{"gene":"KASH5","run_date":"2026-06-10T01:55:23","timeline":{"discoveries":[{"year":2012,"finding":"KASH5 is a germ cell-specific protein that localizes exclusively at telomeres from leptotene to diplotene stages in spermatocytes and oocytes, contains KASH-related sequences that directly interact with SUN1, and mediates telomere localization at the nuclear envelope.","method":"Subcellular localization screening in mouse spermatocytes, co-immunoprecipitation, direct protein interaction assays","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP and localization experiments, replicated by multiple subsequent labs","pmids":["22826121"],"is_preprint":false},{"year":2012,"finding":"KASH5 interacts with the microtubule-associated dynein-dynactin complex, connecting the telomere-associated SUN1 protein to the cytoplasmic force-generating machinery for meiotic chromosome movement.","method":"Co-immunoprecipitation of dynein-dynactin with KASH5 in mouse spermatocytes","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — Co-IP in spermatocytes, independently replicated and extended by multiple subsequent studies","pmids":["22826121"],"is_preprint":false},{"year":2013,"finding":"KASH5 is a dynein-binding protein of the outer nuclear membrane that forms a meiotic complex with SUN1; mice deficient in KASH5 are infertile with meiotic arrest in which pairing of homologous chromosomes fails, demonstrating that telomere attachment to the NE alone is insufficient and that coupling to cytoplasmic dynein is required.","method":"Genetic knockout mouse model (KASH5-deficient mice), immunofluorescence, chromosome spread analysis","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO mouse with defined meiotic arrest phenotype, replicated across multiple labs","pmids":["24062341"],"is_preprint":false},{"year":2015,"finding":"Quantitative 4D fluorescence imaging confirmed that SUN1/KASH5, microtubules, and dynein—but not actin—are necessary for rapid prophase movements (RPMs) of meiotic chromosomes; KASH5 loss results in loss of both nuclear rotation and individual chromosome telomere movements along microtubule tracks.","method":"4D fluorescence imaging in mouse seminiferous tubules, quantitative motion analysis, pharmacological inhibition and genetic depletion","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (live imaging, genetic KO, pharmacological), clear negative control (actin not required)","pmids":["25892231"],"is_preprint":false},{"year":2014,"finding":"CDK2 ablation causes abnormal cap-like nuclear envelope distribution of KASH5 (and SUN1 and lamin C2) facing the centrosome in spermatocytes; CDK2 phosphorylates SUN1 in vitro, and some telomeres detach from the NE and associate with NE-detached vesicles containing SUN1, indicating CDK2 governs NE structure required for proper KASH5/SUN1 function.","method":"Immunofluorescence, electron microscopy, in vitro kinase assay with mouse testis CDK2","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro kinase assay plus IF/EM in CDK2-KO spermatocytes, single lab","pmids":["25380821"],"is_preprint":false},{"year":2016,"finding":"KASH5 depletion in mouse oocytes arrests most oocytes at the germinal vesicle (GV) stage, causes small and abnormal spindles after GVBD, reduces cytoplasmic F-actin mesh, and displaces pericentrin and P150(Glued); SUN1 depletion causes KASH5 to relocalize exclusively near the oocyte cortex, but KASH5 depletion does not affect SUN1 localization, establishing a directional dependency.","method":"Gene silencing (siRNA/morpholino), immunofluorescence, live imaging in mouse oocytes","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KD with defined phenotypic readouts and localization dependency, single lab","pmids":["26842404"],"is_preprint":false},{"year":2020,"finding":"Crystal structures of human SUN2 in complex with the KASH5 peptide reveal that the KASH5 peptide adopts a distinct conformation compared to Nesprin1/2 KASH peptides when bound to SUN2, while sharing core interactions at the C-terminal KASH residues; differences include the KASH-lid and cation loop interactions.","method":"X-ray crystallography of SUN2-KASH5 peptide complex","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — high-resolution crystal structure, single lab but rigorous structural method","pmids":["33058875"],"is_preprint":false},{"year":2021,"finding":"Crystallographic and biophysical evidence shows that SUN-KASH forms a constitutive 6:6 complex (two head-to-head 3:3 trimers), providing a molecular mechanism for branched LINC complex networks; KASH5 participates in this higher-order assembly. Zinc coordination by Nesprin-4 was identified as one distinct mechanism, with KASH5 using a structurally diverse mode to achieve the same 6:6 topology.","method":"X-ray crystallography, biophysical assays (SEC, ITC), structural analysis of SUN-KASH complexes","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structures with biophysical validation, single lab but multiple orthogonal structural methods","pmids":["33393904"],"is_preprint":false},{"year":2021,"finding":"A human infertility-associated KASH5 variant (L535Q) within the transmembrane domain reduces hydrophobicity and misdirects KASH5 from the ER/outer nuclear membrane to the mitochondrial membrane, accounting for the infertility phenotype; amino acid substitution studies mapped the hydrophobicity requirement for ER/ONM targeting.","method":"Site-directed mutagenesis, subcellular fractionation, fluorescence microscopy in cultured cells, hydrophobicity calculations","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutagenesis combined with localization assays, single lab","pmids":["33980926"],"is_preprint":false},{"year":2022,"finding":"KASH5 is a dynein activating adaptor: KASH5 directly binds dynein using a mechanism conserved among activating adaptors and converts dynein into a processive motor in vitro; mutations in the dynein-binding surface of KASH5 abrogate dynein binding in vitro and disrupt recruitment of the dynein machinery to the nuclear envelope in cultured cells and mouse spermatocytes in vivo.","method":"In vitro reconstitution of dynein motility (single-molecule TIRF), pulldown assays, mutagenesis, immunofluorescence in spermatocytes","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution of processive dynein motility, mutagenesis, and in vivo validation in spermatocytes; replicated independently by Garner et al. 2023","pmids":["35703493"],"is_preprint":false},{"year":2022,"finding":"A homozygous missense mutation in CCDC155/KASH5 (p.Leu197Pro) in the conserved CC domain blocks nuclear envelope distribution of KASH5 and prevents NE-specific enrichment of SUN1, causing meiotic arrest and infertility in humans (NOA and POI); the mutation was validated ex vivo and in vitro.","method":"Whole-exome sequencing, functional studies in patient-derived cells (ex vivo/in vitro localization assays), histological analysis","journal":"Human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — patient mutation with ex vivo and in vitro functional validation of localization defect, single study","pmids":["35587281"],"is_preprint":false},{"year":2022,"finding":"A homozygous splicing variant in KASH5 (c.747G>A) disturbs nuclear membrane localization of KASH5 and its binding with SUN1; Kash5 C-terminal deleted mice show defective meiotic homolog pairing and accelerated oocyte depletion, establishing that the KASH5 C-terminus and SUN1 interaction are essential for meiotic prophase I and ovarian reserve maintenance.","method":"Whole-exome sequencing, in vitro functional studies, mouse model (Kash5 C-terminal deletion), histology, oocyte spreads","journal":"The Journal of clinical endocrinology and metabolism","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mouse model plus in vitro binding studies, single lab","pmids":["35708642"],"is_preprint":false},{"year":2023,"finding":"KASH5 promotes dynein motility in vitro as an activating adaptor; KASH5 interacts with dynein light intermediate chain (DYNC1LI1 or DYNC1LI2) via a conserved helix in the LIC C-terminal domain; KASH5 N-terminal EF-hand calcium-binding residues are essential for dynein interaction (mutation of key Ca2+-binding residues disrupts this); dynein can be recruited to KASH5 at the NE independently of dynactin, while LIS1 is essential for dynactin incorporation into the KASH5-dynein complex; cytosolic KASH5 inhibits dynein's interphase functions.","method":"In vitro dynein motility assays, Co-IP, mutagenesis of EF-hand residues, dominant-negative overexpression in cultured cells","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro motility reconstitution, mutagenesis, and mechanistic dissection of assembly hierarchy; independently corroborates Agrawal et al. 2022","pmids":["36946995"],"is_preprint":false},{"year":2023,"finding":"A homozygous KASH5 frameshift mutation (c.1270_1273del, p.Arg424Thrfs*20) causes absence of KASH5 protein in testes and NOA with meiotic arrest before pachytene; truncated KASH5 protein encircles the nucleus similarly to wild-type but shows weakened interaction with SUN1, explaining the meiotic defect.","method":"Whole-exome sequencing, immunofluorescence in testes, co-immunoprecipitation of truncated vs. full-length KASH5 with SUN1 in cultured cells","journal":"Frontiers in endocrinology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — patient mutation validated by Co-IP and localization in cultured cells, single lab","pmids":["36864840"],"is_preprint":false},{"year":2023,"finding":"Loss of SUN1 function in human spermatocytes significantly reduces KASH5 levels at the inner nuclear membrane and disrupts chromosomal telomere attachment, establishing that SUN1 is required for KASH5 enrichment at the NE in a human disease context.","method":"Whole-exome sequencing, immunofluorescence of patient spermatocytes","journal":"Human genetics","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single patient, immunofluorescence only, no in vitro validation","pmids":["36933034"],"is_preprint":false},{"year":2025,"finding":"KIF5B (a kinesin) directly interacts with KASH5 via KASH5's N-terminal EF-hand domains, as shown by co-immunoprecipitation, yeast two-hybrid with KASH5 as bait, TIRF microscopy, and microtubule sedimentation with purified recombinant proteins; KIF5B is recruited by KASH5-SUN1 to the nuclear envelope and colocalizes with KASH5 at telomeres in spermatocytes; chemical inhibition of KIF5B reduces telomere-led chromosome RPMs.","method":"Co-immunoprecipitation, yeast two-hybrid, TIRF microscopy with purified proteins, microtubule sedimentation assay, pharmacological inhibition, immunofluorescence in spermatocytes","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods including in vitro reconstitution with purified proteins and in vivo inhibition, preprint not yet peer-reviewed","pmids":["40501626"],"is_preprint":true}],"current_model":"KASH5 is a meiosis-specific outer nuclear membrane protein that forms a LINC complex with inner nuclear membrane SUN1 (and SUN2) to bridge the nuclear envelope; it recruits both cytoplasmic dynein (as a transmembrane dynein activating adaptor that directly binds dynein light intermediate chain via its N-terminal EF-hand domains and converts dynein into a processive motor) and kinesin KIF5B (via its EF-hand domains) to the nuclear envelope, thereby transducing cytoskeletal forces to telomere-led rapid chromosome movements essential for homolog pairing, synapsis, and recombination during meiotic prophase I, with loss of KASH5 causing complete meiotic arrest and infertility in both males and females."},"narrative":{"mechanistic_narrative":"KASH5 is a meiosis-specific outer nuclear membrane protein that couples telomeres to the cytoskeletal force-generating machinery to drive the chromosome movements required for homolog pairing during meiotic prophase I [PMID:22826121, PMID:24062341]. Restricted to germ cells, it localizes at telomeres from leptotene to diplotene and, through its C-terminal KASH domain, binds the inner nuclear membrane SUN proteins to form a LINC complex spanning the nuclear envelope [PMID:22826121, PMID:33058875]; structural work shows the SUN-KASH5 assembly adopts a constitutive 6:6 topology underlying higher-order LINC networks [PMID:33393904]. On the cytoplasmic face, KASH5 functions as a transmembrane dynein activating adaptor: its N-terminal EF-hand domains bind dynein light intermediate chain and convert dynein into a processive motor in vitro, recruiting the dynein-dynactin machinery to the nuclear envelope, with LIS1 required for dynactin incorporation [PMID:22826121, PMID:35703493, PMID:36946995]. KASH5 thereby transduces microtubule- and dynein-dependent forces into telomere-led rapid prophase chromosome movements and nuclear rotation [PMID:25892231]. Loss or mislocalization of KASH5 causes complete meiotic arrest, failure of homolog pairing, and infertility in mice and humans of both sexes, and pathogenic KASH5 variants disrupting transmembrane targeting, SUN1 binding, or nuclear envelope distribution cause non-obstructive azoospermia and primary ovarian insufficiency [PMID:24062341, PMID:33980926, PMID:35587281, PMID:35708642].","teleology":[{"year":2012,"claim":"Established KASH5 as the missing telomere-to-nuclear-envelope tether by showing it is germ-cell specific, localizes at meiotic telomeres, and bridges SUN1 to the cytoplasmic dynein-dynactin machinery.","evidence":"Localization screening, reciprocal Co-IP, and direct interaction assays in mouse spermatocytes","pmids":["22826121"],"confidence":"High","gaps":["Did not establish whether the dynein link is functionally required for chromosome movement","Mechanism of dynein activation not defined"]},{"year":2013,"claim":"Demonstrated causally that dynein coupling, not mere telomere attachment, is essential for homolog pairing, via a clean loss-of-function phenotype.","evidence":"KASH5-deficient knockout mouse with chromosome spread analysis and immunofluorescence","pmids":["24062341"],"confidence":"High","gaps":["Did not resolve the molecular nature of dynein activation","Movement dynamics not directly visualized"]},{"year":2015,"claim":"Defined which cytoskeletal system powers prophase movements, showing SUN1/KASH5-microtubule-dynein dependence and ruling out actin.","evidence":"Quantitative 4D live imaging in seminiferous tubules with genetic depletion and pharmacological inhibition","pmids":["25892231"],"confidence":"High","gaps":["Did not address how forces are generated at the molecular level","Kinesin contribution not examined"]},{"year":2014,"claim":"Identified an upstream regulatory input, showing CDK2 governs nuclear envelope organization required for proper KASH5/SUN1 distribution.","evidence":"Immunofluorescence, EM, and in vitro kinase assay in CDK2-knockout spermatocytes","pmids":["25380821"],"confidence":"Medium","gaps":["KASH5 itself not shown to be a direct CDK2 substrate","Single lab, no rescue"]},{"year":2016,"claim":"Extended KASH5 function to female meiosis and established directional dependency, with SUN1 controlling KASH5 localization but not vice versa.","evidence":"siRNA/morpholino knockdown, immunofluorescence, and live imaging in mouse oocytes","pmids":["26842404"],"confidence":"Medium","gaps":["Spindle and F-actin phenotypes mechanistically separate from telomere role unclear","Single lab"]},{"year":2020,"claim":"Provided atomic detail of the SUN-KASH5 interface, showing KASH5 binds SUN2 with a distinct conformation versus Nesprin KASH peptides.","evidence":"X-ray crystallography of SUN2-KASH5 peptide complex","pmids":["33058875"],"confidence":"High","gaps":["Binding to SUN1 (the meiotic partner) not structurally resolved","Full-length complex assembly not addressed"]},{"year":2021,"claim":"Revealed the higher-order architecture of the LINC complex, showing SUN-KASH5 forms a 6:6 assembly enabling branched networks.","evidence":"X-ray crystallography with SEC and ITC biophysical validation","pmids":["33393904"],"confidence":"High","gaps":["Functional consequence of 6:6 topology for meiotic force transmission untested in vivo","Single lab"]},{"year":2021,"claim":"Linked a human infertility variant to a membrane-targeting mechanism, showing the transmembrane L535Q substitution misdirects KASH5 to mitochondria.","evidence":"Site-directed mutagenesis, subcellular fractionation, and microscopy in cultured cells","pmids":["33980926"],"confidence":"Medium","gaps":["Patient meiotic phenotype not directly examined","Single lab, cultured cell model"]},{"year":2022,"claim":"Defined the dynein activation mechanism, establishing KASH5 as a transmembrane dynein activating adaptor that converts dynein into a processive motor.","evidence":"Single-molecule TIRF reconstitution, pulldowns, mutagenesis, and immunofluorescence in spermatocytes","pmids":["35703493"],"confidence":"High","gaps":["Did not map the precise LIC contact or assembly hierarchy","Calcium dependence not addressed"]},{"year":2022,"claim":"Confirmed KASH5 as a human meiosis disease gene, with a coiled-coil-domain mutation blocking NE distribution and SUN1 enrichment.","evidence":"Whole-exome sequencing with ex vivo and in vitro localization assays and histology","pmids":["35587281"],"confidence":"Medium","gaps":["Single family","Movement defect inferred, not directly imaged"]},{"year":2022,"claim":"Established the KASH5 C-terminus/SUN1 interaction as essential for prophase I and ovarian reserve via a human variant and matched mouse model.","evidence":"WES, in vitro binding studies, and Kash5 C-terminal deletion mouse with oocyte spreads","pmids":["35708642"],"confidence":"Medium","gaps":["Single lab","Mechanism of accelerated oocyte depletion not fully resolved"]},{"year":2023,"claim":"Dissected the dynein-recruitment hierarchy, identifying LIC binding via the EF-hand domain, calcium-binding requirement, dynactin-independent recruitment, and LIS1 dependence.","evidence":"In vitro motility assays, Co-IP, EF-hand mutagenesis, and dominant-negative overexpression in cultured cells","pmids":["36946995"],"confidence":"High","gaps":["Physiological calcium signal regulating the EF-hands not identified","In vivo consequence of dynactin-independent recruitment untested"]},{"year":2023,"claim":"Added a human truncating allele showing that weakened SUN1 binding alone, despite preserved perinuclear localization, suffices to cause meiotic arrest.","evidence":"WES, immunofluorescence in testes, and Co-IP of truncated vs full-length KASH5 with SUN1","pmids":["36864840"],"confidence":"Medium","gaps":["Single lab","Quantitative threshold of SUN1 binding for function unknown"]},{"year":2023,"claim":"Showed reciprocal dependence in humans, with SUN1 loss reducing KASH5 enrichment at the INM and disrupting telomere attachment.","evidence":"WES and immunofluorescence of patient spermatocytes","pmids":["36933034"],"confidence":"Low","gaps":["Single patient, immunofluorescence only, no in vitro validation","Causality of SUN1 effect on KASH5 not biochemically tested"]},{"year":2025,"claim":"Proposed a second motor for KASH5, showing kinesin KIF5B binds the EF-hand domains and contributes to telomere-led prophase movements.","evidence":"Co-IP, yeast two-hybrid, TIRF and microtubule sedimentation with purified proteins, and pharmacological inhibition (preprint)","pmids":["40501626"],"confidence":"Medium","gaps":["Preprint, not peer-reviewed","How KASH5 coordinates dynein and kinesin binding at the same EF-hand region is unresolved","In vivo genetic test of KIF5B requirement lacking"]},{"year":null,"claim":"How calcium signaling and CDK2-dependent NE remodeling temporally regulate KASH5's switching between dynein and kinesin recruitment to choreograph directional chromosome movements remains unknown.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No identified physiological calcium trigger for the EF-hand domains","Mechanism coordinating opposing motors at one adaptor undefined","Direct CDK2 phosphorylation of KASH5 not demonstrated"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[9,12,1]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[9,12]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[9,12]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0,6,7]}],"localization":[{"term_id":"GO:0005635","term_label":"nuclear envelope","supporting_discovery_ids":[0,2,8]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[8]},{"term_id":"GO:0000228","term_label":"nuclear chromosome","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[2,3,11]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[2,3]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[9,12]}],"complexes":["LINC complex (SUN-KASH)","dynein-dynactin complex"],"partners":["SUN1","SUN2","DYNC1LI1","DYNC1LI2","LIS1","KIF5B"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8N6L0","full_name":"Protein KASH5","aliases":["Coiled-coil domain-containing protein 155","KASH domain-containing protein 5"],"length_aa":562,"mass_kda":62.8,"function":"As a component of the LINC (LInker of Nucleoskeleton and Cytoskeleton) complex, involved in the connection between the nuclear lamina and the cytoskeleton. The nucleocytoplasmic interactions established by the LINC complex play an important role in the transmission of mechanical forces across the nuclear envelope and in nuclear movement and positioning. Required for telomere attachment to nuclear envelope in the prophase of meiosis (PubMed:35587281). Required for rapid telomere prophase movements implicating a SUN1/2:KASH5 LINC complex in which SUN1 and SUN2 seem to act at least partial redundantly. Required for homolog pairing during meiotic prophase in spermatocytes and probably oocytes. Essential for male and female gametogenesis (PubMed:35587281). Recruits cytoplasmic dynein to telomere attachment sites at the nuclear envelope in spermatocytes. In oocytes is involved in meiotic resumption and spindle formation","subcellular_location":"Nucleus outer membrane; Nucleus; Chromosome, telomere; Nucleus envelope","url":"https://www.uniprot.org/uniprotkb/Q8N6L0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KASH5","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/KASH5","total_profiled":1310},"omim":[{"mim_id":"620548","title":"PREMATURE OVARIAN FAILURE 22; POF22","url":"https://www.omim.org/entry/620548"},{"mim_id":"620547","title":"SPERMATOGENIC FAILURE 88; SPGF88","url":"https://www.omim.org/entry/620547"},{"mim_id":"618125","title":"KASH DOMAIN-CONTAINING PROTEIN 5; KASH5","url":"https://www.omim.org/entry/618125"},{"mim_id":"617332","title":"TELOMERE REPEAT-BINDING BOUQUET FORMATION PROTEIN 1; TERB1","url":"https://www.omim.org/entry/617332"},{"mim_id":"617131","title":"TELOMERE REPEAT-BINDING BOUQUET FORMATION PROTEIN 2; TERB2","url":"https://www.omim.org/entry/617131"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"testis","ntpm":52.2}],"url":"https://www.proteinatlas.org/search/KASH5"},"hgnc":{"alias_symbol":["FLJ32658"],"prev_symbol":["CCDC155"]},"alphafold":{"accession":"Q8N6L0","domains":[{"cath_id":"1.10.238.10","chopping":"33-112","consensus_level":"medium","plddt":87.1155,"start":33,"end":112}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8N6L0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8N6L0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8N6L0-F1-predicted_aligned_error_v6.png","plddt_mean":68.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KASH5","jax_strain_url":"https://www.jax.org/strain/search?query=KASH5"},"sequence":{"accession":"Q8N6L0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8N6L0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8N6L0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8N6L0"}},"corpus_meta":[{"pmid":"22826121","id":"PMC_22826121","title":"A conserved KASH domain protein associates with telomeres, SUN1, and dynactin during mammalian meiosis.","date":"2012","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/22826121","citation_count":195,"is_preprint":false},{"pmid":"24062341","id":"PMC_24062341","title":"A mammalian KASH domain protein coupling meiotic chromosomes to the cytoskeleton.","date":"2013","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/24062341","citation_count":187,"is_preprint":false},{"pmid":"29790874","id":"PMC_29790874","title":"Point-of-care whole-exome sequencing of idiopathic male infertility.","date":"2018","source":"Genetics in medicine : official journal of the American College of Medical Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/29790874","citation_count":116,"is_preprint":false},{"pmid":"27153397","id":"PMC_27153397","title":"Mechanisms and Disease Associations of Haplotype-Dependent Allele-Specific DNA Methylation.","date":"2016","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/27153397","citation_count":91,"is_preprint":false},{"pmid":"25892231","id":"PMC_25892231","title":"Mechanism and regulation of rapid telomere prophase movements in mouse meiotic chromosomes.","date":"2015","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/25892231","citation_count":89,"is_preprint":false},{"pmid":"25380821","id":"PMC_25380821","title":"CDK2 regulates nuclear envelope protein dynamics and telomere attachment in mouse meiotic prophase.","date":"2014","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/25380821","citation_count":59,"is_preprint":false},{"pmid":"24870409","id":"PMC_24870409","title":"The meiosis-specific modification of mammalian telomeres.","date":"2014","source":"Cell cycle (Georgetown, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/24870409","citation_count":45,"is_preprint":false},{"pmid":"33393904","id":"PMC_33393904","title":"A molecular mechanism for LINC complex branching by structurally diverse SUN-KASH 6:6 assemblies.","date":"2021","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/33393904","citation_count":37,"is_preprint":false},{"pmid":"35703493","id":"PMC_35703493","title":"The KASH5 protein involved in meiotic chromosomal movements is a novel dynein activating adaptor.","date":"2022","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/35703493","citation_count":36,"is_preprint":false},{"pmid":"34039995","id":"PMC_34039995","title":"The SUN1-SPDYA interaction plays an essential role in meiosis prophase I.","date":"2021","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/34039995","citation_count":31,"is_preprint":false},{"pmid":"29141850","id":"PMC_29141850","title":"Autoantibodies against HSF1 and CCDC155 as Biomarkers of Early-Stage, High-Grade Serous Ovarian Cancer.","date":"2017","source":"Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology","url":"https://pubmed.ncbi.nlm.nih.gov/29141850","citation_count":25,"is_preprint":false},{"pmid":"33058875","id":"PMC_33058875","title":"Structural Analysis of Different LINC Complexes Reveals Distinct Binding Modes.","date":"2020","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/33058875","citation_count":23,"is_preprint":false},{"pmid":"35587281","id":"PMC_35587281","title":"Homozygous missense mutation in CCDC155 disrupts the transmembrane distribution of CCDC155 and SUN1, resulting in non-obstructive azoospermia and premature ovarian insufficiency in humans.","date":"2022","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/35587281","citation_count":22,"is_preprint":false},{"pmid":"24637401","id":"PMC_24637401","title":"The missing LINC: a mammalian KASH-domain protein coupling meiotic chromosomes to the cytoskeleton.","date":"2014","source":"Nucleus (Austin, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/24637401","citation_count":21,"is_preprint":false},{"pmid":"36946995","id":"PMC_36946995","title":"The meiotic LINC complex component KASH5 is an activating adaptor for cytoplasmic dynein.","date":"2023","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/36946995","citation_count":20,"is_preprint":false},{"pmid":"31633067","id":"PMC_31633067","title":"Electron tomography of mouse LINC complexes at meiotic telomere attachment sites with and without microtubules.","date":"2019","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/31633067","citation_count":19,"is_preprint":false},{"pmid":"35674372","id":"PMC_35674372","title":"Novel bi-allelic variants in KASH5 are associated with meiotic arrest and non-obstructive azoospermia.","date":"2022","source":"Molecular human reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/35674372","citation_count":15,"is_preprint":false},{"pmid":"26842404","id":"PMC_26842404","title":"Depletion of the LINC complex disrupts cytoskeleton dynamics and meiotic resumption in mouse oocytes.","date":"2016","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/26842404","citation_count":14,"is_preprint":false},{"pmid":"33238277","id":"PMC_33238277","title":"Fertility Relevance Probability Analysis Shortlists Genetic Markers for Male Fertility Impairment.","date":"2020","source":"Cytogenetic and genome 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complex","date":"2025-05-29","source":"bioRxiv","url":"https://doi.org/10.1101/2025.05.28.656678","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":15059,"output_tokens":3960,"usd":0.052289,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":11703,"output_tokens":4207,"usd":0.081845,"stage2_stop_reason":"end_turn"},"total_usd":0.134134,"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\": 2012,\n      \"finding\": \"KASH5 is a germ cell-specific protein that localizes exclusively at telomeres from leptotene to diplotene stages in spermatocytes and oocytes, contains KASH-related sequences that directly interact with SUN1, and mediates telomere localization at the nuclear envelope.\",\n      \"method\": \"Subcellular localization screening in mouse spermatocytes, co-immunoprecipitation, direct protein interaction assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP and localization experiments, replicated by multiple subsequent labs\",\n      \"pmids\": [\"22826121\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"KASH5 interacts with the microtubule-associated dynein-dynactin complex, connecting the telomere-associated SUN1 protein to the cytoplasmic force-generating machinery for meiotic chromosome movement.\",\n      \"method\": \"Co-immunoprecipitation of dynein-dynactin with KASH5 in mouse spermatocytes\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — Co-IP in spermatocytes, independently replicated and extended by multiple subsequent studies\",\n      \"pmids\": [\"22826121\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"KASH5 is a dynein-binding protein of the outer nuclear membrane that forms a meiotic complex with SUN1; mice deficient in KASH5 are infertile with meiotic arrest in which pairing of homologous chromosomes fails, demonstrating that telomere attachment to the NE alone is insufficient and that coupling to cytoplasmic dynein is required.\",\n      \"method\": \"Genetic knockout mouse model (KASH5-deficient mice), immunofluorescence, chromosome spread analysis\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO mouse with defined meiotic arrest phenotype, replicated across multiple labs\",\n      \"pmids\": [\"24062341\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Quantitative 4D fluorescence imaging confirmed that SUN1/KASH5, microtubules, and dynein—but not actin—are necessary for rapid prophase movements (RPMs) of meiotic chromosomes; KASH5 loss results in loss of both nuclear rotation and individual chromosome telomere movements along microtubule tracks.\",\n      \"method\": \"4D fluorescence imaging in mouse seminiferous tubules, quantitative motion analysis, pharmacological inhibition and genetic depletion\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (live imaging, genetic KO, pharmacological), clear negative control (actin not required)\",\n      \"pmids\": [\"25892231\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"CDK2 ablation causes abnormal cap-like nuclear envelope distribution of KASH5 (and SUN1 and lamin C2) facing the centrosome in spermatocytes; CDK2 phosphorylates SUN1 in vitro, and some telomeres detach from the NE and associate with NE-detached vesicles containing SUN1, indicating CDK2 governs NE structure required for proper KASH5/SUN1 function.\",\n      \"method\": \"Immunofluorescence, electron microscopy, in vitro kinase assay with mouse testis CDK2\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro kinase assay plus IF/EM in CDK2-KO spermatocytes, single lab\",\n      \"pmids\": [\"25380821\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"KASH5 depletion in mouse oocytes arrests most oocytes at the germinal vesicle (GV) stage, causes small and abnormal spindles after GVBD, reduces cytoplasmic F-actin mesh, and displaces pericentrin and P150(Glued); SUN1 depletion causes KASH5 to relocalize exclusively near the oocyte cortex, but KASH5 depletion does not affect SUN1 localization, establishing a directional dependency.\",\n      \"method\": \"Gene silencing (siRNA/morpholino), immunofluorescence, live imaging in mouse oocytes\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KD with defined phenotypic readouts and localization dependency, single lab\",\n      \"pmids\": [\"26842404\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Crystal structures of human SUN2 in complex with the KASH5 peptide reveal that the KASH5 peptide adopts a distinct conformation compared to Nesprin1/2 KASH peptides when bound to SUN2, while sharing core interactions at the C-terminal KASH residues; differences include the KASH-lid and cation loop interactions.\",\n      \"method\": \"X-ray crystallography of SUN2-KASH5 peptide complex\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — high-resolution crystal structure, single lab but rigorous structural method\",\n      \"pmids\": [\"33058875\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Crystallographic and biophysical evidence shows that SUN-KASH forms a constitutive 6:6 complex (two head-to-head 3:3 trimers), providing a molecular mechanism for branched LINC complex networks; KASH5 participates in this higher-order assembly. Zinc coordination by Nesprin-4 was identified as one distinct mechanism, with KASH5 using a structurally diverse mode to achieve the same 6:6 topology.\",\n      \"method\": \"X-ray crystallography, biophysical assays (SEC, ITC), structural analysis of SUN-KASH complexes\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structures with biophysical validation, single lab but multiple orthogonal structural methods\",\n      \"pmids\": [\"33393904\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"A human infertility-associated KASH5 variant (L535Q) within the transmembrane domain reduces hydrophobicity and misdirects KASH5 from the ER/outer nuclear membrane to the mitochondrial membrane, accounting for the infertility phenotype; amino acid substitution studies mapped the hydrophobicity requirement for ER/ONM targeting.\",\n      \"method\": \"Site-directed mutagenesis, subcellular fractionation, fluorescence microscopy in cultured cells, hydrophobicity calculations\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis combined with localization assays, single lab\",\n      \"pmids\": [\"33980926\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"KASH5 is a dynein activating adaptor: KASH5 directly binds dynein using a mechanism conserved among activating adaptors and converts dynein into a processive motor in vitro; mutations in the dynein-binding surface of KASH5 abrogate dynein binding in vitro and disrupt recruitment of the dynein machinery to the nuclear envelope in cultured cells and mouse spermatocytes in vivo.\",\n      \"method\": \"In vitro reconstitution of dynein motility (single-molecule TIRF), pulldown assays, mutagenesis, immunofluorescence in spermatocytes\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution of processive dynein motility, mutagenesis, and in vivo validation in spermatocytes; replicated independently by Garner et al. 2023\",\n      \"pmids\": [\"35703493\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"A homozygous missense mutation in CCDC155/KASH5 (p.Leu197Pro) in the conserved CC domain blocks nuclear envelope distribution of KASH5 and prevents NE-specific enrichment of SUN1, causing meiotic arrest and infertility in humans (NOA and POI); the mutation was validated ex vivo and in vitro.\",\n      \"method\": \"Whole-exome sequencing, functional studies in patient-derived cells (ex vivo/in vitro localization assays), histological analysis\",\n      \"journal\": \"Human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — patient mutation with ex vivo and in vitro functional validation of localization defect, single study\",\n      \"pmids\": [\"35587281\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"A homozygous splicing variant in KASH5 (c.747G>A) disturbs nuclear membrane localization of KASH5 and its binding with SUN1; Kash5 C-terminal deleted mice show defective meiotic homolog pairing and accelerated oocyte depletion, establishing that the KASH5 C-terminus and SUN1 interaction are essential for meiotic prophase I and ovarian reserve maintenance.\",\n      \"method\": \"Whole-exome sequencing, in vitro functional studies, mouse model (Kash5 C-terminal deletion), histology, oocyte spreads\",\n      \"journal\": \"The Journal of clinical endocrinology and metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mouse model plus in vitro binding studies, single lab\",\n      \"pmids\": [\"35708642\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"KASH5 promotes dynein motility in vitro as an activating adaptor; KASH5 interacts with dynein light intermediate chain (DYNC1LI1 or DYNC1LI2) via a conserved helix in the LIC C-terminal domain; KASH5 N-terminal EF-hand calcium-binding residues are essential for dynein interaction (mutation of key Ca2+-binding residues disrupts this); dynein can be recruited to KASH5 at the NE independently of dynactin, while LIS1 is essential for dynactin incorporation into the KASH5-dynein complex; cytosolic KASH5 inhibits dynein's interphase functions.\",\n      \"method\": \"In vitro dynein motility assays, Co-IP, mutagenesis of EF-hand residues, dominant-negative overexpression in cultured cells\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro motility reconstitution, mutagenesis, and mechanistic dissection of assembly hierarchy; independently corroborates Agrawal et al. 2022\",\n      \"pmids\": [\"36946995\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"A homozygous KASH5 frameshift mutation (c.1270_1273del, p.Arg424Thrfs*20) causes absence of KASH5 protein in testes and NOA with meiotic arrest before pachytene; truncated KASH5 protein encircles the nucleus similarly to wild-type but shows weakened interaction with SUN1, explaining the meiotic defect.\",\n      \"method\": \"Whole-exome sequencing, immunofluorescence in testes, co-immunoprecipitation of truncated vs. full-length KASH5 with SUN1 in cultured cells\",\n      \"journal\": \"Frontiers in endocrinology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — patient mutation validated by Co-IP and localization in cultured cells, single lab\",\n      \"pmids\": [\"36864840\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Loss of SUN1 function in human spermatocytes significantly reduces KASH5 levels at the inner nuclear membrane and disrupts chromosomal telomere attachment, establishing that SUN1 is required for KASH5 enrichment at the NE in a human disease context.\",\n      \"method\": \"Whole-exome sequencing, immunofluorescence of patient spermatocytes\",\n      \"journal\": \"Human genetics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single patient, immunofluorescence only, no in vitro validation\",\n      \"pmids\": [\"36933034\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"KIF5B (a kinesin) directly interacts with KASH5 via KASH5's N-terminal EF-hand domains, as shown by co-immunoprecipitation, yeast two-hybrid with KASH5 as bait, TIRF microscopy, and microtubule sedimentation with purified recombinant proteins; KIF5B is recruited by KASH5-SUN1 to the nuclear envelope and colocalizes with KASH5 at telomeres in spermatocytes; chemical inhibition of KIF5B reduces telomere-led chromosome RPMs.\",\n      \"method\": \"Co-immunoprecipitation, yeast two-hybrid, TIRF microscopy with purified proteins, microtubule sedimentation assay, pharmacological inhibition, immunofluorescence in spermatocytes\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods including in vitro reconstitution with purified proteins and in vivo inhibition, preprint not yet peer-reviewed\",\n      \"pmids\": [\"40501626\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"KASH5 is a meiosis-specific outer nuclear membrane protein that forms a LINC complex with inner nuclear membrane SUN1 (and SUN2) to bridge the nuclear envelope; it recruits both cytoplasmic dynein (as a transmembrane dynein activating adaptor that directly binds dynein light intermediate chain via its N-terminal EF-hand domains and converts dynein into a processive motor) and kinesin KIF5B (via its EF-hand domains) to the nuclear envelope, thereby transducing cytoskeletal forces to telomere-led rapid chromosome movements essential for homolog pairing, synapsis, and recombination during meiotic prophase I, with loss of KASH5 causing complete meiotic arrest and infertility in both males and females.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"KASH5 is a meiosis-specific outer nuclear membrane protein that couples telomeres to the cytoskeletal force-generating machinery to drive the chromosome movements required for homolog pairing during meiotic prophase I [#0, #2]. Restricted to germ cells, it localizes at telomeres from leptotene to diplotene and, through its C-terminal KASH domain, binds the inner nuclear membrane SUN proteins to form a LINC complex spanning the nuclear envelope [#0, #6]; structural work shows the SUN-KASH5 assembly adopts a constitutive 6:6 topology underlying higher-order LINC networks [#7]. On the cytoplasmic face, KASH5 functions as a transmembrane dynein activating adaptor: its N-terminal EF-hand domains bind dynein light intermediate chain and convert dynein into a processive motor in vitro, recruiting the dynein-dynactin machinery to the nuclear envelope, with LIS1 required for dynactin incorporation [#1, #9, #12]. KASH5 thereby transduces microtubule- and dynein-dependent forces into telomere-led rapid prophase chromosome movements and nuclear rotation [#3]. Loss or mislocalization of KASH5 causes complete meiotic arrest, failure of homolog pairing, and infertility in mice and humans of both sexes, and pathogenic KASH5 variants disrupting transmembrane targeting, SUN1 binding, or nuclear envelope distribution cause non-obstructive azoospermia and primary ovarian insufficiency [#2, #8, #10, #11].\",\n  \"teleology\": [\n    {\n      \"year\": 2012,\n      \"claim\": \"Established KASH5 as the missing telomere-to-nuclear-envelope tether by showing it is germ-cell specific, localizes at meiotic telomeres, and bridges SUN1 to the cytoplasmic dynein-dynactin machinery.\",\n      \"evidence\": \"Localization screening, reciprocal Co-IP, and direct interaction assays in mouse spermatocytes\",\n      \"pmids\": [\"22826121\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish whether the dynein link is functionally required for chromosome movement\", \"Mechanism of dynein activation not defined\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Demonstrated causally that dynein coupling, not mere telomere attachment, is essential for homolog pairing, via a clean loss-of-function phenotype.\",\n      \"evidence\": \"KASH5-deficient knockout mouse with chromosome spread analysis and immunofluorescence\",\n      \"pmids\": [\"24062341\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve the molecular nature of dynein activation\", \"Movement dynamics not directly visualized\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Defined which cytoskeletal system powers prophase movements, showing SUN1/KASH5-microtubule-dynein dependence and ruling out actin.\",\n      \"evidence\": \"Quantitative 4D live imaging in seminiferous tubules with genetic depletion and pharmacological inhibition\",\n      \"pmids\": [\"25892231\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not address how forces are generated at the molecular level\", \"Kinesin contribution not examined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identified an upstream regulatory input, showing CDK2 governs nuclear envelope organization required for proper KASH5/SUN1 distribution.\",\n      \"evidence\": \"Immunofluorescence, EM, and in vitro kinase assay in CDK2-knockout spermatocytes\",\n      \"pmids\": [\"25380821\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"KASH5 itself not shown to be a direct CDK2 substrate\", \"Single lab, no rescue\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Extended KASH5 function to female meiosis and established directional dependency, with SUN1 controlling KASH5 localization but not vice versa.\",\n      \"evidence\": \"siRNA/morpholino knockdown, immunofluorescence, and live imaging in mouse oocytes\",\n      \"pmids\": [\"26842404\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Spindle and F-actin phenotypes mechanistically separate from telomere role unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Provided atomic detail of the SUN-KASH5 interface, showing KASH5 binds SUN2 with a distinct conformation versus Nesprin KASH peptides.\",\n      \"evidence\": \"X-ray crystallography of SUN2-KASH5 peptide complex\",\n      \"pmids\": [\"33058875\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Binding to SUN1 (the meiotic partner) not structurally resolved\", \"Full-length complex assembly not addressed\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Revealed the higher-order architecture of the LINC complex, showing SUN-KASH5 forms a 6:6 assembly enabling branched networks.\",\n      \"evidence\": \"X-ray crystallography with SEC and ITC biophysical validation\",\n      \"pmids\": [\"33393904\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of 6:6 topology for meiotic force transmission untested in vivo\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Linked a human infertility variant to a membrane-targeting mechanism, showing the transmembrane L535Q substitution misdirects KASH5 to mitochondria.\",\n      \"evidence\": \"Site-directed mutagenesis, subcellular fractionation, and microscopy in cultured cells\",\n      \"pmids\": [\"33980926\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Patient meiotic phenotype not directly examined\", \"Single lab, cultured cell model\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined the dynein activation mechanism, establishing KASH5 as a transmembrane dynein activating adaptor that converts dynein into a processive motor.\",\n      \"evidence\": \"Single-molecule TIRF reconstitution, pulldowns, mutagenesis, and immunofluorescence in spermatocytes\",\n      \"pmids\": [\"35703493\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not map the precise LIC contact or assembly hierarchy\", \"Calcium dependence not addressed\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Confirmed KASH5 as a human meiosis disease gene, with a coiled-coil-domain mutation blocking NE distribution and SUN1 enrichment.\",\n      \"evidence\": \"Whole-exome sequencing with ex vivo and in vitro localization assays and histology\",\n      \"pmids\": [\"35587281\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single family\", \"Movement defect inferred, not directly imaged\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Established the KASH5 C-terminus/SUN1 interaction as essential for prophase I and ovarian reserve via a human variant and matched mouse model.\",\n      \"evidence\": \"WES, in vitro binding studies, and Kash5 C-terminal deletion mouse with oocyte spreads\",\n      \"pmids\": [\"35708642\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Mechanism of accelerated oocyte depletion not fully resolved\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Dissected the dynein-recruitment hierarchy, identifying LIC binding via the EF-hand domain, calcium-binding requirement, dynactin-independent recruitment, and LIS1 dependence.\",\n      \"evidence\": \"In vitro motility assays, Co-IP, EF-hand mutagenesis, and dominant-negative overexpression in cultured cells\",\n      \"pmids\": [\"36946995\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological calcium signal regulating the EF-hands not identified\", \"In vivo consequence of dynactin-independent recruitment untested\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Added a human truncating allele showing that weakened SUN1 binding alone, despite preserved perinuclear localization, suffices to cause meiotic arrest.\",\n      \"evidence\": \"WES, immunofluorescence in testes, and Co-IP of truncated vs full-length KASH5 with SUN1\",\n      \"pmids\": [\"36864840\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Quantitative threshold of SUN1 binding for function unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Showed reciprocal dependence in humans, with SUN1 loss reducing KASH5 enrichment at the INM and disrupting telomere attachment.\",\n      \"evidence\": \"WES and immunofluorescence of patient spermatocytes\",\n      \"pmids\": [\"36933034\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single patient, immunofluorescence only, no in vitro validation\", \"Causality of SUN1 effect on KASH5 not biochemically tested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Proposed a second motor for KASH5, showing kinesin KIF5B binds the EF-hand domains and contributes to telomere-led prophase movements.\",\n      \"evidence\": \"Co-IP, yeast two-hybrid, TIRF and microtubule sedimentation with purified proteins, and pharmacological inhibition (preprint)\",\n      \"pmids\": [\"40501626\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprint, not peer-reviewed\", \"How KASH5 coordinates dynein and kinesin binding at the same EF-hand region is unresolved\", \"In vivo genetic test of KIF5B requirement lacking\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How calcium signaling and CDK2-dependent NE remodeling temporally regulate KASH5's switching between dynein and kinesin recruitment to choreograph directional chromosome movements remains unknown.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No identified physiological calcium trigger for the EF-hand domains\", \"Mechanism coordinating opposing motors at one adaptor undefined\", \"Direct CDK2 phosphorylation of KASH5 not demonstrated\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [9, 12, 1]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [9, 12]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [9, 12]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0, 6, 7]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005635\", \"supporting_discovery_ids\": [0, 2, 8]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [8]},\n      {\"term_id\": \"GO:0000228\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [2, 3, 11]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [2, 3]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [9, 12]}\n    ],\n    \"complexes\": [\"LINC complex (SUN-KASH)\", \"dynein-dynactin complex\"],\n    \"partners\": [\"SUN1\", \"SUN2\", \"DYNC1LI1\", \"DYNC1LI2\", \"LIS1\", \"KIF5B\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}