NUP35

NUP35 is an inner-ring nucleoporin that scaffolds nuclear pore complex (NPC) assembly and selectively controls mRNA export to regulate tissue-specific physiology. Its atypical RRM domain forms homodimers through hydrophobic contacts and is required for smooth muscle integrity in vivo (PMID:16962612, PMID:27427419). NUP35 directly binds Ndc1 and Nup155 to anchor the NPC membrane and recruit the Nup93-containing scaffold; loss of NUP35 blocks NPC assembly and nuclear lamina formation without affecting initial membrane or Nup107 recruitment to chromatin (PMID:16600873, PMID:24363447, PMID:19146848). Beyond its structural role, NUP35 selectively exports specific mRNAs—including NHE1 and Wif1—to regulate cardiomyocyte pH homeostasis and WNT-dependent cardiac remodeling, while rapid depletion shows it does not broadly control transcription or 3D genome organization (PMID:26260029, PMID:41145234, PMID:36323253).

1. 2002 High

   Establishing NUP35 as a bona fide component of the mammalian NPC resolved its identity as a nucleoporin and placed it within the pore proteome for subsequent mechanistic dissection.

   Evidence Biochemical purification of NPC fraction coupled with mass spectrometry

   PMID:12196509

   Open questions at the time

   • Position within the NPC substructure was not defined
   • No interaction partners identified at this stage
2. 2006 High

   Solving the crystal structure of the NUP35 RRM domain revealed an atypical RNA-recognition fold that homodimerizes through specific hydrophobic contacts, providing the first structural framework for understanding its dual roles in self-assembly and RNA binding.

   Evidence X-ray crystallography at 2.7 Å of mouse Nup35 RRM domain with analytical ultracentrifugation

   PMID:16962612

   Open questions at the time

   • RNA substrates recognized by the RRM domain were not identified
   • Functional consequences of homodimerization in NPC context were untested
3. 2006 High

   Demonstrating that the transmembrane nucleoporin Ndc1 directly binds NUP35 in vitro and that RNAi of either protein produces equivalent NPC assembly defects established the Ndc1–NUP35 axis as a membrane-to-scaffold bridge during pore biogenesis.

   Evidence In vitro binding assay and RNAi epistasis in mammalian cells

   PMID:16600873

   Open questions at the time

   • Structural basis of the Ndc1–NUP35 interface was unknown
   • Whether Ndc1 binding modulates NUP35 membrane deformation was untested
4. 2008 High

   Genetic loss-of-function in C. elegans placed NUP35 downstream of nuclear membrane recruitment but upstream of Nup155 and full NPC scaffold assembly, defining its hierarchical position in pore biogenesis.

   Evidence C. elegans npp-19 temperature-sensitive mutant with immunofluorescence of NPC component localization

   PMID:19146848

   Open questions at the time

   • Whether this hierarchy is conserved in vertebrate post-mitotic NPC assembly was not confirmed
   • Molecular basis for NUP35-dependent Nup155 recruitment was undefined
5. 2011 High

   NUP35 was shown to be required for Ran-dependent translocation of integral membrane proteins to the inner nuclear membrane via FG-repeat interactions, extending its function beyond scaffold assembly to active gating of peripheral NPC channels.

   Evidence FRAP with ATP/Ran depletion and NUP35 siRNA knockdown across 15 membrane proteins

   PMID:21444689

   Open questions at the time

   • Direct FG–FG interaction between cargo and NUP35 was inferred but not biochemically reconstituted
   • Contribution of NUP35 FG repeats versus structural role was not separated
6. 2013 High

   Mapping of the Ndc1-binding and Nup155-binding sites on NUP35 showed they are functionally separable, and that the Ndc1-binding region overlaps the membrane-bending domain, revealing how NUP35 coordinates membrane remodeling with scaffold recruitment during NPC assembly.

   Evidence Co-immunoprecipitation, in vitro binding, and functional NPC assembly assays in Xenopus egg extract

   PMID:24363447

   Open questions at the time

   • No high-resolution structure of NUP35 in complex with Ndc1 or Nup155
   • In vivo validation in mammalian somatic cells was limited
7. 2015 Medium

   Discovery that NUP35 selectively exports NHE1 mRNA via its N-terminal domain targeting the 5′-UTR revealed a gene-specific mRNA export function, linking a nucleoporin directly to cardiomyocyte pH homeostasis and ischemic injury.

   Evidence siRNA/overexpression, mRNA nuclear export assay, and ischemia models in cardiomyocytes

   PMID:26260029

   Open questions at the time

   • Direct binding of NUP35 to NHE1 mRNA was not reconstituted with purified components
   • Whether selectivity for NHE1 involves adaptor proteins was unknown
8. 2016 Medium

   An ENU-induced point mutation in the NUP35 RRM domain caused degenerative colonic smooth muscle myopathy in mice, demonstrating that RRM domain integrity is essential for tissue-specific physiology in vivo.

   Evidence Mouse ENU mutagenesis screen with histopathological analysis of RRM domain mutant

   PMID:27427419

   Open questions at the time

   • Molecular mechanism connecting the RRM mutation to smooth muscle degeneration was not resolved
   • Whether the mutation disrupts RNA binding, dimerization, or both was not determined
9. 2018 Medium

   NUP35 was found to relocalize from the nuclear envelope to the meiotic spindle during oocyte maturation and to be required for spindle assembly, chromosome alignment, and kinetochore–microtubule attachment, revealing a non-canonical mitotic/meiotic function.

   Evidence Immunofluorescence localization, siRNA knockdown, spindle assembly checkpoint assay in mouse oocytes

   PMID:30195030

   Open questions at the time

   • Mechanism by which NUP35 promotes spindle assembly is unknown
   • Whether NUP35 phosphorylation at GVBD is required for spindle localization was not tested
   • Single lab study; independent replication needed
10. 2022 High

    Rapid auxin-mediated depletion demonstrated that NUP35, unlike NUP93, has no direct role in gene transcription or 3D genome organization, delimiting its function to transport rather than chromatin regulation.

    Evidence Auxin-inducible degron depletion in human cells with Cut&Run, Hi-C, and HiChIP

    PMID:36323253

    Open questions at the time

    • Whether NUP35 depletion affects mRNA export globally was not assessed in this study
    • Long-term depletion effects were not characterized
11. 2023 Medium

    NUP35 FG motifs were shown to directly engage HIV-1 capsid in a cyclophilin A–dependent manner, identifying NUP35 as a docking site exploited by the virus for nuclear entry.

    Evidence Direct binding assay of FG-motif regions with HIV-1 CA, siRNA knockdown reducing nuclear entry, CypA mutant analysis

    PMID:37355754

    Open questions at the time

    • Relative contribution of NUP35 versus other FG-nucleoporins to HIV-1 entry not quantified
    • Structural basis of the NUP35 FG–capsid interaction is unresolved
12. 2025 High

    Cardiac-specific NUP35 knockout established that NUP35 directly binds Wif1 mRNA and controls its nuclear retention/export, thereby modulating WNT signaling and cardiac fibrosis, confirming NUP35 as a selective mRNA gatekeeper in heart pathophysiology.

    Evidence Cardiac-specific knockout/overexpression mouse models, RIP-seq for direct RNA binding, AAV9-Wif1 rescue

    PMID:41145234

    Open questions at the time

    • Whether NUP35 RNA targets beyond NHE1 and Wif1 share a common cis-element is unknown
    • Contribution of the RRM domain versus other regions to Wif1 mRNA binding was not dissected

• A unifying model explaining how NUP35 selects specific mRNA substrates for nuclear export—including the role of the RRM domain, potential adaptor proteins, and whether selectivity is tissue-specific—remains to be established.
• No transcriptome-wide map of NUP35-dependent mRNA export in multiple tissue contexts
• No structural model of NUP35 in the context of the assembled human inner ring
• Mechanism of NUP35 function at the meiotic spindle is uncharacterized