{"gene":"KAZN","run_date":"2026-06-10T01:55:23","timeline":{"discoveries":[{"year":2004,"finding":"Kazrin is a novel periplakin-interacting protein; the NH2-terminal 133 amino acids of periplakin mediate association with the plasma membrane and bind kazrin. Kazrin colocalizes with periplakin and desmoplakin at desmosomes and with periplakin at the interdesmosomal plasma membrane, and is incorporated into the cornified envelope of cultured keratinocytes. Kazrin's subcellular distribution is independent of periplakin.","method":"Co-immunoprecipitation/binding assay (NH2-terminal periplakin fragment), immunofluorescence colocalization, transfection of isoforms, cornified envelope incorporation assay","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding assay with defined domain, multiple orthogonal methods (pulldown, colocalization, CE incorporation), founding paper replicated in subsequent studies","pmids":["15337775"],"is_preprint":false},{"year":2008,"finding":"Kazrin overexpression in human epidermal keratinocytes reduces filamentous actin, reorganizes keratin filaments, impairs assembly of intercellular junctions, stimulates terminal differentiation, and reduces clonal growth via decreased RhoA activity. Kazrin knockdown decreases differentiation markers and stimulates proliferation without changing total Rho activity, indicating Rho-dependent and Rho-independent mechanisms.","method":"Overexpression and siRNA knockdown in human keratinocytes, phalloidin/immunofluorescence for actin and keratin filaments, Rho activity pull-down assay (GST-rhotekin), clonal growth assay, differentiation marker immunoblotting","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal gain- and loss-of-function experiments with multiple orthogonal readouts (actin, keratin, junctions, Rho activity, differentiation markers), single lab","pmids":["18840647"],"is_preprint":false},{"year":2010,"finding":"Xenopus KazrinA directly binds ARVCF-catenin and stabilizes it; forms a ternary biochemical complex with ARVCF-catenin and β2-spectrin; also binds p190B RhoGAP and selectively associates with δ-catenin and p0071-catenin but not p120-catenin. Kazrin depletion in Xenopus embryos causes ectodermal cell shedding through RhoA activation and altered actin organization and cadherin function, partially rescued by exogenous ARVCF or p190B RhoGAP.","method":"Direct binding assays (co-immunoprecipitation, GST pulldown), resolution of ternary complex, morpholino knockdown in Xenopus embryos, rescue experiments with ARVCF and p190B RhoGAP","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Moderate — direct binding confirmed by pulldown, ternary complex resolved, in vivo epistasis rescue with two independent partners, single lab","pmids":["21062899"],"is_preprint":false},{"year":2009,"finding":"Kazrin F isoform interacts with ARC (apoptosis repressor with caspase recruitment domain) and Bax (Bcl-2-associated X protein) in the cytoplasm; knockdown of Kazrin F by siRNA causes apoptosis and decreased cell viability.","method":"Co-immunoprecipitation, immunofluorescence colocalization, siRNA knockdown, MTT assay, TUNEL assay","journal":"Acta biochimica et biophysica Sinica","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — single Co-IP with colocalization, single lab, no mutagenesis or reconstitution","pmids":["19727525"],"is_preprint":false},{"year":2011,"finding":"Kazrin associates with ARVCF-catenin and delta-catenin and is required for Xenopus craniofacial development; Kazrin knockdown reduces cartilaginous head structures and eye size, affects neural crest cell establishment and migration, and ARVCF partially rescues Kazrin knockdown phenotypes, supporting functional interplay.","method":"Morpholino knockdown in Xenopus, ARVCF rescue experiment, molecular marker analysis (neural crest), histological analysis of cartilage structures","journal":"Developmental dynamics","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — in vivo epistasis/rescue in Xenopus, single lab, limited molecular mechanistic detail beyond binding partners established in prior paper","pmids":["22028074"],"is_preprint":false},{"year":2005,"finding":"In mouse eggs and early embryos, kazrin associates with the spindle apparatus and cytoskeletal sheets; after egg activation it relocates to the cytokinetic ring; before blastocyst stage it associates with the nuclear matrix in a cell cycle-dependent manner and with the cytoplasmic actin cytoskeleton; post-blastocyst, it is found at cell-cell junctions, the cytoskeleton, and the nucleus.","method":"RT-PCR, Western blot, confocal immunofluorescence microscopy across developmental stages","journal":"Developmental dynamics","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — direct localization by immunofluorescence across development, single lab, no functional perturbation","pmids":["16086310"],"is_preprint":false},{"year":2012,"finding":"A kazrin gene-trap mouse expressing only exons 1–4 (N-terminal coiled-coil domain) fused to β-galactosidase showed no defects in skin development or homeostasis, establishing that exons 5–15 (encoding the nuclear localization signal and C-terminal domain) are dispensable for epidermal morphogenesis. The exon 1–4 protein caused keratinocyte shape changes on transfection, localizing the cell-shape regulatory function to the N-terminal coiled-coil domain.","method":"Gene-trap mouse generation, transient transfection of truncated protein, immunofluorescence for desmoplakin/periplakin, β-galactosidase reporter for endogenous expression pattern","journal":"The Journal of investigative dermatology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo genetic truncation with defined domain mapping and cellular phenotype readout, single lab","pmids":["22513779"],"is_preprint":false},{"year":2023,"finding":"Kazrin C acts as a dynein/dynactin adaptor to promote endocytic traffic from early endosomes to recycling endosomes. The N-terminus of kazrin C shares homology with dynein/dynactin adaptors and directly interacts with the dynactin complex and dynein light intermediate chain 1. The C-terminal intrinsically disordered region directly interacts with early endosome components. Kazrin knockout delays juxtanuclear enrichment of internalized material and impairs retrograde motility of early endosomes.","method":"Kazrin knockout mouse embryonic fibroblasts (CRISPR), endocytic trafficking assays (fluorescent cargo internalization), direct binding assays (pulldown of dynactin complex and dynein LIC1), motility tracking of early endosomes, domain mapping","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — knockout cell system, direct in vitro binding to dynactin and dynein LIC1, domain-level dissection, multiple orthogonal assays (trafficking, motility, binding), single lab","pmids":["37096882"],"is_preprint":false},{"year":2021,"finding":"FUS protein interacts with KAZN mRNA and increases its stability; this interaction is mediated downstream of the lncRNA LINC00284, and increased KAZN expression promotes malignant behaviors (proliferation, migration) in oral squamous cell carcinoma cells.","method":"RNA immunoprecipitation (FUS-KAZN mRNA interaction), mRNA stability assay, functional rescue experiments in OSCC cell lines","journal":"Cancer biology & therapy","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single RIP assay and rescue experiment, single lab, mechanistic detail limited in abstract","pmids":["33618612"],"is_preprint":false}],"current_model":"Kazrin is a multifunctional adaptor protein that (1) localizes to desmosomes and the plasma membrane by binding periplakin via its N-terminal coiled-coil domain and associates with the cornified envelope; (2) regulates RhoA activity and actin/keratin cytoskeletal organization to control keratinocyte shape, intercellular junction assembly, and terminal differentiation; (3) directly binds ARVCF-catenin, β2-spectrin, p190B RhoGAP, and select p120-catenin subfamily members to maintain epithelial integrity during development; (4) functions through its kazrin C isoform as a dynein/dynactin adaptor that promotes retrograde transport of early endosomes toward recycling endosomes; and (5) through its kazrin F isoform, interacts with pro- and anti-apoptotic proteins ARC and Bax to modulate apoptosis."},"narrative":{"mechanistic_narrative":"KAZN (kazrin) is a multifunctional adaptor protein that organizes the cytoskeleton and cell junctions of epithelia and, through distinct isoforms, contributes to endosomal trafficking [PMID:15337775, PMID:21062899, PMID:37096882]. It was identified as a periplakin-interacting protein that colocalizes with periplakin and desmoplakin at desmosomes and the interdesmosomal plasma membrane and is incorporated into the keratinocyte cornified envelope, with periplakin binding mediated by its N-terminal region [PMID:15337775]. In keratinocytes, kazrin controls cell shape, intercellular junction assembly, and terminal differentiation by reducing filamentous actin and reorganizing keratin filaments, acting in part through decreased RhoA activity [PMID:18840647]; this cell-shape regulatory activity maps to its N-terminal coiled-coil domain [PMID:22513779]. Kazrin directly binds ARVCF-catenin and stabilizes it, forms a ternary complex with ARVCF-catenin and β2-spectrin, and binds p190B RhoGAP and select p120-catenin subfamily members (δ-catenin, p0071) to maintain epithelial integrity, RhoA control, and cadherin function during Xenopus ectodermal and craniofacial/neural crest development [PMID:21062899, PMID:22028074]. A distinct kazrin C isoform functions as a dynein/dynactin adaptor: its N-terminus directly binds the dynactin complex and dynein light intermediate chain 1 while its C-terminal intrinsically disordered region engages early endosome components, promoting retrograde transport of early endosomes toward recycling endosomes [PMID:37096882].","teleology":[{"year":2004,"claim":"Established kazrin's existence and first molecular anchor by showing it binds periplakin and localizes to desmosomes, the interdesmosomal membrane, and the cornified envelope, placing it in the keratinocyte junctional/cornification machinery.","evidence":"Co-IP with a defined N-terminal periplakin fragment, immunofluorescence colocalization, and cornified envelope incorporation assay in cultured keratinocytes","pmids":["15337775"],"confidence":"High","gaps":["Functional consequence of the kazrin–periplakin interaction not tested","Domain of kazrin mediating binding not mapped here"]},{"year":2005,"claim":"Documented dynamic, cell-cycle- and development-dependent relocalization of kazrin among the spindle, cytokinetic ring, nuclear matrix, and cell-cell junctions, hinting at roles beyond epidermis but without functional perturbation.","evidence":"RT-PCR, Western blot, and confocal immunofluorescence across mouse eggs and early embryos","pmids":["16086310"],"confidence":"Medium","gaps":["Purely descriptive—no loss-of-function test","Molecular partners at each location unidentified"]},{"year":2008,"claim":"Defined kazrin as a regulator of keratinocyte cytoskeleton and differentiation, linking it to RhoA signaling and showing both Rho-dependent and Rho-independent activities.","evidence":"Reciprocal overexpression/siRNA in human keratinocytes with actin/keratin imaging, GST-rhotekin Rho activity pulldown, clonal growth, and differentiation marker assays","pmids":["18840647"],"confidence":"High","gaps":["Mechanism connecting kazrin to RhoA not defined","Identity of the Rho-independent pathway unknown"]},{"year":2009,"claim":"Proposed an apoptosis-modulating role for the kazrin F isoform through interaction with ARC and Bax, expanding kazrin function beyond junctions.","evidence":"Co-IP, colocalization, siRNA knockdown with MTT and TUNEL assays","pmids":["19727525"],"confidence":"Medium","gaps":["Single Co-IP without reciprocal validation or mutagenesis","No reconstitution of the apoptotic mechanism","Binding interface unmapped"]},{"year":2010,"claim":"Identified the direct binding partners (ARVCF-catenin, β2-spectrin, p190B RhoGAP, δ-catenin/p0071) that mechanistically tie kazrin to cadherin function and RhoA regulation, with in vivo epistasis showing kazrin loss drives RhoA activation and cell shedding.","evidence":"Co-IP/GST pulldown, ternary complex resolution, and morpholino knockdown with ARVCF/p190B rescue in Xenopus embryos","pmids":["21062899"],"confidence":"High","gaps":["Selectivity basis for p120-subfamily binding not resolved","How the kazrin–ARVCF–spectrin complex couples to actin/RhoA mechanistically unclear"]},{"year":2011,"claim":"Extended the kazrin–ARVCF/δ-catenin axis to an organismal developmental requirement, showing kazrin is needed for neural crest and craniofacial development.","evidence":"Morpholino knockdown with ARVCF rescue, neural crest marker and cartilage histology in Xenopus","pmids":["22028074"],"confidence":"Medium","gaps":["Limited new molecular mechanism beyond previously established partners","Cell-autonomy of neural crest defect not dissected"]},{"year":2012,"claim":"Localized the cell-shape regulatory function to the N-terminal coiled-coil domain and showed exons 5–15 are dispensable for epidermal morphogenesis in vivo, refining the structure-function map.","evidence":"Gene-trap mouse expressing exon 1–4–β-gal fusion plus truncated-protein transfection and junctional immunofluorescence","pmids":["22513779"],"confidence":"Medium","gaps":["Why full-length isoform functions are dispensable for skin not explained","No defect baseline complicates interpretation of redundancy"]},{"year":2021,"claim":"Placed KAZN downstream of a LINC00284/FUS axis as a stability-regulated, pro-tumorigenic transcript in oral squamous cell carcinoma.","evidence":"RNA immunoprecipitation, mRNA stability assay, and rescue experiments in OSCC cell lines","pmids":["33618612"],"confidence":"Low","gaps":["Single RIP and rescue, not independently confirmed","Mechanism by which KAZN promotes malignancy at the protein level untested"]},{"year":2023,"claim":"Defined a mechanistically distinct role for the kazrin C isoform as a bona fide dynein/dynactin adaptor coupling early endosomes to retrograde transport.","evidence":"CRISPR knockout MEFs, direct pulldown of dynactin and dynein LIC1, endosome motility tracking, cargo internalization assays, and domain mapping","pmids":["37096882"],"confidence":"High","gaps":["Relationship between the trafficking role and junctional/cytoskeletal roles unresolved","Cargo-selection logic of the C-terminal IDR not fully defined"]},{"year":null,"claim":"How kazrin's separable activities—desmosomal/junctional adaptor, RhoA-coupled cytoskeletal regulator, and dynein/dynactin endosomal adaptor—are coordinated across isoforms and tissues remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model linking isoform identity to function","No structural model of kazrin complexes","Physiological role of the apoptotic and cancer functions not integrated"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,2,7]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,2]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[1,2]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[3,7]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[7]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[1,5]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"R-HSA-1500931","term_label":"Cell-Cell communication","supporting_discovery_ids":[0,2]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,2]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[7]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[2,4]}],"complexes":["desmosome","dynein/dynactin complex","kazrin–ARVCF-catenin–β2-spectrin ternary complex"],"partners":["PPL","ARVCF","SPTBN1","ARHGAP5","CTNND2","DLIC1","ARC","BAX"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q674X7","full_name":"Kazrin","aliases":[],"length_aa":775,"mass_kda":86.4,"function":"Component of the cornified envelope of keratinocytes. May be involved in the interplay between adherens junctions and desmosomes. The function in the nucleus is not known","subcellular_location":"Cytoplasm; Cell junction, desmosome; Nucleus","url":"https://www.uniprot.org/uniprotkb/Q674X7/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KAZN","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/KAZN","total_profiled":1310},"omim":[{"mim_id":"618301","title":"KAZRIN, PERIPLAKIN-INTERACTING PROTEIN; KAZN","url":"https://www.omim.org/entry/618301"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Nuclear speckles","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"brain","ntpm":71.8},{"tissue":"lymphoid tissue","ntpm":88.0}],"url":"https://www.proteinatlas.org/search/KAZN"},"hgnc":{"alias_symbol":["KIAA1026","KAZRIN","FLJ43806"],"prev_symbol":["C1orf196"]},"alphafold":{"accession":"Q674X7","domains":[{"cath_id":"1.10.150.50","chopping":"441-517","consensus_level":"medium","plddt":95.7051,"start":441,"end":517},{"cath_id":"1.10.150.50","chopping":"521-686","consensus_level":"medium","plddt":95.319,"start":521,"end":686},{"cath_id":"1.20.5","chopping":"195-241","consensus_level":"medium","plddt":95.986,"start":195,"end":241}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q674X7","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q674X7-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q674X7-F1-predicted_aligned_error_v6.png","plddt_mean":70.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KAZN","jax_strain_url":"https://www.jax.org/strain/search?query=KAZN"},"sequence":{"accession":"Q674X7","fasta_url":"https://rest.uniprot.org/uniprotkb/Q674X7.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q674X7/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q674X7"}},"corpus_meta":[{"pmid":"15337775","id":"PMC_15337775","title":"Kazrin, a novel periplakin-interacting protein associated with desmosomes and the keratinocyte plasma membrane.","date":"2004","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/15337775","citation_count":55,"is_preprint":false},{"pmid":"18840647","id":"PMC_18840647","title":"Kazrin regulates keratinocyte cytoskeletal networks, intercellular junctions and differentiation.","date":"2008","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/18840647","citation_count":34,"is_preprint":false},{"pmid":"28373753","id":"PMC_28373753","title":"Upregulation of kazrin F by miR-186 suppresses apoptosis but promotes epithelial-mesenchymal transition to contribute to malignancy in human cervical cancer cells.","date":"2017","source":"Chinese journal of cancer research = Chung-kuo yen cheng yen chiu","url":"https://pubmed.ncbi.nlm.nih.gov/28373753","citation_count":18,"is_preprint":false},{"pmid":"21062899","id":"PMC_21062899","title":"Xenopus Kazrin interacts with ARVCF-catenin, spectrin and p190B RhoGAP, and modulates RhoA activity and epithelial integrity.","date":"2010","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/21062899","citation_count":17,"is_preprint":false},{"pmid":"33618612","id":"PMC_33618612","title":"Silencing of LINC00284 inhibits cell proliferation and migration in oral squamous cell carcinoma by the miR-211-3p/MAFG axis and FUS/KAZN axis.","date":"2021","source":"Cancer biology & therapy","url":"https://pubmed.ncbi.nlm.nih.gov/33618612","citation_count":14,"is_preprint":false},{"pmid":"22028074","id":"PMC_22028074","title":"Kazrin, and its binding partners ARVCF- and delta-catenin, are required for Xenopus laevis craniofacial development.","date":"2011","source":"Developmental dynamics : an official publication of the American Association of Anatomists","url":"https://pubmed.ncbi.nlm.nih.gov/22028074","citation_count":13,"is_preprint":false},{"pmid":"19727525","id":"PMC_19727525","title":"Kazrin F is involved in apoptosis and interacts with BAX and ARC.","date":"2009","source":"Acta biochimica et biophysica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/19727525","citation_count":8,"is_preprint":false},{"pmid":"16086310","id":"PMC_16086310","title":"Dynamics and unexpected localization of the plakin binding protein, kazrin, in mouse eggs and early embryos.","date":"2005","source":"Developmental dynamics : an official publication of the American Association of Anatomists","url":"https://pubmed.ncbi.nlm.nih.gov/16086310","citation_count":7,"is_preprint":false},{"pmid":"37096882","id":"PMC_37096882","title":"Kazrin promotes dynein/dynactin-dependent traffic from early to recycling endosomes.","date":"2023","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/37096882","citation_count":6,"is_preprint":false},{"pmid":"22513779","id":"PMC_22513779","title":"Exons 5-15 of kazrin are dispensable for murine epidermal morphogenesis and homeostasis.","date":"2012","source":"The Journal of investigative dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/22513779","citation_count":4,"is_preprint":false},{"pmid":"35710397","id":"PMC_35710397","title":"KAZN as a diagnostic marker in ovarian cancer: a comprehensive analysis based on microarray, mRNA-sequencing, and methylation data.","date":"2022","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/35710397","citation_count":4,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.04.20.649706","title":"A quantitative in vivo CRISPR-imaging platform identifies regulators of hyperplastic and hypertrophic adipose morphology in zebrafish","date":"2025-04-21","source":"bioRxiv","url":"https://doi.org/10.1101/2025.04.20.649706","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7677,"output_tokens":2558,"usd":0.0307,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9811,"output_tokens":3508,"usd":0.068377,"stage2_stop_reason":"end_turn"},"total_usd":0.099077,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2004,\n      \"finding\": \"Kazrin is a novel periplakin-interacting protein; the NH2-terminal 133 amino acids of periplakin mediate association with the plasma membrane and bind kazrin. Kazrin colocalizes with periplakin and desmoplakin at desmosomes and with periplakin at the interdesmosomal plasma membrane, and is incorporated into the cornified envelope of cultured keratinocytes. Kazrin's subcellular distribution is independent of periplakin.\",\n      \"method\": \"Co-immunoprecipitation/binding assay (NH2-terminal periplakin fragment), immunofluorescence colocalization, transfection of isoforms, cornified envelope incorporation assay\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding assay with defined domain, multiple orthogonal methods (pulldown, colocalization, CE incorporation), founding paper replicated in subsequent studies\",\n      \"pmids\": [\"15337775\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Kazrin overexpression in human epidermal keratinocytes reduces filamentous actin, reorganizes keratin filaments, impairs assembly of intercellular junctions, stimulates terminal differentiation, and reduces clonal growth via decreased RhoA activity. Kazrin knockdown decreases differentiation markers and stimulates proliferation without changing total Rho activity, indicating Rho-dependent and Rho-independent mechanisms.\",\n      \"method\": \"Overexpression and siRNA knockdown in human keratinocytes, phalloidin/immunofluorescence for actin and keratin filaments, Rho activity pull-down assay (GST-rhotekin), clonal growth assay, differentiation marker immunoblotting\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal gain- and loss-of-function experiments with multiple orthogonal readouts (actin, keratin, junctions, Rho activity, differentiation markers), single lab\",\n      \"pmids\": [\"18840647\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Xenopus KazrinA directly binds ARVCF-catenin and stabilizes it; forms a ternary biochemical complex with ARVCF-catenin and β2-spectrin; also binds p190B RhoGAP and selectively associates with δ-catenin and p0071-catenin but not p120-catenin. Kazrin depletion in Xenopus embryos causes ectodermal cell shedding through RhoA activation and altered actin organization and cadherin function, partially rescued by exogenous ARVCF or p190B RhoGAP.\",\n      \"method\": \"Direct binding assays (co-immunoprecipitation, GST pulldown), resolution of ternary complex, morpholino knockdown in Xenopus embryos, rescue experiments with ARVCF and p190B RhoGAP\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding confirmed by pulldown, ternary complex resolved, in vivo epistasis rescue with two independent partners, single lab\",\n      \"pmids\": [\"21062899\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Kazrin F isoform interacts with ARC (apoptosis repressor with caspase recruitment domain) and Bax (Bcl-2-associated X protein) in the cytoplasm; knockdown of Kazrin F by siRNA causes apoptosis and decreased cell viability.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence colocalization, siRNA knockdown, MTT assay, TUNEL assay\",\n      \"journal\": \"Acta biochimica et biophysica Sinica\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP with colocalization, single lab, no mutagenesis or reconstitution\",\n      \"pmids\": [\"19727525\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Kazrin associates with ARVCF-catenin and delta-catenin and is required for Xenopus craniofacial development; Kazrin knockdown reduces cartilaginous head structures and eye size, affects neural crest cell establishment and migration, and ARVCF partially rescues Kazrin knockdown phenotypes, supporting functional interplay.\",\n      \"method\": \"Morpholino knockdown in Xenopus, ARVCF rescue experiment, molecular marker analysis (neural crest), histological analysis of cartilage structures\",\n      \"journal\": \"Developmental dynamics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — in vivo epistasis/rescue in Xenopus, single lab, limited molecular mechanistic detail beyond binding partners established in prior paper\",\n      \"pmids\": [\"22028074\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"In mouse eggs and early embryos, kazrin associates with the spindle apparatus and cytoskeletal sheets; after egg activation it relocates to the cytokinetic ring; before blastocyst stage it associates with the nuclear matrix in a cell cycle-dependent manner and with the cytoplasmic actin cytoskeleton; post-blastocyst, it is found at cell-cell junctions, the cytoskeleton, and the nucleus.\",\n      \"method\": \"RT-PCR, Western blot, confocal immunofluorescence microscopy across developmental stages\",\n      \"journal\": \"Developmental dynamics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — direct localization by immunofluorescence across development, single lab, no functional perturbation\",\n      \"pmids\": [\"16086310\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"A kazrin gene-trap mouse expressing only exons 1–4 (N-terminal coiled-coil domain) fused to β-galactosidase showed no defects in skin development or homeostasis, establishing that exons 5–15 (encoding the nuclear localization signal and C-terminal domain) are dispensable for epidermal morphogenesis. The exon 1–4 protein caused keratinocyte shape changes on transfection, localizing the cell-shape regulatory function to the N-terminal coiled-coil domain.\",\n      \"method\": \"Gene-trap mouse generation, transient transfection of truncated protein, immunofluorescence for desmoplakin/periplakin, β-galactosidase reporter for endogenous expression pattern\",\n      \"journal\": \"The Journal of investigative dermatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo genetic truncation with defined domain mapping and cellular phenotype readout, single lab\",\n      \"pmids\": [\"22513779\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Kazrin C acts as a dynein/dynactin adaptor to promote endocytic traffic from early endosomes to recycling endosomes. The N-terminus of kazrin C shares homology with dynein/dynactin adaptors and directly interacts with the dynactin complex and dynein light intermediate chain 1. The C-terminal intrinsically disordered region directly interacts with early endosome components. Kazrin knockout delays juxtanuclear enrichment of internalized material and impairs retrograde motility of early endosomes.\",\n      \"method\": \"Kazrin knockout mouse embryonic fibroblasts (CRISPR), endocytic trafficking assays (fluorescent cargo internalization), direct binding assays (pulldown of dynactin complex and dynein LIC1), motility tracking of early endosomes, domain mapping\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — knockout cell system, direct in vitro binding to dynactin and dynein LIC1, domain-level dissection, multiple orthogonal assays (trafficking, motility, binding), single lab\",\n      \"pmids\": [\"37096882\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"FUS protein interacts with KAZN mRNA and increases its stability; this interaction is mediated downstream of the lncRNA LINC00284, and increased KAZN expression promotes malignant behaviors (proliferation, migration) in oral squamous cell carcinoma cells.\",\n      \"method\": \"RNA immunoprecipitation (FUS-KAZN mRNA interaction), mRNA stability assay, functional rescue experiments in OSCC cell lines\",\n      \"journal\": \"Cancer biology & therapy\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single RIP assay and rescue experiment, single lab, mechanistic detail limited in abstract\",\n      \"pmids\": [\"33618612\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"Kazrin is a multifunctional adaptor protein that (1) localizes to desmosomes and the plasma membrane by binding periplakin via its N-terminal coiled-coil domain and associates with the cornified envelope; (2) regulates RhoA activity and actin/keratin cytoskeletal organization to control keratinocyte shape, intercellular junction assembly, and terminal differentiation; (3) directly binds ARVCF-catenin, β2-spectrin, p190B RhoGAP, and select p120-catenin subfamily members to maintain epithelial integrity during development; (4) functions through its kazrin C isoform as a dynein/dynactin adaptor that promotes retrograde transport of early endosomes toward recycling endosomes; and (5) through its kazrin F isoform, interacts with pro- and anti-apoptotic proteins ARC and Bax to modulate apoptosis.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"KAZN (kazrin) is a multifunctional adaptor protein that organizes the cytoskeleton and cell junctions of epithelia and, through distinct isoforms, contributes to endosomal trafficking [#0, #2, #7]. It was identified as a periplakin-interacting protein that colocalizes with periplakin and desmoplakin at desmosomes and the interdesmosomal plasma membrane and is incorporated into the keratinocyte cornified envelope, with periplakin binding mediated by its N-terminal region [#0]. In keratinocytes, kazrin controls cell shape, intercellular junction assembly, and terminal differentiation by reducing filamentous actin and reorganizing keratin filaments, acting in part through decreased RhoA activity [#1]; this cell-shape regulatory activity maps to its N-terminal coiled-coil domain [#6]. Kazrin directly binds ARVCF-catenin and stabilizes it, forms a ternary complex with ARVCF-catenin and \\u03b22-spectrin, and binds p190B RhoGAP and select p120-catenin subfamily members (\\u03b4-catenin, p0071) to maintain epithelial integrity, RhoA control, and cadherin function during Xenopus ectodermal and craniofacial/neural crest development [#2, #4]. A distinct kazrin C isoform functions as a dynein/dynactin adaptor: its N-terminus directly binds the dynactin complex and dynein light intermediate chain 1 while its C-terminal intrinsically disordered region engages early endosome components, promoting retrograde transport of early endosomes toward recycling endosomes [#7].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"Established kazrin's existence and first molecular anchor by showing it binds periplakin and localizes to desmosomes, the interdesmosomal membrane, and the cornified envelope, placing it in the keratinocyte junctional/cornification machinery.\",\n      \"evidence\": \"Co-IP with a defined N-terminal periplakin fragment, immunofluorescence colocalization, and cornified envelope incorporation assay in cultured keratinocytes\",\n      \"pmids\": [\"15337775\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of the kazrin\\u2013periplakin interaction not tested\", \"Domain of kazrin mediating binding not mapped here\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Documented dynamic, cell-cycle- and development-dependent relocalization of kazrin among the spindle, cytokinetic ring, nuclear matrix, and cell-cell junctions, hinting at roles beyond epidermis but without functional perturbation.\",\n      \"evidence\": \"RT-PCR, Western blot, and confocal immunofluorescence across mouse eggs and early embryos\",\n      \"pmids\": [\"16086310\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Purely descriptive\\u2014no loss-of-function test\", \"Molecular partners at each location unidentified\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Defined kazrin as a regulator of keratinocyte cytoskeleton and differentiation, linking it to RhoA signaling and showing both Rho-dependent and Rho-independent activities.\",\n      \"evidence\": \"Reciprocal overexpression/siRNA in human keratinocytes with actin/keratin imaging, GST-rhotekin Rho activity pulldown, clonal growth, and differentiation marker assays\",\n      \"pmids\": [\"18840647\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism connecting kazrin to RhoA not defined\", \"Identity of the Rho-independent pathway unknown\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Proposed an apoptosis-modulating role for the kazrin F isoform through interaction with ARC and Bax, expanding kazrin function beyond junctions.\",\n      \"evidence\": \"Co-IP, colocalization, siRNA knockdown with MTT and TUNEL assays\",\n      \"pmids\": [\"19727525\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single Co-IP without reciprocal validation or mutagenesis\", \"No reconstitution of the apoptotic mechanism\", \"Binding interface unmapped\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identified the direct binding partners (ARVCF-catenin, \\u03b22-spectrin, p190B RhoGAP, \\u03b4-catenin/p0071) that mechanistically tie kazrin to cadherin function and RhoA regulation, with in vivo epistasis showing kazrin loss drives RhoA activation and cell shedding.\",\n      \"evidence\": \"Co-IP/GST pulldown, ternary complex resolution, and morpholino knockdown with ARVCF/p190B rescue in Xenopus embryos\",\n      \"pmids\": [\"21062899\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Selectivity basis for p120-subfamily binding not resolved\", \"How the kazrin\\u2013ARVCF\\u2013spectrin complex couples to actin/RhoA mechanistically unclear\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Extended the kazrin\\u2013ARVCF/\\u03b4-catenin axis to an organismal developmental requirement, showing kazrin is needed for neural crest and craniofacial development.\",\n      \"evidence\": \"Morpholino knockdown with ARVCF rescue, neural crest marker and cartilage histology in Xenopus\",\n      \"pmids\": [\"22028074\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Limited new molecular mechanism beyond previously established partners\", \"Cell-autonomy of neural crest defect not dissected\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Localized the cell-shape regulatory function to the N-terminal coiled-coil domain and showed exons 5\\u201315 are dispensable for epidermal morphogenesis in vivo, refining the structure-function map.\",\n      \"evidence\": \"Gene-trap mouse expressing exon 1\\u20134\\u2013\\u03b2-gal fusion plus truncated-protein transfection and junctional immunofluorescence\",\n      \"pmids\": [\"22513779\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Why full-length isoform functions are dispensable for skin not explained\", \"No defect baseline complicates interpretation of redundancy\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Placed KAZN downstream of a LINC00284/FUS axis as a stability-regulated, pro-tumorigenic transcript in oral squamous cell carcinoma.\",\n      \"evidence\": \"RNA immunoprecipitation, mRNA stability assay, and rescue experiments in OSCC cell lines\",\n      \"pmids\": [\"33618612\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single RIP and rescue, not independently confirmed\", \"Mechanism by which KAZN promotes malignancy at the protein level untested\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined a mechanistically distinct role for the kazrin C isoform as a bona fide dynein/dynactin adaptor coupling early endosomes to retrograde transport.\",\n      \"evidence\": \"CRISPR knockout MEFs, direct pulldown of dynactin and dynein LIC1, endosome motility tracking, cargo internalization assays, and domain mapping\",\n      \"pmids\": [\"37096882\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relationship between the trafficking role and junctional/cytoskeletal roles unresolved\", \"Cargo-selection logic of the C-terminal IDR not fully defined\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How kazrin's separable activities\\u2014desmosomal/junctional adaptor, RhoA-coupled cytoskeletal regulator, and dynein/dynactin endosomal adaptor\\u2014are coordinated across isoforms and tissues remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model linking isoform identity to function\", \"No structural model of kazrin complexes\", \"Physiological role of the apoptotic and cancer functions not integrated\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 2, 7]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [1, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [3, 7]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [1, 5]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1500931\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [2, 4]}\n    ],\n    \"complexes\": [\"desmosome\", \"dynein/dynactin complex\", \"kazrin\\u2013ARVCF-catenin\\u2013\\u03b22-spectrin ternary complex\"],\n    \"partners\": [\"PPL\", \"ARVCF\", \"SPTBN1\", \"ARHGAP5\", \"CTNND2\", \"DLIC1\", \"ARC\", \"BAX\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":5,"faith_pct":80.0}}