{"gene":"NCSTN","run_date":"2026-06-10T05:19:52","timeline":{"discoveries":[{"year":2020,"finding":"NCSTN promotes HCC cell growth and metastasis by cleaving Notch1, which activates AKT and increases AKT/GSK-3β phosphorylation, thereby decreasing the GSK-3β/β-catenin complex, inhibiting β-catenin degradation, promoting nuclear translocation of β-catenin, and upregulating the transcription of Zeb1 to induce EMT.","method":"Notch and AKT inhibitor pharmacological dissection, co-immunoprecipitation, subcellular protein fractionation, immunofluorescence, in vitro cell assays, and in vivo xenograft models","journal":"Journal of experimental & clinical cancer research : CR","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (co-IP, fractionation, inhibitor epistasis, in vivo) in single lab","pmids":["32631394"],"is_preprint":false},{"year":2022,"finding":"LRP1B directly binds to NCSTN protein and affects its expression level, thereby regulating the PI3K/AKT signaling pathway in HCC cells.","method":"Co-immunoprecipitation (Co-IP) and in vitro/in vivo knockdown experiments with pathway readouts","journal":"Genes & diseases","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP binding plus functional KD data, single lab, single study","pmids":["37492741"],"is_preprint":false},{"year":2015,"finding":"Haploinsufficiency of NCSTN caused by a nonsense mutation (c.1258C>T, p.Q420X) results in significantly reduced nicastrin mRNA and protein levels in skin (whole skin, epidermis, dermis) and cultured keratinocytes and fibroblasts from hidradenitis suppurativa patients.","method":"Real-time quantitative PCR and Western blotting on patient-derived skin samples and primary cell cultures","journal":"Clinical and experimental dermatology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal methods (qPCR + WB) across multiple tissue compartments and cell types, single lab","pmids":["26224166"],"is_preprint":false},{"year":2019,"finding":"Keratin 5-Cre-driven epidermis-specific knockout of Ncstn in mice causes hyperkeratosis of hair follicles, inflammation, and markedly increased IL-36α expression starting from postnatal day 0, preceding upregulation of TNF-α, IL-23A, IL-1β, and TLR4; Sprr2 family members are also upregulated.","method":"Conditional knockout mouse model (K5-Cre), RNA-seq, and qRT-PCR","journal":"Frontiers of medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional KO with defined temporal inflammatory phenotype, RNA-seq plus qRT-PCR validation, replicated across multiple cytokine markers","pmids":["31884525"],"is_preprint":false},{"year":2022,"finding":"NCSTN mutation in C57BL/6 mice downregulates nicastrin protein, NICD (Notch intracellular domain), hair cortex cytokeratin, and trichohyalin, and causes abnormal hair follicle structure, leading to HS-like skin lesions.","method":"Western blot, immunohistochemistry, hematoxylin-eosin staining, and transmission electron microscopy in NCSTN-mutant mice","journal":"Dermatology (Basel, Switzerland)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (WB, IHC, EM) in mouse model, single lab","pmids":["35843211"],"is_preprint":false},{"year":2024,"finding":"NCSTN knockout mice show reduced expression of nicastrin, NICD1, and Hes1 in skin, brain, and liver tissues, demonstrating that NCSTN regulates the Notch1-Hes1 signaling pathway in multiple organs.","method":"CRISPR/Cas9-mediated NCSTN knockout mice, qRT-PCR, and immunohistochemistry","journal":"European journal of medical research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO model with two orthogonal detection methods across multiple tissues, single lab","pmids":["39719647"],"is_preprint":false},{"year":2026,"finding":"NCSTN overexpression suppresses airway epithelial basal cell differentiation into ciliated cells and activates Notch3/Hes1 signaling; NCSTN knockdown attenuates CSE-induced reduction in ciliated cell differentiation and inhibits Notch3 activation, placing NCSTN upstream of Notch3-Hes1 in the regulation of ciliated cell differentiation.","method":"Lentiviral overexpression and knockdown in mouse tracheal epithelial basal cells at air-liquid interface, RT-qPCR, and Western blotting","journal":"Experimental lung research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal gain- and loss-of-function with pathway readouts, two orthogonal methods, single lab","pmids":["42105283"],"is_preprint":false},{"year":2018,"finding":"miR-155 downregulates NCSTN expression by binding to the NCSTN 3'UTR; a deletion mutation (c.2584-2585del CA) at the miR-155 binding site in the NCSTN 3'UTR further reduces NCSTN protein levels, representing a loss-of-function mechanism in acne inversa.","method":"Dual-luciferase reporter assay with wild-type and mutant NCSTN 3'UTR constructs, qRT-PCR, and Western blot","journal":"International journal of clinical and experimental pathology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — luciferase reporter with mutant construct plus two orthogonal expression assays, single lab","pmids":["31938294"],"is_preprint":false},{"year":2023,"finding":"A nonsense mutation in NCSTN leads to a premature stop codon, activates nonsense-mediated mRNA decay, and causes NCSTN haploinsufficiency in affected individuals; this haploinsufficiency also reduces protein levels of other γ-secretase complex subunits. Treatment with gentamicin (a readthrough agent) corrected NCSTN levels in patient-derived outer root sheath cells.","method":"Whole exome sequencing, outer root sheath cell isolation from patient hair follicles, gentamicin readthrough experiment, protein quantification","journal":"Experimental dermatology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional cell-based rescue experiment with pharmacological readthrough, multiple molecular readouts, single lab","pmids":["37665193"],"is_preprint":false},{"year":2026,"finding":"In NCSTN conditional knockout mouse skin, JAK1, JAK3, and TYK2 are upregulated in the epidermis, and JAK2 is upregulated in the dermis, implicating the JAK/STAT signaling pathway downstream of NCSTN loss.","method":"Tamoxifen-induced conditional NCSTN knockout mice, immunohistochemistry with ImageJ quantification","journal":"Clinical laboratory","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single method (IHC) in single lab, no direct functional link established beyond expression change","pmids":["41670523"],"is_preprint":false}],"current_model":"NCSTN encodes nicastrin, a core subunit of the γ-secretase complex; loss-of-function mutations cause haploinsufficiency (partly via nonsense-mediated mRNA decay and miR-155-mediated suppression) that reduces γ-secretase activity, impairs Notch1/Notch3 cleavage and downstream Hes1 signaling, disrupts hair follicle differentiation, and triggers IL-36α-driven inflammation underlying hidradenitis suppurativa/acne inversa, while overexpression in cancer contexts activates Notch1→AKT→GSK-3β→β-catenin nuclear translocation to promote EMT and tumor progression."},"narrative":{"mechanistic_narrative":"NCSTN encodes nicastrin, a subunit of the γ-secretase complex whose principal characterized function is to drive regulated intramembrane proteolysis of Notch receptors, coupling nicastrin dosage to Notch-dependent differentiation and inflammatory programs [PMID:39719647]. In skin, NCSTN loss-of-function lowers nicastrin and reduces the Notch intracellular domain (NICD) together with downstream Hes1, and this Notch1–Hes1 axis is regulated by NCSTN across skin, brain, and liver [PMID:35843211, PMID:39719647]. Epidermis-specific deletion of Ncstn in mice produces hair-follicle hyperkeratosis with reduced hair-cortex cytokeratin and trichohyalin, and triggers an early, IL-36α-led inflammatory cascade that precedes upregulation of TNF-α, IL-23A, IL-1β, and TLR4 [PMID:31884525, PMID:35843211]. NCSTN haploinsufficiency in hidradenitis suppurativa/acne inversa arises through several convergent loss-of-function routes: a nonsense mutation that lowers nicastrin mRNA and protein in skin and keratinocytes [PMID:26224166], nonsense-mediated decay that also depletes other γ-secretase subunits and is correctable by the readthrough agent gentamicin [PMID:37665193], and miR-155-mediated 3'UTR suppression accentuated by a binding-site deletion [PMID:31938294]. NCSTN also gates Notch3–Hes1 signaling to control airway basal-cell differentiation into ciliated cells [PMID:42105283]. In hepatocellular carcinoma, by contrast, NCSTN cleaves Notch1 to activate AKT signaling, phosphorylating GSK-3β to stabilize β-catenin, promote its nuclear translocation, and upregulate Zeb1-driven EMT; this axis is modulated by direct binding of LRP1B to nicastrin [PMID:32631394, PMID:37492741].","teleology":[{"year":2015,"claim":"Established that a patient nonsense mutation produces true haploinsufficiency rather than a non-functional full-length protein, anchoring NCSTN dosage as the disease-relevant variable in hidradenitis suppurativa.","evidence":"qPCR and Western blot on patient skin compartments and primary keratinocytes/fibroblasts","pmids":["26224166"],"confidence":"Medium","gaps":["Does not define how reduced nicastrin alters γ-secretase activity or Notch signaling in this tissue","Single patient genotype"]},{"year":2018,"claim":"Identified a post-transcriptional loss-of-function route, showing miR-155 represses NCSTN via its 3'UTR and that a binding-site deletion deepens repression, broadening disease mechanisms beyond coding mutations.","evidence":"Dual-luciferase 3'UTR reporter with mutant construct, qRT-PCR, Western blot","pmids":["31938294"],"confidence":"Medium","gaps":["No in vivo demonstration that miR-155 drives disease","Downstream Notch consequences not measured here"]},{"year":2019,"claim":"Demonstrated causally that epidermal Ncstn loss is sufficient to produce follicular hyperkeratosis and a defined inflammatory sequence led by IL-36α, linking nicastrin deficiency to the inflammatory phenotype.","evidence":"K5-Cre conditional knockout mice, RNA-seq, qRT-PCR","pmids":["31884525"],"confidence":"High","gaps":["Does not establish whether IL-36α induction is Notch-dependent","Trigger linking nicastrin loss to IL-36α not defined"]},{"year":2020,"claim":"Defined a gain-of-function oncogenic role in HCC, mapping NCSTN through Notch1 cleavage to AKT/GSK-3β/β-catenin and Zeb1-driven EMT, contrasting with the loss-of-function skin disease axis.","evidence":"Co-IP, subcellular fractionation, Notch/AKT inhibitor epistasis, xenografts","pmids":["32631394"],"confidence":"Medium","gaps":["Single tumor type","Direct enzymatic substrate role versus complex-level effect not separated"]},{"year":2022,"claim":"Connected NCSTN to an upstream regulator and to its hair-follicle differentiation output, with LRP1B binding controlling nicastrin levels/PI3K-AKT in HCC and NCSTN mutation reducing NICD, trichohyalin and hair-cortex cytokeratin in mice.","evidence":"Co-IP plus knockdown with PI3K/AKT readouts (HCC); WB, IHC, H&E, TEM in NCSTN-mutant mice","pmids":["37492741","35843211"],"confidence":"Medium","gaps":["LRP1B–nicastrin interaction studied only in HCC, not skin","Whether NICD loss directly causes the structural follicle defect not proven"]},{"year":2023,"claim":"Mechanistically resolved the haploinsufficiency route as nonsense-mediated decay that co-depletes other γ-secretase subunits, and provided a pharmacological correction by readthrough.","evidence":"Whole exome sequencing, patient outer root sheath cells, gentamicin readthrough rescue","pmids":["37665193"],"confidence":"Medium","gaps":["Rescue shown at protein level only, not for disease phenotype","Single mutation/patient context"]},{"year":2024,"claim":"Generalized the NCSTN→Notch1→Hes1 regulatory axis beyond skin, showing coordinate reduction of nicastrin, NICD1 and Hes1 across skin, brain, and liver.","evidence":"CRISPR/Cas9 NCSTN knockout mice, qRT-PCR, immunohistochemistry","pmids":["39719647"],"confidence":"Medium","gaps":["Functional consequences in brain and liver not characterized","Expression-level changes only"]},{"year":2026,"claim":"Extended NCSTN's developmental role to airway epithelium, placing it upstream of Notch3–Hes1 in suppressing basal-cell differentiation into ciliated cells, and added JAK/STAT as a candidate inflammatory effector of skin NCSTN loss.","evidence":"Reciprocal lentiviral overexpression/knockdown in tracheal basal cells at ALI (RT-qPCR, WB); tamoxifen-induced conditional KO skin with JAK isoform IHC","pmids":["42105283","41670523"],"confidence":"Medium","gaps":["JAK/STAT link is expression-only by single-method IHC (Low confidence) with no functional test","Whether Notch1 versus Notch3 engagement is tissue-specific not resolved"]},{"year":null,"claim":"How a single quantitative reduction in nicastrin selectively produces inflammatory follicular disease in skin yet tumor-promoting EMT in HCC, and the molecular trigger linking nicastrin/Notch loss to IL-36α and JAK/STAT induction, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No reconciliation of loss-of-function versus gain-of-function context dependence","IL-36α induction mechanism downstream of nicastrin not defined","No structural/biochemical accounting of how nicastrin dosage tunes γ-secretase output in these tissues"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,5]}],"localization":[],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,5,6]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[3,4,6]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[3,9]}],"complexes":["γ-secretase complex"],"partners":["NOTCH1","NOTCH3","LRP1B"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q92542","full_name":"Nicastrin","aliases":[],"length_aa":709,"mass_kda":78.4,"function":"Essential subunit of the gamma-secretase complex, an endoprotease complex that catalyzes the intramembrane cleavage of integral membrane proteins such as Notch receptors and APP (amyloid-beta precursor protein) (PubMed:10993067, PubMed:12679784, PubMed:25043039, PubMed:26280335, PubMed:30598546, PubMed:30630874). The gamma-secretase complex plays a role in Notch and Wnt signaling cascades and regulation of downstream processes via its role in processing key regulatory proteins, and by regulating cytosolic CTNNB1 levels","subcellular_location":"Membrane; Cytoplasmic vesicle membrane; Melanosome","url":"https://www.uniprot.org/uniprotkb/Q92542/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/NCSTN","classification":"Not Classified","n_dependent_lines":42,"n_total_lines":1208,"dependency_fraction":0.0347682119205298},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CANX","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/NCSTN","total_profiled":1310},"omim":[{"mim_id":"613736","title":"ACNE INVERSA, FAMILIAL, 2, WITH OR WITHOUT DOWLING-DEGOS DISEASE; ACNINV2","url":"https://www.omim.org/entry/613736"},{"mim_id":"607632","title":"PRESENILIN ENHANCER, GAMMA-SECRETASE SUBUNIT; PSENEN","url":"https://www.omim.org/entry/607632"},{"mim_id":"607630","title":"APH1 HOMOLOG B, GAMMA-SECRETASE SUBUNIT; APH1B","url":"https://www.omim.org/entry/607630"},{"mim_id":"607629","title":"APH1 HOMOLOG A, GAMMA SECRETASE SUBUNIT; APH1A","url":"https://www.omim.org/entry/607629"},{"mim_id":"605254","title":"NICASTRIN; NCSTN","url":"https://www.omim.org/entry/605254"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/NCSTN"},"hgnc":{"alias_symbol":["KIAA0253","APH2"],"prev_symbol":[]},"alphafold":{"accession":"Q92542","domains":[{"cath_id":"3.50.30","chopping":"37-134_169-221_655-667","consensus_level":"high","plddt":90.2973,"start":37,"end":667},{"cath_id":"3.40.630","chopping":"252-576_624-631","consensus_level":"high","plddt":92.7783,"start":252,"end":631}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q92542","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q92542-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q92542-F1-predicted_aligned_error_v6.png","plddt_mean":89.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=NCSTN","jax_strain_url":"https://www.jax.org/strain/search?query=NCSTN"},"sequence":{"accession":"Q92542","fasta_url":"https://rest.uniprot.org/uniprotkb/Q92542.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q92542/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q92542"}},"corpus_meta":[{"pmid":"37492741","id":"PMC_37492741","title":"LRP1B suppresses HCC progression through the NCSTN/PI3K/AKT signaling axis and affects doxorubicin resistance.","date":"2022","source":"Genes & diseases","url":"https://pubmed.ncbi.nlm.nih.gov/37492741","citation_count":52,"is_preprint":false},{"pmid":"22834455","id":"PMC_22834455","title":"A novel splice site mutation in NCSTN underlies a Japanese family with hidradenitis suppurativa.","date":"2013","source":"The British journal of dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/22834455","citation_count":44,"is_preprint":false},{"pmid":"32631394","id":"PMC_32631394","title":"NCSTN promotes hepatocellular carcinoma cell growth and metastasis via β-catenin activation in a Notch1/AKT dependent manner.","date":"2020","source":"Journal of experimental & clinical cancer research : CR","url":"https://pubmed.ncbi.nlm.nih.gov/32631394","citation_count":40,"is_preprint":false},{"pmid":"22759192","id":"PMC_22759192","title":"Two novel mutations of the NCSTN gene in Chinese familial acne inverse.","date":"2012","source":"Journal of the European Academy of Dermatology and Venereology : JEADV","url":"https://pubmed.ncbi.nlm.nih.gov/22759192","citation_count":36,"is_preprint":false},{"pmid":"25953768","id":"PMC_25953768","title":"Functional Variants in Notch Pathway Genes NCOR2, NCSTN, and MAML2 Predict Survival of Patients with Cutaneous Melanoma.","date":"2015","source":"Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology","url":"https://pubmed.ncbi.nlm.nih.gov/25953768","citation_count":22,"is_preprint":false},{"pmid":"31884525","id":"PMC_31884525","title":"Keratin 5-Cre-driven deletion of Ncstn in an acne inversa-like mouse model leads to a markedly increased IL-36a and Sprr2 expression.","date":"2019","source":"Frontiers of medicine","url":"https://pubmed.ncbi.nlm.nih.gov/31884525","citation_count":22,"is_preprint":false},{"pmid":"30030622","id":"PMC_30030622","title":"A novel NCSTN gene mutation in a Chinese family with acne inversa.","date":"2018","source":"Molecular genetics and genomics : MGG","url":"https://pubmed.ncbi.nlm.nih.gov/30030622","citation_count":15,"is_preprint":false},{"pmid":"33911744","id":"PMC_33911744","title":"Novel Mutation of the NCSTN Gene Identified in a Chinese Acne Inversa Family.","date":"2020","source":"Annals of dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/33911744","citation_count":11,"is_preprint":false},{"pmid":"37275792","id":"PMC_37275792","title":"An Updated Mutation Spectrum of the γ-Secretase Complex: Novel NCSTN Gene Mutation in an Indian Family with Hidradenitis Suppurativa and Acne Conglobata.","date":"2023","source":"Indian journal of dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/37275792","citation_count":10,"is_preprint":false},{"pmid":"26224166","id":"PMC_26224166","title":"Haploinsufficiency caused by a nonsense mutation in NCSTN underlying hidradenitis suppurativa in a Chinese family.","date":"2015","source":"Clinical and experimental dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/26224166","citation_count":9,"is_preprint":false},{"pmid":"25863267","id":"PMC_25863267","title":"A strategy focused on MAPT, APP, NCSTN and BACE1 to build blood classifiers for Alzheimer's disease.","date":"2015","source":"Journal of theoretical biology","url":"https://pubmed.ncbi.nlm.nih.gov/25863267","citation_count":9,"is_preprint":false},{"pmid":"37665193","id":"PMC_37665193","title":"A loss-of-function NCSTN mutation associated with familial Dowling Degos disease and hidradenitis suppurativa.","date":"2023","source":"Experimental dermatology","url":"https://pubmed.ncbi.nlm.nih.gov/37665193","citation_count":7,"is_preprint":false},{"pmid":"35843211","id":"PMC_35843211","title":"Effects of NCSTN Mutation on Hair Follicle Components in Mice.","date":"2022","source":"Dermatology (Basel, Switzerland)","url":"https://pubmed.ncbi.nlm.nih.gov/35843211","citation_count":6,"is_preprint":false},{"pmid":"31938294","id":"PMC_31938294","title":"hsa-miR-155 targeted NCSTN 3'UTR mutation promotes the pathogenesis and development of acne inversa.","date":"2018","source":"International journal of clinical and experimental pathology","url":"https://pubmed.ncbi.nlm.nih.gov/31938294","citation_count":6,"is_preprint":false},{"pmid":"35368949","id":"PMC_35368949","title":"A Novel NCSTN Mutation in a Three-Generation Chinese Family with Hidradenitis Suppurative.","date":"2022","source":"Journal of healthcare engineering","url":"https://pubmed.ncbi.nlm.nih.gov/35368949","citation_count":5,"is_preprint":false},{"pmid":"32208881","id":"PMC_32208881","title":"The combination between NCSTN gene copy number variation and growth traits in Chinese cattle.","date":"2020","source":"Animal biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/32208881","citation_count":3,"is_preprint":false},{"pmid":"37490873","id":"PMC_37490873","title":"Discovery and Potential Functional Characterization of Long Noncoding RNAs Associated with Familial Acne Inversa with NCSTN Mutation.","date":"2023","source":"Dermatology (Basel, Switzerland)","url":"https://pubmed.ncbi.nlm.nih.gov/37490873","citation_count":3,"is_preprint":false},{"pmid":"39719647","id":"PMC_39719647","title":"Expression of nicastrin, NICD1, and Hes1 in NCSTN knockout mice: implications for hidradenitis suppurativa, Alzheimer's, and liver cancer.","date":"2024","source":"European journal of medical research","url":"https://pubmed.ncbi.nlm.nih.gov/39719647","citation_count":2,"is_preprint":false},{"pmid":"41670523","id":"PMC_41670523","title":"Immunolocalization and Expression of JAK/STAT Signaling Molecules in the Skin of NCSTN Knockout Mouse.","date":"2026","source":"Clinical laboratory","url":"https://pubmed.ncbi.nlm.nih.gov/41670523","citation_count":0,"is_preprint":false},{"pmid":"40357971","id":"PMC_40357971","title":"Pathogenic variants in PSENEN and NCSTN genes cause 'follicular' Dowling-Degos disease: Report of five unrelated Indian families.","date":"2025","source":"Indian journal of dermatology, venereology and leprology","url":"https://pubmed.ncbi.nlm.nih.gov/40357971","citation_count":0,"is_preprint":false},{"pmid":"37662678","id":"PMC_37662678","title":"Retracted: A Novel NCSTN Mutation in a Three-Generation Chinese Family with Hidradenitis Suppurative.","date":"2023","source":"Journal of healthcare engineering","url":"https://pubmed.ncbi.nlm.nih.gov/37662678","citation_count":0,"is_preprint":false},{"pmid":"42105283","id":"PMC_42105283","title":"Mechanistic study on the role of NCSTN in regulating the differentiation of airway epithelial basal cells into ciliated cells following CSE exposure.","date":"2026","source":"Experimental lung research","url":"https://pubmed.ncbi.nlm.nih.gov/42105283","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":12728,"output_tokens":2392,"usd":0.037032,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9558,"output_tokens":3056,"usd":0.062095,"stage2_stop_reason":"end_turn"},"total_usd":0.099127,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2020,\n      \"finding\": \"NCSTN promotes HCC cell growth and metastasis by cleaving Notch1, which activates AKT and increases AKT/GSK-3β phosphorylation, thereby decreasing the GSK-3β/β-catenin complex, inhibiting β-catenin degradation, promoting nuclear translocation of β-catenin, and upregulating the transcription of Zeb1 to induce EMT.\",\n      \"method\": \"Notch and AKT inhibitor pharmacological dissection, co-immunoprecipitation, subcellular protein fractionation, immunofluorescence, in vitro cell assays, and in vivo xenograft models\",\n      \"journal\": \"Journal of experimental & clinical cancer research : CR\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (co-IP, fractionation, inhibitor epistasis, in vivo) in single lab\",\n      \"pmids\": [\"32631394\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"LRP1B directly binds to NCSTN protein and affects its expression level, thereby regulating the PI3K/AKT signaling pathway in HCC cells.\",\n      \"method\": \"Co-immunoprecipitation (Co-IP) and in vitro/in vivo knockdown experiments with pathway readouts\",\n      \"journal\": \"Genes & diseases\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP binding plus functional KD data, single lab, single study\",\n      \"pmids\": [\"37492741\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Haploinsufficiency of NCSTN caused by a nonsense mutation (c.1258C>T, p.Q420X) results in significantly reduced nicastrin mRNA and protein levels in skin (whole skin, epidermis, dermis) and cultured keratinocytes and fibroblasts from hidradenitis suppurativa patients.\",\n      \"method\": \"Real-time quantitative PCR and Western blotting on patient-derived skin samples and primary cell cultures\",\n      \"journal\": \"Clinical and experimental dermatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal methods (qPCR + WB) across multiple tissue compartments and cell types, single lab\",\n      \"pmids\": [\"26224166\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Keratin 5-Cre-driven epidermis-specific knockout of Ncstn in mice causes hyperkeratosis of hair follicles, inflammation, and markedly increased IL-36α expression starting from postnatal day 0, preceding upregulation of TNF-α, IL-23A, IL-1β, and TLR4; Sprr2 family members are also upregulated.\",\n      \"method\": \"Conditional knockout mouse model (K5-Cre), RNA-seq, and qRT-PCR\",\n      \"journal\": \"Frontiers of medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional KO with defined temporal inflammatory phenotype, RNA-seq plus qRT-PCR validation, replicated across multiple cytokine markers\",\n      \"pmids\": [\"31884525\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"NCSTN mutation in C57BL/6 mice downregulates nicastrin protein, NICD (Notch intracellular domain), hair cortex cytokeratin, and trichohyalin, and causes abnormal hair follicle structure, leading to HS-like skin lesions.\",\n      \"method\": \"Western blot, immunohistochemistry, hematoxylin-eosin staining, and transmission electron microscopy in NCSTN-mutant mice\",\n      \"journal\": \"Dermatology (Basel, Switzerland)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (WB, IHC, EM) in mouse model, single lab\",\n      \"pmids\": [\"35843211\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"NCSTN knockout mice show reduced expression of nicastrin, NICD1, and Hes1 in skin, brain, and liver tissues, demonstrating that NCSTN regulates the Notch1-Hes1 signaling pathway in multiple organs.\",\n      \"method\": \"CRISPR/Cas9-mediated NCSTN knockout mice, qRT-PCR, and immunohistochemistry\",\n      \"journal\": \"European journal of medical research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO model with two orthogonal detection methods across multiple tissues, single lab\",\n      \"pmids\": [\"39719647\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"NCSTN overexpression suppresses airway epithelial basal cell differentiation into ciliated cells and activates Notch3/Hes1 signaling; NCSTN knockdown attenuates CSE-induced reduction in ciliated cell differentiation and inhibits Notch3 activation, placing NCSTN upstream of Notch3-Hes1 in the regulation of ciliated cell differentiation.\",\n      \"method\": \"Lentiviral overexpression and knockdown in mouse tracheal epithelial basal cells at air-liquid interface, RT-qPCR, and Western blotting\",\n      \"journal\": \"Experimental lung research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal gain- and loss-of-function with pathway readouts, two orthogonal methods, single lab\",\n      \"pmids\": [\"42105283\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"miR-155 downregulates NCSTN expression by binding to the NCSTN 3'UTR; a deletion mutation (c.2584-2585del CA) at the miR-155 binding site in the NCSTN 3'UTR further reduces NCSTN protein levels, representing a loss-of-function mechanism in acne inversa.\",\n      \"method\": \"Dual-luciferase reporter assay with wild-type and mutant NCSTN 3'UTR constructs, qRT-PCR, and Western blot\",\n      \"journal\": \"International journal of clinical and experimental pathology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — luciferase reporter with mutant construct plus two orthogonal expression assays, single lab\",\n      \"pmids\": [\"31938294\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"A nonsense mutation in NCSTN leads to a premature stop codon, activates nonsense-mediated mRNA decay, and causes NCSTN haploinsufficiency in affected individuals; this haploinsufficiency also reduces protein levels of other γ-secretase complex subunits. Treatment with gentamicin (a readthrough agent) corrected NCSTN levels in patient-derived outer root sheath cells.\",\n      \"method\": \"Whole exome sequencing, outer root sheath cell isolation from patient hair follicles, gentamicin readthrough experiment, protein quantification\",\n      \"journal\": \"Experimental dermatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional cell-based rescue experiment with pharmacological readthrough, multiple molecular readouts, single lab\",\n      \"pmids\": [\"37665193\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"In NCSTN conditional knockout mouse skin, JAK1, JAK3, and TYK2 are upregulated in the epidermis, and JAK2 is upregulated in the dermis, implicating the JAK/STAT signaling pathway downstream of NCSTN loss.\",\n      \"method\": \"Tamoxifen-induced conditional NCSTN knockout mice, immunohistochemistry with ImageJ quantification\",\n      \"journal\": \"Clinical laboratory\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single method (IHC) in single lab, no direct functional link established beyond expression change\",\n      \"pmids\": [\"41670523\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"NCSTN encodes nicastrin, a core subunit of the γ-secretase complex; loss-of-function mutations cause haploinsufficiency (partly via nonsense-mediated mRNA decay and miR-155-mediated suppression) that reduces γ-secretase activity, impairs Notch1/Notch3 cleavage and downstream Hes1 signaling, disrupts hair follicle differentiation, and triggers IL-36α-driven inflammation underlying hidradenitis suppurativa/acne inversa, while overexpression in cancer contexts activates Notch1→AKT→GSK-3β→β-catenin nuclear translocation to promote EMT and tumor progression.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"NCSTN encodes nicastrin, a subunit of the γ-secretase complex whose principal characterized function is to drive regulated intramembrane proteolysis of Notch receptors, coupling nicastrin dosage to Notch-dependent differentiation and inflammatory programs [#5]. In skin, NCSTN loss-of-function lowers nicastrin and reduces the Notch intracellular domain (NICD) together with downstream Hes1, and this Notch1–Hes1 axis is regulated by NCSTN across skin, brain, and liver [#4, #5]. Epidermis-specific deletion of Ncstn in mice produces hair-follicle hyperkeratosis with reduced hair-cortex cytokeratin and trichohyalin, and triggers an early, IL-36α-led inflammatory cascade that precedes upregulation of TNF-α, IL-23A, IL-1β, and TLR4 [#3, #4]. NCSTN haploinsufficiency in hidradenitis suppurativa/acne inversa arises through several convergent loss-of-function routes: a nonsense mutation that lowers nicastrin mRNA and protein in skin and keratinocytes [#2], nonsense-mediated decay that also depletes other γ-secretase subunits and is correctable by the readthrough agent gentamicin [#8], and miR-155-mediated 3'UTR suppression accentuated by a binding-site deletion [#7]. NCSTN also gates Notch3–Hes1 signaling to control airway basal-cell differentiation into ciliated cells [#6]. In hepatocellular carcinoma, by contrast, NCSTN cleaves Notch1 to activate AKT signaling, phosphorylating GSK-3β to stabilize β-catenin, promote its nuclear translocation, and upregulate Zeb1-driven EMT; this axis is modulated by direct binding of LRP1B to nicastrin [#0, #1].\",\n  \"teleology\": [\n    {\n      \"year\": 2015,\n      \"claim\": \"Established that a patient nonsense mutation produces true haploinsufficiency rather than a non-functional full-length protein, anchoring NCSTN dosage as the disease-relevant variable in hidradenitis suppurativa.\",\n      \"evidence\": \"qPCR and Western blot on patient skin compartments and primary keratinocytes/fibroblasts\",\n      \"pmids\": [\"26224166\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not define how reduced nicastrin alters γ-secretase activity or Notch signaling in this tissue\", \"Single patient genotype\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identified a post-transcriptional loss-of-function route, showing miR-155 represses NCSTN via its 3'UTR and that a binding-site deletion deepens repression, broadening disease mechanisms beyond coding mutations.\",\n      \"evidence\": \"Dual-luciferase 3'UTR reporter with mutant construct, qRT-PCR, Western blot\",\n      \"pmids\": [\"31938294\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No in vivo demonstration that miR-155 drives disease\", \"Downstream Notch consequences not measured here\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstrated causally that epidermal Ncstn loss is sufficient to produce follicular hyperkeratosis and a defined inflammatory sequence led by IL-36α, linking nicastrin deficiency to the inflammatory phenotype.\",\n      \"evidence\": \"K5-Cre conditional knockout mice, RNA-seq, qRT-PCR\",\n      \"pmids\": [\"31884525\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not establish whether IL-36α induction is Notch-dependent\", \"Trigger linking nicastrin loss to IL-36α not defined\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Defined a gain-of-function oncogenic role in HCC, mapping NCSTN through Notch1 cleavage to AKT/GSK-3β/β-catenin and Zeb1-driven EMT, contrasting with the loss-of-function skin disease axis.\",\n      \"evidence\": \"Co-IP, subcellular fractionation, Notch/AKT inhibitor epistasis, xenografts\",\n      \"pmids\": [\"32631394\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single tumor type\", \"Direct enzymatic substrate role versus complex-level effect not separated\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Connected NCSTN to an upstream regulator and to its hair-follicle differentiation output, with LRP1B binding controlling nicastrin levels/PI3K-AKT in HCC and NCSTN mutation reducing NICD, trichohyalin and hair-cortex cytokeratin in mice.\",\n      \"evidence\": \"Co-IP plus knockdown with PI3K/AKT readouts (HCC); WB, IHC, H&E, TEM in NCSTN-mutant mice\",\n      \"pmids\": [\"37492741\", \"35843211\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"LRP1B–nicastrin interaction studied only in HCC, not skin\", \"Whether NICD loss directly causes the structural follicle defect not proven\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Mechanistically resolved the haploinsufficiency route as nonsense-mediated decay that co-depletes other γ-secretase subunits, and provided a pharmacological correction by readthrough.\",\n      \"evidence\": \"Whole exome sequencing, patient outer root sheath cells, gentamicin readthrough rescue\",\n      \"pmids\": [\"37665193\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Rescue shown at protein level only, not for disease phenotype\", \"Single mutation/patient context\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Generalized the NCSTN→Notch1→Hes1 regulatory axis beyond skin, showing coordinate reduction of nicastrin, NICD1 and Hes1 across skin, brain, and liver.\",\n      \"evidence\": \"CRISPR/Cas9 NCSTN knockout mice, qRT-PCR, immunohistochemistry\",\n      \"pmids\": [\"39719647\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequences in brain and liver not characterized\", \"Expression-level changes only\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Extended NCSTN's developmental role to airway epithelium, placing it upstream of Notch3–Hes1 in suppressing basal-cell differentiation into ciliated cells, and added JAK/STAT as a candidate inflammatory effector of skin NCSTN loss.\",\n      \"evidence\": \"Reciprocal lentiviral overexpression/knockdown in tracheal basal cells at ALI (RT-qPCR, WB); tamoxifen-induced conditional KO skin with JAK isoform IHC\",\n      \"pmids\": [\"42105283\", \"41670523\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"JAK/STAT link is expression-only by single-method IHC (Low confidence) with no functional test\", \"Whether Notch1 versus Notch3 engagement is tissue-specific not resolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How a single quantitative reduction in nicastrin selectively produces inflammatory follicular disease in skin yet tumor-promoting EMT in HCC, and the molecular trigger linking nicastrin/Notch loss to IL-36α and JAK/STAT induction, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No reconciliation of loss-of-function versus gain-of-function context dependence\", \"IL-36α induction mechanism downstream of nicastrin not defined\", \"No structural/biochemical accounting of how nicastrin dosage tunes γ-secretase output in these tissues\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 5]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 5, 6]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [3, 4, 6]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [3, 9]}\n    ],\n    \"complexes\": [\"γ-secretase complex\"],\n    \"partners\": [\"NOTCH1\", \"NOTCH3\", \"LRP1B\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}