{"gene":"SPDL1","run_date":"2026-06-10T07:46:39","timeline":{"discoveries":[{"year":2008,"finding":"C. elegans SPDL-1 (Spindly ortholog) is required for dynein/dynactin targeting to kinetochores; its inhibition abolishes dynein/dynactin kinetochore localization without perturbing RZZ complex localization, preventing the formation of load-bearing kinetochore-microtubule attachments during prometaphase and causing extensive chromosome missegregation. Epistasis shows that coinhibition of SPDL-1 together with the RZZ complex reduces phenotypic severity to that of RZZ inhibition alone, placing SPDL-1 downstream of RZZ in controlling dynein-mediated kinetochore activity.","method":"RNAi-based loss-of-function in C. elegans embryos, genetic epistasis (double inhibition of SPDL-1 + RZZ), live imaging of kinetochore-microtubule attachments","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean RNAi loss-of-function with specific phenotypic readout, genetic epistasis, live imaging; replicated across multiple conditions in a single rigorous study","pmids":["18765790"],"is_preprint":false},{"year":2008,"finding":"C. elegans SPDL-1 is required for Mad1/MDF-1 localization to kinetochores and for spindle assembly checkpoint (SAC) activation. SPDL-1 co-immunoprecipitates with MDF-1/MAD1 in vivo, and SPDL-1 kinetochore localization depends on KNL-1 and CZW-1/ZW10 (RZZ complex component), establishing SPDL-1 as a kinetochore receptor for MAD1.","method":"RNAi loss-of-function, co-immunoprecipitation, live imaging of SAC protein localization in monopolar spindle embryos","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP combined with genetic loss-of-function and localization experiments in two independent studies (PMID 18765790 and 18936247) showing consistent results","pmids":["18936247","18765790"],"is_preprint":false},{"year":2010,"finding":"Human Spindly (hSpindly/SPDL1) is a cell cycle-regulated mitotic phosphoprotein that interacts with the Rod/ZW10/Zwilch (RZZ) complex. Kinetochore levels of Spindly are regulated by microtubule attachment and biorientation-induced tension. Dominant-negative deletion mutants (NDelta253 or DeltaSB lacking the Spindly box) strongly localize to kinetochores, prevent removal of RZZ and MAD2 from bioriented chromosomes, and arrest cells at metaphase, demonstrating that RZZ-Spindly removal is required to silence the mitotic checkpoint. RNAi depletion of Spindly delays microtubule attachment, and this defect is rescued by co-depletion of ZW10, placing Spindly as a functional component coupling dynein-dependent poleward chromosome movement to efficient microtubule attachment.","method":"Co-immunoprecipitation (Spindly-RZZ interaction), RNAi depletion, deletion mutant overexpression, live-cell imaging, genetic epistasis (Spindly + ZW10 co-depletion)","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (Co-IP, RNAi, dominant-negative mutants, epistasis) in a single study with clear mechanistic readouts","pmids":["20427577"],"is_preprint":false},{"year":2023,"finding":"In chicken cone cells, a previously uncharacterized isoform of SPDL1 (SPDL1-L) localizes to lipid droplets and recruits centrins (CETN3, CETN1) to the cone cell lipid droplet via their C-terminal calcium-binding domains, enabling apical positioning of the single lipid droplet required for normal light sensitivity.","method":"Live imaging, overexpression of truncated centrin constructs, loss-of-function (CETN3 knockout), lipid droplet fractionation, isoform characterization","journal":"Developmental cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiments with functional consequence (light sensitivity), loss-of-function phenotype, but single lab study in a non-canonical cell-type context","pmids":["37699389"],"is_preprint":false},{"year":2024,"finding":"SPDL1 is crucial for maintaining spindle/chromosome structure and chromosome euploidy in postovulatory-aged mouse oocytes; injection of exogenous Spdl1 mRNA into aged MII oocytes remarkably recovers meiotic defects, establishing a direct functional role for SPDL1 in meiotic spindle integrity.","method":"mRNA injection rescue experiment in mouse oocytes, RNA-seq and proteomics of aged oocytes, siRNA knockdown","journal":"Cell proliferation","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mRNA rescue and siRNA knockdown with specific meiotic phenotype, single lab with two complementary approaches","pmids":["39629683"],"is_preprint":false},{"year":2019,"finding":"MRTFB transcriptionally regulates SPDL1 expression; siRNA knockdown of SPDL1 in human CRC cells significantly increases invasion and migration and enhances tumor development in xenograft assays, placing SPDL1 downstream of MRTFB as a functional tumor-suppressor effector in colorectal cancer.","method":"siRNA knockdown, RNA-seq (transcriptome after MRTFB knockdown), Transwell invasion/migration assays, in vivo xenograft tumor assays, Mrtfb knockout mice","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (transcriptomics, cell-based assays, in vivo xenograft) in a single study establishing pathway position","pmids":["31690663"],"is_preprint":false},{"year":2025,"finding":"SPDL1 inhibition in HCT116 colorectal cancer cells promotes cell proliferation, migration, and invasion via activation of the EGFR/ERK signaling pathway and induction of epithelial-mesenchymal transition (EMT); treatment with the MEK inhibitor U0126 reverses these effects, placing SPDL1 upstream of EGFR/ERK/EMT in CRC progression.","method":"SPDL1 knockdown in HCT116 cells, cell viability assay, Transwell migration/invasion assay, Western blot, RNA sequencing, flow cytometry (cell cycle), U0126 pharmacological rescue","journal":"World journal of gastrointestinal oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods with pharmacological epistasis in a single lab study","pmids":["40487946"],"is_preprint":false},{"year":2026,"finding":"Icariin suppresses TNBC proliferation, invasion, and pulmonary metastasis by downregulating SPDL1, which in turn suppresses phosphorylation and activation of the JAK2/STAT3 signaling axis; RNA sequencing confirmed alterations in JAK-STAT pathway molecules downstream of SPDL1 modulation.","method":"In vitro TNBC cell models and in vivo pulmonary metastasis mouse model, RNA sequencing, Western blot (JAK2/STAT3 phosphorylation), SPDL1 knockdown/overexpression","journal":"Cancer cell international","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab study with limited mechanistic validation of the SPDL1-JAK2/STAT3 link; no direct biochemical interaction shown between SPDL1 and JAK2","pmids":["41680875"],"is_preprint":false},{"year":2025,"finding":"hSpindly (SPDL1) is a dynamic protein that oligomerizes at unattached kinetochores and controls Mad1-Mad2 recruitment through the RZZ pathway independently of the KBB (KNL1-Bub3-Bub1) pathway. Threonine 552 is identified as a critical phosphorylation site: the non-phosphorylatable T552A mutant stabilizes hSpindly at kinetochores, impairs SAC signaling, and increases cellular resistance to antimitotic drugs.","method":"Phosphomutant analysis (T552A), kinetochore dynamics (live imaging/FRAP-type mobility assays), SAC signaling readouts, cell viability assay with antimitotic drugs","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — site-directed mutagenesis with multiple functional readouts (localization dynamics, SAC activity, drug resistance), preprint not yet peer-reviewed","pmids":["bio_10.1101_2025.07.25.666731"],"is_preprint":true}],"current_model":"SPDL1/hSpindly is a coiled-coil kinetochore protein that acts downstream of the RZZ (Rod-Zwilch-Zw10) complex to recruit dynein/dynactin to kinetochores, thereby promoting the transition from lateral to end-coupled microtubule attachments, localizing Mad1-Mad2 to unattached kinetochores for spindle assembly checkpoint (SAC) activation, and being removed from bioriented kinetochores (in a process requiring the Spindly box) to silence the checkpoint; phosphorylation at T552 regulates hSpindly's kinetochore dynamics and SAC function, and outside mitosis an SPDL1 isoform (SPDL1-L) localizes to lipid droplets in avian cone cells to position centrins."},"narrative":{"mechanistic_narrative":"SPDL1 (Spindly/hSpindly) is a coiled-coil kinetochore protein that couples the spindle assembly checkpoint to the establishment of load-bearing microtubule attachments during cell division [PMID:18765790, PMID:20427577]. Acting downstream of the RZZ (Rod-Zwilch-Zw10) complex, SPDL1 is required to target dynein/dynactin to kinetochores, and its loss abolishes dynein/dynactin kinetochore localization and prevents formation of stable kinetochore-microtubule attachments without disrupting RZZ itself [PMID:18765790]. SPDL1 also serves as a kinetochore receptor that recruits Mad1 (MDF-1) to drive checkpoint activation, with its own kinetochore loading depending on KNL-1 and the RZZ component ZW10 [PMID:18936247, PMID:18765790, PMID:bio_10.1101_2025.07.25.666731]. Kinetochore levels of SPDL1 are tuned by microtubule attachment and biorientation-induced tension, and removal of the RZZ-Spindly module from bioriented kinetochores—a step requiring the Spindly box—is necessary to silence the checkpoint; dominant-negative mutants that resist removal arrest cells at metaphase [PMID:20427577]. Phosphorylation at T552 governs SPDL1 kinetochore dynamics and SAC output, as a non-phosphorylatable T552A mutant stabilizes the protein at kinetochores, impairs checkpoint signaling, and confers resistance to antimitotic drugs [PMID:bio_10.1101_2025.07.25.666731]. Consistent with this mitotic and meiotic role, SPDL1 maintains spindle integrity and chromosome euploidy in aged oocytes [PMID:39629683]. A distinct non-mitotic isoform, SPDL1-L, localizes to lipid droplets in chicken cone cells and recruits centrins to position the droplet for normal light sensitivity [PMID:37699389]. In colorectal cancer, SPDL1 behaves as a tumor-suppressor effector downstream of MRTFB whose loss promotes invasion and migration [PMID:31690663, PMID:40487946].","teleology":[{"year":2008,"claim":"Established that Spindly is the kinetochore factor coupling RZZ to dynein/dynactin recruitment, answering how dynein reaches kinetochores to build load-bearing attachments.","evidence":"RNAi loss-of-function with genetic epistasis and live imaging of kinetochore-microtubule attachments in C. elegans embryos","pmids":["18765790"],"confidence":"High","gaps":["Does not define the direct binding interface between Spindly and dynein/dynactin","Mechanism of how Spindly is itself loaded onto RZZ not resolved"]},{"year":2008,"claim":"Showed Spindly is a kinetochore receptor for Mad1 and is required for SAC activation, linking dynein recruitment to checkpoint signaling.","evidence":"RNAi, reciprocal co-immunoprecipitation, and live imaging of SAC protein localization in monopolar spindle C. elegans embryos","pmids":["18936247","18765790"],"confidence":"High","gaps":["Direct vs indirect nature of the Spindly-Mad1 interaction not biochemically resolved","Whether Mad1 recruitment is mechanistically separable from dynein recruitment unclear at this stage"]},{"year":2010,"claim":"Defined the human ortholog hSpindly as an RZZ-interacting phosphoprotein whose tension-regulated removal via the Spindly box silences the mitotic checkpoint.","evidence":"Co-IP, RNAi, dominant-negative deletion mutants (NDelta253, DeltaSB), live-cell imaging, and Spindly+ZW10 co-depletion epistasis in human cells","pmids":["20427577"],"confidence":"High","gaps":["Identity of the phosphorylation sites controlling dynamics not yet mapped","Molecular trigger linking biorientation tension to RZZ-Spindly stripping unresolved"]},{"year":2019,"claim":"Placed SPDL1 in a tumor-suppressive transcriptional axis, showing it is an MRTFB-regulated effector whose loss drives colorectal cancer invasion.","evidence":"siRNA knockdown, RNA-seq after MRTFB knockdown, Transwell assays, xenograft tumor assays, and Mrtfb knockout mice","pmids":["31690663"],"confidence":"Medium","gaps":["Whether the tumor-suppressive role reflects mitotic function or a distinct activity is unclear","Direct transcriptional binding of MRTFB to SPDL1 not shown"]},{"year":2023,"claim":"Revealed a non-mitotic moonlighting function: the SPDL1-L isoform positions lipid droplets in cone cells by recruiting centrins.","evidence":"Live imaging, truncated centrin overexpression, CETN3 knockout, lipid droplet fractionation, and isoform characterization in chicken cone cells","pmids":["37699389"],"confidence":"Medium","gaps":["Single lab study in a non-canonical cell type","Relationship between SPDL1-L lipid droplet function and the mitotic kinetochore role unexplored"]},{"year":2024,"claim":"Demonstrated a functional requirement for SPDL1 in meiotic spindle integrity, since exogenous Spdl1 mRNA rescues defects in aged oocytes.","evidence":"mRNA injection rescue, RNA-seq/proteomics, and siRNA knockdown in mouse oocytes","pmids":["39629683"],"confidence":"Medium","gaps":["Mechanism by which SPDL1 declines with oocyte aging not defined","Whether the meiotic role uses the same RZZ/dynein pathway as mitosis untested"]},{"year":2025,"claim":"Identified T552 phosphorylation as the regulator of hSpindly kinetochore dynamics and checkpoint output, connecting a post-translational switch to SAC strength and drug resistance.","evidence":"T552A phosphomutant analysis, kinetochore mobility assays, SAC readouts, and antimitotic drug viability assays (preprint)","pmids":["bio_10.1101_2025.07.25.666731"],"confidence":"Medium","gaps":["Kinase responsible for T552 phosphorylation not identified","Preprint not yet peer-reviewed","Structural basis of how phosphorylation alters kinetochore residence unknown"]},{"year":2025,"claim":"Extended the cancer role mechanistically, showing SPDL1 loss activates EGFR/ERK signaling and EMT in colorectal cancer cells.","evidence":"SPDL1 knockdown in HCT116 cells, migration/invasion assays, Western blot, RNA-seq, and U0126 MEK-inhibitor pharmacological rescue","pmids":["40487946"],"confidence":"Medium","gaps":["Direct molecular link between SPDL1 and EGFR/ERK activation not established","Whether effect depends on SPDL1's mitotic function unresolved"]},{"year":null,"claim":"How SPDL1's well-defined kinetochore/SAC machinery mechanistically intersects with its reported tumor-suppressive signaling and non-mitotic lipid-droplet functions remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying biochemical mechanism links the mitotic and signaling/cancer roles","Direct SPDL1 binding partners in the EGFR/ERK and JAK2/STAT3 contexts not demonstrated","Structural model of SPDL1 engaging dynein/dynactin and Mad1 lacking"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1,2]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005694","term_label":"chromosome","supporting_discovery_ids":[0,1,2,8]},{"term_id":"GO:0005811","term_label":"lipid droplet","supporting_discovery_ids":[3]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[0,1,2]}],"complexes":["RZZ complex (associated)","kinetochore"],"partners":["ZW10","MAD1","CETN3","CETN1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q96EA4","full_name":"Protein Spindly","aliases":["Arsenite-related gene 1 protein","Coiled-coil domain-containing protein 99","Rhabdomyosarcoma antigen MU-RMS-40.4A","Spindle apparatus coiled-coil domain-containing protein 1"],"length_aa":605,"mass_kda":70.2,"function":"Required for the localization of dynein and dynactin to the mitotic kinetochore. Dynein is believed to control the initial lateral interaction between the kinetochore and spindle microtubules and to facilitate the subsequent formation of end-on kinetochore-microtubule attachments mediated by the NDC80 complex. Also required for correct spindle orientation. Does not appear to be required for the removal of spindle assembly checkpoint (SAC) proteins from the kinetochore upon bipolar spindle attachment (PubMed:17576797, PubMed:19468067). Acts as an adapter protein linking the dynein motor complex to various cargos and converts dynein from a non-processive to a highly processive motor in the presence of dynactin. Facilitates the interaction between dynein and dynactin and activates dynein processivity (the ability to move along a microtubule for a long distance without falling off the track) (PubMed:25035494). Plays a role in cell migration (PubMed:30258100)","subcellular_location":"Cytoplasm, cytoskeleton, microtubule organizing center, centrosome; Chromosome, centromere, kinetochore; Nucleus; Cytoplasm, cytoskeleton, spindle pole","url":"https://www.uniprot.org/uniprotkb/Q96EA4/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/SPDL1","classification":"Common Essential","n_dependent_lines":1197,"n_total_lines":1208,"dependency_fraction":0.9908940397350994},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SPDL1","total_profiled":1310},"omim":[{"mim_id":"616401","title":"SPINDLE APPARATUS COILED-COIL PROTEIN 1; SPDL1","url":"https://www.omim.org/entry/616401"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"testis","ntpm":33.2}],"url":"https://www.proteinatlas.org/search/SPDL1"},"hgnc":{"alias_symbol":["FLJ20364","hSpindly"],"prev_symbol":["CCDC99"]},"alphafold":{"accession":"Q96EA4","domains":[{"cath_id":"-","chopping":"21-26_35-154_165-248_261-349_392-438","consensus_level":"medium","plddt":89.6195,"start":21,"end":438}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96EA4","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96EA4-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96EA4-F1-predicted_aligned_error_v6.png","plddt_mean":74.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SPDL1","jax_strain_url":"https://www.jax.org/strain/search?query=SPDL1"},"sequence":{"accession":"Q96EA4","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96EA4.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96EA4/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96EA4"}},"corpus_meta":[{"pmid":"18765790","id":"PMC_18765790","title":"A new mechanism controlling kinetochore-microtubule interactions revealed by comparison of two dynein-targeting components: SPDL-1 and the Rod/Zwilch/Zw10 complex.","date":"2008","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/18765790","citation_count":144,"is_preprint":false},{"pmid":"28638732","id":"PMC_28638732","title":"Serum levels of soluble programmed death protein 1 (sPD-1) and soluble programmed death ligand 1 (sPD-L1) in advanced pancreatic cancer.","date":"2017","source":"Oncoimmunology","url":"https://pubmed.ncbi.nlm.nih.gov/28638732","citation_count":119,"is_preprint":false},{"pmid":"20427577","id":"PMC_20427577","title":"Spindly/CCDC99 is required for efficient chromosome congression and mitotic checkpoint regulation.","date":"2010","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/20427577","citation_count":118,"is_preprint":false},{"pmid":"34204509","id":"PMC_34204509","title":"Soluble Programmed Death Ligand-1 (sPD-L1): A Pool of Circulating Proteins Implicated in Health and Diseases.","date":"2021","source":"Cancers","url":"https://pubmed.ncbi.nlm.nih.gov/34204509","citation_count":99,"is_preprint":false},{"pmid":"27780932","id":"PMC_27780932","title":"Soluble programmed death-ligand 1 (sPDL1) and neutrophil-to-lymphocyte ratio (NLR) predicts survival in advanced biliary tract cancer patients treated with palliative chemotherapy.","date":"2016","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/27780932","citation_count":87,"is_preprint":false},{"pmid":"29366520","id":"PMC_29366520","title":"Clinical significance of soluble programmed cell death ligand-1 (sPD-L1) in hepatocellular carcinoma patients treated with radiotherapy.","date":"2018","source":"Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and 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Wroclaw Medical University","url":"https://pubmed.ncbi.nlm.nih.gov/33438375","citation_count":1,"is_preprint":false},{"pmid":"39042994","id":"PMC_39042994","title":"Elevated serum soluble programmed death ligand 1 (sPD-L1) level correlate with clinical characteristics in breast cancer patients: A study at Hospital Universiti Sains Malaysia.","date":"2024","source":"Cytokine","url":"https://pubmed.ncbi.nlm.nih.gov/39042994","citation_count":1,"is_preprint":false},{"pmid":"40943153","id":"PMC_40943153","title":"Immune Checkpoint Dysregulation in Aneurysmal Subarachnoid Hemorrhage: A Prospective Study of sCTLA-4 and sPD-L1 as Biomarkers of Symptomatic Vasospasm.","date":"2025","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/40943153","citation_count":1,"is_preprint":false},{"pmid":"39842384","id":"PMC_39842384","title":"Association between clinical activity score and serum sPD-1 and sPD-L1 levels during systemic glucocorticoid treatment for active moderate-to-severe thyroid eye disease.","date":"2025","source":"Cytokine","url":"https://pubmed.ncbi.nlm.nih.gov/39842384","citation_count":1,"is_preprint":false},{"pmid":"38071053","id":"PMC_38071053","title":"[Levels and Clinical Significances of sPD-1 and sPD-L1 in Peripheral Blood of Lymphoma Patients].","date":"2023","source":"Zhongguo shi yan xue ye xue za zhi","url":"https://pubmed.ncbi.nlm.nih.gov/38071053","citation_count":0,"is_preprint":false},{"pmid":"41680875","id":"PMC_41680875","title":"Mechanism by which Icariin suppresses pulmonary metastasis in triple-negative breast cancer through downregulation of the SPDL1/JAK2/STAT3 signaling pathway.","date":"2026","source":"Cancer cell international","url":"https://pubmed.ncbi.nlm.nih.gov/41680875","citation_count":0,"is_preprint":false},{"pmid":"39328700","id":"PMC_39328700","title":"Maternal Soluble Programmed Death Ligand-1 (sPD-L1) and T-regulatory Cells (Tregs) Alteration in Preeclampsia: A Cross-Sectional Study From Eastern India.","date":"2024","source":"Cureus","url":"https://pubmed.ncbi.nlm.nih.gov/39328700","citation_count":0,"is_preprint":false},{"pmid":"42189082","id":"PMC_42189082","title":"Aptamer-Coupled Droplet CRISPR/Cas12a Enables Ultrasensitive sPD-L1 Detection.","date":"2026","source":"Analytical chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/42189082","citation_count":0,"is_preprint":false},{"pmid":"41603965","id":"PMC_41603965","title":"Circulating sPD-L1 as a tumor microenvironment-derived biomarker: enhancing diagnostic discrimination accuracy in breast cancer.","date":"2026","source":"Cancer immunology, immunotherapy : CII","url":"https://pubmed.ncbi.nlm.nih.gov/41603965","citation_count":0,"is_preprint":false},{"pmid":"37503446","id":"PMC_37503446","title":"Retracted: The Change of Soluble Programmed Death Ligand 1 (sPD-L1) in Plasma of Small Cell Lung Cancer and Its Clinical Significance.","date":"2023","source":"Computational and mathematical methods in medicine","url":"https://pubmed.ncbi.nlm.nih.gov/37503446","citation_count":0,"is_preprint":false},{"pmid":"42258041","id":"PMC_42258041","title":"Serum Soluble Programmed Death Ligand-1 (sPD-L1) as a Diagnostic Marker in Neonatal Sepsis.","date":"2026","source":"Indian journal of pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/42258041","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.07.25.666731","title":"hSpindly’s dynamic controls SAC activity independently of the KBB pathway at unattached kinetochores","date":"2025-07-25","source":"bioRxiv","url":"https://doi.org/10.1101/2025.07.25.666731","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":40526,"output_tokens":2789,"usd":0.081707,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10013,"output_tokens":3167,"usd":0.06462,"stage2_stop_reason":"end_turn"},"total_usd":0.146327,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2008,\n      \"finding\": \"C. elegans SPDL-1 (Spindly ortholog) is required for dynein/dynactin targeting to kinetochores; its inhibition abolishes dynein/dynactin kinetochore localization without perturbing RZZ complex localization, preventing the formation of load-bearing kinetochore-microtubule attachments during prometaphase and causing extensive chromosome missegregation. Epistasis shows that coinhibition of SPDL-1 together with the RZZ complex reduces phenotypic severity to that of RZZ inhibition alone, placing SPDL-1 downstream of RZZ in controlling dynein-mediated kinetochore activity.\",\n      \"method\": \"RNAi-based loss-of-function in C. elegans embryos, genetic epistasis (double inhibition of SPDL-1 + RZZ), live imaging of kinetochore-microtubule attachments\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean RNAi loss-of-function with specific phenotypic readout, genetic epistasis, live imaging; replicated across multiple conditions in a single rigorous study\",\n      \"pmids\": [\"18765790\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"C. elegans SPDL-1 is required for Mad1/MDF-1 localization to kinetochores and for spindle assembly checkpoint (SAC) activation. SPDL-1 co-immunoprecipitates with MDF-1/MAD1 in vivo, and SPDL-1 kinetochore localization depends on KNL-1 and CZW-1/ZW10 (RZZ complex component), establishing SPDL-1 as a kinetochore receptor for MAD1.\",\n      \"method\": \"RNAi loss-of-function, co-immunoprecipitation, live imaging of SAC protein localization in monopolar spindle embryos\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP combined with genetic loss-of-function and localization experiments in two independent studies (PMID 18765790 and 18936247) showing consistent results\",\n      \"pmids\": [\"18936247\", \"18765790\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Human Spindly (hSpindly/SPDL1) is a cell cycle-regulated mitotic phosphoprotein that interacts with the Rod/ZW10/Zwilch (RZZ) complex. Kinetochore levels of Spindly are regulated by microtubule attachment and biorientation-induced tension. Dominant-negative deletion mutants (NDelta253 or DeltaSB lacking the Spindly box) strongly localize to kinetochores, prevent removal of RZZ and MAD2 from bioriented chromosomes, and arrest cells at metaphase, demonstrating that RZZ-Spindly removal is required to silence the mitotic checkpoint. RNAi depletion of Spindly delays microtubule attachment, and this defect is rescued by co-depletion of ZW10, placing Spindly as a functional component coupling dynein-dependent poleward chromosome movement to efficient microtubule attachment.\",\n      \"method\": \"Co-immunoprecipitation (Spindly-RZZ interaction), RNAi depletion, deletion mutant overexpression, live-cell imaging, genetic epistasis (Spindly + ZW10 co-depletion)\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (Co-IP, RNAi, dominant-negative mutants, epistasis) in a single study with clear mechanistic readouts\",\n      \"pmids\": [\"20427577\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In chicken cone cells, a previously uncharacterized isoform of SPDL1 (SPDL1-L) localizes to lipid droplets and recruits centrins (CETN3, CETN1) to the cone cell lipid droplet via their C-terminal calcium-binding domains, enabling apical positioning of the single lipid droplet required for normal light sensitivity.\",\n      \"method\": \"Live imaging, overexpression of truncated centrin constructs, loss-of-function (CETN3 knockout), lipid droplet fractionation, isoform characterization\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiments with functional consequence (light sensitivity), loss-of-function phenotype, but single lab study in a non-canonical cell-type context\",\n      \"pmids\": [\"37699389\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SPDL1 is crucial for maintaining spindle/chromosome structure and chromosome euploidy in postovulatory-aged mouse oocytes; injection of exogenous Spdl1 mRNA into aged MII oocytes remarkably recovers meiotic defects, establishing a direct functional role for SPDL1 in meiotic spindle integrity.\",\n      \"method\": \"mRNA injection rescue experiment in mouse oocytes, RNA-seq and proteomics of aged oocytes, siRNA knockdown\",\n      \"journal\": \"Cell proliferation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mRNA rescue and siRNA knockdown with specific meiotic phenotype, single lab with two complementary approaches\",\n      \"pmids\": [\"39629683\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"MRTFB transcriptionally regulates SPDL1 expression; siRNA knockdown of SPDL1 in human CRC cells significantly increases invasion and migration and enhances tumor development in xenograft assays, placing SPDL1 downstream of MRTFB as a functional tumor-suppressor effector in colorectal cancer.\",\n      \"method\": \"siRNA knockdown, RNA-seq (transcriptome after MRTFB knockdown), Transwell invasion/migration assays, in vivo xenograft tumor assays, Mrtfb knockout mice\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (transcriptomics, cell-based assays, in vivo xenograft) in a single study establishing pathway position\",\n      \"pmids\": [\"31690663\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SPDL1 inhibition in HCT116 colorectal cancer cells promotes cell proliferation, migration, and invasion via activation of the EGFR/ERK signaling pathway and induction of epithelial-mesenchymal transition (EMT); treatment with the MEK inhibitor U0126 reverses these effects, placing SPDL1 upstream of EGFR/ERK/EMT in CRC progression.\",\n      \"method\": \"SPDL1 knockdown in HCT116 cells, cell viability assay, Transwell migration/invasion assay, Western blot, RNA sequencing, flow cytometry (cell cycle), U0126 pharmacological rescue\",\n      \"journal\": \"World journal of gastrointestinal oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods with pharmacological epistasis in a single lab study\",\n      \"pmids\": [\"40487946\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Icariin suppresses TNBC proliferation, invasion, and pulmonary metastasis by downregulating SPDL1, which in turn suppresses phosphorylation and activation of the JAK2/STAT3 signaling axis; RNA sequencing confirmed alterations in JAK-STAT pathway molecules downstream of SPDL1 modulation.\",\n      \"method\": \"In vitro TNBC cell models and in vivo pulmonary metastasis mouse model, RNA sequencing, Western blot (JAK2/STAT3 phosphorylation), SPDL1 knockdown/overexpression\",\n      \"journal\": \"Cancer cell international\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab study with limited mechanistic validation of the SPDL1-JAK2/STAT3 link; no direct biochemical interaction shown between SPDL1 and JAK2\",\n      \"pmids\": [\"41680875\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"hSpindly (SPDL1) is a dynamic protein that oligomerizes at unattached kinetochores and controls Mad1-Mad2 recruitment through the RZZ pathway independently of the KBB (KNL1-Bub3-Bub1) pathway. Threonine 552 is identified as a critical phosphorylation site: the non-phosphorylatable T552A mutant stabilizes hSpindly at kinetochores, impairs SAC signaling, and increases cellular resistance to antimitotic drugs.\",\n      \"method\": \"Phosphomutant analysis (T552A), kinetochore dynamics (live imaging/FRAP-type mobility assays), SAC signaling readouts, cell viability assay with antimitotic drugs\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — site-directed mutagenesis with multiple functional readouts (localization dynamics, SAC activity, drug resistance), preprint not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2025.07.25.666731\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"SPDL1/hSpindly is a coiled-coil kinetochore protein that acts downstream of the RZZ (Rod-Zwilch-Zw10) complex to recruit dynein/dynactin to kinetochores, thereby promoting the transition from lateral to end-coupled microtubule attachments, localizing Mad1-Mad2 to unattached kinetochores for spindle assembly checkpoint (SAC) activation, and being removed from bioriented kinetochores (in a process requiring the Spindly box) to silence the checkpoint; phosphorylation at T552 regulates hSpindly's kinetochore dynamics and SAC function, and outside mitosis an SPDL1 isoform (SPDL1-L) localizes to lipid droplets in avian cone cells to position centrins.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SPDL1 (Spindly/hSpindly) is a coiled-coil kinetochore protein that couples the spindle assembly checkpoint to the establishment of load-bearing microtubule attachments during cell division [#0, #2]. Acting downstream of the RZZ (Rod-Zwilch-Zw10) complex, SPDL1 is required to target dynein/dynactin to kinetochores, and its loss abolishes dynein/dynactin kinetochore localization and prevents formation of stable kinetochore-microtubule attachments without disrupting RZZ itself [#0]. SPDL1 also serves as a kinetochore receptor that recruits Mad1 (MDF-1) to drive checkpoint activation, with its own kinetochore loading depending on KNL-1 and the RZZ component ZW10 [#1, #8]. Kinetochore levels of SPDL1 are tuned by microtubule attachment and biorientation-induced tension, and removal of the RZZ-Spindly module from bioriented kinetochores—a step requiring the Spindly box—is necessary to silence the checkpoint; dominant-negative mutants that resist removal arrest cells at metaphase [#2]. Phosphorylation at T552 governs SPDL1 kinetochore dynamics and SAC output, as a non-phosphorylatable T552A mutant stabilizes the protein at kinetochores, impairs checkpoint signaling, and confers resistance to antimitotic drugs [#8]. Consistent with this mitotic and meiotic role, SPDL1 maintains spindle integrity and chromosome euploidy in aged oocytes [#4]. A distinct non-mitotic isoform, SPDL1-L, localizes to lipid droplets in chicken cone cells and recruits centrins to position the droplet for normal light sensitivity [#3]. In colorectal cancer, SPDL1 behaves as a tumor-suppressor effector downstream of MRTFB whose loss promotes invasion and migration [#5, #6].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Established that Spindly is the kinetochore factor coupling RZZ to dynein/dynactin recruitment, answering how dynein reaches kinetochores to build load-bearing attachments.\",\n      \"evidence\": \"RNAi loss-of-function with genetic epistasis and live imaging of kinetochore-microtubule attachments in C. elegans embryos\",\n      \"pmids\": [\"18765790\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not define the direct binding interface between Spindly and dynein/dynactin\", \"Mechanism of how Spindly is itself loaded onto RZZ not resolved\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Showed Spindly is a kinetochore receptor for Mad1 and is required for SAC activation, linking dynein recruitment to checkpoint signaling.\",\n      \"evidence\": \"RNAi, reciprocal co-immunoprecipitation, and live imaging of SAC protein localization in monopolar spindle C. elegans embryos\",\n      \"pmids\": [\"18936247\", \"18765790\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct vs indirect nature of the Spindly-Mad1 interaction not biochemically resolved\", \"Whether Mad1 recruitment is mechanistically separable from dynein recruitment unclear at this stage\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Defined the human ortholog hSpindly as an RZZ-interacting phosphoprotein whose tension-regulated removal via the Spindly box silences the mitotic checkpoint.\",\n      \"evidence\": \"Co-IP, RNAi, dominant-negative deletion mutants (NDelta253, DeltaSB), live-cell imaging, and Spindly+ZW10 co-depletion epistasis in human cells\",\n      \"pmids\": [\"20427577\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the phosphorylation sites controlling dynamics not yet mapped\", \"Molecular trigger linking biorientation tension to RZZ-Spindly stripping unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Placed SPDL1 in a tumor-suppressive transcriptional axis, showing it is an MRTFB-regulated effector whose loss drives colorectal cancer invasion.\",\n      \"evidence\": \"siRNA knockdown, RNA-seq after MRTFB knockdown, Transwell assays, xenograft tumor assays, and Mrtfb knockout mice\",\n      \"pmids\": [\"31690663\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether the tumor-suppressive role reflects mitotic function or a distinct activity is unclear\", \"Direct transcriptional binding of MRTFB to SPDL1 not shown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Revealed a non-mitotic moonlighting function: the SPDL1-L isoform positions lipid droplets in cone cells by recruiting centrins.\",\n      \"evidence\": \"Live imaging, truncated centrin overexpression, CETN3 knockout, lipid droplet fractionation, and isoform characterization in chicken cone cells\",\n      \"pmids\": [\"37699389\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab study in a non-canonical cell type\", \"Relationship between SPDL1-L lipid droplet function and the mitotic kinetochore role unexplored\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Demonstrated a functional requirement for SPDL1 in meiotic spindle integrity, since exogenous Spdl1 mRNA rescues defects in aged oocytes.\",\n      \"evidence\": \"mRNA injection rescue, RNA-seq/proteomics, and siRNA knockdown in mouse oocytes\",\n      \"pmids\": [\"39629683\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which SPDL1 declines with oocyte aging not defined\", \"Whether the meiotic role uses the same RZZ/dynein pathway as mitosis untested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified T552 phosphorylation as the regulator of hSpindly kinetochore dynamics and checkpoint output, connecting a post-translational switch to SAC strength and drug resistance.\",\n      \"evidence\": \"T552A phosphomutant analysis, kinetochore mobility assays, SAC readouts, and antimitotic drug viability assays (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.07.25.666731\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Kinase responsible for T552 phosphorylation not identified\", \"Preprint not yet peer-reviewed\", \"Structural basis of how phosphorylation alters kinetochore residence unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Extended the cancer role mechanistically, showing SPDL1 loss activates EGFR/ERK signaling and EMT in colorectal cancer cells.\",\n      \"evidence\": \"SPDL1 knockdown in HCT116 cells, migration/invasion assays, Western blot, RNA-seq, and U0126 MEK-inhibitor pharmacological rescue\",\n      \"pmids\": [\"40487946\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular link between SPDL1 and EGFR/ERK activation not established\", \"Whether effect depends on SPDL1's mitotic function unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How SPDL1's well-defined kinetochore/SAC machinery mechanistically intersects with its reported tumor-suppressive signaling and non-mitotic lipid-droplet functions remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying biochemical mechanism links the mitotic and signaling/cancer roles\", \"Direct SPDL1 binding partners in the EGFR/ERK and JAK2/STAT3 contexts not demonstrated\", \"Structural model of SPDL1 engaging dynein/dynactin and Mad1 lacking\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005694\", \"supporting_discovery_ids\": [0, 1, 2, 8]},\n      {\"term_id\": \"GO:0005811\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [0, 1, 2]}\n    ],\n    \"complexes\": [\"RZZ complex (associated)\", \"kinetochore\"],\n    \"partners\": [\"ZW10\", \"MAD1\", \"CETN3\", \"CETN1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}