Affinage

RAI14

Ankycorbin · UniProt Q9P0K7

Length
980 aa
Mass
110.0 kDa
Annotated
2026-06-10
25 papers in source corpus 15 papers cited in narrative 15 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/7 claims corpus-supported (86%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

RAI14 (NORPEG) is an actin-binding cytoskeletal adaptor protein with six ankyrin repeats and a long coiled-coil domain that organizes F-actin and couples receptor and signaling complexes to the actomyosin network (PMID:11042181, PMID:23565266). Its localization is cell-density dependent, partitioning between the nucleus—via a defined monopartite NLS (PKKRKAP, residues 270–276)—in sparse cells and cytoplasmic/cytoskeletal compartments in confluent cells (PMID:16729964). At the testicular ectoplasmic specialization it binds directly to F-actin and the actin cross-linker palladin to maintain actin filament bundle integrity, adhesion, and the permeability barrier (PMID:23565266, PMID:23885305), although CRISPR knockout demonstrated RAI14 is dispensable for mouse spermatogenesis (PMID:33643708). RAI14 acts as a cytoskeletal effector in distinct contexts: it interacts with Invariant chain (CD74) and myosin II at membrane ruffles and macropinosomes to drive macropinocytosis and MHC II trafficking in antigen-presenting cells (PMID:37545539), and proximity interactomics place it in the Wnt/PCP pathway alongside ROR1/2, VANGL2, DVL3 and PRICKLE1, where it links the receptor complex to effector actomyosin to control convergent extension and cell orientation [PMID:bio_10.1101_2025.01.15.633117]. In renal fibrosis, RAI14 binds and stabilizes TRIOBP by blocking HECTD1-mediated ubiquitination, enhancing F-actin assembly and cytoskeletal tension that drive YAP nuclear translocation and profibrotic transcription (PMID:41242366). RAI14 protein abundance is set post-translationally: the deubiquitinase STAMBP stabilizes it by suppressing K48-linked ubiquitination and proteasomal degradation (PMID:36434041). Across multiple cancers, RAI14 promotes proliferation, migration, and invasion through pathways including Akt and STAT3 signaling (PMID:30349303, PMID:32957082).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2000 Medium

    Established RAI14 as a cytoskeleton-associated protein, defining its core architecture before any binding partner or pathway was known.

    Evidence FLAG-fusion expression in COS-7 cells with confocal imaging and detergent fractionation

    PMID:11042181

    Open questions at the time
    • No direct actin binding demonstrated
    • No physiological partner identified
    • Cytoskeletal association inferred from solubility, not direct interaction
  2. 2006 High

    Resolved that RAI14 localization is regulated, identifying a functional NLS and a nuclear-cytoplasmic shift tied to cell density.

    Evidence GFP-fusion expression with NLS deletion/point mutagenesis in ARPE-19 and COS-7 cells

    PMID:16729964

    Open questions at the time
    • Nuclear function of RAI14 unresolved
    • Signal coupling density to localization unknown
    • No nuclear binding partners identified
  3. 2013 High

    Defined RAI14's molecular activity as a direct F-actin and palladin binder that maintains actin bundle integrity at the ectoplasmic specialization.

    Evidence Reciprocal Co-IP/binding assays and RNAi knockdown in rat Sertoli cells in vitro and in vivo

    PMID:23565266 PMID:23885305

    Open questions at the time
    • Binding interface mapping not done
    • Mechanism of actin bundle regulation unresolved
    • RNAi-only loss of function
  4. 2021 Medium

    Tested the genetic requirement for RAI14 in spermatogenesis, revealing it is dispensable in mouse and contradicting the rat RNAi phenotype.

    Evidence CRISPR/Cas9 knockout mice with CASA, histology, TEM, immunofluorescence, TUNEL

    PMID:33643708

    Open questions at the time
    • Source of species discrepancy unexplained
    • Possible genetic compensation untested
    • Does not address non-testis roles
  5. 2022 High

    Identified the post-translational mechanism setting RAI14 abundance, linking STAMBP deubiquitinase activity to RAI14 stability.

    Evidence IP-MS, Co-IP, K48-linked ubiquitination assays, and TNBC tumor growth assays in vitro and in vivo

    PMID:36434041

    Open questions at the time
    • E3 ligase opposing STAMBP not identified here
    • Ubiquitination sites on RAI14 unmapped
    • Functional consequence of stabilized RAI14 in cytoskeleton not addressed
  6. 2023 High

    Placed RAI14 in membrane trafficking, showing it bridges Invariant chain and myosin II to drive macropinocytosis and MHC II internalization.

    Evidence Yeast two-hybrid, Co-IP, immunofluorescence, and depletion with macropinocytosis/MHC II internalization functional assays in antigen-presenting cells

    PMID:37545539

    Open questions at the time
    • Stoichiometry of RAI14-Ii-myosin II complex unknown
    • Whether macropinocytosis role is direct or via actin remodeling unresolved
    • In vivo immune relevance not established here
  7. 2025 High

    Defined a mechanotransduction axis in which RAI14 stabilizes TRIOBP against HECTD1 ubiquitination to drive actin tension and YAP-mediated profibrotic transcription.

    Evidence Spatial metabolomics, single-cell transcriptomics, Co-IP, ubiquitination assays, F-actin/YAP translocation assays, and RAI14 knockout in an in vivo renal fibrosis model

    PMID:41242366

    Open questions at the time
    • Direct RAI14-TRIOBP binding interface unmapped
    • How RAI14 blocks HECTD1 access mechanistically unclear
    • Generality beyond renal fibroblasts untested
  8. 2025 Medium

    Extended RAI14 into Wnt/PCP signaling, positioning it as a connector between PCP receptor complexes and effector actomyosin.

    Evidence BioID proximity interactomics with PCP components and zebrafish loss-of-function (convergent extension, lateral organ orientation, melanoma migration) (preprint)

    PMID:bio_10.1101_2025.01.15.633117

    Open questions at the time
    • Proximity labeling does not prove direct binding
    • Preprint, not peer reviewed
    • Direct receptor-RAI14 contact not demonstrated

Open questions

Synthesis pass · forward-looking unresolved questions
  • How RAI14's regulated nuclear-cytoplasmic shuttling, its actin-organizing activity, and its multiple signaling roles (Wnt/PCP, mTOR, YAP, trafficking) are integrated into a single coherent function remains unresolved.
  • No structural model of RAI14 bound to actin or partners
  • Nuclear role of RAI14 entirely uncharacterized
  • Unified mechanism reconciling cancer, fibrosis, immune, and developmental roles absent

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0060090 molecular adaptor activity 3 GO:0008092 cytoskeletal protein binding 2
Localization
GO:0005829 cytosol 2 GO:0005856 cytoskeleton 2 GO:0005634 nucleus 1 GO:0005886 plasma membrane 1
Pathway
R-HSA-162582 Signal Transduction 2 R-HSA-168256 Immune System 2 R-HSA-5653656 Vesicle-mediated transport 1

Evidence

Reading pass · 15 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2000 NORPEG (RAI14) encodes a ~110 kDa protein with six ankyrin repeats and a long coiled-coil domain; when transiently expressed in COS-7 cells as a FLAG fusion, it localizes to the cytoplasm in thread-like projections reminiscent of the cytoskeleton, and the expressed protein shows resistance to solubilization by Triton X-100 and KCl, consistent with cytoskeletal association. Transient expression of FLAG-fusion protein in COS-7 cells, confocal immunofluorescence, detergent fractionation The Journal of biological chemistry Medium 11042181
2006 NORPEG (RAI14) subcellular localization is cell-density dependent: it is predominantly nuclear in non-confluent ARPE-19 cells but shifts to cytoplasmic/cytoskeletal localization in confluent cultures. A conserved monopartite nuclear localization signal (PKKRKAP, residues 270–276) was identified; deletion and mutation analysis showed this NLS is indispensable for nuclear targeting. Confocal immunofluorescence with polyclonal antibody, GFP-fusion protein expression, deletion and point mutation analysis, expression in ARPE-19 and COS-7 cells Biochemical and biophysical research communications High 16729964
2013 RAI14 is an actin-binding protein expressed at the ectoplasmic specialization (ES) in rat testis; it co-associates with the actin cross-linking protein palladin. RNAi knockdown of Rai14 in Sertoli cells in vitro disrupted F-actin organization and perturbed tight junction-permeability barrier function; in vivo knockdown caused defects in spermatid polarity, adhesion, and transport via changes in F-actin organization and protein mis-localization at the apical ES. RNAi knockdown in vitro and in vivo, co-immunoprecipitation/binding assays with actin and palladin, immunofluorescence, tight junction permeability assays PloS one High 23565266
2013 RAI14 binds directly to both F-actin and palladin (an actin cross-linking/bundling protein) in the testis, functioning as a regulator of actin filament bundle integrity at the ectoplasmic specialization during spermatogenesis. Co-immunoprecipitation, immunofluorescence co-localization, functional RNAi studies Spermatogenesis Medium 23885305
2018 RAI14 knockdown in gastric cancer cells inhibited proliferation, migration, and invasion, and promoted apoptosis by downregulating Bcl-2 and upregulating Bax; the mechanism was linked to inhibition of Akt pathway activation, and overexpression of RAB31 rescued the reduced proliferation caused by RAI14 knockdown, placing RAB31 downstream of RAI14. siRNA knockdown, cell proliferation/migration/invasion assays, flow cytometry apoptosis, Western blot, Akt pathway activation with IGF-1, RAB31 rescue experiments OncoTargets and therapy Medium 30349303
2018 RAI14 promotes mTOR-mediated NF-κB inflammatory signaling in U87 glioblastoma cells; RAI14 knockdown attenuated pro-inflammatory cytokine production via inhibition of the IKK/NF-κB pathway, and mTOR inhibitor (everolimus) reduced NF-κB activity and IKKα/β phosphorylation through RAI14 signaling. RAI14 also enhanced mTOR-mediated NF-κB activation under chemical hypoxia. siRNA knockdown, mTOR inhibitor (everolimus) treatment, Western blot for IKK/NF-κB pathway components, LPS/TNF-α and CoCl2 stimulation models Cellular and molecular neurobiology Medium 30554401
2019 RAI14 knockdown in breast cancer cells inhibits proliferation, migration, and invasion by regulating cell cycle and EMT through the Akt/Cyclin D1 axis and modulating MMP2, MMP9, and ZEB1/E-cadherin/Vimentin pathway. siRNA knockdown, cell proliferation/migration/invasion assays, Western blot for pathway markers Journal of Cancer Low 31772666
2020 RAI14 silencing in esophageal cancer cells induces apoptosis and cell cycle arrest; RAI14 activates the STAT3 pathway, upregulates Mcl-1 and cyclin D1, and inhibits cleaved caspase-3; STAT3 inhibition restored the oncogenic effect of RAI14. siRNA knockdown, overexpression, Western blot, STAT3 inhibitor rescue, in vivo xenograft Aging Medium 32957082
2021 Rai14 knockout (via CRISPR/Cas9) in mice did not disrupt spermatogenesis, fertility, sperm parameters, F-actin organization at the ectoplasmic specialization, or ES junction morphology — in contrast to results from siRNA knockdown in rats. This negative result indicates Rai14 is dispensable for mouse spermatogenesis. CRISPR/Cas9 knockout, CASA sperm analysis, histology, immunofluorescence, TEM, TUNEL assay PeerJ Medium 33643708
2022 The deubiquitinase STAMBP physically interacts with RAI14 and stabilizes it by suppressing K48-linked ubiquitination of RAI14, preventing its proteasomal degradation; STAMBP knockdown reduces RAI14 protein levels and suppresses TNBC tumor growth in vitro and in vivo. Immunoprecipitation-mass spectrometry, co-immunoprecipitation, siRNA knockdown, ubiquitination assays (K48-linked), in vitro and in vivo tumor growth assays Experimental & molecular medicine High 36434041
2022 RAI14 affects the transcriptional expression of FBXO32 (an E3 ubiquitin ligase for c-MYC) and thereby regulates the stability of c-MYC protein in melanoma cells; RAI14 expression affects proliferation and invasion of melanoma cells. RAI14 overexpression/knockdown, Western blot for FBXO32 and c-MYC, cell proliferation and invasion assays International journal of molecular sciences Low 36233342
2023 RAI14 interacts with Invariant chain (Ii/CD74) as identified by yeast two-hybrid screening, confirmed by co-immunoprecipitation; RAI14 localizes to membrane ruffles and macropinosomes. Depletion of RAI14 in antigen-presenting cells delays MHC II internalization and reduces macropinocytic activity. RAI14 also binds myosin II, suggesting RAI14, Ii, and myosin II cooperate to coordinate macropinocytosis and cell motility. Yeast two-hybrid screening, co-immunoprecipitation, immunofluorescence localization, RAI14 depletion with functional macropinocytosis and MHC II internalization assays, myosin II binding assay Frontiers in immunology High 37545539
2025 RA-induced RAI14 upregulation in renal fibroblasts promotes fibroblast-to-myofibroblast transition; RAI14 binds and stabilizes TRIOBP by preventing HECTD1-mediated ubiquitination and degradation of TRIOBP. This stabilization enhances F-actin assembly and cytoskeletal tension, leading to YAP nuclear translocation and activation of profibrotic transcriptional programs. Genetic ablation of RAI14 significantly attenuates renal fibrosis in vivo. Spatial metabolomics, single-cell transcriptomics, co-immunoprecipitation (RAI14-TRIOBP interaction), ubiquitination assays (HECTD1-mediated), F-actin assembly assays, YAP nuclear translocation assays, RAI14 genetic knockout in vivo fibrosis model Cellular signalling High 41242366
2025 RNASEH2C enhances TRAF3IP1 expression to promote lysosomal degradation of RAI14, suppressing the mTOR pathway; HSC70 and CMTM6 play opposing roles in RAI14 degradation. RAI14 functions as a skeletal protein that facilitates macropinocytosis of MHC II molecules and tumor-associated antigen in macrophages, thereby activating Th1 cells in hepatocellular carcinoma. Single-cell RNA sequencing, immunoblotting, immunofluorescence, immunoprecipitation, flow cytometry, in vitro and mouse tumor models Cell death & disease Medium 41361104
2025 RAI14, EPHA2, and PHACTR4 are components of the Wnt/PCP pathway identified by BioID proximity interactomics with key PCP components (ROR1, ROR2, VANGL2, DVL3, PRICKLE1); loss-of-function of rai14 in zebrafish disrupted convergent extension, orientation of lateral organ cells, and migration of melanoma cells (Wnt/PCP-dependent processes). Mechanistically, RAI14 connects the receptor complex to effector actomyosin. BioID proximity-dependent biotinylation interactomics, zebrafish loss-of-function (convergent extension, lateral organ orientation, melanoma cell migration assays) bioRxivpreprint Medium bio_10.1101_2025.01.15.633117

Source papers

Stage 0 corpus · 25 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2000 Molecular characterization and developmental expression of NORPEG, a novel gene induced by retinoic acid. The Journal of biological chemistry 44 11042181
2020 Long non-coding RNA AFAP1-AS1 accelerates the progression of melanoma by targeting miR-653-5p/RAI14 axis. BMC cancer 40 32228518
2021 Retinoic Acid Induced Protein 14 (Rai14) is dispensable for mouse spermatogenesis. PeerJ 30 33643708
2022 The deubiquitinating enzyme STAMBP is a newly discovered driver of triple-negative breast cancer progression that maintains RAI14 protein stability. Experimental & molecular medicine 28 36434041
2013 Rai14 (retinoic acid induced protein 14) is involved in regulating f-actin dynamics at the ectoplasmic specialization in the rat testis*. PloS one 24 23565266
2018 Knockdown of RAI14 suppresses the progression of gastric cancer. OncoTargets and therapy 21 30349303
2018 Retinoic Acid-Induced Protein 14 (RAI14) Promotes mTOR-Mediated Inflammation Under Inflammatory Stress and Chemical Hypoxia in a U87 Glioblastoma Cell Line. Cellular and molecular neurobiology 18 30554401
2017 Super enhancer associated RAI14 is a new potential biomarker in lung adenocarcinoma. Oncotarget 18 29285248
2019 Downregulation of RAI14 inhibits the proliferation and invasion of breast cancer cells. Journal of Cancer 17 31772666
2006 Cell density-dependent nuclear/cytoplasmic localization of NORPEG (RAI14) protein. Biochemical and biophysical research communications 17 16729964
2005 Expression of a novel alternative transcript of the novel retinal pigment epithelial cell gene NORPEG in human testes. Asian journal of andrology 17 16110356
2013 RAI14 (retinoic acid induced protein 14) is an F-actin regulator: Lesson from the testis. Spermatogenesis 15 23885305
2021 Bta-miR-34b controls milk fat biosynthesis via the Akt/mTOR signaling pathway by targeting RAI14 in bovine mammary epithelial cells. Journal of animal science and biotechnology 14 34275467
2023 Lnc-TRTMFS promotes milk fat synthesis via the miR-132x/RAI14/mTOR pathway in BMECs. Journal of animal science 12 37367933
2021 RAI14 Regulated by circNFATC3/miR-23b-3p axis Facilitates Cell Growth and Invasion in Gastric Cancer. Cell transplantation 12 33840258
2020 RAI14 silencing suppresses progression of esophageal cancer via the STAT3 pathway. Aging 11 32957082
2022 RAI14 Promotes Melanoma Progression by Regulating the FBXO32/c-MYC Pathway. International journal of molecular sciences 6 36233342
2006 Immunofluorescence analysis of the expression of Norpeg (Rai14) in retinal Müller and ganglion cells. Neuroscience letters 6 16806700
2023 The dual-crosslinked prospective values of RAI14 for the diagnosis and chemosurveillance in triple negative breast cancer. Annals of medicine 3 36880986
2023 Rai14 is a novel interactor of Invariant chain that regulates macropinocytosis. Frontiers in immunology 3 37545539
2020 RAI14 in the blood feather regulates chicken pigmentation. Archives animal breeding 3 34084896
2025 RNASEH2C enhances TRAF3IP1 to degrade RAI14 in lysosomes thus hindering macrophage antigen presentation and advancing liver cancer. Cell death & disease 1 41361104
2026 [Antitumor component-Ι in Agkistrodon halys venom inhibits proliferation and migration of cisplatin-resistant gastric cancer cells by downregulating RAI14]. Nan fang yi ke da xue xue bao = Journal of Southern Medical University 0 41540697
2025 Unveiling the role of RAI14 in cancer: Biological significance and translational perspectives. Seminars in oncology 0 40902302
2025 Renal tubular-derived retinoic acid drives renal fibrosis via a RAI14-TRIOBP-YAP mechanotransduction axis. Cellular signalling 0 41242366

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