Affinage

NPHP3

Nephrocystin-3 · UniProt Q7Z494

Length
1330 aa
Mass
150.9 kDa
Annotated
2026-06-10
22 papers in source corpus 6 papers cited in narrative 6 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 5/5 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

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).

Mechanistic history

Synthesis pass · year-by-year structured walk · 6 steps
  1. 2003 Medium

    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

    PMID:12872122

    Open questions at the time
    • Single interaction assay without reciprocal or stoichiometric validation
    • Functional consequence of the NPHP1 interaction not defined
    • Subcellular site of the interaction not established
  2. 2010 High

    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

    PMID:20169535

    Open questions at the time
    • Molecular nature of the Nphp3-Inv anchoring contact not mapped
    • Does not explain how Nphp3 first enters the cilium
  3. 2011 High

    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

    PMID:22085962

    Open questions at the time
    • Specificity of UNC119b versus other cargo not fully delimited
    • In vivo requirement of the cycle in kidney not tested
  4. 2012 High

    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

    PMID:22328406

    Open questions at the time
    • Coiled-coil binding partner at the basal body not identified
    • Relationship between the coiled-coil signal and the UNC119b carrier route not integrated
  5. 2013 High

    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

    PMID:23793029

    Open questions at the time
    • Functional output of altered complex composition on NPHP3 activity not defined
    • Physiological role of HIF1AN regulation in mammalian kidney untested
  6. 2026 Medium

    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

    PMID:41898549

    Open questions at the time
    • Mechanistic link from ciliary NPHP3 loss to vasopressin/MEK pathway activation not resolved
    • Whether the rescue reflects disease modification or symptomatic slowing unclear

Open questions

Synthesis pass · forward-looking unresolved questions
  • How the ciliary NPHP3 module transduces signals to control tubular morphogenesis and how its compositional regulation feeds into cystogenic signaling remain unresolved.
  • 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

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 2
Localization
GO:0005929 cilium 3 GO:0005815 microtubule organizing center 1
Pathway
R-HSA-9609507 Protein localization 2 R-HSA-162582 Signal Transduction 1
Partners
ANKS6ARL3INVSNEK8NPHP1RP2UNC119B
Complex memberships
INVS-ANKS6-NEK8-NPHP3 proximal-cilium module

Evidence

Reading pass · 6 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2003 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. Protein-protein interaction assay (co-immunoprecipitation/pulldown implied by 'interaction shown') Nature genetics Medium 12872122
2010 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. Immunofluorescence/confocal microscopy of primary cilia in cultured cells and mouse tissues; genetic epistasis using inv mutant mice Cytoskeleton (Hoboken, N.J.) High 20169535
2011 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. 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 Genes & development High 22085962
2012 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. GFP-tagged deletion constructs of Nphp3 expressed in cultured cells; confocal microscopy; site-directed mutagenesis of G2 myristoylation site Cytoskeleton (Hoboken, N.J.) High 22328406
2013 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. Co-immunoprecipitation/network proteomics; ANKS6 knockdown in zebrafish and Xenopus; Hif1an knockdown in Xenopus; biochemical hydroxylation assay Nature genetics High 23793029
2026 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. Conditional knockout mouse (Cdh16-Cre; Nphp3fl); histology; renal function assays; pharmacological inhibition with tolvaptan and CI-1040 International journal of molecular sciences Medium 41898549

Source papers

Stage 0 corpus · 22 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2003 Mutations in a novel gene, NPHP3, cause adolescent nephronophthisis, tapeto-retinal degeneration and hepatic fibrosis. Nature genetics 270 12872122
2011 An ARL3-UNC119-RP2 GTPase cycle targets myristoylated NPHP3 to the primary cilium. Genes & development 190 22085962
2013 ANKS6 is a central component of a nephronophthisis module linking NEK8 to INVS and NPHP3. Nature genetics 170 23793029
2009 Mutations of NPHP2 and NPHP3 in infantile nephronophthisis. Kidney international 89 19177160
2010 Inv acts as a molecular anchor for Nphp3 and Nek8 in the proximal segment of primary cilia. Cytoskeleton (Hoboken, N.J.) 82 20169535
2012 Targeting of Nphp3 to the primary cilia is controlled by an N-terminal myristoylation site and coiled-coil domains. Cytoskeleton (Hoboken, N.J.) 33 22328406
2016 High mutation rate of NPHP3 in 18 Chinese infantile nephronophthisis patients. Nephrology (Carlton, Vic.) 16 26184788
2021 BIRC5, GAJ5, and lncRNA NPHP3-AS1 Are Correlated with the Development of Atrial Fibrillation-Valvular Heart Disease. International heart journal 13 33518654
2021 A discarded synonymous variant in NPHP3 explains nephronophthisis and congenital hepatic fibrosis in several families. Human mutation 13 34212438
2009 Lethal cystic kidney disease in Amish neonates associated with homozygous nonsense mutation of NPHP3. American journal of kidney diseases : the official journal of the National Kidney Foundation 12 19303681
2011 Caroli disease, bilateral diffuse cystic renal dysplasia, situs inversus, postaxial polydactyly, and preauricular fistulas: a ciliopathy caused by a homozygous NPHP3 mutation. European journal of pediatrics 7 21845392
2019 Renal-Hepatic-Pancreatic Dysplasia: An Ultra-Rare Ciliopathy with a Novel NPHP3 Genotype. Journal of pediatric genetics 5 32341812
2014 NPHP3 mutations are associated with neonatal onset multiorgan polycystic disease in two siblings. Journal of perinatology : official journal of the California Perinatal Association 5 24776604
2013 Renal-hepatic-pancreatic dysplasia: a sibship with skeletal and central nervous system anomalies and NPHP3 mutation. American journal of medical genetics. Part A 5 23686967
2022 Renal-hepatic-pancreatic dysplasia-1 with a novel NPHP3 genotype: a case report and review of the literature. BMC pediatrics 4 36253741
2018 Transplantation for infantile nephronophthisis with loss-of-function mutation in NPHP3: Lesson from a case. Pediatric transplantation 4 29869359
2022 NPHP3 splice acceptor site variant is associated with infantile nephronophthisis and asphyxiating thoracic dystrophy; A rare combination. European journal of medical genetics 3 35987473
2017 Homozygous mutation in the NPHP3 gene causing foetal nephronophthisis. Nephrology (Carlton, Vic.) 3 28921755
2022 [Enlarged multicystic dysplastic kidneys with oligohydramnios during infancy caused by NPHP3 gene mutation]. Zhonghua yi xue yi chuan xue za zhi = Zhonghua yixue yichuanxue zazhi = Chinese journal of medical genetics 2 35598267
2023 Identification of a Splicing Variant c.3813-3A>G in NPHP3 by Reanalysis of Whole Exome Sequencing in a Chinese Boy with Nephronophthisis. Nephron 1 36878198
2026 Renal Tubule-Specific Deletion of Nephrocystin 3 (Nphp3) Causes Infantile Nephronophthisis-like Phenotypes in Mice. International journal of molecular sciences 0 41898549
2024 Renal cell carcinoma in an adult-onset ESRD patient with nephronophthisis harboring NPHP3 deletion: A case report. Heliyon 0 38617907

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