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NXF3

Nuclear RNA export factor 3 · UniProt Q9H4D5

Length
531 aa
Mass
60.1 kDa
Annotated
2026-06-10
26 papers in source corpus 9 papers cited in narrative 9 extracted findings
Cross-family judge faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

NXF3 is a divergent member of the nuclear RNA export factor family that has shed the canonical mRNA-export properties of NXF1, instead carrying out specialized, CRM1-dependent RNA export functions across germline and somatic contexts (PMID:11073998, PMID:11545741). Unlike NXF1, NXF3 does not bind RNA directly in standard assays, does not associate with FG-repeat nucleoporins, and does not enhance bulk mRNA export; in the mouse it localizes exclusively to the cytoplasm (PMID:11073998, PMID:15820316). It compensates for the lack of a nucleoporin-targeting domain through a novel leucine-rich nuclear export signal that drives nucleocytoplasmic shuttling and export of tethered RNA via the CRM1 pathway, blocked by leptomycin B but not by TAP/NXF1 inhibition (PMID:11545741, PMID:15820316). NXF3 heterodimerizes with the export cofactor NXT1/p15, and human NXF3 also engages NXT2 through its NTF2-like domain (PMID:11073998, PMID:15820316, PMID:40624043). In the Drosophila germline, Nxf3 forms a complex with Nxt1, the RNA helicase UAP56, and Bootlegger that is recruited to heterochromatic piRNA source loci, where it binds dual-strand piRNA precursor transcripts and exports them via CRM1 to peri-nuclear nuage for piRNA biogenesis; its loss abolishes piRNA production and de-represses transposons (PMID:31398345, PMID:31416967). In mammals NXF3 operates beyond piRNA biology: it controls the nucleocytoplasmic distribution of box C/D and box H/ACA snoRNAs in an NXF1-independent manner (PMID:29021253), regulates TGF-β signaling in Sertoli cells by physically binding STRAP and disrupting Smad7–STRAP–TGF-βRI complex formation through an export-independent mechanism (PMID:23438076), and facilitates nuclear export of CDK5RAP3 mRNA to promote cell cycle progression in gastric cancer (PMID:40032765). Loss-of-function variants in human NXF3 impair later stages of spermatogenesis, establishing a role in normal male fertility (PMID:40624043).

Mechanistic history

Synthesis pass · year-by-year structured walk · 7 steps
  1. 2000 Medium

    Established that NXF3, despite belonging to the NXF family, fundamentally diverges from NXF1 by lacking RNA-binding, nuclear-rim localization, and mRNA-export activity, reframing it as a non-canonical export factor that nonetheless retains the NXT1/NXT2 cofactor interface.

    Evidence RNA binding, localization, and mRNA export assays plus binding assays with p15/NXT1 and NXT2 in a single study

    PMID:11073998

    Open questions at the time
    • Did not explain how NXF3 reaches the cytoplasm without nucleoporin binding
    • Functional cargo and physiological role unidentified
  2. 2001 High

    Resolved how NXF3 exports cargo without a nucleoporin-targeting domain by identifying a leucine-rich CRM1-dependent nuclear export signal, defining an export route mechanistically distinct from the TAP/NXF1 pathway.

    Evidence Tethered RNA export assay with leptomycin B inhibition, NES mapping, and shuttling assay

    PMID:11545741

    Open questions at the time
    • Used tethered/reporter RNA rather than a physiological cargo
    • Did not identify endogenous RNA substrates
  3. 2005 Medium

    Confirmed in the mouse ortholog that the divergent properties of NXF3 are conserved — cytoplasmic localization driven by the NES, no nucleoporin binding, NXT1 binding, and no reporter mRNA export enhancement.

    Evidence GFP-fusion localization, NES mutagenesis, LMB treatment, Co-IP with p15/NXT1, and mRNA export reporter in mouse

    PMID:15820316

    Open questions at the time
    • Endogenous cargo still unknown
    • No in vivo physiological function established
  4. 2013 Medium

    Revealed an export-independent signaling function: NXF3 binds STRAP and disrupts the Smad7–STRAP–TGF-βRI complex to regulate TGF-β target gene transcription in Sertoli cells, showing NXF3 acts beyond RNA transport.

    Evidence shRNA knockdown in Sertoli cells, reciprocal Co-IP, complex disruption assay, and qRT-PCR/Western readouts

    PMID:23438076

    Open questions at the time
    • Single lab; structural basis of STRAP interaction undefined
    • Relationship between this signaling role and any RNA-export role unclear
  5. 2017 Medium

    Identified an endogenous RNA-distribution function: NXF3 controls nucleocytoplasmic partitioning of box C/D and box H/ACA snoRNAs in an NXF1-independent and cAMP/forskolin-responsive manner.

    Evidence Genome-wide shRNA screen, RNA-seq, gain/loss-of-function, subcellular fractionation, and forskolin stimulation

    PMID:29021253

    Open questions at the time
    • Direct binding of NXF3 to snoRNAs not demonstrated
    • Mechanistic link to the CRM1 export pathway not established here
  6. 2019 High

    Defined the best-characterized physiological cargo and complex: Drosophila Nxf3 assembles with Nxt1, UAP56, and Bootlegger at heterochromatic piRNA loci to bind and CRM1-export dual-strand piRNA precursors to nuage, with loss causing piRNA failure and transposon de-repression.

    Evidence Co-IP, RNA-IP, CRM1 inhibitor assay, nuage imaging, and genetic loss-of-function across two independent labs

    PMID:31398345 PMID:31416967

    Open questions at the time
    • Whether mammalian NXF3 exports piRNA precursors by the same mechanism untested
    • Structural basis of precursor recognition not defined
  7. 2025 Medium

    Connected NXF3 to human disease and to a cancer-relevant cargo: NXF3 binds NXT2 via its NTF2-like domain and is required for late spermatogenesis, while in gastric cancer it exports CDK5RAP3 mRNA to drive proliferation.

    Evidence In vivo Co-IP, human loss-of-function variant identification with histological phenotyping; and shRNA knockdown with RIP-Seq, nuclear-cytoplasmic transcriptomics, and xenografts

    PMID:40032765 PMID:40624043

    Open questions at the time
    • Direct biochemical demonstration that NXF3 binds CDK5RAP3 mRNA versus indirect effect not fully resolved
    • How the spermatogenesis phenotype maps onto specific molecular cargoes unclear
    • Single study each

Open questions

Synthesis pass · forward-looking unresolved questions
  • It remains unresolved how NXF3 selects its diverse cargoes (piRNA precursors, snoRNAs, specific mRNAs) without canonical RNA-binding activity, and whether its export, snoRNA-distribution, and TGF-β signaling roles are mechanistically unified.
  • No structural model of NXF3 cargo recognition
  • Adaptor requirements for mammalian cargo selection unidentified
  • Integration of export-dependent and export-independent functions unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0003723 RNA binding 2 GO:0060090 molecular adaptor activity 2 GO:0140104 molecular carrier activity 2
Localization
GO:0005634 nucleus 1 GO:0005829 cytosol 1
Pathway
R-HSA-8953854 Metabolism of RNA 3 R-HSA-1474165 Reproduction 2 R-HSA-9609507 Protein localization 2
Partners
BOOTLEGGERCRM1NXT1NXT2STRAPUAP56
Complex memberships
Nxf3–Nxt1–UAP56–Bootlegger piRNA export complex

Evidence

Reading pass · 9 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2000 NXF3 does not bind RNA and does not localize to the nuclear rim, and has no RNA export activity in a standard mRNA export assay. Both human p15/NXT1 and NXT2 bind NXF3. RNA binding assay, subcellular localization (nuclear rim assay), RNA export assay, binding assay with p15/NXT1 and NXT2 Molecular and cellular biology Medium 11073998
2001 NXF3 contains a novel leucine-rich CRM1-dependent nuclear export signal that compensates for the absence of a nuclear pore targeting domain, enabling NXF3 to shuttle between nucleus and cytoplasm and export tethered RNA via the CRM1 pathway; this export is blocked by leptomycin B (a CRM1 inhibitor) but not by inhibitors of TAP/NXF1. Tethered RNA export assay, CRM1 inhibitor (leptomycin B) treatment, nuclear export signal mapping, shuttling assay Molecular cell High 11545741
2005 Mouse NXF3 does not bind FG-repeat nucleoporins, localizes exclusively to the cytoplasm (unlike NXF1 which is nuclear), and cytoplasmic localization is abolished by mutation of its leucine-rich NES or by leptomycin B treatment. p15/NXT1 binds mouse NXF3. Mouse NXF3 does not enhance nuclear export of a reporter mRNA substrate. Nucleoporin binding assay, GFP-fusion subcellular localization, LMB treatment, NES mutagenesis, co-immunoprecipitation with p15/NXT1, mRNA export reporter assay Genomics Medium 15820316
2013 Mouse NXF3 is required for TGF-β-induced down-regulation of TGF-β3 (Tgfb3) mRNA and protein in Sertoli cells, acting in an mRNA export activity-independent manner. NXF3 physically interacts with STRAP (serine/threonine kinase receptor-associated protein) and inhibits complex formation among Smad7, STRAP, and activated type I TGF-β receptor, thereby regulating transcription of TGF-β target genes. shRNA knockdown in Sertoli cells, co-immunoprecipitation (NXF3–STRAP interaction), Smad7/STRAP/TGF-βRI complex disruption assay, qRT-PCR and Western blot for target genes The Biochemical journal Medium 23438076
2017 NXF3 regulates the nucleocytoplasmic distribution of box C/D and box H/ACA snoRNAs: gain-of-function of NXF3 decreases cytosolic snoRNAs from the Rpl13a locus, while loss-of-function increases cytosolic snoRNAs. This activity is dependent on NXF3 but not NXF1, and the adenylyl cyclase activator forskolin diminishes cytosolic snoRNAs through an NXF3-dependent mechanism. Genome-wide shRNA screen, RNA-sequencing, gain- and loss-of-function experiments, subcellular fractionation, pharmacological stimulation (forskolin) The Journal of biological chemistry Medium 29021253
2019 Drosophila Nxf3 forms a heterodimer with Nxt1 and interacts with UAP56 (a nuclear RNA helicase) and Bootlegger/CG13741 to form a complex that is recruited to heterochromatic piRNA source loci. Upon cargo binding, Nxf3 exports piRNA precursor transcripts from the nucleus via the exportin CRM1. After export, Nxf3 and Bootlegger accumulate in peri-nuclear nuage, delivering precursor transcripts to piRNA processing sites. Co-immunoprecipitation (Nxf3–Nxt1, Nxf3–UAP56, Nxf3–Bootlegger), RNA immunoprecipitation (Nxf3 binds piRNA precursors), CRM1 inhibitor assay, fluorescence imaging of nuage localization, loss-of-function genetics (Nxf3 depletion blocks piRNA precursor export) Cell High 31398345 31416967
2019 Drosophila Nxf3 specifically binds piRNA precursor transcripts from dual-strand clusters and is essential for their export to piRNA biogenesis sites; Bootlegger is specifically recruited to piRNA clusters and recruits Nxf3. Loss of Nxf3 causes failure of piRNA production and transposon de-repression. RNA immunoprecipitation, genetic depletion/knockout of Nxf3 and Bootlegger, fluorescence imaging, transposon silencing assays Genes & development High 31398345 31416967
2025 Human NXF3 interacts in vivo with NXT2 (mediated by NXT2's NTF2-like domain), and loss-of-function variants in NXF3 in infertile men impair later stages of spermatogenesis, resulting in quantitatively and qualitatively impaired sperm production. In vivo co-immunoprecipitation (NXT2–NXF3 interaction), identification of human NXF3 loss-of-function variants in infertile men, clinical and histological characterization of spermatogenesis defects Nature communications Medium 40624043
2025 NXF3 facilitates the nuclear export of CDK5RAP3 mRNA in gastric cancer cells, promoting cell cycle progression and cancer cell proliferation; NXF3 also modulates piRNA-target networks involving CCND1/CDKN1A-p53 and TGF-β3/TGFBR2 pathways. shRNA knockdown of NXF3 in gastric cancer cells, RNA immunoprecipitation sequencing (RIP-Seq), nuclear-cytoplasmic transcriptomics, IP-MS, piRNA-Seq, RNA-Seq, in vitro proliferation/invasion assays, in vivo xenograft Cellular and molecular life sciences : CMLS Medium 40032765

Source papers

Stage 0 corpus · 26 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2000 TAP (NXF1) belongs to a multigene family of putative RNA export factors with a conserved modular architecture. Molecular and cellular biology 173 11073998
2001 NXF1/p15 heterodimers are essential for mRNA nuclear export in Drosophila. RNA (New York, N.Y.) 144 11780633
2001 Two closely related human nuclear export factors utilize entirely distinct export pathways. Molecular cell 93 11545741
2019 A Heterochromatin-Specific RNA Export Pathway Facilitates piRNA Production. Cell 88 31398345
2001 NXF5, a novel member of the nuclear RNA export factor family, is lost in a male patient with a syndromic form of mental retardation. Current biology : CB 61 11566096
2019 Specialization of the Drosophila nuclear export family protein Nxf3 for piRNA precursor export. Genes & development 57 31416967
2017 Systematic review: Tumor-associated antigen autoantibodies and ovarian cancer early detection. Gynecologic oncology 57 28800944
2017 Autoantibody biomarkers for the detection of serous ovarian cancer. Gynecologic oncology 53 28427776
2009 Inactivation of Nxf2 causes defects in male meiosis and age-dependent depletion of spermatogonia. Developmental biology 48 19345203
2007 NXF2 is involved in cytoplasmic mRNA dynamics through interactions with motor proteins. Nucleic acids research 41 17403691
2005 Molecular cloning and functional characterization of mouse Nxf family gene products. Genomics 33 15820316
2017 Nuclear export factor 3 regulates localization of small nucleolar RNAs. The Journal of biological chemistry 18 29021253
2013 Nuclear export factor 3 is involved in regulating the expression of TGF-β3 in an mRNA export activity-independent manner in mouse Sertoli cells. The Biochemical journal 15 23438076
2019 Anti-cancer effect of dung beetle glycosaminoglycans on melanoma. BMC cancer 14 30611221
2011 Nxf3 is expressed in Sertoli cells, but is dispensable for spermatogenesis. Molecular reproduction and development 13 21308854
2011 De novo duplication of Xq22.1→q24 with a disruption of the NXF gene cluster in a mentally retarded woman with short stature and premature ovarian failure. Taiwanese journal of obstetrics & gynecology 13 22030050
2019 Nxf3: a middleman with the right connections for unspliced piRNA precursor export. Genes & development 12 31481534
2013 A 1.1-Mb segmental deletion on the X chromosome causes meiotic failure in male mice. Biology of reproduction 12 23677977
2014 Respiratory failure, cleft palate and epilepsy in the mouse model of human Xq22.1 deletion syndrome. Human molecular genetics 11 24569167
2024 Transcriptomic analysis to identify genes associated with hypothalamus vulnerability in aging mice with cognitive decline. Behavioural brain research 7 38452974
2023 Detection of aberrant DNA methylation patterns in sperm of male recurrent spontaneous abortion patients. Zygote (Cambridge, England) 7 36617979
2013 An X-chromosomal association study identifies a susceptibility locus at Xq22.1 for hepatitis B virus-related hepatocellular carcinoma. Clinics and research in hepatology and gastroenterology 5 24209690
2017 AF119895 regulates NXF3 expression to promote migration and invasion of hepatocellular carcinoma through an interaction with miR-6508-3p. Experimental cell research 4 29274323
2025 Nuclear translocation of CDK5RAP3 regulated by NXF3 promotes the progression of gastric cancer. Cellular and molecular life sciences : CMLS 1 40032765
2026 Lentiviral-mediated expression of cytochrome P450 2D6 in HepaRG cells: new means for in vitro xenobiotic biotransformation and cellular response to chimeric viral mRNA. Archives of toxicology 0 42166010
2025 NXT2 is a key component of the RNA nuclear export factor complex in the human testis and essential for spermatogenesis. Nature communications 0 40624043

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