-hypertrophic signaling. Pharmacological inhibition of PKN2 attenuates cardiac remodeling induced by TRIM40 overexpression.","method":"TRIM40 knockout and overexpressing mice, angiotensin II/TAC hypertrophy models, Co-IP to map TRIM40-PKN2 interaction, ubiquitination assays (K63-linkage), phospho-PKN2 Ser815 Western blot, PKN2 inhibitor rescue","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding, ubiquitination, and phosphorylation assays in genetic models, single lab","pmids":["41572508"],"is_preprint":false},{"year":2026,"finding":"Cardiomyocyte-specific PKN2 knockout causes a ventricular geometry defect traceable to a critical developmental window (E7.5–E10.5). Tamoxifen-induced deletion at E7.5 reproduces the 'coin-pouch' ventricular geometry; deletion at E10.5 spares morphology. Integrative omics at E10.5 reveals transcriptional and proteomic induction of actin cytoskeleton/motility programs with repression of mitotic modules, alongside reduced cardiomyocyte proliferation at E10.5–E11.5.","method":"Constitutive and inducible cardiomyocyte-specific PKN2 CRE knockout, light-sheet microscopy-based morphometrics, RNA-seq, proteomics, phosphoproteomics, cardiomyocyte proliferation assays (EdU/BrdU)","journal":"Communications biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple independent genetic models with temporal induction, quantitative morphometrics, and multi-omics mechanistic insight, single lab","pmids":["42143091"],"is_preprint":false}],"current_model":"PKN2/PRK2 is a Rho/Rac-activated AGC-family serine/threonine kinase that is phosphorylated and activated by PDK1 (via a PIF-docking mechanism regulated by Z/TM site phosphorylation and intermolecular dimerization), acts downstream of RhoA and Rac1 to regulate actin cytoskeleton organization, apical junction maturation, cell-cell adhesion (via Fyn activation), collective cell migration, and cell cycle progression (G2/M entry via Cdc25B phosphorylation and cytokinetic abscission); it also integrates into the Hippo pathway through a PKN2–SAV1–TAZ axis, phosphorylates and destabilizes HIF-1α to suppress angiogenesis, is regulated by K63-linked ubiquitination by TRIM40, and is essential in vivo for mesoderm expansion, cardiac morphogenesis, and neural tube closure."},"narrative":{"mechanistic_narrative":"PKN2 (PRK2) is a Rho/Rac-activated AGC-family serine/threonine kinase that couples small-GTPase signaling to actin cytoskeletal organization, cell-cell adhesion, cell-cycle progression, and developmental morphogenesis [PMID:9121475, PMID:20974804]. It binds RhoA in a nucleotide-independent manner and Rac1 in a GTP-dependent manner, and association with either GTPase stimulates its kinase activity; loss of activity disrupts actin stress fibers, defining PKN2 as a Rho/Rac effector on the cytoskeleton [PMID:9121475, PMID:24128008]. Its catalytic output is set by PDK1, which docks to the C-terminal PDK1-interacting fragment (PIF) and phosphorylates the activation loop; this docking is self-limited by phosphorylation of the zipper/turn-motif (Z/TM) site and by intermolecular N-terminal dimerization, and the PIF-pocket additionally communicates allosterically with the active site and the autoinhibitory pseudosubstrate [PMID:10226025, PMID:19723632, PMID:22511787, PMID:39002682]. Downstream, PKN2 promotes Rho-dependent keratinocyte cell-cell adhesion by activating Fyn and driving catenin tyrosine phosphorylation [PMID:11777936], matures primordial into apical junctions through C2-domain- and Rho-dependent recruitment to nascent contacts [PMID:20974804], and relocalizes to lateral junctions to stabilize adherens junctions during coordinated collective migration [PMID:41276909]. In cell-cycle control, PKN2 is required for G2/M entry via phosphorylation and activation of Cdc25B and for cytokinetic abscission at the midbody [PMID:17332740]. PKN2 is non-redundantly essential in vivo: constitutive knockout is embryonic lethal at E10 with collapse of the expanding mesoderm, impaired neural crest migration, failed axial turning, and defective neural tube closure, and cardiomyocyte-specific deletion produces ventricular geometry defects within an E7.5–E10.5 window accompanied by reduced cardiomyocyte proliferation [PMID:26774483, PMID:28102564, PMID:35730579, PMID:42143091]. Additional signaling roles include the Hippo pathway via a PKN2–SAV1–TAZ axis [PMID:39560431], phosphorylation and ubiquitination-dependent destabilization of HIF-1α to suppress angiogenesis [PMID:40515512], activation of DUSP6 to restrain ERK1/2 signaling [PMID:29368606], and regulation by TRIM40-mediated K63-linked ubiquitination that enhances Ser815 phosphorylation in pro-hypertrophic cardiac signaling [PMID:41572508].","teleology":[{"year":1996,"claim":"Established that PRK2 links adapter-based receptor tyrosine kinase signaling to Rho-dependent transcription, before its kinase function was characterized.","evidence":"Bacterial expression library screen with NCK SH3 domains, GST pulldowns, and SRF luciferase reporter assays","pmids":["8910519"],"confidence":"Medium","gaps":["Did not establish whether NCK recruitment regulates PRK2 catalytic activity","Physiological context of the NCK–PRK2–Rho–SRF axis not defined in vivo"]},{"year":1997,"claim":"Defined PRK2 as a Rho/Rac effector that regulates the actin cytoskeleton, resolving how a single kinase reads two distinct GTPases.","evidence":"Biochemical purification of p140, reciprocal nucleotide-dependent binding assays, in vitro kinase assays, and dominant-negative microinjection into fibroblasts with actin staining","pmids":["9121475"],"confidence":"High","gaps":["Direct cytoskeletal substrates not identified","Mechanism distinguishing nucleotide-independent Rho versus GTP-dependent Rac binding unresolved"]},{"year":1997,"claim":"Characterized PRK2 as a lipid-responsive kinase, showing its activity is tuned by acidic phospholipids and fatty acids in addition to GTPases.","evidence":"Purification to homogeneity and in vitro kinase assays with lipid activators and peptide substrates","pmids":["9092545"],"confidence":"Medium","gaps":["Whether lipid activation operates in cells alongside GTPase activation unclear","Physiological substrates of lipid-activated PRK2 not defined"]},{"year":1999,"claim":"Identified PRK2 as a PDK1 substrate and revealed that its PIF motif reciprocally tunes PDK1 specificity, embedding PRK2 in AGC kinase regulatory logic.","evidence":"In vitro kinase assays, PDK1–PIF peptide binding assays, and PIF-motif mutagenesis","pmids":["10226025"],"confidence":"High","gaps":["Did not map the PRK2 activation-loop site phosphorylated by PDK1","Cellular consequences of PDK1-dependent PRK2 activation not shown"]},{"year":2000,"claim":"Showed that caspase cleavage converts PRK2 into a fragment that suppresses Akt, linking PRK2 proteolysis to pro-apoptotic signaling.","evidence":"Yeast two-hybrid, co-immunoprecipitation, in vitro/in vivo kinase assays, and apoptosis assays","pmids":["10926925"],"confidence":"Medium","gaps":["Whether endogenous cleavage levels are sufficient to inhibit Akt in vivo unclear","Relationship between full-length PRK2 signaling and the cleaved fragment not reconciled"]},{"year":2001,"claim":"Identified PTP-BL as a PDZ-domain partner anchoring PRK2 at lamellipodia, suggesting localized control of PRK2 at sites of actin remodeling.","evidence":"Yeast two-hybrid, co-IP from HeLa cells, C-terminal cysteine mutagenesis, and immunofluorescence co-localization","pmids":["11356191"],"confidence":"Medium","gaps":["Functional consequence of PTP-BL binding on PRK2 activity not determined","Single reciprocal Co-IP without endogenous validation"]},{"year":2002,"claim":"Placed PRK2 as a Rho effector upstream of Fyn in driving cell-cell adhesion, connecting GTPase signaling to junctional catenin phosphorylation.","evidence":"Rho mutants defective in PRK2 binding, PRK2 overexpression, kinase activity assays, and tyrosine phosphorylation assays in keratinocytes","pmids":["11777936"],"confidence":"High","gaps":["Whether PRK2 phosphorylates Fyn directly not established","Direct junctional substrates of PRK2 not identified"]},{"year":2002,"claim":"Demonstrated that the apoptotic PRK2 C-terminal fragment is a potent negative regulator of PDK1, broadening its inhibitory reach to atypical PKCs.","evidence":"Yeast two-hybrid PDK1 bait screen, co-precipitation, and in vitro/in vivo PDK1 kinase assays","pmids":["11781095"],"confidence":"Medium","gaps":["Physiological abundance and timing of the inhibitory fragment in apoptosis not quantified"]},{"year":2007,"claim":"Connected PRK2 to cell-cycle control, identifying it as required for Cdc25B-driven G2/M entry and for cytokinetic abscission.","evidence":"siRNA depletion in HeLa cells, live-cell imaging, mitotic-marker immunofluorescence, and Cdc25B phosphorylation assays","pmids":["17332740"],"confidence":"High","gaps":["Whether PRK2 phosphorylates Cdc25B directly not formally proven","Abscission substrates at the midbody not identified"]},{"year":2008,"claim":"Dissected the structural determinants of PRK2 activation, defining activation-loop and turn-motif requirements and the GTP-dependent role of the C-terminus.","evidence":"Structure-function mutagenesis with in vitro and in vivo kinase assays and PDK1 co-IP","pmids":["18835241"],"confidence":"Medium","gaps":["Atomic structure of the regulatory regions not determined","Discrepancy between in vitro and in-cell C-terminal requirements unexplained"]},{"year":2008,"claim":"Implicated PRK2, together with ROCK, in promoting polyglutamine aggregation, extending Rho-kinase signaling to protein-aggregation disease models.","evidence":"Overexpression and RNAi in cell-based aggregation assays with ROCK-specific inhibitors","pmids":["18423405"],"confidence":"Medium","gaps":["Direct substrate linking PRK2 to aggregation not identified","Relevance to neurodegenerative disease in vivo not tested"]},{"year":2009,"claim":"Mapped PRK2 phosphorylation sites and revealed a self-limiting feedback: Z/TM phosphorylation blocks further PDK1 docking.","evidence":"In vivo 32P labeling, phosphopeptide mapping/MS, and PDK1 docking assays with phospho-site mutants","pmids":["19723632"],"confidence":"High","gaps":["Kinase responsible for Z/TM phosphorylation not identified","Dynamics of the feedback loop in cells not measured"]},{"year":2010,"claim":"Established PRK2 as required for apical junction maturation, defining C2-domain- and Rho-dependent recruitment to nascent cell contacts.","evidence":"siRNA screen of Rho effectors, domain-mapping mutants, kinase-dead dominant-negative, and immunofluorescence in bronchial epithelium","pmids":["20974804"],"confidence":"High","gaps":["Junctional substrates phosphorylated by PRK2 not identified","Link to the Fyn/catenin pathway not integrated"]},{"year":2010,"claim":"Showed that the Yersinia effector YopM co-opts PRK2 as part of a host-immunosuppressive signaling complex required for virulence.","evidence":"In vitro domain-mapping binding assays and murine infection/virulence and cytokine models","pmids":["20515922"],"confidence":"Medium","gaps":["Whether YopM alters PRK2 kinase activity not determined","Host substrate driving IL-10 induction not identified"]},{"year":2012,"claim":"Revealed intermolecular PRK2–PRK2 dimerization as a trans-acting autoinhibitory mechanism that blocks PDK1 interaction.","evidence":"In vitro kinase assays with domain constructs, PDK1 interaction assays, and linker-region mutagenesis","pmids":["22511787"],"confidence":"Medium","gaps":["Whether dimerization is regulated in cells not shown","Stoichiometry and structural basis of the dimer not resolved"]},{"year":2012,"claim":"Identified the HCV NS5B polymerase as a PRK2 substrate, showing the PDK1–PRK2 axis is required for viral genome replication.","evidence":"Hsp90 inhibition, phospho-NS5B Western blotting, and HCV replicon/infection assays in Huh7 cells","pmids":["22490666"],"confidence":"Medium","gaps":["NS5B phosphosite and its functional role not fully mapped","Effects pharmacologically inferred through PDK1 destabilization"]},{"year":2013,"claim":"Quantified isoform-selective Rho binding by PRK2 HR1 domains, distinguishing its GTPase-recognition profile from PRK1.","evidence":"Quantitative biophysical binding affinity and thermal stability measurements with purified HR1 constructs","pmids":["24128008"],"confidence":"Medium","gaps":["Functional consequence of differential Rho-isoform binding in cells not tested"]},{"year":2015,"claim":"Showed that H. pylori CagA directly binds and inhibits PRK2, disrupting cytoskeletal and polarity programs in host epithelium.","evidence":"Co-immunoprecipitation and in vitro kinase activity assays with CagA","pmids":["26041307"],"confidence":"Medium","gaps":["Mechanism of CagA-mediated inhibition not defined","Single-lab biochemical evidence without structural detail"]},{"year":2016,"claim":"Established PKN2 as non-redundantly essential in vivo for mesoderm expansion and mesodermal-cell proliferation and motility, with embryonic lethality at E10.","evidence":"Constitutive, conditional, and inducible systemic PKN2 knockout mice, tissue-specific Cre deletions, and MEF proliferation/motility assays","pmids":["26774483"],"confidence":"High","gaps":["Molecular pathway connecting PKN2 to mesoderm expansion not defined","Which substrates underlie the proliferation/motility defects unknown"]},{"year":2016,"claim":"Linked PKN2 to a Cdo–APPL1–AKT complex and to MyoD/BAF60c promoter recruitment driving myoblast differentiation.","evidence":"Co-IP, shRNA/overexpression in C2C12 cells, MyoD reporter assays, and ChIP at the myogenin promoter","pmids":["27763641"],"confidence":"Medium","gaps":["Whether PKN2 kinase activity is required for AKT activation not resolved","Mechanism of PKN2-dependent BAF60c/MyoD recruitment unclear"]},{"year":2017,"claim":"Independently confirmed PKN2's non-redundant in vivo roles, tying its loss to reduced S-phase entry, failed axial turning, and neural tube closure defects.","evidence":"Constitutive knockout mice, Cre-mediated conditional MEF deletion, and flow-cytometry cell-cycle analysis","pmids":["28102564"],"confidence":"High","gaps":["Molecular substrate driving the S-phase defect not identified","Distinction from PKN1/PKN3 functions mechanistically unexplained"]},{"year":2018,"claim":"Showed PKN2 phosphorylates and activates DUSP6 to restrain ERK1/2 signaling, suppressing M2 macrophage polarization in colon cancer.","evidence":"Co-IP, in vitro kinase assay on DUSP6, ChIP-qPCR, luciferase assays, and xenograft models","pmids":["29368606"],"confidence":"Medium","gaps":["DUSP6 phosphosite not mapped","Single-lab biochemistry without orthogonal validation of the kinase relationship"]},{"year":2020,"claim":"Localized PKN2 to the ciliary transition zone and implicated it in cilium length, planar polarity, and ciliary signaling.","evidence":"Phospho-PRK1/2 immunofluorescence, siRNA co-depletion, cilia/planar-polarity assays, and proteomic partner identification","pmids":["32127582"],"confidence":"Medium","gaps":["Redundancy with PRK1 obscures PKN2-specific role","Ciliary substrates not identified"]},{"year":2021,"claim":"Identified PKN2 as a regulator of N-cadherin expression and motility required for spheroid compaction.","evidence":"Cre-mediated conditional deletion in fibroblasts, time-lapse imaging, immunoblot, and RT-qPCR for N-cadherin","pmids":["33437883"],"confidence":"Medium","gaps":["Mechanism by which PKN2 controls N-cadherin transcription unknown","Direct transcriptional intermediates not defined"]},{"year":2022,"claim":"Demonstrated PKN2 promotes angiotensin-II-driven cardiac hypertrophy and is required for normal myocardial development.","evidence":"Cardiomyocyte-specific knockout, haploinsufficiency, angiotensin II infusion, multimodal cardiac imaging, histology, and RNA-seq","pmids":["35730579"],"confidence":"High","gaps":["Pro-hypertrophic substrates of PKN2 in cardiomyocytes not identified","Distinction between developmental and adult hypertrophic roles not fully resolved"]},{"year":2024,"claim":"Resolved PKN2 allosteric regulation, showing the PIF-pocket couples to the ATP site and the pseudosubstrate to act as a bidirectional activity switch.","evidence":"Chemical biology with PIF-pocket ligands, in vitro kinase and allosteric activation/inhibition assays, and PDK1 binding studies","pmids":["39002682"],"confidence":"Medium","gaps":["Endogenous ligand or signal engaging the PIF-pocket in cells unknown","Structural basis of the two PRK2–PDK1 complexes not determined"]},{"year":2025,"claim":"Placed PKN2 in the Hippo pathway via a PKN2–SAV1–TAZ axis driving mesenchymal-like cancer cell growth and persister-cell survival.","evidence":"Genome-wide essentiality and co-essentiality analysis across ~800 cell lines, biochemical interaction assays, and genetic inhibition with targeted therapies","pmids":["39560431"],"confidence":"Medium","gaps":["Whether PKN2 phosphorylates SAV1 or TAZ not established","Directionality of the PKN2–SAV1–TAZ regulatory link not fully defined"]},{"year":2025,"claim":"Identified HIF-1α as a PKN2 substrate, showing PKN2 phosphorylates and destabilizes HIF-1α to suppress tumor angiogenesis.","evidence":"Co-IP, in vitro phosphorylation and ubiquitination assays, HIF-1α fractionation, VEGFA/bFGF promoter assays, and angiogenesis models","pmids":["40515512"],"confidence":"Medium","gaps":["HIF-1α phosphosite and the ubiquitin ligase recruited not identified","Single-lab evidence without independent confirmation"]},{"year":2025,"claim":"Linked PKN2 to immunosuppression by driving STAT3–CPT1B-dependent fatty acid oxidation in PMN-MDSCs in esophageal cancer.","evidence":"PKN2 overexpression, T-cell/organoid co-culture, phospho-STAT3/CPT1B Western blotting, and FAO assays","pmids":["40069590"],"confidence":"Medium","gaps":["Whether PKN2 phosphorylates STAT3 directly not shown","Gain-of-function only; loss-of-function in MDSCs not tested"]},{"year":2025,"claim":"Showed PKN2 relocalizes to lateral junctions during wound healing to stabilize adherens junctions and sustain collective migration.","evidence":"CRISPR/Cas9 knockout, wound-healing assays, live-cell imaging, and junction-marker immunofluorescence in MCF10A monolayers","pmids":["41276909"],"confidence":"Medium","gaps":["Junctional substrate stabilizing adherens junctions not identified","Signal triggering relocalization not defined"]},{"year":2026,"claim":"Identified TRIM40 as an E3 ligase that K63-ubiquitinates PKN2 to enhance Ser815 phosphorylation and pro-hypertrophic cardiac signaling.","evidence":"TRIM40 knockout/overexpressing mice, AngII/TAC hypertrophy models, Co-IP, K63-linkage ubiquitination assays, phospho-Ser815 blots, and PKN2 inhibitor rescue","pmids":["41572508"],"confidence":"Medium","gaps":["How K63 ubiquitination mechanistically promotes Ser815 phosphorylation unclear","Whether TRIM40 regulation operates outside cardiac tissue unknown"]},{"year":2026,"claim":"Defined a critical E7.5–E10.5 developmental window for PKN2 in ventricular morphogenesis, linking its loss to cytoskeletal/motility induction, mitotic repression, and reduced cardiomyocyte proliferation.","evidence":"Constitutive and inducible cardiomyocyte-specific knockouts, light-sheet morphometrics, RNA-seq, proteomics, phosphoproteomics, and EdU/BrdU proliferation assays","pmids":["42143091"],"confidence":"High","gaps":["Direct phosphorylation targets driving the proliferation/morphology programs not pinpointed","Mechanistic link between actin program induction and ventricular geometry defect not established"]},{"year":null,"claim":"The direct physiological substrates that mediate PKN2's cytoskeletal, junctional, cell-cycle, and developmental functions remain largely unidentified, and how upstream signals select among its many regulatory inputs (GTPase, lipid, PDK1, dimerization, ubiquitination) is unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No comprehensive substrate map for endogenous PKN2","Mechanistic integration of competing autoinhibitory and activating inputs in cells not established","No high-resolution structure of the full-length regulated kinase"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,9,22,29]},{"term_id":"GO:0140097","term_label":"catalytic activity, acting on DNA","supporting_discovery_ids":[16]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,2,3]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[2]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[2,4,31]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[14,31]},{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[24]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,7,14,28]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[9,21]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[19,21,26,33]},{"term_id":"R-HSA-1500931","term_label":"Cell-Cell communication","supporting_discovery_ids":[7,14,31]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[3,12,32]}],"complexes":[],"partners":["RHOA","RAC1","PDPK1","FYN","SAV1","HIF1A","TRIM40","DUSP6"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q16513","full_name":"Serine/threonine-protein kinase N2","aliases":["PKN gamma","Protein kinase C-like 2","Protein-kinase C-related kinase 2"],"length_aa":984,"mass_kda":112.0,"function":"PKC-related serine/threonine-protein kinase and Rho/Rac effector protein that participates in specific signal transduction responses in the cell. Plays a role in the regulation of cell cycle progression, actin cytoskeleton assembly, cell migration, cell adhesion, tumor cell invasion and transcription activation signaling processes. Phosphorylates CTTN in hyaluronan-induced astrocytes and hence decreases CTTN ability to associate with filamentous actin. Phosphorylates HDAC5, therefore lead to impair HDAC5 import. Direct RhoA target required for the regulation of the maturation of primordial junctions into apical junction formation in bronchial epithelial cells. Required for G2/M phases of the cell cycle progression and abscission during cytokinesis in a ECT2-dependent manner. Stimulates FYN kinase activity that is required for establishment of skin cell-cell adhesion during keratinocytes differentiation. Regulates epithelial bladder cells speed and direction of movement during cell migration and tumor cell invasion. Inhibits Akt pro-survival-induced kinase activity. Mediates Rho protein-induced transcriptional activation via the c-fos serum response factor (SRF). Involved in the negative regulation of ciliogenesis (PubMed:27104747) (Microbial infection) Phosphorylates HCV NS5B leading to stimulation of HCV RNA replication","subcellular_location":"Cytoplasm; Nucleus; Membrane; Cell projection, lamellipodium; Cytoplasm, cytoskeleton; Cleavage furrow; Midbody; Cell junction","url":"https://www.uniprot.org/uniprotkb/Q16513/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PKN2","classification":"Not Classified","n_dependent_lines":367,"n_total_lines":1208,"dependency_fraction":0.3038079470198676},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000065243","cell_line_id":"CID001240","localizations":[{"compartment":"cytoplasmic","grade":3},{"compartment":"er","grade":3},{"compartment":"membrane","grade":1},{"compartment":"nucleoplasm","grade":1}],"interactors":[{"gene":"PDCD11","stoichiometry":10.0},{"gene":"CETN2","stoichiometry":4.0},{"gene":"CAPZB","stoichiometry":0.2},{"gene":"FKBP5","stoichiometry":0.2},{"gene":"PKN1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID001240","total_profiled":1310},"omim":[{"mim_id":"602549","title":"PROTEIN KINASE N2; PKN2","url":"https://www.omim.org/entry/602549"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Intermediate filaments","reliability":"Supported"},{"location":"Nuclear bodies","reliability":"Additional"},{"location":"Plasma membrane","reliability":"Additional"},{"location":"Centrosome","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PKN2"},"hgnc":{"alias_symbol":["PRK2","Pak-2","STK7"],"prev_symbol":["PRKCL2"]},"alphafold":{"accession":"Q16513","domains":[{"cath_id":"1.10.287.160","chopping":"39-108","consensus_level":"medium","plddt":78.39,"start":39,"end":108},{"cath_id":"1.10.287.160","chopping":"133-204","consensus_level":"medium","plddt":71.1075,"start":133,"end":204},{"cath_id":"1.10.287.160","chopping":"215-295","consensus_level":"medium","plddt":80.3379,"start":215,"end":295},{"cath_id":"3.30.200.20","chopping":"655-742_942-979","consensus_level":"high","plddt":88.3224,"start":655,"end":979},{"cath_id":"1.10.510.10","chopping":"744-927","consensus_level":"high","plddt":93.0809,"start":744,"end":927}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q16513","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q16513-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q16513-F1-predicted_aligned_error_v6.png","plddt_mean":71.44},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PKN2","jax_strain_url":"https://www.jax.org/strain/search?query=PKN2"},"sequence":{"accession":"Q16513","fasta_url":"https://rest.uniprot.org/uniprotkb/Q16513.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q16513/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q16513"}},"corpus_meta":[{"pmid":"10226025","id":"PMC_10226025","title":"PDK1 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(PK-N2).","date":"1990","source":"Hybridoma","url":"https://pubmed.ncbi.nlm.nih.gov/2076898","citation_count":8,"is_preprint":false},{"pmid":"30947997","id":"PMC_30947997","title":"An epoxysilane modified indium tin oxide electrode for the determination of PAK 2: Application in human serum samples.","date":"2019","source":"Analytica chimica acta","url":"https://pubmed.ncbi.nlm.nih.gov/30947997","citation_count":8,"is_preprint":false},{"pmid":"17543336","id":"PMC_17543336","title":"c-Abl-binding protein interacts with p21-activated kinase 2 (PAK-2) to regulate PDGF-induced membrane ruffles.","date":"2007","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/17543336","citation_count":7,"is_preprint":false},{"pmid":"35895078","id":"PMC_35895078","title":"Genome-Wide Association Study for Idiopathic Ventricular Tachyarrhythmias Identifies Key Role of CCR7 and PKN2 in Calcium Homeostasis and Cardiac Rhythm Maintenance.","date":"2022","source":"Circulation. Genomic and precision medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35895078","citation_count":7,"is_preprint":false},{"pmid":"15907542","id":"PMC_15907542","title":"Cryptic plasmid pRK2 from Escherichia coli W: sequence analysis and segregational stability.","date":"2005","source":"Plasmid","url":"https://pubmed.ncbi.nlm.nih.gov/15907542","citation_count":6,"is_preprint":false},{"pmid":"39560431","id":"PMC_39560431","title":"PKN2 Is a Dependency of the Mesenchymal-like Cancer Cell State.","date":"2025","source":"Cancer discovery","url":"https://pubmed.ncbi.nlm.nih.gov/39560431","citation_count":5,"is_preprint":false},{"pmid":"35730579","id":"PMC_35730579","title":"PKN2 deficiency leads both to prenatal 'congenital' cardiomyopathy and defective angiotensin II stress responses.","date":"2022","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/35730579","citation_count":5,"is_preprint":false},{"pmid":"35104640","id":"PMC_35104640","title":"Development of 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HIF-1α in Colon Cancer.","date":"2025","source":"The Kaohsiung journal of medical sciences","url":"https://pubmed.ncbi.nlm.nih.gov/40515512","citation_count":2,"is_preprint":false},{"pmid":"38505918","id":"PMC_38505918","title":"Increased PKN2 and M2-Polarized Macrophages Promote HCT116 Cell Invasion.","date":"2024","source":"Critical reviews in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/38505918","citation_count":2,"is_preprint":false},{"pmid":"40069590","id":"PMC_40069590","title":"PKN2 enhances the immunosuppressive activity of polymorphonuclear myeloid-derived suppressor cells in esophageal carcinoma by mediating fatty acid oxidation.","date":"2025","source":"Molecular medicine (Cambridge, Mass.)","url":"https://pubmed.ncbi.nlm.nih.gov/40069590","citation_count":2,"is_preprint":false},{"pmid":"41276909","id":"PMC_41276909","title":"Identification of PKN2 and MOB4 as Coordinators of Collective Cell Migration.","date":"2025","source":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/41276909","citation_count":1,"is_preprint":false},{"pmid":"39002682","id":"PMC_39002682","title":"Molecular insights into the regulatory landscape of PKC-related kinase-2 (PRK2/PKN2) using targeted small compounds.","date":"2024","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/39002682","citation_count":0,"is_preprint":false},{"pmid":"41572508","id":"PMC_41572508","title":"TRIM40 Drives Pathological Cardiac Hypertrophy and Heart Failure via Ubiquitination of PKN2.","date":"2026","source":"Advanced science (Weinheim, Baden-Wurttemberg, Germany)","url":"https://pubmed.ncbi.nlm.nih.gov/41572508","citation_count":0,"is_preprint":false},{"pmid":"39575558","id":"PMC_39575558","title":"PKN2 Promotes Peripheral Nerve Repair by Regulating Autophagy via Activation of the AKT-mTOR Pathway: An In Vitro Study.","date":"2024","source":"Journal of biochemical and molecular 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Interaction with Rho is nucleotide-independent, whereas interaction with Rac is GTP-dependent. Association with either GTPase stimulates PRK2 kinase activity. Expression of kinase-deficient PRK2 in microinjected fibroblasts disrupts actin stress fibers, establishing PRK2 as a downstream effector of Rho/Rac that regulates actin cytoskeletal organization.\",\n      \"method\": \"Biochemical purification of p140 from tissues, peptide microsequencing, in vitro binding/nucleotide-dependence assays, in vitro kinase assays with activated GTPases, dominant-negative microinjection into fibroblasts with actin staining\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding assays, in vitro kinase activity, and dominant-negative cellular phenotype in a single focused study; replicated conceptually by multiple subsequent papers\",\n      \"pmids\": [\"9121475\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"PRK2 specifically binds to the middle SH3 domain of the NCK adapter protein and interacts with Rho in a GTP-dependent manner. PRK2 cooperates with Rho family proteins to activate serum response factor (SRF)-dependent transcription, suggesting it bridges receptor tyrosine kinase signals (via NCK) with Rho-dependent transcriptional outputs.\",\n      \"method\": \"Bacterial expression library screen with NCK SH3 domains, in vitro GST pulldown, GTP-dependence binding assays, SRF luciferase reporter assays, mouse chromosome mapping by interspecific backcross\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding assays and functional reporter assay in a single lab\",\n      \"pmids\": [\"8910519\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Rat PRK2 (isolated as PAK-2/PRK2 from liver) is a 130-kDa cytosolic serine/threonine kinase activated by acidic phospholipids (especially cardiolipin) and unsaturated fatty acids. Its catalytic properties — substrate preferences, sensitivity to PKC pseudosubstrate inhibitors — are distinct from but overlapping with PKN/PRK1.\",\n      \"method\": \"Protein purification to homogeneity, tryptic peptide sequencing, RT-PCR cDNA analysis, in vitro kinase assays with lipid activators and peptide substrates\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro biochemical characterization with purified enzyme, single lab\",\n      \"pmids\": [\"9092545\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"The C-terminal PDK1-interacting fragment (PIF) of PRK2 docks to PDK1 via a conserved hydrophobic motif; this interaction converts PDK1 from an enzyme that phosphorylates only PKBα Thr308 to one that also phosphorylates Ser473 in a PtdIns(3,4,5)P3-dependent manner, and activates PDK1 ~3-fold by PtdIns(3,4,5)P3. Mutation of conserved PIF residues abolishes the interaction. PRK2 is identified as a probable PDK1 substrate.\",\n      \"method\": \"In vitro kinase assays, PDK1–PIF peptide binding assays, mutagenesis of PIF motif, partial purification of brain PDK2 activity and immunoprecipitation with PDK1 antibodies\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstituted in vitro with mutagenesis, replicated across subsequent AGC kinase studies\",\n      \"pmids\": [\"10226025\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"PRK2 is expressed as the predominant PKC-like maternal transcript in starfish oocytes, localizes to the cytoplasm in immature oocytes, and redistributes partially to the disintegrating germinal vesicle during meiotic maturation. PRK2 is phosphorylated in vivo in response to 1-methyladenine stimulus, preceding MPF activation, placing it as an early regulator during meiotic re-entry.\",\n      \"method\": \"RT-PCR cloning, subcellular fractionation/immunolocalization, in vivo 32P-labeling after 1-methyladenine stimulation\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization and in vivo phosphorylation with functional context, single lab\",\n      \"pmids\": [\"9466886\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"During TNF-induced apoptosis, caspase cleavage of PRK2 generates a C-terminal fragment (aa 862–908) that specifically binds Akt (identified by yeast two-hybrid and confirmed in mammalian cells) and inhibits Akt kinase activity by blocking phosphorylation at Thr308 and Ser473, leading to inhibition of downstream Akt signaling including BAD phosphorylation and anti-apoptotic activity.\",\n      \"method\": \"Yeast two-hybrid screen, co-immunoprecipitation in mammalian cells, in vitro and in vivo kinase assays, apoptosis assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — yeast two-hybrid confirmed by co-IP, functional kinase inhibition shown, single lab\",\n      \"pmids\": [\"10926925\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"PRK2 interacts with the PDZ3 domain of the protein tyrosine phosphatase PTP-BL via the extreme C-terminal cysteine of PRK2 (a novel PDZ-binding motif). This interaction was demonstrated by yeast two-hybrid and co-immunoprecipitation from transfected HeLa cells, with co-localization of both proteins in lamellipodia-like structures.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation from transfected HeLa cells, site-directed mutagenesis of C-terminal cysteine, immunofluorescence co-localization\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal yeast two-hybrid and co-IP with mutagenesis, single lab\",\n      \"pmids\": [\"11356191\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Rho–PRK2 signaling promotes keratinocyte cell-cell adhesion via activation of the Fyn tyrosine kinase. An activated Rho mutant defective in PRK2/PKN binding fails to induce cell-cell adhesion. Increased endogenous PRK2 kinase activity during keratinocyte differentiation is sufficient to promote cell-cell adhesion, induce tyrosine phosphorylation of β- and γ-catenin and p120ctn, and activate Fyn, placing PRK2 as a Rho effector upstream of Fyn in this pathway.\",\n      \"method\": \"Dominant-negative and constitutively active Rho mutants, Rho mutants with defective PRK2 binding, PRK2 overexpression, kinase activity assays, co-immunoprecipitation, tyrosine phosphorylation assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — epistasis defined by Rho mutant defective in PRK2 binding, kinase activity assays, and cellular phenotype; multiple orthogonal approaches\",\n      \"pmids\": [\"11777936\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"A caspase-3-generated C-terminal PRK2 fragment inhibits PDK1 autophosphorylation by >90% and blocks PDK1-mediated phosphorylation of PKC-ζ and PKC-δ in vitro and in vivo. The C-terminal tail of PKC is required for PKC-ζ/δ phosphorylation by PDK1. This establishes that the apoptotic PRK2 cleavage product acts as a potent negative regulator of PDK1.\",\n      \"method\": \"Yeast two-hybrid PDK1 bait screen, co-precipitation from mammalian cells, in vitro PDK1 kinase assays, in vivo phosphorylation assays with PRK2 fragment expression\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro and in vivo kinase inhibition assays, single lab, consistent with prior PDK1–PRK2 interaction data\",\n      \"pmids\": [\"11781095\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"PRK2 is required for entry into mitosis and exit from cytokinesis in HeLa cells. Specifically, PRK2 is required for abscission at the midbody at the end of cell division, and for phosphorylation and activation of Cdc25B, the phosphatase that activates mitotic cyclin/Cdk1 at the G2/M transition. This links Rho GTPase signaling through PRK2 to cell cycle control.\",\n      \"method\": \"siRNA depletion of PRK2 in HeLa S3 cells, live-cell imaging, immunofluorescence for mitotic markers, Cdc25B phosphorylation assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — siRNA loss-of-function with specific mitotic and cytokinetic phenotypes and defined molecular substrate (Cdc25B), single rigorous study\",\n      \"pmids\": [\"17332740\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"The extreme C-terminal segment of PRK2 is critical for full activation by RhoA in cells in a GTP-dependent manner, although it is dispensable for in vitro activation by RhoA. Two conserved threonines in the activation loop and turn motif are essential for catalytic activity; the phosphomimetic Asp-978 at the hydrophobic motif is dispensable. The PRK2-Δ958 mutant (turn motif truncated) still interacts with PDK1, indicating the hydrophobic and turn motifs are dispensable for PDK1 docking.\",\n      \"method\": \"Structure-function mutagenesis, in vitro kinase assays, in vivo RhoA activation assays, PDK1 co-immunoprecipitation\",\n      \"journal\": \"Archives of biochemistry and biophysics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis with in vitro and in vivo kinase assays, single lab\",\n      \"pmids\": [\"18835241\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Both ROCK and PRK2 kinases promote polyglutamine (huntingtin and androgen receptor) aggregation in cultured cells. Overexpression of either increases aggregation; RNAi knockdown of either reduces aggregation; and the inhibitory effect of Y-27632 on aggregation requires both kinases (epistasis by RNAi).\",\n      \"method\": \"Overexpression and RNAi knockdown in cell-based aggregation assays with ROCK-specific inhibitors\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function and gain-of-function with pharmacological validation, single lab\",\n      \"pmids\": [\"18423405\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"PDK1 phosphorylates the activation loop of PRK2. In-vivo 32P labeling identified two PRK2 phosphorylation sites: the activation loop and the zipper/turn-motif (Z/TM) in the C-terminal extension. Phosphorylation of the Z/TM site negatively regulates PRK2 docking to PDK1, providing a self-limiting regulatory mechanism where PRK2 activation inhibits further PDK1 interaction.\",\n      \"method\": \"In vivo 32P labeling of recombinant PRK2, phosphopeptide mapping/mass spectrometry, PDK1 docking interaction assays with phospho-site mutants\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vivo phosphorylation site mapping combined with mechanistic docking assays, multiple orthogonal methods, single lab\",\n      \"pmids\": [\"19723632\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"The Yersinia effector YopM interacts with PRK2 via an internal leucine-rich repeat region (LRR6–LRR15). Both the PRK2-binding domain and the RSK1-binding domain of YopM are required for IL-10 induction in vivo and for virulence, establishing that PRK2 is co-opted by a bacterial effector as part of a signaling complex that suppresses host immunity.\",\n      \"method\": \"In vitro binding assays with truncated YopM proteins, murine infection models, serum cytokine measurements, orogastric infection virulence assays\",\n      \"journal\": \"Infection and immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro domain mapping combined with in vivo genetic requirement, single lab\",\n      \"pmids\": [\"20515922\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"PRK2 is required for maturation of primordial junctions into apical junctions in human bronchial epithelial cells. PRK2 is recruited to nascent cell-cell contacts via its C2-like domain; Rho binding facilitates this recruitment and is essential for PRK2 function. Kinase-dead PRK2 acts as a dominant-negative, and RhoA binding-deficient PRK2 fails to rescue junction formation, establishing that Rho-activated PRK2 kinase activity is required downstream of Rho for apical junction maturation.\",\n      \"method\": \"siRNA library screen targeting 28 Rho effectors, PRK2 depletion by siRNA, domain-mapping with C2-like and Rho-binding mutants, kinase-dead dominant-negative, immunofluorescence localization\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — siRNA screen identification followed by domain dissection with multiple mutants and cellular phenotype, single rigorous study\",\n      \"pmids\": [\"20974804\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PRK2 regulation is mediated in trans by an intermolecular PRK2–PRK2 dimerization through its N-terminal region, which prevents interaction with upstream kinase PDK1. Amino acids 487–501 in the linker between N-terminal domains and the catalytic domain contribute to dimer formation. The C-terminal region intramolecularly activates PRK2, and the catalytic domain mediates cross-talk between inhibitory N-terminal and activating C-terminal regions.\",\n      \"method\": \"In vitro kinase assays with N-terminal and C-terminal domain constructs, PDK1 interaction assays, mutagenesis of linker region\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro biochemical dissection with domain mutants, single lab\",\n      \"pmids\": [\"22511787\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PRK2 phosphorylates the HCV NS5B RNA-dependent RNA polymerase, and this phosphorylation is required for HCV replication. Hsp90 inhibition destabilizes PDK1 (via proteasomal degradation), reducing active PRK2 levels and thereby decreasing NS5B phosphorylation and HCV genome replication.\",\n      \"method\": \"Pharmacological Hsp90 inhibition (17-DMAG), Western blotting of phospho-NS5B, HCV replicon replication assays in Huh7 cells, HCV-infected cell assays\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — defined phosphorylation substrate (NS5B) with pathway epistasis through PDK1-PRK2, single lab; confirmed by siRNA-based follow-up\",\n      \"pmids\": [\"22490666\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PRK2 HR1a and HR1b domains bind RhoA, RhoB, and RhoC with distinct affinities; RhoB binds more tightly than RhoA or RhoC to PRK isoforms. The PRK1 HR1ab didomain shows similar affinities for RhoA and RhoC as HR1a alone, but RhoB additionally recruits the HR1b domain. PRK2 HR1 domains bind all Rho isoforms less well than PRK1 domains. The PRK2 HR1a domain has the highest thermal stability among PRK HR1 domains.\",\n      \"method\": \"Quantitative binding affinity measurements (biophysical assays), thermal stability analysis, domain-specific HR1a and HR1ab constructs\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — quantitative in vitro binding assays with purified domains, single lab\",\n      \"pmids\": [\"24128008\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"H. pylori CagA toxin interacts directly with PRK2 and inhibits its kinase activity. This interaction disrupts PRK2-dependent cytoskeletal rearrangements and cell polarity pathways in host epithelial cells.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase activity assay with CagA\",\n      \"journal\": \"Cellular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct co-IP and kinase inhibition assay, single lab\",\n      \"pmids\": [\"26041307\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Constitutive PKN2 knockout in mice results in embryonic lethality at E10 with cardiovascular and morphogenetic defects. The lethal phenotype is not recapitulated by endothelial- or cardiac-specific deletion but is reproduced by inducible systemic deletion after E7, causing collapse of the embryonic mesoderm. Mouse embryonic fibroblasts from PKN2-null embryos are defective in proliferation and motility, and neural crest migration is impaired in vivo, establishing PKN2 as a non-redundant, cell-autonomous regulator of mesoderm expansion and mesodermal-cell function.\",\n      \"method\": \"Constitutive and conditional PKN2 knockout mice, inducible systemic deletion (tamoxifen-inducible), tissue-specific Cre deletions, MEF proliferation/motility assays, in vivo neural crest migration analysis\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple independent genetic models with specific cellular phenotypes, replicated by independent PKN2 knockout study (PMID:28102564)\",\n      \"pmids\": [\"26774483\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"PKN2 forms a complex with Cdo, APPL1, and AKT via its C-terminal region during myoblast differentiation, and this interaction promotes AKT activation and myoblast differentiation. PKN2 overexpression enhances C2C12 differentiation; PKN2 depletion impairs it. PKN2 also mediates recruitment of BAF60c and MyoD to the myogenin promoter, promoting MyoD-responsive transcription.\",\n      \"method\": \"Co-immunoprecipitation, shRNA knockdown, overexpression in C2C12 myoblasts, MyoD-responsive luciferase reporter assay, ChIP for BAF60c and MyoD at myogenin promoter, differentiation marker assays\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, ChIP, and loss/gain-of-function with multiple cellular phenotypes, single lab\",\n      \"pmids\": [\"27763641\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"PKN2 knockout MEFs fail to proliferate, and Cre-mediated ablation of PKN2 in floxed MEFs causes impaired cell proliferation with a decrease in S-phase population by cell cycle analysis. PKN2 knockout mouse embryos fail to undergo axial turning and show insufficient neural tube closure, confirming non-redundant in vivo functions distinct from PKN1 and PKN3.\",\n      \"method\": \"Constitutive PKN2 knockout mice, Cre-mediated conditional deletion in MEFs, cell cycle analysis (flow cytometry), proliferation assays\",\n      \"journal\": \"Genes to cells\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout confirmed in two cell systems with defined cell cycle phenotype; independently replicates PMID:26774483\",\n      \"pmids\": [\"28102564\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"PKN2 in colon cancer cells directly associates with and phosphorylates/activates DUSP6, a dual-specificity phosphatase that dephosphorylates/inactivates ERK1/2. This suppresses ERK1/2 phosphorylation, reducing CREB/Elk-1 binding to IL-4 and IL-10 promoters, thereby inhibiting M2 macrophage polarization.\",\n      \"method\": \"Co-immunoprecipitation (Co-IP) of PKN2 and DUSP6, kinase activity assay for PKN2 on DUSP6, ChIP-qPCR for CREB/Elk-1, luciferase promoter assays, PKN2 siRNA, xenograft models\",\n      \"journal\": \"Molecular cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct Co-IP, kinase activity assay, and ChIP-qPCR, single lab\",\n      \"pmids\": [\"29368606\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Muscle-specific genetic ablation of PAK2/PKN2 (note: this paper uses 'PAK2' to refer to the p21-activated kinase PAK2, NOT PKN2/PRK2; the gene symbol collision must be assessed). Assessment: The paper describes PAK2 (group I PAK family, activated by Rac/Cdc42) in insulin-stimulated glucose uptake in skeletal muscle — this is PAK2 (gene: PAK2), NOT PKN2/PRK2. EXCLUDED as alias collision.\",\n      \"method\": \"N/A\",\n      \"journal\": \"The Journal of physiology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Excluded — alias collision (PAK2 = p21-activated kinase 2, different gene from PKN2/PRK2)\",\n      \"pmids\": [\"32844438\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PKN2 localizes to the transition zone of primary cilia upon serum withdrawal (where activating pPRK2 signal is detected), and co-depletion of PRK1 and PRK2 results in reduced cilia length, impaired planar polarity, and impaired cilia-associated signaling. PRK2 depletion also reduces spheroid growth.\",\n      \"method\": \"Immunofluorescence localization of phospho-PRK1/2, siRNA co-depletion, cilia length measurement, planar polarity assays, spheroid growth assays, proteomic identification of PRK2 binding partners\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization and loss-of-function with defined cilia phenotype, single lab\",\n      \"pmids\": [\"32127582\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PKN2 depletion in fibroblasts reduces cell motility velocity and delays recovery of N-cadherin expression (both protein and mRNA) after trypsin dissociation, impairing cell aggregate compaction and spheroid formation in suspension culture. This establishes PKN2 as a regulator of N-cadherin transcription and cell motility required for spheroid formation.\",\n      \"method\": \"Cre-mediated PKN2 deletion in floxed fibroblasts, time-lapse microscopy, immunoblot for N-cadherin, RT-qPCR for N-cadherin mRNA, spheroid formation assays in low-attachment plates\",\n      \"journal\": \"Biochemistry and biophysics reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional KO with multiple phenotypic readouts and mRNA analysis, single lab\",\n      \"pmids\": [\"33437883\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PKN2 promotes cardiac hypertrophy downstream of angiotensin II: cardiomyocyte-specific PKN2 knockout causes developmental myocardial defects (clefts, ventricular septal defects) and PKN2 haploinsufficiency in adults attenuates angiotensin II-induced cardiac hypertrophy, cardiomyocyte hypertrophy, and fibrosis.\",\n      \"method\": \"Cardiomyocyte-specific conditional PKN2 knockout, global PKN2 haploinsufficiency, angiotensin II infusion model, high-resolution episcopic microscopy, MRI, micro-CT, echocardiography, histology, RNAseq\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple independent genetic models with detailed cardiac phenotyping using multiple imaging modalities\",\n      \"pmids\": [\"35730579\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"PKN2 allosteric regulation involves a PIF-pocket that communicates with both the ATP-binding site and the pseudosubstrate PKL-binding site. A small compound binding to the PIF-pocket can act as either an allosteric activator (displacing the PKL pseudosubstrate from the active site) or an allosteric inhibitor of PRK2 catalytic activity. PIFtide peptide binding to the PIF-pocket similarly activates PRK2 allosterically. At least two distinct complexes between PRK2 and PDK1 were identified.\",\n      \"method\": \"Chemical biology with small compound PIF-pocket ligands, in vitro kinase assays, allosteric activation/inhibition assays, binding interaction studies with PDK1\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution with chemical tools and mechanistic interpretation, single lab\",\n      \"pmids\": [\"39002682\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PKN2 promotes mesenchymal-like cancer cell growth through a PKN2–SAV1–TAZ signaling mechanism, identifying PKN2 as a core regulator of the Hippo tumor suppressor pathway. Biochemical experiments demonstrated the PKN2-SAV1-TAZ interaction, and genetic PKN2 inhibition suppresses drug-tolerant persister cells driven by the mesenchymal-like state.\",\n      \"method\": \"Genome-wide essentiality analysis (~800 cancer cell lines), co-essentiality mapping, biochemical interaction experiments (Co-IP/pulldown), genomic analysis of patient tumors, genetic PKN2 inhibition combined with targeted therapies\",\n      \"journal\": \"Cancer discovery\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — biochemical interaction confirmed with functional genetic validation, single lab; novel pathway placement\",\n      \"pmids\": [\"39560431\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PKN2 directly interacts with HIF-1α protein, phosphorylates it, and induces ubiquitination-dependent degradation of HIF-1α, thereby suppressing HIF-1α nuclear accumulation and transcription of VEGFA and bFGF. This inhibits tumor angiogenesis in colon cancer.\",\n      \"method\": \"Co-immunoprecipitation of PKN2 and HIF-1α, in vitro phosphorylation assay, ubiquitination assay, HIF-1α nuclear localization by fractionation/immunofluorescence, VEGFA/bFGF promoter assays, in vitro and in vivo tumor angiogenesis models\",\n      \"journal\": \"The Kaohsiung journal of medical sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct biochemical interaction, phosphorylation, and ubiquitination assays with functional angiogenesis phenotype, single lab\",\n      \"pmids\": [\"40515512\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PKN2 promotes immunosuppressive activity of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) in esophageal cancer by upregulating STAT3 phosphorylation, which drives CPT1B transcription and fatty acid oxidation (FAO) in PMN-MDSCs.\",\n      \"method\": \"PKN2 overexpression in PMN-MDSCs, co-culture with T cells and organoids, Western blotting for phospho-STAT3 and CPT1B, FAO measurement assays\",\n      \"journal\": \"Molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gain-of-function with defined downstream signaling (STAT3-CPT1B) and functional immunosuppression readout, single lab\",\n      \"pmids\": [\"40069590\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Upon wound healing, PKN2 relocalizes from cytoplasm to lateral cell-cell junctions in MCF10A epithelial monolayers, where it stabilizes adherens junctions and maintains coordinated collective migration. PKN2 CRISPR KO reduces collective migration due to destabilization of adherens junctions.\",\n      \"method\": \"CRISPR/Cas9 PKN2 knockout, wound healing assay, live-cell imaging, immunofluorescence for junction markers, PKN2 relocalization imaging\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR KO with defined junction phenotype and direct relocalization imaging, single lab\",\n      \"pmids\": [\"41276909\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"The E3 ubiquitin ligase TRIM40 binds PKN2 via its B-box domain and promotes K63-linked ubiquitination of PKN2 in an E3 ligase activity-dependent manner, enhancing PKN2 phosphorylation at Ser815 and activating downstream pro-hypertrophic signaling. Pharmacological inhibition of PKN2 attenuates cardiac remodeling induced by TRIM40 overexpression.\",\n      \"method\": \"TRIM40 knockout and overexpressing mice, angiotensin II/TAC hypertrophy models, Co-IP to map TRIM40-PKN2 interaction, ubiquitination assays (K63-linkage), phospho-PKN2 Ser815 Western blot, PKN2 inhibitor rescue\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding, ubiquitination, and phosphorylation assays in genetic models, single lab\",\n      \"pmids\": [\"41572508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Cardiomyocyte-specific PKN2 knockout causes a ventricular geometry defect traceable to a critical developmental window (E7.5–E10.5). Tamoxifen-induced deletion at E7.5 reproduces the 'coin-pouch' ventricular geometry; deletion at E10.5 spares morphology. Integrative omics at E10.5 reveals transcriptional and proteomic induction of actin cytoskeleton/motility programs with repression of mitotic modules, alongside reduced cardiomyocyte proliferation at E10.5–E11.5.\",\n      \"method\": \"Constitutive and inducible cardiomyocyte-specific PKN2 CRE knockout, light-sheet microscopy-based morphometrics, RNA-seq, proteomics, phosphoproteomics, cardiomyocyte proliferation assays (EdU/BrdU)\",\n      \"journal\": \"Communications biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple independent genetic models with temporal induction, quantitative morphometrics, and multi-omics mechanistic insight, single lab\",\n      \"pmids\": [\"42143091\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PKN2/PRK2 is a Rho/Rac-activated AGC-family serine/threonine kinase that is phosphorylated and activated by PDK1 (via a PIF-docking mechanism regulated by Z/TM site phosphorylation and intermolecular dimerization), acts downstream of RhoA and Rac1 to regulate actin cytoskeleton organization, apical junction maturation, cell-cell adhesion (via Fyn activation), collective cell migration, and cell cycle progression (G2/M entry via Cdc25B phosphorylation and cytokinetic abscission); it also integrates into the Hippo pathway through a PKN2–SAV1–TAZ axis, phosphorylates and destabilizes HIF-1α to suppress angiogenesis, is regulated by K63-linked ubiquitination by TRIM40, and is essential in vivo for mesoderm expansion, cardiac morphogenesis, and neural tube closure.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PKN2 (PRK2) is a Rho/Rac-activated AGC-family serine/threonine kinase that couples small-GTPase signaling to actin cytoskeletal organization, cell-cell adhesion, cell-cycle progression, and developmental morphogenesis [#0, #14]. It binds RhoA in a nucleotide-independent manner and Rac1 in a GTP-dependent manner, and association with either GTPase stimulates its kinase activity; loss of activity disrupts actin stress fibers, defining PKN2 as a Rho/Rac effector on the cytoskeleton [#0, #17]. Its catalytic output is set by PDK1, which docks to the C-terminal PDK1-interacting fragment (PIF) and phosphorylates the activation loop; this docking is self-limited by phosphorylation of the zipper/turn-motif (Z/TM) site and by intermolecular N-terminal dimerization, and the PIF-pocket additionally communicates allosterically with the active site and the autoinhibitory pseudosubstrate [#3, #12, #15, #27]. Downstream, PKN2 promotes Rho-dependent keratinocyte cell-cell adhesion by activating Fyn and driving catenin tyrosine phosphorylation [#7], matures primordial into apical junctions through C2-domain- and Rho-dependent recruitment to nascent contacts [#14], and relocalizes to lateral junctions to stabilize adherens junctions during coordinated collective migration [#31]. In cell-cycle control, PKN2 is required for G2/M entry via phosphorylation and activation of Cdc25B and for cytokinetic abscission at the midbody [#9]. PKN2 is non-redundantly essential in vivo: constitutive knockout is embryonic lethal at E10 with collapse of the expanding mesoderm, impaired neural crest migration, failed axial turning, and defective neural tube closure, and cardiomyocyte-specific deletion produces ventricular geometry defects within an E7.5–E10.5 window accompanied by reduced cardiomyocyte proliferation [#19, #21, #26, #33]. Additional signaling roles include the Hippo pathway via a PKN2–SAV1–TAZ axis [#28], phosphorylation and ubiquitination-dependent destabilization of HIF-1α to suppress angiogenesis [#29], activation of DUSP6 to restrain ERK1/2 signaling [#22], and regulation by TRIM40-mediated K63-linked ubiquitination that enhances Ser815 phosphorylation in pro-hypertrophic cardiac signaling [#32].\",\n  \"teleology\": [\n    {\n      \"year\": 1996,\n      \"claim\": \"Established that PRK2 links adapter-based receptor tyrosine kinase signaling to Rho-dependent transcription, before its kinase function was characterized.\",\n      \"evidence\": \"Bacterial expression library screen with NCK SH3 domains, GST pulldowns, and SRF luciferase reporter assays\",\n      \"pmids\": [\"8910519\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not establish whether NCK recruitment regulates PRK2 catalytic activity\", \"Physiological context of the NCK–PRK2–Rho–SRF axis not defined in vivo\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Defined PRK2 as a Rho/Rac effector that regulates the actin cytoskeleton, resolving how a single kinase reads two distinct GTPases.\",\n      \"evidence\": \"Biochemical purification of p140, reciprocal nucleotide-dependent binding assays, in vitro kinase assays, and dominant-negative microinjection into fibroblasts with actin staining\",\n      \"pmids\": [\"9121475\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct cytoskeletal substrates not identified\", \"Mechanism distinguishing nucleotide-independent Rho versus GTP-dependent Rac binding unresolved\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Characterized PRK2 as a lipid-responsive kinase, showing its activity is tuned by acidic phospholipids and fatty acids in addition to GTPases.\",\n      \"evidence\": \"Purification to homogeneity and in vitro kinase assays with lipid activators and peptide substrates\",\n      \"pmids\": [\"9092545\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether lipid activation operates in cells alongside GTPase activation unclear\", \"Physiological substrates of lipid-activated PRK2 not defined\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Identified PRK2 as a PDK1 substrate and revealed that its PIF motif reciprocally tunes PDK1 specificity, embedding PRK2 in AGC kinase regulatory logic.\",\n      \"evidence\": \"In vitro kinase assays, PDK1–PIF peptide binding assays, and PIF-motif mutagenesis\",\n      \"pmids\": [\"10226025\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not map the PRK2 activation-loop site phosphorylated by PDK1\", \"Cellular consequences of PDK1-dependent PRK2 activation not shown\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Showed that caspase cleavage converts PRK2 into a fragment that suppresses Akt, linking PRK2 proteolysis to pro-apoptotic signaling.\",\n      \"evidence\": \"Yeast two-hybrid, co-immunoprecipitation, in vitro/in vivo kinase assays, and apoptosis assays\",\n      \"pmids\": [\"10926925\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether endogenous cleavage levels are sufficient to inhibit Akt in vivo unclear\", \"Relationship between full-length PRK2 signaling and the cleaved fragment not reconciled\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Identified PTP-BL as a PDZ-domain partner anchoring PRK2 at lamellipodia, suggesting localized control of PRK2 at sites of actin remodeling.\",\n      \"evidence\": \"Yeast two-hybrid, co-IP from HeLa cells, C-terminal cysteine mutagenesis, and immunofluorescence co-localization\",\n      \"pmids\": [\"11356191\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of PTP-BL binding on PRK2 activity not determined\", \"Single reciprocal Co-IP without endogenous validation\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Placed PRK2 as a Rho effector upstream of Fyn in driving cell-cell adhesion, connecting GTPase signaling to junctional catenin phosphorylation.\",\n      \"evidence\": \"Rho mutants defective in PRK2 binding, PRK2 overexpression, kinase activity assays, and tyrosine phosphorylation assays in keratinocytes\",\n      \"pmids\": [\"11777936\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PRK2 phosphorylates Fyn directly not established\", \"Direct junctional substrates of PRK2 not identified\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Demonstrated that the apoptotic PRK2 C-terminal fragment is a potent negative regulator of PDK1, broadening its inhibitory reach to atypical PKCs.\",\n      \"evidence\": \"Yeast two-hybrid PDK1 bait screen, co-precipitation, and in vitro/in vivo PDK1 kinase assays\",\n      \"pmids\": [\"11781095\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological abundance and timing of the inhibitory fragment in apoptosis not quantified\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Connected PRK2 to cell-cycle control, identifying it as required for Cdc25B-driven G2/M entry and for cytokinetic abscission.\",\n      \"evidence\": \"siRNA depletion in HeLa cells, live-cell imaging, mitotic-marker immunofluorescence, and Cdc25B phosphorylation assays\",\n      \"pmids\": [\"17332740\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PRK2 phosphorylates Cdc25B directly not formally proven\", \"Abscission substrates at the midbody not identified\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Dissected the structural determinants of PRK2 activation, defining activation-loop and turn-motif requirements and the GTP-dependent role of the C-terminus.\",\n      \"evidence\": \"Structure-function mutagenesis with in vitro and in vivo kinase assays and PDK1 co-IP\",\n      \"pmids\": [\"18835241\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Atomic structure of the regulatory regions not determined\", \"Discrepancy between in vitro and in-cell C-terminal requirements unexplained\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Implicated PRK2, together with ROCK, in promoting polyglutamine aggregation, extending Rho-kinase signaling to protein-aggregation disease models.\",\n      \"evidence\": \"Overexpression and RNAi in cell-based aggregation assays with ROCK-specific inhibitors\",\n      \"pmids\": [\"18423405\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct substrate linking PRK2 to aggregation not identified\", \"Relevance to neurodegenerative disease in vivo not tested\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Mapped PRK2 phosphorylation sites and revealed a self-limiting feedback: Z/TM phosphorylation blocks further PDK1 docking.\",\n      \"evidence\": \"In vivo 32P labeling, phosphopeptide mapping/MS, and PDK1 docking assays with phospho-site mutants\",\n      \"pmids\": [\"19723632\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinase responsible for Z/TM phosphorylation not identified\", \"Dynamics of the feedback loop in cells not measured\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Established PRK2 as required for apical junction maturation, defining C2-domain- and Rho-dependent recruitment to nascent cell contacts.\",\n      \"evidence\": \"siRNA screen of Rho effectors, domain-mapping mutants, kinase-dead dominant-negative, and immunofluorescence in bronchial epithelium\",\n      \"pmids\": [\"20974804\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Junctional substrates phosphorylated by PRK2 not identified\", \"Link to the Fyn/catenin pathway not integrated\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Showed that the Yersinia effector YopM co-opts PRK2 as part of a host-immunosuppressive signaling complex required for virulence.\",\n      \"evidence\": \"In vitro domain-mapping binding assays and murine infection/virulence and cytokine models\",\n      \"pmids\": [\"20515922\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether YopM alters PRK2 kinase activity not determined\", \"Host substrate driving IL-10 induction not identified\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Revealed intermolecular PRK2–PRK2 dimerization as a trans-acting autoinhibitory mechanism that blocks PDK1 interaction.\",\n      \"evidence\": \"In vitro kinase assays with domain constructs, PDK1 interaction assays, and linker-region mutagenesis\",\n      \"pmids\": [\"22511787\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether dimerization is regulated in cells not shown\", \"Stoichiometry and structural basis of the dimer not resolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identified the HCV NS5B polymerase as a PRK2 substrate, showing the PDK1–PRK2 axis is required for viral genome replication.\",\n      \"evidence\": \"Hsp90 inhibition, phospho-NS5B Western blotting, and HCV replicon/infection assays in Huh7 cells\",\n      \"pmids\": [\"22490666\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"NS5B phosphosite and its functional role not fully mapped\", \"Effects pharmacologically inferred through PDK1 destabilization\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Quantified isoform-selective Rho binding by PRK2 HR1 domains, distinguishing its GTPase-recognition profile from PRK1.\",\n      \"evidence\": \"Quantitative biophysical binding affinity and thermal stability measurements with purified HR1 constructs\",\n      \"pmids\": [\"24128008\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of differential Rho-isoform binding in cells not tested\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Showed that H. pylori CagA directly binds and inhibits PRK2, disrupting cytoskeletal and polarity programs in host epithelium.\",\n      \"evidence\": \"Co-immunoprecipitation and in vitro kinase activity assays with CagA\",\n      \"pmids\": [\"26041307\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of CagA-mediated inhibition not defined\", \"Single-lab biochemical evidence without structural detail\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Established PKN2 as non-redundantly essential in vivo for mesoderm expansion and mesodermal-cell proliferation and motility, with embryonic lethality at E10.\",\n      \"evidence\": \"Constitutive, conditional, and inducible systemic PKN2 knockout mice, tissue-specific Cre deletions, and MEF proliferation/motility assays\",\n      \"pmids\": [\"26774483\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular pathway connecting PKN2 to mesoderm expansion not defined\", \"Which substrates underlie the proliferation/motility defects unknown\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Linked PKN2 to a Cdo–APPL1–AKT complex and to MyoD/BAF60c promoter recruitment driving myoblast differentiation.\",\n      \"evidence\": \"Co-IP, shRNA/overexpression in C2C12 cells, MyoD reporter assays, and ChIP at the myogenin promoter\",\n      \"pmids\": [\"27763641\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether PKN2 kinase activity is required for AKT activation not resolved\", \"Mechanism of PKN2-dependent BAF60c/MyoD recruitment unclear\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Independently confirmed PKN2's non-redundant in vivo roles, tying its loss to reduced S-phase entry, failed axial turning, and neural tube closure defects.\",\n      \"evidence\": \"Constitutive knockout mice, Cre-mediated conditional MEF deletion, and flow-cytometry cell-cycle analysis\",\n      \"pmids\": [\"28102564\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular substrate driving the S-phase defect not identified\", \"Distinction from PKN1/PKN3 functions mechanistically unexplained\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showed PKN2 phosphorylates and activates DUSP6 to restrain ERK1/2 signaling, suppressing M2 macrophage polarization in colon cancer.\",\n      \"evidence\": \"Co-IP, in vitro kinase assay on DUSP6, ChIP-qPCR, luciferase assays, and xenograft models\",\n      \"pmids\": [\"29368606\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"DUSP6 phosphosite not mapped\", \"Single-lab biochemistry without orthogonal validation of the kinase relationship\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Localized PKN2 to the ciliary transition zone and implicated it in cilium length, planar polarity, and ciliary signaling.\",\n      \"evidence\": \"Phospho-PRK1/2 immunofluorescence, siRNA co-depletion, cilia/planar-polarity assays, and proteomic partner identification\",\n      \"pmids\": [\"32127582\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Redundancy with PRK1 obscures PKN2-specific role\", \"Ciliary substrates not identified\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified PKN2 as a regulator of N-cadherin expression and motility required for spheroid compaction.\",\n      \"evidence\": \"Cre-mediated conditional deletion in fibroblasts, time-lapse imaging, immunoblot, and RT-qPCR for N-cadherin\",\n      \"pmids\": [\"33437883\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which PKN2 controls N-cadherin transcription unknown\", \"Direct transcriptional intermediates not defined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrated PKN2 promotes angiotensin-II-driven cardiac hypertrophy and is required for normal myocardial development.\",\n      \"evidence\": \"Cardiomyocyte-specific knockout, haploinsufficiency, angiotensin II infusion, multimodal cardiac imaging, histology, and RNA-seq\",\n      \"pmids\": [\"35730579\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Pro-hypertrophic substrates of PKN2 in cardiomyocytes not identified\", \"Distinction between developmental and adult hypertrophic roles not fully resolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Resolved PKN2 allosteric regulation, showing the PIF-pocket couples to the ATP site and the pseudosubstrate to act as a bidirectional activity switch.\",\n      \"evidence\": \"Chemical biology with PIF-pocket ligands, in vitro kinase and allosteric activation/inhibition assays, and PDK1 binding studies\",\n      \"pmids\": [\"39002682\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Endogenous ligand or signal engaging the PIF-pocket in cells unknown\", \"Structural basis of the two PRK2–PDK1 complexes not determined\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Placed PKN2 in the Hippo pathway via a PKN2–SAV1–TAZ axis driving mesenchymal-like cancer cell growth and persister-cell survival.\",\n      \"evidence\": \"Genome-wide essentiality and co-essentiality analysis across ~800 cell lines, biochemical interaction assays, and genetic inhibition with targeted therapies\",\n      \"pmids\": [\"39560431\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether PKN2 phosphorylates SAV1 or TAZ not established\", \"Directionality of the PKN2–SAV1–TAZ regulatory link not fully defined\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified HIF-1α as a PKN2 substrate, showing PKN2 phosphorylates and destabilizes HIF-1α to suppress tumor angiogenesis.\",\n      \"evidence\": \"Co-IP, in vitro phosphorylation and ubiquitination assays, HIF-1α fractionation, VEGFA/bFGF promoter assays, and angiogenesis models\",\n      \"pmids\": [\"40515512\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"HIF-1α phosphosite and the ubiquitin ligase recruited not identified\", \"Single-lab evidence without independent confirmation\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Linked PKN2 to immunosuppression by driving STAT3–CPT1B-dependent fatty acid oxidation in PMN-MDSCs in esophageal cancer.\",\n      \"evidence\": \"PKN2 overexpression, T-cell/organoid co-culture, phospho-STAT3/CPT1B Western blotting, and FAO assays\",\n      \"pmids\": [\"40069590\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether PKN2 phosphorylates STAT3 directly not shown\", \"Gain-of-function only; loss-of-function in MDSCs not tested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Showed PKN2 relocalizes to lateral junctions during wound healing to stabilize adherens junctions and sustain collective migration.\",\n      \"evidence\": \"CRISPR/Cas9 knockout, wound-healing assays, live-cell imaging, and junction-marker immunofluorescence in MCF10A monolayers\",\n      \"pmids\": [\"41276909\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Junctional substrate stabilizing adherens junctions not identified\", \"Signal triggering relocalization not defined\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Identified TRIM40 as an E3 ligase that K63-ubiquitinates PKN2 to enhance Ser815 phosphorylation and pro-hypertrophic cardiac signaling.\",\n      \"evidence\": \"TRIM40 knockout/overexpressing mice, AngII/TAC hypertrophy models, Co-IP, K63-linkage ubiquitination assays, phospho-Ser815 blots, and PKN2 inhibitor rescue\",\n      \"pmids\": [\"41572508\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How K63 ubiquitination mechanistically promotes Ser815 phosphorylation unclear\", \"Whether TRIM40 regulation operates outside cardiac tissue unknown\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Defined a critical E7.5–E10.5 developmental window for PKN2 in ventricular morphogenesis, linking its loss to cytoskeletal/motility induction, mitotic repression, and reduced cardiomyocyte proliferation.\",\n      \"evidence\": \"Constitutive and inducible cardiomyocyte-specific knockouts, light-sheet morphometrics, RNA-seq, proteomics, phosphoproteomics, and EdU/BrdU proliferation assays\",\n      \"pmids\": [\"42143091\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct phosphorylation targets driving the proliferation/morphology programs not pinpointed\", \"Mechanistic link between actin program induction and ventricular geometry defect not established\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The direct physiological substrates that mediate PKN2's cytoskeletal, junctional, cell-cycle, and developmental functions remain largely unidentified, and how upstream signals select among its many regulatory inputs (GTPase, lipid, PDK1, dimerization, ubiquitination) is unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No comprehensive substrate map for endogenous PKN2\", \"Mechanistic integration of competing autoinhibitory and activating inputs in cells not established\", \"No high-resolution structure of the full-length regulated kinase\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 9, 22, 29]},\n      {\"term_id\": \"GO:0140097\", \"supporting_discovery_ids\": [16]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 2, 3]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [2, 4, 31]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [14, 31]},\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [24]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 7, 14, 28]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [9, 21]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [19, 21, 26, 33]},\n      {\"term_id\": \"R-HSA-1500931\", \"supporting_discovery_ids\": [7, 14, 31]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [3, 12, 32]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"RHOA\", \"RAC1\", \"PDPK1\", \"FYN\", \"SAV1\", \"HIF1A\", \"TRIM40\", \"DUSP6\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}