{"gene":"SPRR1A","run_date":"2026-04-28T20:42:08","timeline":{"discoveries":[{"year":1998,"finding":"The 173-bp proximal promoter of SPRR1A is necessary and sufficient for regulated expression in primary keratinocytes; calcium-induced expression requires both an AP-1 and an Ets binding site, while TPA/PKC signaling acts primarily through the Ets element. The ESE-1 Ets transcription factor is induced by TPA with kinetics similar to SPRR1A, and binding site swapping revealed that flanking nucleotides and global promoter context determine AP-1 contribution.","method":"Promoter deletion/mutational analysis, binding site swapping, reporter assays, gel-shift assays in primary keratinocytes stimulated with calcium or TPA","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — multiple orthogonal methods (mutagenesis, reporter assays, EMSA) in a single rigorous study","pmids":["9733767"],"is_preprint":false},{"year":2011,"finding":"Sox11 transcriptionally activates Sprr1a in adult peripheral neurons, and this activation is required for Sox11-mediated nerve regeneration; Sox11 binds the Sprr1a promoter (shown by chromatin immunoprecipitation), and mutation of the Sox11 binding site abolishes transactivation and the regenerative phenotype.","method":"HSV-vector-mediated Sox11 overexpression in DRG neurons, chromatin immunoprecipitation (ChIP) assay, promoter mutational analysis, in vivo saphenous nerve crush model, neurite elongation assay","journal":"Experimental neurology","confidence":"High","confidence_rationale":"Tier 1-2 — ChIP plus mutagenesis plus in vivo rescue establish direct transcriptional regulation","pmids":["22024412"],"is_preprint":false},{"year":2019,"finding":"miR-463-3p directly targets SPRR1A mRNA and post-transcriptionally suppresses its expression, thereby inhibiting neurite outgrowth, percentage of cells with neurites, and cell branching in tibial nerve cells; inhibition of miR-463-3p increases SPRR1A expression and improves tibial nerve regeneration in vivo.","method":"Gain- and loss-of-function of miR-463-3p in primary tibial nerve cells, bioinformatics target prediction, in vivo tibial nerve crush model with miR-463-3p modulation and SPRR1A expression measurement","journal":"Artificial cells, nanomedicine, and biotechnology","confidence":"Medium","confidence_rationale":"Tier 2-3 — functional gain/loss-of-function with defined phenotypic readouts, but direct 3′-UTR luciferase validation not explicitly described","pmids":["31468997"],"is_preprint":false},{"year":2023,"finding":"SPRR1A is a direct downstream target of miR-150 in cardiomyocytes and cardiac fibroblasts; miR-150 represses SPRR1A expression, and Sprr1a knockdown in a miR-150 knockout mouse rescues adverse post-MI cardiac remodeling (dysfunction and fibrosis). In human cardiac fibroblasts, hypoxia/reoxygenation upregulates SPRR1A, carvedilol downregulates it inversely to miR-150, and the protective effects of miR-150 are mediated through functional repression of profibrotic SPRR1A.","method":"miR-150 knockout combined with Sprr1a-hypomorphic mouse model (double-mutant epistasis), human cardiac fibroblast culture under hypoxia/reoxygenation, carvedilol treatment, cardiac function and fibrosis readouts post-MI","journal":"Cell death & disease","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis with double-mutant mouse model plus human cell mechanistic validation across multiple conditions","pmids":["37468478"],"is_preprint":false},{"year":2024,"finding":"SPRR1A knockdown (siRNA) in osteosarcoma cancer stem cell-like cells (MG-OKS) reduces cell proliferation, migration, and in vivo tumorigenicity, with RNA sequencing revealing suppression of cell adhesion genes, indicating SPRR1A functions as a cell adhesion-related molecule promoting osteosarcoma progression.","method":"siRNA knockdown, cell proliferation and migration assays, RNA sequencing, in vivo subcutaneous tumor transplantation in nude mice","journal":"Oncology reports","confidence":"Medium","confidence_rationale":"Tier 2-3 — clean KO with defined cellular phenotype and transcriptomic pathway placement, single lab study","pmids":["39704263"],"is_preprint":false}],"current_model":"SPRR1A is a regeneration-associated and differentiation-linked small proline-rich protein whose transcription is activated in keratinocytes by AP-1 and Ets factors (including ESE-1) downstream of calcium and PKC signaling, and in injured neurons by Sox11 via direct promoter binding; its expression is post-transcriptionally repressed by miR-150 (in cardiomyocytes and cardiac fibroblasts, where it promotes profibrotic remodeling) and by miR-463-3p (in peripheral neurons, where it supports axon regeneration), and it promotes cell adhesion, proliferation, and migration in osteosarcoma stem-like cells."},"narrative":{"teleology":[{"year":1998,"claim":"Defining the cis-regulatory logic of SPRR1A transcription in keratinocytes revealed that a minimal 173-bp promoter integrates calcium and PKC signals through cooperative AP-1 and Ets (ESE-1) binding sites, establishing SPRR1A as a direct transcriptional target of differentiation-linked signaling.","evidence":"Promoter deletion/mutation, reporter assays, EMSA, and binding-site swapping in primary keratinocytes stimulated with calcium or TPA","pmids":["9733767"],"confidence":"High","gaps":["Identity of the specific AP-1 heterodimer(s) responsible in vivo not determined","Contribution of chromatin remodeling or distal enhancers not addressed","Whether similar promoter logic operates in non-keratinocyte contexts unknown"]},{"year":2011,"claim":"Demonstrating that Sox11 directly binds and transactivates the Sprr1a promoter in adult DRG neurons, and that this is required for Sox11-driven nerve regeneration, established SPRR1A as a functionally essential regeneration-associated gene downstream of an injury-induced transcription factor.","evidence":"ChIP, promoter mutagenesis, HSV-mediated Sox11 overexpression in DRG neurons, and in vivo saphenous nerve crush model","pmids":["22024412"],"confidence":"High","gaps":["Mechanism by which SPRR1A protein promotes axon elongation is unknown","Whether Sox11 and SPRR1A operate in central nervous system regeneration not tested","Relationship between Sox11 and the AP-1/Ets pathway in neurons not explored"]},{"year":2019,"claim":"Identification of miR-463-3p as a post-transcriptional repressor of SPRR1A in tibial nerve cells showed that SPRR1A levels are tuned by microRNA regulation and that derepression enhances neurite outgrowth and nerve regeneration in vivo.","evidence":"Gain- and loss-of-function of miR-463-3p in primary tibial nerve cells and in vivo tibial nerve crush model","pmids":["31468997"],"confidence":"Medium","gaps":["Direct 3′-UTR luciferase reporter validation of the miR-463-3p binding site was not explicitly shown","Whether miR-463-3p regulation of SPRR1A operates in DRG or central neurons not assessed","Downstream effectors of SPRR1A in neurite outgrowth remain uncharacterized"]},{"year":2023,"claim":"Genetic epistasis in miR-150 knockout × Sprr1a-hypomorphic mice demonstrated that SPRR1A mediates adverse profibrotic cardiac remodeling after myocardial infarction, expanding its functional role beyond epithelial differentiation and nerve regeneration into pathological fibrosis.","evidence":"Double-mutant mouse model post-MI, human cardiac fibroblast hypoxia/reoxygenation culture, carvedilol treatment, and cardiac function/fibrosis readouts","pmids":["37468478"],"confidence":"High","gaps":["Molecular mechanism by which SPRR1A promotes fibrosis (direct binding partners or signaling pathway in fibroblasts) is unknown","Whether SPRR1A acts cell-autonomously in cardiomyocytes versus fibroblasts not resolved","Relevance to human heart failure beyond the mouse model not established"]},{"year":2024,"claim":"SPRR1A knockdown in osteosarcoma stem-like cells reduced proliferation, migration, and tumorigenicity with transcriptomic evidence of suppressed cell adhesion programs, placing SPRR1A as a cell adhesion-related promoter of tumor progression.","evidence":"siRNA knockdown in MG-OKS cells, proliferation/migration assays, RNA-seq, and in vivo nude mouse tumor transplantation","pmids":["39704263"],"confidence":"Medium","gaps":["Single laboratory study; independent replication in additional osteosarcoma models needed","Direct protein interaction partners mediating cell adhesion effects are unidentified","Whether SPRR1A's pro-tumorigenic role extends to other cancer types is unknown"]},{"year":null,"claim":"The biochemical mechanism of action of SPRR1A protein — its direct binding partners, structural role in the cell envelope or cytoskeleton, and how a small proline-rich protein promotes adhesion, migration, and regeneration across such diverse tissues — remains undefined.","evidence":"","pmids":[],"confidence":"Low","gaps":["No crystal or cryo-EM structure of SPRR1A or its complexes exists","Direct protein-protein interaction partners have not been identified by unbiased methods","No reconstituted biochemical activity has been demonstrated for SPRR1A"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098631","term_label":"cell adhesion mediator activity","supporting_discovery_ids":[4]}],"localization":[],"pathway":[{"term_id":"R-HSA-1500931","term_label":"Cell-Cell communication","supporting_discovery_ids":[4]}],"complexes":[],"partners":["SOX11","ESE1"],"other_free_text":[]},"mechanistic_narrative":"SPRR1A is a small proline-rich protein that functions as a regeneration-associated and differentiation-linked effector promoting cell adhesion, proliferation, and migration in multiple tissue contexts. In keratinocytes, SPRR1A transcription is driven by a compact 173-bp proximal promoter requiring cooperative AP-1 and Ets (ESE-1) elements activated downstream of calcium and PKC signaling [PMID:9733767]. In injured peripheral neurons, Sox11 directly binds the Sprr1a promoter to activate transcription required for axon regeneration, and post-transcriptional repression by miR-463-3p limits SPRR1A-dependent neurite outgrowth [PMID:22024412, PMID:31468997]. In the heart, miR-150 represses SPRR1A in cardiomyocytes and cardiac fibroblasts, and genetic epistasis demonstrates that SPRR1A mediates profibrotic remodeling after myocardial infarction [PMID:37468478]."},"prefetch_data":{"uniprot":{"accession":"P35321","full_name":"Cornifin-A","aliases":["19 kDa pancornulin","SPRK","Small proline-rich protein IA","SPR-IA"],"length_aa":89,"mass_kda":9.9,"function":"Cross-linked envelope protein of keratinocytes. It is a keratinocyte protein that first appears in the cell cytosol, but ultimately becomes cross-linked to membrane proteins by transglutaminase. All that results in the formation of an insoluble envelope beneath the plasma membrane","subcellular_location":"Cytoplasm","url":"https://www.uniprot.org/uniprotkb/P35321/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SPRR1A","classification":"Not Classified","n_dependent_lines":30,"n_total_lines":381,"dependency_fraction":0.07874015748031496},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/SPRR1A","total_profiled":1310},"omim":[{"mim_id":"616363","title":"SMALL PROLINE-RICH PROTEIN 4; SPRR4","url":"https://www.omim.org/entry/616363"},{"mim_id":"182266","title":"SMALL PROLINE-RICH PROTEIN 1B; SPRR1B","url":"https://www.omim.org/entry/182266"},{"mim_id":"182265","title":"SMALL PROLINE-RICH PROTEIN 1A; SPRR1A","url":"https://www.omim.org/entry/182265"},{"mim_id":"135940","title":"FILAGGRIN; FLG","url":"https://www.omim.org/entry/135940"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"cervix","ntpm":1194.2},{"tissue":"esophagus","ntpm":3332.0},{"tissue":"vagina","ntpm":1903.3}],"url":"https://www.proteinatlas.org/search/SPRR1A"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"P35321","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P35321","model_url":"https://alphafold.ebi.ac.uk/files/AF-P35321-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P35321-F1-predicted_aligned_error_v6.png","plddt_mean":69.5},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SPRR1A","jax_strain_url":"https://www.jax.org/strain/search?query=SPRR1A"},"sequence":{"accession":"P35321","fasta_url":"https://rest.uniprot.org/uniprotkb/P35321.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P35321/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P35321"}},"corpus_meta":[{"pmid":"22024412","id":"PMC_22024412","title":"The transcription factor Sox11 promotes nerve regeneration through activation of the regeneration-associated gene Sprr1a.","date":"2011","source":"Experimental neurology","url":"https://pubmed.ncbi.nlm.nih.gov/22024412","citation_count":73,"is_preprint":false},{"pmid":"9733767","id":"PMC_9733767","title":"AP-1 and ets transcription factors regulate the expression of the human SPRR1A keratinocyte terminal differentiation marker.","date":"1998","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9733767","citation_count":72,"is_preprint":false},{"pmid":"19107756","id":"PMC_19107756","title":"Expression of the regeneration-associated protein SPRR1A in primary sensory neurons and spinal cord of the adult mouse following peripheral and central injury.","date":"2009","source":"The Journal of comparative neurology","url":"https://pubmed.ncbi.nlm.nih.gov/19107756","citation_count":62,"is_preprint":false},{"pmid":"16321384","id":"PMC_16321384","title":"Selective temporal and regional alterations of Nogo-A and small proline-rich repeat protein 1A (SPRR1A) but not Nogo-66 receptor (NgR) occur following traumatic brain injury in the rat.","date":"2006","source":"Experimental neurology","url":"https://pubmed.ncbi.nlm.nih.gov/16321384","citation_count":43,"is_preprint":false},{"pmid":"35768785","id":"PMC_35768785","title":"Survival-related indicators ALOX12B and SPRR1A are associated with DNA damage repair and tumor microenvironment status in HPV 16-negative head and neck squamous cell carcinoma patients.","date":"2022","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/35768785","citation_count":15,"is_preprint":false},{"pmid":"37468478","id":"PMC_37468478","title":"SPRR1A is a key downstream effector of MiR-150 during both maladaptive cardiac remodeling in mice and human cardiac fibroblast activation.","date":"2023","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/37468478","citation_count":14,"is_preprint":false},{"pmid":"24886019","id":"PMC_24886019","title":"Clinical implications of SPRR1A expression in diffuse large B-cell lymphomas: a prospective, observational study.","date":"2014","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/24886019","citation_count":12,"is_preprint":false},{"pmid":"25424702","id":"PMC_25424702","title":"Clinical significance of SPRR1A expression in progesterone receptor-positive breast cancer.","date":"2014","source":"Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine","url":"https://pubmed.ncbi.nlm.nih.gov/25424702","citation_count":11,"is_preprint":false},{"pmid":"30652380","id":"PMC_30652380","title":"The combined use of EFS, GPX2, and SPRR1A expression could distinguish favorable from poor clinical outcome among epithelial-like head and neck carcinoma subtypes.","date":"2019","source":"Head & neck","url":"https://pubmed.ncbi.nlm.nih.gov/30652380","citation_count":11,"is_preprint":false},{"pmid":"31468997","id":"PMC_31468997","title":"MiR-463-3p inhibits tibial nerve regeneration via post-transcriptional suppression of SPRR1A.","date":"2019","source":"Artificial cells, nanomedicine, and biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/31468997","citation_count":4,"is_preprint":false},{"pmid":"39704263","id":"PMC_39704263","title":"SPRR1A is a potential therapeutic target for osteosarcoma: in vitro and in vivo evaluations using generated artificial osteosarcoma cancer stem cell‑like cells.","date":"2024","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/39704263","citation_count":2,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7381,"output_tokens":1478,"usd":0.022156},"stage2":{"model":"claude-opus-4-6","input_tokens":4699,"output_tokens":1739,"usd":0.100455},"total_usd":0.122611,"stage1_batch_id":"msgbatch_011rkcQdVV1RaFq9XhcG6df6","stage2_batch_id":"msgbatch_01RzgrJafdF4EWHhj5mNi6dh","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1998,\n      \"finding\": \"The 173-bp proximal promoter of SPRR1A is necessary and sufficient for regulated expression in primary keratinocytes; calcium-induced expression requires both an AP-1 and an Ets binding site, while TPA/PKC signaling acts primarily through the Ets element. The ESE-1 Ets transcription factor is induced by TPA with kinetics similar to SPRR1A, and binding site swapping revealed that flanking nucleotides and global promoter context determine AP-1 contribution.\",\n      \"method\": \"Promoter deletion/mutational analysis, binding site swapping, reporter assays, gel-shift assays in primary keratinocytes stimulated with calcium or TPA\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — multiple orthogonal methods (mutagenesis, reporter assays, EMSA) in a single rigorous study\",\n      \"pmids\": [\"9733767\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Sox11 transcriptionally activates Sprr1a in adult peripheral neurons, and this activation is required for Sox11-mediated nerve regeneration; Sox11 binds the Sprr1a promoter (shown by chromatin immunoprecipitation), and mutation of the Sox11 binding site abolishes transactivation and the regenerative phenotype.\",\n      \"method\": \"HSV-vector-mediated Sox11 overexpression in DRG neurons, chromatin immunoprecipitation (ChIP) assay, promoter mutational analysis, in vivo saphenous nerve crush model, neurite elongation assay\",\n      \"journal\": \"Experimental neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — ChIP plus mutagenesis plus in vivo rescue establish direct transcriptional regulation\",\n      \"pmids\": [\"22024412\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"miR-463-3p directly targets SPRR1A mRNA and post-transcriptionally suppresses its expression, thereby inhibiting neurite outgrowth, percentage of cells with neurites, and cell branching in tibial nerve cells; inhibition of miR-463-3p increases SPRR1A expression and improves tibial nerve regeneration in vivo.\",\n      \"method\": \"Gain- and loss-of-function of miR-463-3p in primary tibial nerve cells, bioinformatics target prediction, in vivo tibial nerve crush model with miR-463-3p modulation and SPRR1A expression measurement\",\n      \"journal\": \"Artificial cells, nanomedicine, and biotechnology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — functional gain/loss-of-function with defined phenotypic readouts, but direct 3′-UTR luciferase validation not explicitly described\",\n      \"pmids\": [\"31468997\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"SPRR1A is a direct downstream target of miR-150 in cardiomyocytes and cardiac fibroblasts; miR-150 represses SPRR1A expression, and Sprr1a knockdown in a miR-150 knockout mouse rescues adverse post-MI cardiac remodeling (dysfunction and fibrosis). In human cardiac fibroblasts, hypoxia/reoxygenation upregulates SPRR1A, carvedilol downregulates it inversely to miR-150, and the protective effects of miR-150 are mediated through functional repression of profibrotic SPRR1A.\",\n      \"method\": \"miR-150 knockout combined with Sprr1a-hypomorphic mouse model (double-mutant epistasis), human cardiac fibroblast culture under hypoxia/reoxygenation, carvedilol treatment, cardiac function and fibrosis readouts post-MI\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with double-mutant mouse model plus human cell mechanistic validation across multiple conditions\",\n      \"pmids\": [\"37468478\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SPRR1A knockdown (siRNA) in osteosarcoma cancer stem cell-like cells (MG-OKS) reduces cell proliferation, migration, and in vivo tumorigenicity, with RNA sequencing revealing suppression of cell adhesion genes, indicating SPRR1A functions as a cell adhesion-related molecule promoting osteosarcoma progression.\",\n      \"method\": \"siRNA knockdown, cell proliferation and migration assays, RNA sequencing, in vivo subcutaneous tumor transplantation in nude mice\",\n      \"journal\": \"Oncology reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — clean KO with defined cellular phenotype and transcriptomic pathway placement, single lab study\",\n      \"pmids\": [\"39704263\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SPRR1A is a regeneration-associated and differentiation-linked small proline-rich protein whose transcription is activated in keratinocytes by AP-1 and Ets factors (including ESE-1) downstream of calcium and PKC signaling, and in injured neurons by Sox11 via direct promoter binding; its expression is post-transcriptionally repressed by miR-150 (in cardiomyocytes and cardiac fibroblasts, where it promotes profibrotic remodeling) and by miR-463-3p (in peripheral neurons, where it supports axon regeneration), and it promotes cell adhesion, proliferation, and migration in osteosarcoma stem-like cells.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"SPRR1A is a small proline-rich protein that functions as a regeneration-associated and differentiation-linked effector promoting cell adhesion, proliferation, and migration in multiple tissue contexts. In keratinocytes, SPRR1A transcription is driven by a compact 173-bp proximal promoter requiring cooperative AP-1 and Ets (ESE-1) elements activated downstream of calcium and PKC signaling [PMID:9733767]. In injured peripheral neurons, Sox11 directly binds the Sprr1a promoter to activate transcription required for axon regeneration, and post-transcriptional repression by miR-463-3p limits SPRR1A-dependent neurite outgrowth [PMID:22024412, PMID:31468997]. In the heart, miR-150 represses SPRR1A in cardiomyocytes and cardiac fibroblasts, and genetic epistasis demonstrates that SPRR1A mediates profibrotic remodeling after myocardial infarction [PMID:37468478].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Defining the cis-regulatory logic of SPRR1A transcription in keratinocytes revealed that a minimal 173-bp promoter integrates calcium and PKC signals through cooperative AP-1 and Ets (ESE-1) binding sites, establishing SPRR1A as a direct transcriptional target of differentiation-linked signaling.\",\n      \"evidence\": \"Promoter deletion/mutation, reporter assays, EMSA, and binding-site swapping in primary keratinocytes stimulated with calcium or TPA\",\n      \"pmids\": [\"9733767\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Identity of the specific AP-1 heterodimer(s) responsible in vivo not determined\",\n        \"Contribution of chromatin remodeling or distal enhancers not addressed\",\n        \"Whether similar promoter logic operates in non-keratinocyte contexts unknown\"\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Demonstrating that Sox11 directly binds and transactivates the Sprr1a promoter in adult DRG neurons, and that this is required for Sox11-driven nerve regeneration, established SPRR1A as a functionally essential regeneration-associated gene downstream of an injury-induced transcription factor.\",\n      \"evidence\": \"ChIP, promoter mutagenesis, HSV-mediated Sox11 overexpression in DRG neurons, and in vivo saphenous nerve crush model\",\n      \"pmids\": [\"22024412\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanism by which SPRR1A protein promotes axon elongation is unknown\",\n        \"Whether Sox11 and SPRR1A operate in central nervous system regeneration not tested\",\n        \"Relationship between Sox11 and the AP-1/Ets pathway in neurons not explored\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identification of miR-463-3p as a post-transcriptional repressor of SPRR1A in tibial nerve cells showed that SPRR1A levels are tuned by microRNA regulation and that derepression enhances neurite outgrowth and nerve regeneration in vivo.\",\n      \"evidence\": \"Gain- and loss-of-function of miR-463-3p in primary tibial nerve cells and in vivo tibial nerve crush model\",\n      \"pmids\": [\"31468997\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct 3′-UTR luciferase reporter validation of the miR-463-3p binding site was not explicitly shown\",\n        \"Whether miR-463-3p regulation of SPRR1A operates in DRG or central neurons not assessed\",\n        \"Downstream effectors of SPRR1A in neurite outgrowth remain uncharacterized\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Genetic epistasis in miR-150 knockout × Sprr1a-hypomorphic mice demonstrated that SPRR1A mediates adverse profibrotic cardiac remodeling after myocardial infarction, expanding its functional role beyond epithelial differentiation and nerve regeneration into pathological fibrosis.\",\n      \"evidence\": \"Double-mutant mouse model post-MI, human cardiac fibroblast hypoxia/reoxygenation culture, carvedilol treatment, and cardiac function/fibrosis readouts\",\n      \"pmids\": [\"37468478\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular mechanism by which SPRR1A promotes fibrosis (direct binding partners or signaling pathway in fibroblasts) is unknown\",\n        \"Whether SPRR1A acts cell-autonomously in cardiomyocytes versus fibroblasts not resolved\",\n        \"Relevance to human heart failure beyond the mouse model not established\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"SPRR1A knockdown in osteosarcoma stem-like cells reduced proliferation, migration, and tumorigenicity with transcriptomic evidence of suppressed cell adhesion programs, placing SPRR1A as a cell adhesion-related promoter of tumor progression.\",\n      \"evidence\": \"siRNA knockdown in MG-OKS cells, proliferation/migration assays, RNA-seq, and in vivo nude mouse tumor transplantation\",\n      \"pmids\": [\"39704263\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single laboratory study; independent replication in additional osteosarcoma models needed\",\n        \"Direct protein interaction partners mediating cell adhesion effects are unidentified\",\n        \"Whether SPRR1A's pro-tumorigenic role extends to other cancer types is unknown\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The biochemical mechanism of action of SPRR1A protein — its direct binding partners, structural role in the cell envelope or cytoskeleton, and how a small proline-rich protein promotes adhesion, migration, and regeneration across such diverse tissues — remains undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No crystal or cryo-EM structure of SPRR1A or its complexes exists\",\n        \"Direct protein-protein interaction partners have not been identified by unbiased methods\",\n        \"No reconstituted biochemical activity has been demonstrated for SPRR1A\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098631\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1500931\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"SOX11\",\n      \"ESE1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}