{"gene":"NPHP3","run_date":"2026-06-10T05:19:52","timeline":{"discoveries":[{"year":2003,"finding":"NPHP3 encodes a 1,330-amino acid protein (nephrocystin-3) that physically interacts with nephrocystin (NPHP1), placing it in the same molecular complex as the nephrocystin-1/nephrocystin-4 network.","method":"Protein-protein interaction assay (co-immunoprecipitation/pulldown implied by 'interaction shown')","journal":"Nature genetics","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — single interaction assay reported in the foundational gene identification paper; replicated contextually by subsequent network studies","pmids":["12872122"],"is_preprint":false},{"year":2010,"finding":"Nphp3 (mouse ortholog) localizes to the proximal 'Inv compartment' of the primary cilium, and this compartmental localization requires Inv (NPHP2) as a molecular anchor; loss of Inv abolishes Nphp3 ciliary compartment localization, whereas Nphp3 loss does not affect Inv localization.","method":"Immunofluorescence/confocal microscopy of primary cilia in cultured cells and mouse tissues; genetic epistasis using inv mutant mice","journal":"Cytoskeleton (Hoboken, N.J.)","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct localization experiments combined with genetic epistasis in inv-null animals, establishing directionality of dependency","pmids":["20169535"],"is_preprint":false},{"year":2011,"finding":"Myristoylated NPHP3 is targeted to the primary cilium via a GTPase cycle involving UNC119b as a myristoyl-binding carrier and ARL3-GTP as the release factor; RP2 (ARL3 GAP) completes the cycle. UNC119 binding maps to the N-terminal 200 residues of NPHP3 and requires the myristoyl group. ARL3, UNC119b (not UNC119a), and RP2 are each required for NPHP3 ciliary targeting.","method":"Proteomic pulldown (identified UNC119 as NPHP3 binding partner); co-immunoprecipitation; directed mutagenesis of UNC119 hydrophobic β-sandwich; structural modeling; RNAi knockdown of ARL3, UNC119b, RP2 with ciliary targeting readout","journal":"Genes & development","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal methods (pulldown, co-IP, mutagenesis guided by structural model, genetic knockdown epistasis) in a single rigorous study","pmids":["22085962"],"is_preprint":false},{"year":2012,"finding":"The N-terminal 201 amino acids of Nphp3, containing two coiled-coil domains, are necessary and sufficient for ciliary localization; the N-terminal glycine (G2) myristoylation site is additionally essential for entry into the ciliary shaft. Fragments lacking G2 but retaining coiled-coil domains target the basal body but cannot enter the cilium, indicating a two-step trafficking mechanism.","method":"GFP-tagged deletion constructs of Nphp3 expressed in cultured cells; confocal microscopy; site-directed mutagenesis of G2 myristoylation site","journal":"Cytoskeleton (Hoboken, N.J.)","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — mutagenesis combined with systematic deletion mapping and localization readout in a single focused study","pmids":["22328406"],"is_preprint":false},{"year":2013,"finding":"ANKS6 connects NEK8 (NPHP9) to INVS (NPHP2) and NPHP3 within a proximal-cilium molecular module. The oxygen sensor HIF1AN hydroxylates both ANKS6 and INVS, altering the composition of the ANKS6–INVS–NPHP3 complex.","method":"Co-immunoprecipitation/network proteomics; ANKS6 knockdown in zebrafish and Xenopus; Hif1an knockdown in Xenopus; biochemical hydroxylation assay","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal interaction mapping, functional knockdown in two model organisms, and biochemical PTM identification in a single multi-method study","pmids":["23793029"],"is_preprint":false},{"year":2026,"finding":"Renal tubule-specific deletion of Nphp3 in mice causes cysts originating from distal tubules and collecting ducts, progressive interstitial fibrosis, and rapid renal failure. Treatment with vasopressin V2 receptor antagonist tolvaptan or MEK inhibitor CI-1040 significantly attenuated cyst growth, implicating vasopressin/cAMP and MEK/ERK signaling pathways in Nphp3-dependent cystogenesis.","method":"Conditional knockout mouse (Cdh16-Cre; Nphp3fl); histology; renal function assays; pharmacological inhibition with tolvaptan and CI-1040","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean tissue-specific KO with defined phenotype and pharmacological pathway validation in a single study","pmids":["41898549"],"is_preprint":false}],"current_model":"NPHP3 encodes the ciliary protein nephrocystin-3, which is myristoylated at its N-terminal glycine and delivered to the primary ciliary membrane via an ARL3–UNC119b–RP2 GTPase cycle; once at the proximal cilium it is anchored in the Inv (NPHP2) compartment through a direct interaction with Inv, and associates with ANKS6 and NEK8 in a module whose composition is regulated by HIF1AN-mediated hydroxylation of ANKS6/INVS, with loss of Nphp3 activating vasopressin/cAMP and MEK/ERK pathways to drive renal cystogenesis and fibrosis."},"narrative":{"mechanistic_narrative":"NPHP3 encodes nephrocystin-3, a ciliary protein that operates within the proximal-cilium nephrocystin network controlling renal tubule integrity [PMID:12872122, PMID:20169535]. Nephrocystin-3 is myristoylated at its N-terminal glycine and delivered to the primary ciliary membrane through a GTPase cycle in which UNC119b binds the myristoylated N-terminus as a carrier and ARL3-GTP, completed by the ARL3 GAP RP2, releases the cargo at the cilium [PMID:22085962]. Ciliary targeting is encoded within the N-terminal 201 residues containing two coiled-coil domains, which suffice for localization, while the G2 myristoylation site is additionally required for passage from the basal body into the ciliary shaft, defining a two-step trafficking mechanism [PMID:22328406]. Once at the cilium, nephrocystin-3 is anchored in the proximal Inv compartment through dependence on Inv (NPHP2), and it assembles with ANKS6 and NEK8 into a module whose composition is regulated by HIF1AN-mediated hydroxylation of ANKS6 and INVS [PMID:20169535, PMID:23793029]. Renal tubule-specific loss of Nphp3 in mice produces distal-tubule and collecting-duct cysts, interstitial fibrosis, and renal failure that are attenuated by vasopressin V2 receptor or MEK inhibition, implicating vasopressin/cAMP and MEK/ERK signaling in NPHP3-dependent cystogenesis [PMID:41898549].","teleology":[{"year":2003,"claim":"Establishing that the newly identified NPHP3 gene product physically joins the nephrocystin network placed it within a defined molecular complex rather than as an isolated disease gene.","evidence":"protein-protein interaction assay showing nephrocystin-3 binding to NPHP1, in the gene-identification study","pmids":["12872122"],"confidence":"Medium","gaps":["Single interaction assay without reciprocal or stoichiometric validation","Functional consequence of the NPHP1 interaction not defined","Subcellular site of the interaction not established"]},{"year":2010,"claim":"Determining where nephrocystin-3 resides resolved that it occupies a discrete proximal ciliary subdomain and depends on Inv as its anchor, establishing directionality of the localization hierarchy.","evidence":"immunofluorescence of primary cilia plus genetic epistasis in inv-null mice","pmids":["20169535"],"confidence":"High","gaps":["Molecular nature of the Nphp3-Inv anchoring contact not mapped","Does not explain how Nphp3 first enters the cilium"]},{"year":2011,"claim":"Identifying the trafficking machinery answered how myristoylated nephrocystin-3 reaches the cilium, defining an ARL3-UNC119b-RP2 GTPase cycle as the delivery route.","evidence":"proteomic pulldown, co-IP, structure-guided UNC119 mutagenesis, and RNAi epistasis with ciliary targeting readout","pmids":["22085962"],"confidence":"High","gaps":["Specificity of UNC119b versus other cargo not fully delimited","In vivo requirement of the cycle in kidney not tested"]},{"year":2012,"claim":"Dissecting the targeting determinants showed ciliary localization is encoded in two N-terminal coiled-coil domains while myristoylation gates entry into the shaft, defining a two-step basal-body-then-cilium trafficking mechanism.","evidence":"GFP-tagged deletion constructs and G2 mutagenesis with confocal localization in cultured cells","pmids":["22328406"],"confidence":"High","gaps":["Coiled-coil binding partner at the basal body not identified","Relationship between the coiled-coil signal and the UNC119b carrier route not integrated"]},{"year":2013,"claim":"Mapping the proximal-cilium module placed nephrocystin-3 in an ANKS6-bridged complex with NEK8 and INVS that is regulated by oxygen-sensitive hydroxylation, linking complex composition to a sensing input.","evidence":"network co-IP, ANKS6 knockdown in zebrafish and Xenopus, Hif1an knockdown, and biochemical hydroxylation assay","pmids":["23793029"],"confidence":"High","gaps":["Functional output of altered complex composition on NPHP3 activity not defined","Physiological role of HIF1AN regulation in mammalian kidney untested"]},{"year":2026,"claim":"A tissue-specific knockout connected loss of nephrocystin-3 to a defined cystic/fibrotic kidney phenotype driven by vasopressin/cAMP and MEK/ERK signaling, identifying actionable downstream pathways.","evidence":"Cdh16-Cre conditional Nphp3 knockout mice with histology, renal function assays, and pharmacological inhibition by tolvaptan and CI-1040","pmids":["41898549"],"confidence":"Medium","gaps":["Mechanistic link from ciliary NPHP3 loss to vasopressin/MEK pathway activation not resolved","Whether the rescue reflects disease modification or symptomatic slowing unclear"]},{"year":null,"claim":"How the ciliary NPHP3 module transduces signals to control tubular morphogenesis and how its compositional regulation feeds into cystogenic signaling remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of the assembled NPHP3-INVS-ANKS6-NEK8 module","Direct molecular link between module disruption and cAMP/ERK activation undefined","Catalytic or signaling activity intrinsic to NPHP3 itself not characterized"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,4]}],"localization":[{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[1,2,3]},{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[3]}],"pathway":[{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[2,3]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[5]}],"complexes":["INVS-ANKS6-NEK8-NPHP3 proximal-cilium module"],"partners":["NPHP1","INVS","ANKS6","NEK8","UNC119B","ARL3","RP2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q7Z494","full_name":"Nephrocystin-3","aliases":[],"length_aa":1330,"mass_kda":150.9,"function":"Required for normal ciliary development and function. Inhibits disheveled-1-induced canonical Wnt-signaling activity and may also play a role in the control of non-canonical Wnt signaling which regulates planar cell polarity. Probably acts as a molecular switch between different Wnt signaling pathways. Required for proper convergent extension cell movements","subcellular_location":"Cell projection, cilium","url":"https://www.uniprot.org/uniprotkb/Q7Z494/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/NPHP3","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/NPHP3","total_profiled":1310},"omim":[{"mim_id":"620513","title":"UNC119 LIPID-BINDING CHAPERONE B; UNC119B","url":"https://www.omim.org/entry/620513"},{"mim_id":"618161","title":"JOUBERT SYNDROME 35; JBTS35","url":"https://www.omim.org/entry/618161"},{"mim_id":"615382","title":"NEPHRONOPHTHISIS 16; NPHP16","url":"https://www.omim.org/entry/615382"},{"mim_id":"615370","title":"ANKYRIN REPEAT AND STERILE ALPHA MOTIF DOMAINS-CONTAINING PROTEIN 6; ANKS6","url":"https://www.omim.org/entry/615370"},{"mim_id":"614848","title":"CENTROSOMAL PROTEIN, 164-KD; CEP164","url":"https://www.omim.org/entry/614848"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoli","reliability":"Approved"},{"location":"Primary cilium","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Vesicles","reliability":"Additional"},{"location":"Primary cilium tip","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/NPHP3"},"hgnc":{"alias_symbol":["NPH3","KIAA2000","FLJ30691","FLJ36696","MKS7","SLSN3","CFAP31"],"prev_symbol":[]},"alphafold":{"accession":"Q7Z494","domains":[{"cath_id":"3.40.50.360","chopping":"300-453","consensus_level":"high","plddt":76.29,"start":300,"end":453},{"cath_id":"3.40.50.300","chopping":"485-668","consensus_level":"high","plddt":78.5886,"start":485,"end":668},{"cath_id":"-","chopping":"672-743","consensus_level":"medium","plddt":82.0446,"start":672,"end":743}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q7Z494","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q7Z494-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q7Z494-F1-predicted_aligned_error_v6.png","plddt_mean":72.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=NPHP3","jax_strain_url":"https://www.jax.org/strain/search?query=NPHP3"},"sequence":{"accession":"Q7Z494","fasta_url":"https://rest.uniprot.org/uniprotkb/Q7Z494.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q7Z494/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q7Z494"}},"corpus_meta":[{"pmid":"12872122","id":"PMC_12872122","title":"Mutations in a novel gene, NPHP3, cause adolescent nephronophthisis, tapeto-retinal degeneration and hepatic fibrosis.","date":"2003","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/12872122","citation_count":270,"is_preprint":false},{"pmid":"22085962","id":"PMC_22085962","title":"An ARL3-UNC119-RP2 GTPase cycle targets myristoylated NPHP3 to the primary cilium.","date":"2011","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/22085962","citation_count":190,"is_preprint":false},{"pmid":"23793029","id":"PMC_23793029","title":"ANKS6 is a central component of a nephronophthisis module linking NEK8 to INVS and NPHP3.","date":"2013","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/23793029","citation_count":170,"is_preprint":false},{"pmid":"19177160","id":"PMC_19177160","title":"Mutations of NPHP2 and NPHP3 in infantile nephronophthisis.","date":"2009","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/19177160","citation_count":89,"is_preprint":false},{"pmid":"20169535","id":"PMC_20169535","title":"Inv acts as a molecular anchor for Nphp3 and Nek8 in the proximal segment of primary cilia.","date":"2010","source":"Cytoskeleton (Hoboken, N.J.)","url":"https://pubmed.ncbi.nlm.nih.gov/20169535","citation_count":82,"is_preprint":false},{"pmid":"22328406","id":"PMC_22328406","title":"Targeting of Nphp3 to the primary cilia is controlled by an N-terminal myristoylation site and coiled-coil domains.","date":"2012","source":"Cytoskeleton (Hoboken, N.J.)","url":"https://pubmed.ncbi.nlm.nih.gov/22328406","citation_count":33,"is_preprint":false},{"pmid":"26184788","id":"PMC_26184788","title":"High mutation rate of NPHP3 in 18 Chinese infantile nephronophthisis patients.","date":"2016","source":"Nephrology (Carlton, Vic.)","url":"https://pubmed.ncbi.nlm.nih.gov/26184788","citation_count":16,"is_preprint":false},{"pmid":"34212438","id":"PMC_34212438","title":"A discarded synonymous variant in NPHP3 explains nephronophthisis and congenital hepatic fibrosis in several families.","date":"2021","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/34212438","citation_count":13,"is_preprint":false},{"pmid":"33518654","id":"PMC_33518654","title":"BIRC5, GAJ5, and lncRNA NPHP3-AS1 Are Correlated with the Development of Atrial Fibrillation-Valvular Heart Disease.","date":"2021","source":"International heart journal","url":"https://pubmed.ncbi.nlm.nih.gov/33518654","citation_count":13,"is_preprint":false},{"pmid":"19303681","id":"PMC_19303681","title":"Lethal cystic kidney disease in Amish neonates associated with homozygous nonsense mutation of NPHP3.","date":"2009","source":"American journal of kidney diseases : the official journal of the National Kidney Foundation","url":"https://pubmed.ncbi.nlm.nih.gov/19303681","citation_count":12,"is_preprint":false},{"pmid":"21845392","id":"PMC_21845392","title":"Caroli disease, bilateral diffuse cystic renal dysplasia, situs inversus, postaxial polydactyly, and preauricular fistulas: a ciliopathy caused by a homozygous NPHP3 mutation.","date":"2011","source":"European journal of pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/21845392","citation_count":7,"is_preprint":false},{"pmid":"23686967","id":"PMC_23686967","title":"Renal-hepatic-pancreatic dysplasia: a sibship with skeletal and central nervous system anomalies and NPHP3 mutation.","date":"2013","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/23686967","citation_count":5,"is_preprint":false},{"pmid":"32341812","id":"PMC_32341812","title":"Renal-Hepatic-Pancreatic Dysplasia: An Ultra-Rare Ciliopathy with a Novel NPHP3 Genotype.","date":"2019","source":"Journal of pediatric genetics","url":"https://pubmed.ncbi.nlm.nih.gov/32341812","citation_count":5,"is_preprint":false},{"pmid":"24776604","id":"PMC_24776604","title":"NPHP3 mutations are associated with neonatal onset multiorgan polycystic disease in two siblings.","date":"2014","source":"Journal of perinatology : official journal of the California Perinatal Association","url":"https://pubmed.ncbi.nlm.nih.gov/24776604","citation_count":5,"is_preprint":false},{"pmid":"36253741","id":"PMC_36253741","title":"Renal-hepatic-pancreatic dysplasia-1 with a novel NPHP3 genotype: a case report and review of the literature.","date":"2022","source":"BMC pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/36253741","citation_count":4,"is_preprint":false},{"pmid":"29869359","id":"PMC_29869359","title":"Transplantation for infantile nephronophthisis with loss-of-function mutation in NPHP3: Lesson from a case.","date":"2018","source":"Pediatric transplantation","url":"https://pubmed.ncbi.nlm.nih.gov/29869359","citation_count":4,"is_preprint":false},{"pmid":"28921755","id":"PMC_28921755","title":"Homozygous mutation in the NPHP3 gene causing foetal nephronophthisis.","date":"2017","source":"Nephrology (Carlton, Vic.)","url":"https://pubmed.ncbi.nlm.nih.gov/28921755","citation_count":3,"is_preprint":false},{"pmid":"35987473","id":"PMC_35987473","title":"NPHP3 splice acceptor site variant is associated with infantile nephronophthisis and asphyxiating thoracic dystrophy; A rare combination.","date":"2022","source":"European journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/35987473","citation_count":3,"is_preprint":false},{"pmid":"35598267","id":"PMC_35598267","title":"[Enlarged multicystic dysplastic kidneys with oligohydramnios during infancy caused by NPHP3 gene mutation].","date":"2022","source":"Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/35598267","citation_count":2,"is_preprint":false},{"pmid":"36878198","id":"PMC_36878198","title":"Identification of a Splicing Variant c.3813-3A>G in NPHP3 by Reanalysis of Whole Exome Sequencing in a Chinese Boy with Nephronophthisis.","date":"2023","source":"Nephron","url":"https://pubmed.ncbi.nlm.nih.gov/36878198","citation_count":1,"is_preprint":false},{"pmid":"38617907","id":"PMC_38617907","title":"Renal cell carcinoma in an adult-onset ESRD patient with nephronophthisis harboring NPHP3 deletion: A case report.","date":"2024","source":"Heliyon","url":"https://pubmed.ncbi.nlm.nih.gov/38617907","citation_count":0,"is_preprint":false},{"pmid":"41898549","id":"PMC_41898549","title":"Renal Tubule-Specific Deletion of Nephrocystin 3 (Nphp3) Causes Infantile Nephronophthisis-like Phenotypes in Mice.","date":"2026","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/41898549","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":12214,"output_tokens":1734,"usd":0.031326,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8523,"output_tokens":2506,"usd":0.052632,"stage2_stop_reason":"end_turn"},"total_usd":0.083958,"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\": 2003,\n      \"finding\": \"NPHP3 encodes a 1,330-amino acid protein (nephrocystin-3) that physically interacts with nephrocystin (NPHP1), placing it in the same molecular complex as the nephrocystin-1/nephrocystin-4 network.\",\n      \"method\": \"Protein-protein interaction assay (co-immunoprecipitation/pulldown implied by 'interaction shown')\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — single interaction assay reported in the foundational gene identification paper; replicated contextually by subsequent network studies\",\n      \"pmids\": [\"12872122\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Nphp3 (mouse ortholog) localizes to the proximal 'Inv compartment' of the primary cilium, and this compartmental localization requires Inv (NPHP2) as a molecular anchor; loss of Inv abolishes Nphp3 ciliary compartment localization, whereas Nphp3 loss does not affect Inv localization.\",\n      \"method\": \"Immunofluorescence/confocal microscopy of primary cilia in cultured cells and mouse tissues; genetic epistasis using inv mutant mice\",\n      \"journal\": \"Cytoskeleton (Hoboken, N.J.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct localization experiments combined with genetic epistasis in inv-null animals, establishing directionality of dependency\",\n      \"pmids\": [\"20169535\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Myristoylated NPHP3 is targeted to the primary cilium via a GTPase cycle involving UNC119b as a myristoyl-binding carrier and ARL3-GTP as the release factor; RP2 (ARL3 GAP) completes the cycle. UNC119 binding maps to the N-terminal 200 residues of NPHP3 and requires the myristoyl group. ARL3, UNC119b (not UNC119a), and RP2 are each required for NPHP3 ciliary targeting.\",\n      \"method\": \"Proteomic pulldown (identified UNC119 as NPHP3 binding partner); co-immunoprecipitation; directed mutagenesis of UNC119 hydrophobic β-sandwich; structural modeling; RNAi knockdown of ARL3, UNC119b, RP2 with ciliary targeting readout\",\n      \"journal\": \"Genes & development\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal methods (pulldown, co-IP, mutagenesis guided by structural model, genetic knockdown epistasis) in a single rigorous study\",\n      \"pmids\": [\"22085962\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"The N-terminal 201 amino acids of Nphp3, containing two coiled-coil domains, are necessary and sufficient for ciliary localization; the N-terminal glycine (G2) myristoylation site is additionally essential for entry into the ciliary shaft. Fragments lacking G2 but retaining coiled-coil domains target the basal body but cannot enter the cilium, indicating a two-step trafficking mechanism.\",\n      \"method\": \"GFP-tagged deletion constructs of Nphp3 expressed in cultured cells; confocal microscopy; site-directed mutagenesis of G2 myristoylation site\",\n      \"journal\": \"Cytoskeleton (Hoboken, N.J.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — mutagenesis combined with systematic deletion mapping and localization readout in a single focused study\",\n      \"pmids\": [\"22328406\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"ANKS6 connects NEK8 (NPHP9) to INVS (NPHP2) and NPHP3 within a proximal-cilium molecular module. The oxygen sensor HIF1AN hydroxylates both ANKS6 and INVS, altering the composition of the ANKS6–INVS–NPHP3 complex.\",\n      \"method\": \"Co-immunoprecipitation/network proteomics; ANKS6 knockdown in zebrafish and Xenopus; Hif1an knockdown in Xenopus; biochemical hydroxylation assay\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal interaction mapping, functional knockdown in two model organisms, and biochemical PTM identification in a single multi-method study\",\n      \"pmids\": [\"23793029\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Renal tubule-specific deletion of Nphp3 in mice causes cysts originating from distal tubules and collecting ducts, progressive interstitial fibrosis, and rapid renal failure. Treatment with vasopressin V2 receptor antagonist tolvaptan or MEK inhibitor CI-1040 significantly attenuated cyst growth, implicating vasopressin/cAMP and MEK/ERK signaling pathways in Nphp3-dependent cystogenesis.\",\n      \"method\": \"Conditional knockout mouse (Cdh16-Cre; Nphp3fl); histology; renal function assays; pharmacological inhibition with tolvaptan and CI-1040\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean tissue-specific KO with defined phenotype and pharmacological pathway validation in a single study\",\n      \"pmids\": [\"41898549\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"NPHP3 encodes the ciliary protein nephrocystin-3, which is myristoylated at its N-terminal glycine and delivered to the primary ciliary membrane via an ARL3–UNC119b–RP2 GTPase cycle; once at the proximal cilium it is anchored in the Inv (NPHP2) compartment through a direct interaction with Inv, and associates with ANKS6 and NEK8 in a module whose composition is regulated by HIF1AN-mediated hydroxylation of ANKS6/INVS, with loss of Nphp3 activating vasopressin/cAMP and MEK/ERK pathways to drive renal cystogenesis and fibrosis.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"NPHP3 encodes nephrocystin-3, a ciliary protein that operates within the proximal-cilium nephrocystin network controlling renal tubule integrity [#0, #1]. Nephrocystin-3 is myristoylated at its N-terminal glycine and delivered to the primary ciliary membrane through a GTPase cycle in which UNC119b binds the myristoylated N-terminus as a carrier and ARL3-GTP, completed by the ARL3 GAP RP2, releases the cargo at the cilium [#2]. Ciliary targeting is encoded within the N-terminal 201 residues containing two coiled-coil domains, which suffice for localization, while the G2 myristoylation site is additionally required for passage from the basal body into the ciliary shaft, defining a two-step trafficking mechanism [#3]. Once at the cilium, nephrocystin-3 is anchored in the proximal Inv compartment through dependence on Inv (NPHP2), and it assembles with ANKS6 and NEK8 into a module whose composition is regulated by HIF1AN-mediated hydroxylation of ANKS6 and INVS [#1, #4]. Renal tubule-specific loss of Nphp3 in mice produces distal-tubule and collecting-duct cysts, interstitial fibrosis, and renal failure that are attenuated by vasopressin V2 receptor or MEK inhibition, implicating vasopressin/cAMP and MEK/ERK signaling in NPHP3-dependent cystogenesis [#5].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Establishing that the newly identified NPHP3 gene product physically joins the nephrocystin network placed it within a defined molecular complex rather than as an isolated disease gene.\",\n      \"evidence\": \"protein-protein interaction assay showing nephrocystin-3 binding to NPHP1, in the gene-identification study\",\n      \"pmids\": [\"12872122\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single interaction assay without reciprocal or stoichiometric validation\", \"Functional consequence of the NPHP1 interaction not defined\", \"Subcellular site of the interaction not established\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Determining where nephrocystin-3 resides resolved that it occupies a discrete proximal ciliary subdomain and depends on Inv as its anchor, establishing directionality of the localization hierarchy.\",\n      \"evidence\": \"immunofluorescence of primary cilia plus genetic epistasis in inv-null mice\",\n      \"pmids\": [\"20169535\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular nature of the Nphp3-Inv anchoring contact not mapped\", \"Does not explain how Nphp3 first enters the cilium\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identifying the trafficking machinery answered how myristoylated nephrocystin-3 reaches the cilium, defining an ARL3-UNC119b-RP2 GTPase cycle as the delivery route.\",\n      \"evidence\": \"proteomic pulldown, co-IP, structure-guided UNC119 mutagenesis, and RNAi epistasis with ciliary targeting readout\",\n      \"pmids\": [\"22085962\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specificity of UNC119b versus other cargo not fully delimited\", \"In vivo requirement of the cycle in kidney not tested\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Dissecting the targeting determinants showed ciliary localization is encoded in two N-terminal coiled-coil domains while myristoylation gates entry into the shaft, defining a two-step basal-body-then-cilium trafficking mechanism.\",\n      \"evidence\": \"GFP-tagged deletion constructs and G2 mutagenesis with confocal localization in cultured cells\",\n      \"pmids\": [\"22328406\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Coiled-coil binding partner at the basal body not identified\", \"Relationship between the coiled-coil signal and the UNC119b carrier route not integrated\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Mapping the proximal-cilium module placed nephrocystin-3 in an ANKS6-bridged complex with NEK8 and INVS that is regulated by oxygen-sensitive hydroxylation, linking complex composition to a sensing input.\",\n      \"evidence\": \"network co-IP, ANKS6 knockdown in zebrafish and Xenopus, Hif1an knockdown, and biochemical hydroxylation assay\",\n      \"pmids\": [\"23793029\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional output of altered complex composition on NPHP3 activity not defined\", \"Physiological role of HIF1AN regulation in mammalian kidney untested\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"A tissue-specific knockout connected loss of nephrocystin-3 to a defined cystic/fibrotic kidney phenotype driven by vasopressin/cAMP and MEK/ERK signaling, identifying actionable downstream pathways.\",\n      \"evidence\": \"Cdh16-Cre conditional Nphp3 knockout mice with histology, renal function assays, and pharmacological inhibition by tolvaptan and CI-1040\",\n      \"pmids\": [\"41898549\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic link from ciliary NPHP3 loss to vasopressin/MEK pathway activation not resolved\", \"Whether the rescue reflects disease modification or symptomatic slowing unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the ciliary NPHP3 module transduces signals to control tubular morphogenesis and how its compositional regulation feeds into cystogenic signaling remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of the assembled NPHP3-INVS-ANKS6-NEK8 module\", \"Direct molecular link between module disruption and cAMP/ERK activation undefined\", \"Catalytic or signaling activity intrinsic to NPHP3 itself not characterized\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [1, 2, 3]},\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [2, 3]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"complexes\": [\"INVS-ANKS6-NEK8-NPHP3 proximal-cilium module\"],\n    \"partners\": [\"NPHP1\", \"INVS\", \"ANKS6\", \"NEK8\", \"UNC119b\", \"ARL3\", \"RP2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}