Affinage

NHLRC2

NHL repeat-containing protein 2 · UniProt Q8NBF2

Length
726 aa
Mass
79.4 kDa
Annotated
2026-06-10
14 papers in source corpus 8 papers cited in narrative 8 extracted findings
Cross-family judge faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

NHLRC2 is an essential, ubiquitously required protein that integrates cytoskeletal organization, vesicle transport, and RNA metabolism, and whose complete loss arrests mouse embryonic development at gastrulation around E7.5 despite normal pre-implantation proliferation (PMID:35258166). Structurally it comprises an N-terminal thioredoxin-like domain adjacent to an NHL-repeat β-propeller, together forming a cleft containing a conserved CCINC motif with an extended negative electrostatic surface that constitutes a likely ligand/partner-binding site, while the non-conserved C-terminal domain remains spatially separate; the FINCA-associated Asp148Tyr substitution destabilizes the fold (PMID:30138417). Despite the thioredoxin-like domain, recombinant NHLRC2 lacks detectable thioredoxin reductase activity (PMID:29423877). During ROS-induced apoptosis the thioredoxin-like domain binds pro-caspase-8 and NHLRC2 is cleaved at Asp580, and its depletion sensitizes cells to ROS-induced death (PMID:29242562). Loss of NHLRC2 function disrupts vimentin filament organization, vesicle transport, and Rho GTPase signalling, promotes fibroblast-to-myofibroblast differentiation, perturbs RNA metabolism through accumulation of hnRNP C2, and impairs innate immune responses including interferon-γ production (PMID:30239752, PMID:33297935, PMID:40510178). Biallelic non-truncating NHLRC2 variants cause the multisystem FINCA disease, with residual protein level correlating with phenotype severity (PMID:37188825). Beyond these findings, the direct molecular substrate or enzymatic/scaffolding function executed through the CCINC cleft has not been defined in the available corpus.

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2017 High

    Established the first direct molecular handle on NHLRC2 by linking it to apoptotic signalling, showing it is a caspase-8 substrate whose loss sensitizes cells to oxidative stress.

    Evidence In vitro cleavage assay mapping Asp580, Co-IP of the Trx-like domain with pro-caspase-8, and siRNA/shRNA/CRISPR loss-of-function with ROS-apoptosis readout

    PMID:29242562

    Open questions at the time
    • Does not define NHLRC2's baseline (non-apoptotic) molecular function
    • Functional consequence of the cleavage fragment unknown
    • No structural basis for the caspase-8 interaction
  2. 2018 High

    Solved the domain architecture, revealing a Trx-like plus NHL-repeat β-propeller arrangement forming a conserved CCINC cleft as the candidate functional surface and showing a disease mutation destabilizes the protein.

    Evidence X-ray crystallography to 2.7 Å, SAXS of full-length protein, and thermal stability assay of the Asp148Tyr mutant

    PMID:30138417

    Open questions at the time
    • No ligand or partner bound in the CCINC cleft was identified
    • C-terminal domain structure unresolved
    • Catalytic role of the cleft unknown
  3. 2018 Medium

    Tested whether the thioredoxin-like domain confers redox enzymatic activity, finding none and arguing the domain serves a binding/structural rather than catalytic role.

    Evidence Insulin turbidity assay on recombinant NHLRC2

    PMID:29423877

    Open questions at the time
    • Single in vitro assay and method
    • Negative result does not exclude other redox-related activities
    • No alternative function assigned to the Trx-like domain
  4. 2018 Medium

    Connected NHLRC2 to cellular physiology by showing FINCA patient cells display abnormal vimentin organization and myofibroblast features, placing the protein in cytoskeletal organization and vesicle transport.

    Evidence BioID proximity-labeling MS, TEM of patient-derived immortalized fibroblasts, and knockdown/overexpression in normal fibroblasts

    PMID:30239752

    Open questions at the time
    • Direct vs. indirect partners not distinguished from BioID
    • Mechanism linking NHLRC2 to vimentin not defined
    • Single lab and patient-derived background
  5. 2018 Medium

    Defined the developmental window of NHLRC2 essentiality, showing it is dispensable pre-implantation but required for gastrulation.

    Evidence Nhlrc2 knockout mouse with timed staging, IVF, and LacZ expression mapping

    PMID:35258166

    Open questions at the time
    • Molecular cause of gastrulation arrest unknown
    • Lethality precludes adult tissue analysis
    • Does not identify the essential downstream pathway
  6. 2020 Medium

    Linked NHLRC2 dysfunction to RNA metabolism in neural tissue by identifying hnRNP C2 accumulation alongside altered vesicular-transport and actin-dynamics proteins.

    Evidence FINCA knockin x KO mouse model with 2D-DIGE proteomics of E13.5 cortical neuronal precursors and Western validation

    PMID:33297935

    Open questions at the time
    • Causal link between NHLRC2 and hnRNP C2 not mechanistically resolved
    • Whether RNA metabolism defect is primary or secondary unclear
    • Single lab
  7. 2023 Low

    Established a genotype-phenotype rule for FINCA, showing residual NHLRC2 protein level scales with disease severity.

    Evidence Expression of non-truncating variants in HEK293 cells with protein-level quantification

    PMID:37188825

    Open questions at the time
    • Single overexpression assay with no mechanistic dissection
    • Protein level read out in non-native cell context
    • Does not address how reduced levels cause specific phenotypes
  8. 2025 Medium

    Converged multiple datasets on Rho GTPase signalling as a core affected pathway and extended NHLRC2 dysfunction to innate immunity via reduced interferon-γ.

    Evidence Variant-vs-WT BioID proximity-labeling MS, mESC transcriptomics, and FINCA mouse T cell/cytokine profiling

    PMID:40510178

    Open questions at the time
    • Direct effector linking NHLRC2 to Rho GTPase signalling not identified
    • Mechanism of impaired interferon-γ production unresolved
    • Single lab

Open questions

Synthesis pass · forward-looking unresolved questions
  • The direct biochemical activity or binding partner engaged through the conserved CCINC cleft, and the molecular event that makes NHLRC2 essential for gastrulation, remain undefined.
  • No defined molecular substrate or ligand
  • Mechanism unifying cytoskeletal, vesicular, RNA, and immune phenotypes unknown
  • No structure-function link from the CCINC cleft to a cellular activity

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Pathway
R-HSA-1266738 Developmental Biology 1 R-HSA-162582 Signal Transduction 1 R-HSA-5357801 Programmed Cell Death 1
Partners
CASP8

Evidence

Reading pass · 8 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2017 NHLRC2 is cleaved by caspase-8 at Asp580 in vitro during ROS-induced apoptosis; the thioredoxin-like domain of NHLRC2 physically interacts with the proenzyme form of caspase-8, and siRNA knockdown of caspase-8 blocked ROS-induced decrease in NHLRC2 protein levels. Loss of NHLRC2 (shRNA or CRISPR-Cas9) increased susceptibility to ROS-induced apoptosis. In vitro cleavage assay identifying Asp580 as the caspase-8 cleavage site; co-immunoprecipitation of NHLRC2 thioredoxin-like domain with pro-caspase-8; siRNA knockdown; shRNA and CRISPR-Cas9 loss-of-function with apoptosis readout Cell death & disease High 29242562
2018 Crystal structure of the Trx-like and NHL repeat β-propeller domains of human NHLRC2 determined to 2.7 Å resolution, revealing two adjacent domains forming a cleft containing a conserved CCINC motif with an extended negative electrostatic surface proposed to form a ligand/partner binding site. SAXS of full-length NHLRC2 shows the non-conserved C-terminal domain does not pack against the N-terminal domains. The FINCA disease-associated Asp148Tyr mutation destabilizes the protein structure by 2°C. X-ray crystallography (2.7 Å) and SAXS for full-length protein; thermal stability assay for Asp148Tyr mutant PloS one High 30138417
2018 An insulin turbidity assay on recombinant human NHLRC2 showed NO thioredoxin reductase activity, despite the protein containing a thioredoxin-like domain. Insulin turbidity assay (in vitro enzymatic assay) with recombinant NHLRC2 Acta neuropathologica Medium 29423877
2018 Proximity-labeling mass spectrometry identified putative interacting partners for NHLRC2, and functional studies using FINCA patient-derived immortalized fibroblasts (carrying compound heterozygous mutations) showed multilamellar bodies, distinctly organized vimentin filaments, and features of myofibroblast differentiation. NHLRC2 knockdown and overexpression experiments placed NHLRC2 in regulation of cytoskeletal organization and vesicle transport; loss of NHLRC2 function enhanced fibroblast-to-myofibroblast differentiation. Proximity-labeling (BioID) mass spectrometry; transmission electron microscopy of patient-derived immortalized cells; NHLRC2 knockdown and overexpression in normal fibroblasts Human molecular genetics Medium 30239752
2018 Nhlrc2 null mouse embryos implanted and appeared normal at E6.5 but development arrested at E7.5, with only 6% of E8.5 embryos homozygous null; KO embryos showed failed gastrulation and amniotic folding. Embryonic stem cells from null blastocysts proliferated normally despite complete loss of NHLRC2 protein, indicating the essential role is post-implantation. Nhlrc2 knockout mouse (C57BL/6NCrl-Nhlrc2tm1a(KOMP)Wtsi/Oulu); timed matings with genotyping; in vitro fertilization; LacZ reporter for expression mapping Genesis (New York, N.Y. : 2000) Medium 35258166
2020 In a FINCA mouse model (compound heterozygote: Nhlrc2 p.Asp148Tyr knockin × Nhlrc2 knockout), 2D-DIGE proteomics of E13.5 cortical neuronal precursor cells identified 19 altered proteins, including significant upregulation of hnRNP C2 in both developing neurons and adult hippocampus. Several altered proteins are involved in vesicular transport pathways and actin dynamics, connecting NHLRC2 dysfunction to disrupted RNA metabolism and cytoskeletal regulation in neurons. CRISPR/Cas9 knockin mouse; 2D-DIGE comparative proteomics of embryonic cortical neuronal precursor cells; Western blot validation Molecular medicine (Cambridge, Mass.) Medium 33297935
2023 Expression of novel and previously published non-truncating NHLRC2 variants in HEK293 cells demonstrated that greater reduction in NHLRC2 protein expression is associated with a more severe disease phenotype, supporting a genotype-phenotype correlation based on residual protein levels. Cloning and expression of NHLRC2 variants in HEK293 cells with protein level quantification European journal of human genetics : EJHG Low 37188825
2025 Proximity-labeling mass spectrometry comparing wild-type and p.Asp148Tyr NHLRC2 in HEK293 cells, combined with transcriptional profiling of mouse embryonic stem cells homozygous for p.Asp148Tyr or Nhlrc2 KO, identified Rho GTPase signalling as a pathway commonly affected by NHLRC2 dysfunction. FINCA mice showed altered innate immune response, particularly reduced interferon-γ production in splenocytes. Proximity-labeling (BioID) mass spectrometry with variant vs. wild-type comparison; transcriptomics of mESCs; T cell and cytokine profiling (interferon-γ) of FINCA compound heterozygous mice Brain, behavior, & immunity - health Medium 40510178

Source papers

Stage 0 corpus · 14 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2017 ROS-induced cleavage of NHLRC2 by caspase-8 leads to apoptotic cell death in the HCT116 human colon cancer cell line. Cell death & disease 47 29242562
2018 NHLRC2 variants identified in patients with fibrosis, neurodegeneration, and cerebral angiomatosis (FINCA): characterisation of a novel cerebropulmonary disease. Acta neuropathologica 26 29423877
2018 Biallelic mutations in human NHLRC2 enhance myofibroblast differentiation in FINCA disease. Human molecular genetics 19 30239752
2018 Structural analysis of human NHLRC2, mutations of which are associated with FINCA disease. PloS one 15 30138417
2020 Novel compound heterozygous variants in NHLRC2 in a patient with FINCA syndrome. Journal of human genetics 13 32435055
2022 Nhlrc2 is crucial during mouse gastrulation. Genesis (New York, N.Y. : 2000) 8 35258166
2020 Variant in NHLRC2 leads to increased hnRNP C2 in developing neurons and the hippocampus of a mouse model of FINCA disease. Molecular medicine (Cambridge, Mass.) 8 33297935
2023 Novel patients with NHLRC2 variants expand the phenotypic spectrum of FINCA disease. Frontiers in neuroscience 5 37179546
2023 Broadening the phenotypic and molecular spectrum of FINCA syndrome: Biallelic NHLRC2 variants in 15 novel individuals. European journal of human genetics : EJHG 5 37188825
2022 Case report: novel mutations of NDUFS6 and NHLRC2 genes potentially cause the quick postnatal death of a Chinese Hani minority neonate with mitochondrial complex I deficiency and FINCA syndrome. Medicine 5 35801790
2022 NHLRC2 expression is increased in idiopathic pulmonary fibrosis. Respiratory research 5 35964085
2023 High NHLRC2 expression is associated with shortened survival in lung adenocarcinoma. Translational lung cancer research 3 37425408
2025 Altered behaviour and immune response in mice with NHLRC2 p.Asp148Tyr variant. Brain, behavior, & immunity - health 0 40510178
2024 Case Report: Clinical manifestations and treatment of two Chinese patients with FINCA syndrome carrying a novel variant of NHLRC2. Frontiers in pediatrics 0 39328589

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