{"gene":"RPS4X","run_date":"2026-06-10T07:46:27","timeline":{"discoveries":[{"year":1991,"finding":"The human RPS4X gene (identified as CCG2) complements the temperature-sensitive BHK-derived cell cycle mutant tsBN63, which arrests in G1 (and partly G2) at non-permissive temperature due to failure to initiate DNA synthesis. This established that RPS4X (ribosomal protein S4, X-linked) is required for cell cycle progression through G1 and the initiation of DNA synthesis.","method":"DNA-mediated gene transfer complementation of temperature-sensitive mutant; cDNA cloning and nucleotide sequencing","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 1 / Strong — functional complementation of defined cell cycle mutant with cloned cDNA, confirmed by sequence identity; single rigorous study with clear phenotypic rescue","pmids":["1795030"],"is_preprint":false},{"year":1992,"finding":"RPS4X escapes X chromosome inactivation: its mRNA levels in fibroblasts correlate with gene copy number across numerical and structural X chromosome aberrations, including structurally aberrant X chromosomes in Turner syndrome patients.","method":"mRNA quantification by Northern/expression analysis in fibroblast lines with varying X chromosome complements","journal":"Human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct measurement of transcription across multiple patient-derived cell lines; single lab but multiple independent aberration types tested","pmids":["1587534"],"is_preprint":false},{"year":1993,"finding":"RPS4X is physically linked to the X inactivation center (XIC) in Xq13, positioned in a 2.6 Mb YAC contig alongside PHKA1, XIST, and DXS128E. Gene orientation relative to the XIC was determined, providing structural context for its escape from X inactivation.","method":"YAC contig mapping, rare-cutter restriction mapping, CpG island identification, gene orientation analysis","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — physical mapping with multiple restriction enzymes and YAC contig; single study but rigorous genomic approach","pmids":["8401491"],"is_preprint":false},{"year":1996,"finding":"Haploinsufficiency of RPS4X does NOT cause Ullrich-Turner syndrome (UTS): fibroblasts from 46,X,i(Xq) UTS patients (who have three RPS4X copies) show significantly increased RPS4X mRNA, ruling out RPS4X haploinsufficiency as the cause of the UTS phenotype.","method":"mRNA quantification in fibroblasts from karyotypically defined UTS patients with i(Xq)","journal":"Human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct mRNA measurement in clinically defined patient cells; finding is a negative result (haploinsufficiency excluded), single lab","pmids":["8557258"],"is_preprint":false},{"year":2020,"finding":"SLFN11 physically associates with RPS4X (identified by co-immunoprecipitation and LC-MS/MS), and this interaction blocks the mTOR signaling pathway in hepatocellular carcinoma (HCC) cells. Overexpression of SLFN11 inhibits HCC cell proliferation, migration, and invasion in an RPS4X-dependent manner, and suppresses tumor growth in orthotopic mouse models.","method":"Immunoprecipitation (Co-IP) and LC-MS/MS to identify RPS4X as SLFN11-interacting protein; co-IP and immunofluorescence to confirm interaction; loss-of-function and gain-of-function cellular assays; in vivo orthotopic xenograft models; mTOR pathway readout","journal":"Theranostics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus LC-MS/MS identification plus in vitro and in vivo functional assays; single lab but multiple orthogonal methods","pmids":["32292519"],"is_preprint":false},{"year":2021,"finding":"GTF2E2 physically interacts with RPS4X (identified by LC-MS/MS shotgun proteomics), and knockdown of GTF2E2 inhibits lung adenocarcinoma (LUAD) cell proliferation, migration, invasion and tumor growth in vivo. The downstream effect is mediated through the mTOR pathway via RPS4X.","method":"LC-MS/MS shotgun proteomics to identify RPS4X as a GTF2E2-interacting protein; shRNA knockdown of GTF2E2 with proliferation, migration, invasion, and apoptosis assays in vitro; xenograft tumor model in vivo; mTOR pathway analysis","journal":"Cancer cell international","confidence":"Low","confidence_rationale":"Tier 3 / Weak — LC-MS/MS interaction identified but not confirmed by reciprocal Co-IP for RPS4X specifically; single lab, mechanistic follow-up of RPS4X is indirect","pmids":["33757492"],"is_preprint":false},{"year":2024,"finding":"Knockdown of RPS4X in colorectal cancer (CRC) cells reduces tumor stemness markers (including CD44) and suppresses tumor growth and metastatic potential both in vitro and in vivo, placing RPS4X upstream of CRC cell stemness regulation.","method":"shRNA/siRNA knockdown of RPS4X; in vitro stemness assays; in vivo tumor models; correlation with CD44 expression; tumor microarray validation","journal":"Heliyon","confidence":"Low","confidence_rationale":"Tier 3 / Weak — loss-of-function with phenotypic readout but no direct biochemical mechanism for RPS4X in stemness identified; single lab, limited mechanistic depth for RPS4X specifically","pmids":["38439884"],"is_preprint":false}],"current_model":"RPS4X encodes ribosomal protein S4 (X-linked), which escapes X chromosome inactivation and is required for cell cycle progression through G1 and initiation of DNA synthesis; it physically interacts with SLFN11 (and potentially GTF2E2) to modulate mTOR signaling, and its expression level influences tumor cell proliferation and stemness, though its canonical role remains that of a structural ribosomal component whose dosage is tied to translational capacity rather than Turner syndrome etiology."},"narrative":{"mechanistic_narrative":"RPS4X encodes ribosomal protein S4 (X-linked) and was first defined functionally as a gene required for cell cycle progression through G1 and the initiation of DNA synthesis, established by complementation of the temperature-sensitive G1-arrest mutant tsBN63 [PMID:1795030]. It is one of the genes that escapes X chromosome inactivation, with mRNA levels scaling with X chromosome gene copy number across numerical and structural aberrations [PMID:1587534]; it maps physically adjacent to the X inactivation center in Xq13 alongside XIST and PHKA1 [PMID:8401491]. Despite early speculation, RPS4X haploinsufficiency does not underlie Ullrich-Turner syndrome, as i(Xq) patient fibroblasts carrying three copies show elevated rather than reduced RPS4X mRNA [PMID:8557258]. Beyond its ribosomal dosage role, RPS4X physically associates with SLFN11, an interaction that blocks mTOR signaling and constrains hepatocellular carcinoma proliferation, migration, and invasion in an RPS4X-dependent manner [PMID:32292519]. No structural or biochemical mechanism connecting RPS4X to mTOR regulation or to tumor stemness has been characterized in the available corpus.","teleology":[{"year":1991,"claim":"Established that RPS4X has a function beyond mere structural ribosomal residence by showing it is required to traverse G1 and begin DNA synthesis.","evidence":"DNA-mediated gene transfer complementation of the temperature-sensitive G1-arrest mutant tsBN63 with cloned cDNA, confirmed by sequencing","pmids":["1795030"],"confidence":"High","gaps":["Does not define whether the cell cycle requirement reflects general translational capacity or a specific extra-ribosomal function","No molecular partners or substrates identified"]},{"year":1992,"claim":"Answered whether RPS4X is subject to X inactivation, showing its expression is dosage-sensitive to X chromosome copy number, which framed its candidacy for X-aneuploidy phenotypes.","evidence":"mRNA quantification in fibroblast lines with varying X chromosome complements including Turner syndrome aberrations","pmids":["1587534"],"confidence":"Medium","gaps":["Correlation of mRNA with copy number does not establish a phenotypic consequence","Single lab"]},{"year":1993,"claim":"Placed RPS4X in genomic context by mapping it physically adjacent to the X inactivation center, providing structural rationale for its escape from inactivation.","evidence":"YAC contig and rare-cutter restriction mapping with CpG island and orientation analysis in Xq13","pmids":["8401491"],"confidence":"Medium","gaps":["Mapping does not establish a mechanism for escape from inactivation","No functional link to neighboring genes"]},{"year":1996,"claim":"Resolved whether RPS4X dosage causes Turner syndrome by demonstrating that i(Xq) patients have increased, not decreased, RPS4X mRNA, excluding haploinsufficiency as the etiology.","evidence":"mRNA quantification in karyotypically defined Ullrich-Turner syndrome fibroblasts","pmids":["8557258"],"confidence":"Medium","gaps":["Negative result; does not exclude other dosage-sensitive genes","Single lab"]},{"year":2020,"claim":"Identified a direct protein partner and signaling output for RPS4X, showing it binds SLFN11 to block mTOR signaling and mediate suppression of hepatocellular carcinoma.","evidence":"Co-IP and LC-MS/MS identification, reciprocal Co-IP, immunofluorescence, loss/gain-of-function assays, and orthotopic xenografts with mTOR readout","pmids":["32292519"],"confidence":"Medium","gaps":["Molecular mechanism by which the SLFN11-RPS4X interaction blocks mTOR is undefined","Whether this is a ribosome-dependent or extra-ribosomal activity is unresolved","Single lab"]},{"year":2021,"claim":"Extended the RPS4X-mTOR axis to a second cancer context by linking GTF2E2 to RPS4X and lung adenocarcinoma growth.","evidence":"LC-MS/MS shotgun proteomics, shRNA knockdown with proliferation/migration/invasion assays, xenografts, and mTOR pathway analysis","pmids":["33757492"],"confidence":"Low","gaps":["Interaction not confirmed by reciprocal Co-IP for RPS4X","RPS4X mechanistic role inferred indirectly","Single lab"]},{"year":2024,"claim":"Implicated RPS4X in regulation of tumor cell stemness, placing it upstream of CD44-associated stemness in colorectal cancer.","evidence":"shRNA/siRNA knockdown with stemness assays, in vivo tumor models, and tumor microarray correlation with CD44","pmids":["38439884"],"confidence":"Low","gaps":["No direct biochemical mechanism for RPS4X in stemness identified","Correlation with CD44 does not establish causality","Single lab"]},{"year":null,"claim":"It remains unresolved whether RPS4X's cell cycle and cancer-associated functions are extra-ribosomal activities or downstream consequences of its structural role in translational capacity.","evidence":"No discovery in the corpus directly distinguishes ribosomal from non-ribosomal mechanism","pmids":[],"confidence":"Low","gaps":["No structural model of RPS4X interactions","Mechanism of mTOR pathway modulation undefined","No reconciliation of dosage-based and partner-based functions"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005840","term_label":"ribosome","supporting_discovery_ids":[0]}],"pathway":[],"complexes":["ribosome"],"partners":["SLFN11"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P62701","full_name":"Small ribosomal subunit protein eS4, X isoform","aliases":["40S ribosomal protein S4","SCR10","Single copy abundant mRNA protein"],"length_aa":263,"mass_kda":29.6,"function":"Component of the small ribosomal subunit. The ribosome is a large ribonucleoprotein complex responsible for the synthesis of proteins in the cell (PubMed:23636399). Part of the small subunit (SSU) processome, first precursor of the small eukaryotic ribosomal subunit. During the assembly of the SSU processome in the nucleolus, many ribosome biogenesis factors, an RNA chaperone and ribosomal proteins associate with the nascent pre-rRNA and work in concert to generate RNA folding, modifications, rearrangements and cleavage as well as targeted degradation of pre-ribosomal RNA by the RNA exosome (PubMed:34516797)","subcellular_location":"Cytoplasm; Nucleus, nucleolus","url":"https://www.uniprot.org/uniprotkb/P62701/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/RPS4X","classification":"Common Essential","n_dependent_lines":1185,"n_total_lines":1208,"dependency_fraction":0.9809602649006622},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"RACK1","stoichiometry":10.0},{"gene":"RPL4","stoichiometry":10.0},{"gene":"RPL5","stoichiometry":10.0},{"gene":"ENY2","stoichiometry":4.0},{"gene":"NCL","stoichiometry":4.0},{"gene":"PFN1","stoichiometry":4.0},{"gene":"TPT1","stoichiometry":4.0},{"gene":"ABCE1","stoichiometry":0.2},{"gene":"ATG13","stoichiometry":0.2},{"gene":"ATG4B","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/RPS4X","total_profiled":1310},"omim":[{"mim_id":"470000","title":"RIBOSOMAL PROTEIN S4, Y-LINKED, 1; RPS4Y1","url":"https://www.omim.org/entry/470000"},{"mim_id":"400030","title":"RIBOSOMAL PROTEIN S4, Y-LINKED, 2; RPS4Y2","url":"https://www.omim.org/entry/400030"},{"mim_id":"314670","title":"X INACTIVATION-SPECIFIC TRANSCRIPT; XIST","url":"https://www.omim.org/entry/314670"},{"mim_id":"314200","title":"THYROXINE-BINDING GLOBULIN OF SERUM; TBG","url":"https://www.omim.org/entry/314200"},{"mim_id":"312760","title":"RIBOSOMAL PROTEIN S4, X-LINKED; RPS4X","url":"https://www.omim.org/entry/312760"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/RPS4X"},"hgnc":{"alias_symbol":["DXS306","CCG2","SCAR","SCR10","FLJ40595","RPS4","eS4"],"prev_symbol":[]},"alphafold":{"accession":"P62701","domains":[{"cath_id":"3.10.290.10","chopping":"8-85","consensus_level":"high","plddt":96.4171,"start":8,"end":85},{"cath_id":"2.40.50.740","chopping":"121-172","consensus_level":"medium","plddt":96.8133,"start":121,"end":172},{"cath_id":"2.30.30.30","chopping":"178-233","consensus_level":"medium","plddt":96.1677,"start":178,"end":233}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P62701","model_url":"https://alphafold.ebi.ac.uk/files/AF-P62701-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P62701-F1-predicted_aligned_error_v6.png","plddt_mean":95.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RPS4X","jax_strain_url":"https://www.jax.org/strain/search?query=RPS4X"},"sequence":{"accession":"P62701","fasta_url":"https://rest.uniprot.org/uniprotkb/P62701.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P62701/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P62701"}},"corpus_meta":[{"pmid":"10483914","id":"PMC_10483914","title":"The glial scar and central nervous system repair.","date":"1999","source":"Brain research bulletin","url":"https://pubmed.ncbi.nlm.nih.gov/10483914","citation_count":1374,"is_preprint":false},{"pmid":"8030742","id":"PMC_8030742","title":"Morphological and immunochemical differences between keloid and hypertrophic scar.","date":"1994","source":"The American journal of pathology","url":"https://pubmed.ncbi.nlm.nih.gov/8030742","citation_count":430,"is_preprint":false},{"pmid":"10773228","id":"PMC_10773228","title":"Infarct scar: a dynamic tissue.","date":"2000","source":"Cardiovascular research","url":"https://pubmed.ncbi.nlm.nih.gov/10773228","citation_count":406,"is_preprint":false},{"pmid":"32931733","id":"PMC_32931733","title":"Targeting Mitochondria-Located circRNA SCAR Alleviates NASH via Reducing mROS Output.","date":"2020","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/32931733","citation_count":390,"is_preprint":false},{"pmid":"15365369","id":"PMC_15365369","title":"Histopathological differential diagnosis of keloid and hypertrophic scar.","date":"2004","source":"The American Journal of dermatopathology","url":"https://pubmed.ncbi.nlm.nih.gov/15365369","citation_count":215,"is_preprint":false},{"pmid":"30938269","id":"PMC_30938269","title":"Regenerative Scar-Free Skin Wound Healing.","date":"2019","source":"Tissue engineering. 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Journal canadien de chirurgie","url":"https://pubmed.ncbi.nlm.nih.gov/9854530","citation_count":33,"is_preprint":false},{"pmid":"36336030","id":"PMC_36336030","title":"Glial scar survives until the chronic phase by recruiting scar-forming astrocytes after spinal cord injury.","date":"2022","source":"Experimental neurology","url":"https://pubmed.ncbi.nlm.nih.gov/36336030","citation_count":29,"is_preprint":false},{"pmid":"8475990","id":"PMC_8475990","title":"CD44 and hyaluronan expression in human cutaneous scar fibroblasts.","date":"1993","source":"The American journal of pathology","url":"https://pubmed.ncbi.nlm.nih.gov/8475990","citation_count":26,"is_preprint":false},{"pmid":"21989717","id":"PMC_21989717","title":"PTEN inhibits proliferation and functions of hypertrophic scar fibroblasts.","date":"2011","source":"Molecular and cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21989717","citation_count":26,"is_preprint":false},{"pmid":"37739405","id":"PMC_37739405","title":"SCAR: Single-cell and Spatially-resolved Cancer Resources.","date":"2024","source":"Nucleic acids research","url":"https://pubmed.ncbi.nlm.nih.gov/37739405","citation_count":25,"is_preprint":false},{"pmid":"1587534","id":"PMC_1587534","title":"Expression of RPS4X in fibroblasts from patients with structural aberrations of the X chromosome.","date":"1992","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/1587534","citation_count":23,"is_preprint":false},{"pmid":"34684690","id":"PMC_34684690","title":"Advances in Skin Wound and Scar Repair by Polymer Scaffolds.","date":"2021","source":"Molecules (Basel, Switzerland)","url":"https://pubmed.ncbi.nlm.nih.gov/34684690","citation_count":22,"is_preprint":false},{"pmid":"28393182","id":"PMC_28393182","title":"Expression of TGF-β1/mTOR signaling pathway in pathological scar fibroblasts.","date":"2017","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/28393182","citation_count":22,"is_preprint":false},{"pmid":"28273314","id":"PMC_28273314","title":"Losartan Attenuates Scar Formation in Filtering Bleb After Trabeculectomy.","date":"2017","source":"Investigative ophthalmology & visual science","url":"https://pubmed.ncbi.nlm.nih.gov/28273314","citation_count":22,"is_preprint":false},{"pmid":"35050211","id":"PMC_35050211","title":"Characterizing Neonatal Heart Maturation, Regeneration, and Scar Resolution Using Spatial Transcriptomics.","date":"2021","source":"Journal of cardiovascular development and disease","url":"https://pubmed.ncbi.nlm.nih.gov/35050211","citation_count":22,"is_preprint":false},{"pmid":"1795030","id":"PMC_1795030","title":"Molecular cloning of the human gene, CCG2, that complements the BHK-derived temperature-sensitive cell cycle mutant tsBN63: identity of CCG2 with the human X chromosomal SCAR/RPS4X gene.","date":"1991","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/1795030","citation_count":21,"is_preprint":false},{"pmid":"33073427","id":"PMC_33073427","title":"Galectin-1 production is elevated in hypertrophic scar.","date":"2020","source":"Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society","url":"https://pubmed.ncbi.nlm.nih.gov/33073427","citation_count":21,"is_preprint":false},{"pmid":"17716843","id":"PMC_17716843","title":"Closure of supporting cell scar formations requires dynamic actin mechanisms.","date":"2007","source":"Hearing research","url":"https://pubmed.ncbi.nlm.nih.gov/17716843","citation_count":21,"is_preprint":false},{"pmid":"1430555","id":"PMC_1430555","title":"Scar wars strategies. Target collagen.","date":"1992","source":"The Journal of dermatologic surgery and oncology","url":"https://pubmed.ncbi.nlm.nih.gov/1430555","citation_count":21,"is_preprint":false},{"pmid":"31283910","id":"PMC_31283910","title":"MicroRNA-130a has pro-fibroproliferative potential in hypertrophic scar by targeting CYLD.","date":"2019","source":"Archives of biochemistry and biophysics","url":"https://pubmed.ncbi.nlm.nih.gov/31283910","citation_count":20,"is_preprint":false},{"pmid":"16822579","id":"PMC_16822579","title":"Cell motility and SCAR localisation in axenically growing Dictyostelium cells.","date":"2006","source":"European journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/16822579","citation_count":20,"is_preprint":false},{"pmid":"20438387","id":"PMC_20438387","title":"Burn scar carcinoma.","date":"2010","source":"The Journal of dermatological treatment","url":"https://pubmed.ncbi.nlm.nih.gov/20438387","citation_count":19,"is_preprint":false},{"pmid":"33757492","id":"PMC_33757492","title":"Knockdown of GTF2E2 inhibits the growth and progression of lung adenocarcinoma via RPS4X in vitro and in vivo.","date":"2021","source":"Cancer cell international","url":"https://pubmed.ncbi.nlm.nih.gov/33757492","citation_count":19,"is_preprint":false},{"pmid":"19769727","id":"PMC_19769727","title":"Differential expression of cyclooxygenases in hypertrophic scar and keloid tissues.","date":"2009","source":"Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society","url":"https://pubmed.ncbi.nlm.nih.gov/19769727","citation_count":19,"is_preprint":false},{"pmid":"36828096","id":"PMC_36828096","title":"Peptide deregulated in hypertrophic scar-1 alleviates hypertrophic scar fibrosis by targeting focal adhesion kinase and pyruvate kinase M2 and remodeling the metabolic landscape.","date":"2023","source":"International journal of biological macromolecules","url":"https://pubmed.ncbi.nlm.nih.gov/36828096","citation_count":19,"is_preprint":false},{"pmid":"29701269","id":"PMC_29701269","title":"Mechanical and migratory properties of normal, scar, and Dupuytren's fibroblasts.","date":"2018","source":"Journal of molecular recognition : JMR","url":"https://pubmed.ncbi.nlm.nih.gov/29701269","citation_count":17,"is_preprint":false},{"pmid":"8557258","id":"PMC_8557258","title":"Ullrich-Turner syndrome is not caused by haploinsufficiency of RPS4X.","date":"1996","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/8557258","citation_count":17,"is_preprint":false},{"pmid":"36291182","id":"PMC_36291182","title":"Recent Advancements in Molecular Therapeutics for Corneal Scar Treatment.","date":"2022","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/36291182","citation_count":17,"is_preprint":false},{"pmid":"12063286","id":"PMC_12063286","title":"Scar and pulmonary expression and shedding of ACE in rat myocardial infarction.","date":"2002","source":"American journal of physiology. 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Via Microdot Biomaterials for Inhibiting Scar Adhesion.","date":"2024","source":"Advanced materials (Deerfield Beach, Fla.)","url":"https://pubmed.ncbi.nlm.nih.gov/38563392","citation_count":13,"is_preprint":false},{"pmid":"35924378","id":"PMC_35924378","title":"Extravillous trophoblast invasion and decidualization in cesarean scar pregnancies.","date":"2022","source":"Acta obstetricia et gynecologica Scandinavica","url":"https://pubmed.ncbi.nlm.nih.gov/35924378","citation_count":13,"is_preprint":false},{"pmid":"32813921","id":"PMC_32813921","title":"Shedding of proangiogenic microvesicles from hypertrophic scar myofibroblasts.","date":"2020","source":"Experimental dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/32813921","citation_count":13,"is_preprint":false},{"pmid":"32979396","id":"PMC_32979396","title":"A novel transgenic mouse model for corneal scar visualization.","date":"2020","source":"Experimental eye research","url":"https://pubmed.ncbi.nlm.nih.gov/32979396","citation_count":13,"is_preprint":false},{"pmid":"15763924","id":"PMC_15763924","title":"Indirect injury stimulates scar formation-adaptation or pathology?","date":"2004","source":"Connective tissue research","url":"https://pubmed.ncbi.nlm.nih.gov/15763924","citation_count":13,"is_preprint":false},{"pmid":"32310858","id":"PMC_32310858","title":"Wnt Signaling Pathway Proteins in Scar, Hypertrophic Scar, and Keloid: Evidence for a Continuum?","date":"2020","source":"The American Journal of dermatopathology","url":"https://pubmed.ncbi.nlm.nih.gov/32310858","citation_count":12,"is_preprint":false},{"pmid":"39045898","id":"PMC_39045898","title":"Decorin attenuates hypertrophic scar fibrosis via TGFβ/Smad signalling.","date":"2024","source":"Experimental dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/39045898","citation_count":12,"is_preprint":false},{"pmid":"39059459","id":"PMC_39059459","title":"Piezo1 promotes peripheral nerve fibrotic scar formation through Schwann cell senescence.","date":"2024","source":"Neuroscience letters","url":"https://pubmed.ncbi.nlm.nih.gov/39059459","citation_count":12,"is_preprint":false},{"pmid":"22363853","id":"PMC_22363853","title":"Biologicals and fetal cell therapy for wound and scar management.","date":"2011","source":"ISRN dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/22363853","citation_count":12,"is_preprint":false},{"pmid":"35769829","id":"PMC_35769829","title":"Control of fibrosis and hypertrophic scar formation via glycolysis regulation with IR780.","date":"2022","source":"Burns & trauma","url":"https://pubmed.ncbi.nlm.nih.gov/35769829","citation_count":12,"is_preprint":false},{"pmid":"32458517","id":"PMC_32458517","title":"Scar sarcoidosis following rituximab therapy.","date":"2020","source":"Dermatologic therapy","url":"https://pubmed.ncbi.nlm.nih.gov/32458517","citation_count":11,"is_preprint":false},{"pmid":"31912089","id":"PMC_31912089","title":"Heterogeneity of human fibroblasts isolated from hypertrophic scar.","date":"2019","source":"Romanian journal of morphology and embryology = Revue roumaine de morphologie et embryologie","url":"https://pubmed.ncbi.nlm.nih.gov/31912089","citation_count":11,"is_preprint":false},{"pmid":"21136250","id":"PMC_21136250","title":"Current concepts in scar evolution and control.","date":"2010","source":"Aesthetic plastic surgery","url":"https://pubmed.ncbi.nlm.nih.gov/21136250","citation_count":10,"is_preprint":false},{"pmid":"36963720","id":"PMC_36963720","title":"Collagen matricryptin promotes cardiac function by mediating scar formation.","date":"2023","source":"Life sciences","url":"https://pubmed.ncbi.nlm.nih.gov/36963720","citation_count":10,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":43925,"output_tokens":2107,"usd":0.08169,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8719,"output_tokens":2344,"usd":0.051097,"stage2_stop_reason":"end_turn"},"total_usd":0.132787,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"Looking through the abstracts, I need to identify papers specifically about the RPS4X protein (ribosomal protein S4, X-linked) and its mechanism of action.\n\nRelevant papers:\n- PMID 32292519: SLFN11 physically associates with RPS4X and blocks mTOR signaling in HCC\n- PMID 33757492: GTF2E2 interacts with RPS4X and mediates effects through mTOR pathway in LUAD\n- PMID 1795030: CCG2/RPS4X complements a cell cycle mutant (tsBN63), establishing it as essential for cell proliferation\n- PMID 8401491: Physical mapping of RPS4X in the X inactivation center region\n- PMID 1587534: RPS4X escapes X inactivation; mRNA correlates with gene copy number\n- PMID 8557258: RPS4X haploinsufficiency is NOT the cause of Turner syndrome (negative finding)\n- PMID 38439884: RPS4X knockdown reduces tumor stemness and CD44 in CRC\n\nPapers about SCAR (the actin regulator WAVE/SCAR complex) - these are a different protein family and should be excluded.\nPaper PMID 32931733 is about circRNA SCAR - excluded.\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1991,\n      \"finding\": \"The human RPS4X gene (identified as CCG2) complements the temperature-sensitive BHK-derived cell cycle mutant tsBN63, which arrests in G1 (and partly G2) at non-permissive temperature due to failure to initiate DNA synthesis. This established that RPS4X (ribosomal protein S4, X-linked) is required for cell cycle progression through G1 and the initiation of DNA synthesis.\",\n      \"method\": \"DNA-mediated gene transfer complementation of temperature-sensitive mutant; cDNA cloning and nucleotide sequencing\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — functional complementation of defined cell cycle mutant with cloned cDNA, confirmed by sequence identity; single rigorous study with clear phenotypic rescue\",\n      \"pmids\": [\"1795030\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1992,\n      \"finding\": \"RPS4X escapes X chromosome inactivation: its mRNA levels in fibroblasts correlate with gene copy number across numerical and structural X chromosome aberrations, including structurally aberrant X chromosomes in Turner syndrome patients.\",\n      \"method\": \"mRNA quantification by Northern/expression analysis in fibroblast lines with varying X chromosome complements\",\n      \"journal\": \"Human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct measurement of transcription across multiple patient-derived cell lines; single lab but multiple independent aberration types tested\",\n      \"pmids\": [\"1587534\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1993,\n      \"finding\": \"RPS4X is physically linked to the X inactivation center (XIC) in Xq13, positioned in a 2.6 Mb YAC contig alongside PHKA1, XIST, and DXS128E. Gene orientation relative to the XIC was determined, providing structural context for its escape from X inactivation.\",\n      \"method\": \"YAC contig mapping, rare-cutter restriction mapping, CpG island identification, gene orientation analysis\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — physical mapping with multiple restriction enzymes and YAC contig; single study but rigorous genomic approach\",\n      \"pmids\": [\"8401491\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"Haploinsufficiency of RPS4X does NOT cause Ullrich-Turner syndrome (UTS): fibroblasts from 46,X,i(Xq) UTS patients (who have three RPS4X copies) show significantly increased RPS4X mRNA, ruling out RPS4X haploinsufficiency as the cause of the UTS phenotype.\",\n      \"method\": \"mRNA quantification in fibroblasts from karyotypically defined UTS patients with i(Xq)\",\n      \"journal\": \"Human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct mRNA measurement in clinically defined patient cells; finding is a negative result (haploinsufficiency excluded), single lab\",\n      \"pmids\": [\"8557258\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"SLFN11 physically associates with RPS4X (identified by co-immunoprecipitation and LC-MS/MS), and this interaction blocks the mTOR signaling pathway in hepatocellular carcinoma (HCC) cells. Overexpression of SLFN11 inhibits HCC cell proliferation, migration, and invasion in an RPS4X-dependent manner, and suppresses tumor growth in orthotopic mouse models.\",\n      \"method\": \"Immunoprecipitation (Co-IP) and LC-MS/MS to identify RPS4X as SLFN11-interacting protein; co-IP and immunofluorescence to confirm interaction; loss-of-function and gain-of-function cellular assays; in vivo orthotopic xenograft models; mTOR pathway readout\",\n      \"journal\": \"Theranostics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus LC-MS/MS identification plus in vitro and in vivo functional assays; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"32292519\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"GTF2E2 physically interacts with RPS4X (identified by LC-MS/MS shotgun proteomics), and knockdown of GTF2E2 inhibits lung adenocarcinoma (LUAD) cell proliferation, migration, invasion and tumor growth in vivo. The downstream effect is mediated through the mTOR pathway via RPS4X.\",\n      \"method\": \"LC-MS/MS shotgun proteomics to identify RPS4X as a GTF2E2-interacting protein; shRNA knockdown of GTF2E2 with proliferation, migration, invasion, and apoptosis assays in vitro; xenograft tumor model in vivo; mTOR pathway analysis\",\n      \"journal\": \"Cancer cell international\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — LC-MS/MS interaction identified but not confirmed by reciprocal Co-IP for RPS4X specifically; single lab, mechanistic follow-up of RPS4X is indirect\",\n      \"pmids\": [\"33757492\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Knockdown of RPS4X in colorectal cancer (CRC) cells reduces tumor stemness markers (including CD44) and suppresses tumor growth and metastatic potential both in vitro and in vivo, placing RPS4X upstream of CRC cell stemness regulation.\",\n      \"method\": \"shRNA/siRNA knockdown of RPS4X; in vitro stemness assays; in vivo tumor models; correlation with CD44 expression; tumor microarray validation\",\n      \"journal\": \"Heliyon\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — loss-of-function with phenotypic readout but no direct biochemical mechanism for RPS4X in stemness identified; single lab, limited mechanistic depth for RPS4X specifically\",\n      \"pmids\": [\"38439884\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RPS4X encodes ribosomal protein S4 (X-linked), which escapes X chromosome inactivation and is required for cell cycle progression through G1 and initiation of DNA synthesis; it physically interacts with SLFN11 (and potentially GTF2E2) to modulate mTOR signaling, and its expression level influences tumor cell proliferation and stemness, though its canonical role remains that of a structural ribosomal component whose dosage is tied to translational capacity rather than Turner syndrome etiology.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"RPS4X encodes ribosomal protein S4 (X-linked) and was first defined functionally as a gene required for cell cycle progression through G1 and the initiation of DNA synthesis, established by complementation of the temperature-sensitive G1-arrest mutant tsBN63 [#0]. It is one of the genes that escapes X chromosome inactivation, with mRNA levels scaling with X chromosome gene copy number across numerical and structural aberrations [#1]; it maps physically adjacent to the X inactivation center in Xq13 alongside XIST and PHKA1 [#2]. Despite early speculation, RPS4X haploinsufficiency does not underlie Ullrich-Turner syndrome, as i(Xq) patient fibroblasts carrying three copies show elevated rather than reduced RPS4X mRNA [#3]. Beyond its ribosomal dosage role, RPS4X physically associates with SLFN11, an interaction that blocks mTOR signaling and constrains hepatocellular carcinoma proliferation, migration, and invasion in an RPS4X-dependent manner [#4]. No structural or biochemical mechanism connecting RPS4X to mTOR regulation or to tumor stemness has been characterized in the available corpus.\"\n  ,\n  \"teleology\": [\n    {\n      \"year\": 1991,\n      \"claim\": \"Established that RPS4X has a function beyond mere structural ribosomal residence by showing it is required to traverse G1 and begin DNA synthesis.\",\n      \"evidence\": \"DNA-mediated gene transfer complementation of the temperature-sensitive G1-arrest mutant tsBN63 with cloned cDNA, confirmed by sequencing\",\n      \"pmids\": [\"1795030\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not define whether the cell cycle requirement reflects general translational capacity or a specific extra-ribosomal function\", \"No molecular partners or substrates identified\"]\n    },\n    {\n      \"year\": 1992,\n      \"claim\": \"Answered whether RPS4X is subject to X inactivation, showing its expression is dosage-sensitive to X chromosome copy number, which framed its candidacy for X-aneuploidy phenotypes.\",\n      \"evidence\": \"mRNA quantification in fibroblast lines with varying X chromosome complements including Turner syndrome aberrations\",\n      \"pmids\": [\"1587534\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Correlation of mRNA with copy number does not establish a phenotypic consequence\", \"Single lab\"]\n    },\n    {\n      \"year\": 1993,\n      \"claim\": \"Placed RPS4X in genomic context by mapping it physically adjacent to the X inactivation center, providing structural rationale for its escape from inactivation.\",\n      \"evidence\": \"YAC contig and rare-cutter restriction mapping with CpG island and orientation analysis in Xq13\",\n      \"pmids\": [\"8401491\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mapping does not establish a mechanism for escape from inactivation\", \"No functional link to neighboring genes\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Resolved whether RPS4X dosage causes Turner syndrome by demonstrating that i(Xq) patients have increased, not decreased, RPS4X mRNA, excluding haploinsufficiency as the etiology.\",\n      \"evidence\": \"mRNA quantification in karyotypically defined Ullrich-Turner syndrome fibroblasts\",\n      \"pmids\": [\"8557258\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Negative result; does not exclude other dosage-sensitive genes\", \"Single lab\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identified a direct protein partner and signaling output for RPS4X, showing it binds SLFN11 to block mTOR signaling and mediate suppression of hepatocellular carcinoma.\",\n      \"evidence\": \"Co-IP and LC-MS/MS identification, reciprocal Co-IP, immunofluorescence, loss/gain-of-function assays, and orthotopic xenografts with mTOR readout\",\n      \"pmids\": [\"32292519\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular mechanism by which the SLFN11-RPS4X interaction blocks mTOR is undefined\", \"Whether this is a ribosome-dependent or extra-ribosomal activity is unresolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Extended the RPS4X-mTOR axis to a second cancer context by linking GTF2E2 to RPS4X and lung adenocarcinoma growth.\",\n      \"evidence\": \"LC-MS/MS shotgun proteomics, shRNA knockdown with proliferation/migration/invasion assays, xenografts, and mTOR pathway analysis\",\n      \"pmids\": [\"33757492\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Interaction not confirmed by reciprocal Co-IP for RPS4X\", \"RPS4X mechanistic role inferred indirectly\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Implicated RPS4X in regulation of tumor cell stemness, placing it upstream of CD44-associated stemness in colorectal cancer.\",\n      \"evidence\": \"shRNA/siRNA knockdown with stemness assays, in vivo tumor models, and tumor microarray correlation with CD44\",\n      \"pmids\": [\"38439884\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No direct biochemical mechanism for RPS4X in stemness identified\", \"Correlation with CD44 does not establish causality\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved whether RPS4X's cell cycle and cancer-associated functions are extra-ribosomal activities or downstream consequences of its structural role in translational capacity.\",\n      \"evidence\": \"No discovery in the corpus directly distinguishes ribosomal from non-ribosomal mechanism\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of RPS4X interactions\", \"Mechanism of mTOR pathway modulation undefined\", \"No reconciliation of dosage-based and partner-based functions\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005840\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [],\n    \"complexes\": [\"ribosome\"],\n    \"partners\": [\"SLFN11\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":4,"faith_total":4,"faith_pct":100.0}}