TEX14

TEX14 is a testis-enriched protein that builds and stabilizes the permanent germ cell intercellular bridges (ICBs) required for spermatogenesis, and its loss abolishes ICBs and arrests germ cell development before completion of meiosis (PMID:16549803, PMID:19020301). The molecular basis of bridge stabilization is competitive occupancy of the abscission machinery: TEX14 binds the CEP55-EABR domain through a conserved AxGPPx3YxPP motif with high affinity and a low dissociation rate, thereby excluding ALIX and TSG101 and preventing ESCRT-mediated recruitment that would otherwise complete cytokinetic abscission (PMID:20176808, PMID:26392564). Beyond germ cells, TEX14 acts in somatic mitosis: it is recruited to kinetochores by Plk1 in a Cdk1-dependent manner to support kinetochore-microtubule attachment, chromosome congression, and spindle assembly checkpoint signaling, after which Plk1 phosphorylation triggers APC/C(Cdc20)-mediated degradation to permit the metaphase-to-anaphase transition (PMID:22405274). TEX14 expression is controlled post-transcriptionally, with the germ cell RNA-binding protein DAZL promoting TEX14 translation via its 3'UTR to drive ICB formation and primordial follicle assembly (PMID:31659914). Loss-of-function TEX14 variants cause spermatogenic arrest with failed ICB assembly in humans, recapitulated in mouse models (PMID:40492599, PMID:41603674).

1. 2003 Medium

   Before any function was known, defining the protein's domain architecture and expression pattern established TEX14 as a testis-specific, meiosis-associated multidomain protein worth functional dissection.

   Evidence Sequence analysis, Northern blot, and in situ hybridization of the TEX14 transcript

   PMID:12711554

   Open questions at the time

   • No functional role assigned
   • Kinase domain catalytic activity not tested
   • No protein localization data
2. 2006 High

   The central question of what TEX14 does in germ cells was answered by knockout, showing it is required to build intercellular bridges and for progression through meiosis.

   Evidence Targeted gene knockout in mice with EM and immunofluorescence

   PMID:16549803

   Open questions at the time

   • Molecular mechanism of bridge formation not defined
   • Binding partners unknown
   • Does not address somatic roles
3. 2008 High

   Extending the role beyond the testis, TEX14 was shown to be essential for both male and female embryonic germ cell bridges, and KIF23 was identified as a bridge component, placing TEX14 within a defined cytokinetic protein context.

   Evidence Tex14 knockout mice, EM, and KIF23 immunofluorescence

   PMID:19020301

   Open questions at the time

   • Direct TEX14-KIF23 interaction not demonstrated
   • Mechanism linking TEX14 to bridge stabilization still unknown
4. 2010 High

   The mechanism of permanent bridge stabilization was established: TEX14 binds CEP55 via a GPPX3Y motif and competitively excludes the ESCRT adaptors ALIX and TSG101, explaining how abscission is blocked.

   Evidence Biochemical enrichment of intercellular bridges, co-IP, and competitive binding assays

   PMID:20176808

   Open questions at the time

   • Structural basis of competition not resolved
   • Affinity/kinetics not quantified
   • Does not address mitotic kinetochore function
5. 2011 Medium

   A natural porcine loss-of-function mutation confirmed that TEX14 is required for spermatogenesis across mammals, generalizing the mouse phenotype.

   Evidence SNP scan, candidate gene sequencing, RT-PCR, Western blot, and testis histology in pigs

   PMID:22136159

   Open questions at the time

   • Single species and lab
   • Mechanism of arrest not dissected
   • Bridge-specific defect not directly imaged
6. 2012 High

   A distinct somatic function was uncovered, showing TEX14 is a Plk1- and Cdk1-regulated kinetochore factor supporting microtubule attachment and the spindle checkpoint, then degraded by APC/C(Cdc20) to allow anaphase.

   Evidence Kinase assays, loss-of-function, phospho-site mutagenesis, live-cell imaging, and chromosome segregation assays

   PMID:22405274

   Open questions at the time

   • Single lab
   • Relationship between mitotic and germ cell roles unclear
   • Direct kinetochore-binding interface not mapped
7. 2015 High

   The competitive exclusion mechanism was given atomic resolution, defining the AxGPPx3YxPP residues and showing high affinity, slow off-rate, and local concentration cooperatively block ALIX/ESCRT recruitment.

   Evidence X-ray crystallography of CEP55-EABR bound to TEX14 peptide with binding kinetics and chimeric peptide assays

   PMID:26392564

   Open questions at the time

   • Full-length TEX14 structure not determined
   • In vivo dynamics of competition not measured
8. 2019 Medium

   How TEX14 levels are set in germ cells was addressed by showing DAZL drives TEX14 translation via its 3'UTR without changing mRNA, linking RNA-binding control to bridge formation and follicle assembly.

   Evidence 3'UTR-luciferase reporter, Dazl hypomorph immunostaining, and RT-qPCR

   PMID:31659914

   Open questions at the time

   • Single lab
   • Direct DAZL binding to TEX14 3'UTR not mapped
   • Mechanism of translational activation unresolved
9. 2025 Medium

   TEX14 loss-of-function was confirmed as a cause of human germ cell failure, with biallelic variants disrupting protein synthesis and ICB assembly and arresting meiosis.

   Evidence Exome/Sanger sequencing, Western blot, immunofluorescence, and testis histology in patients

   PMID:40492599

   Open questions at the time

   • Single lab
   • Limited patient numbers
   • Variant-specific mechanism not isolated from general loss
10. 2025 Medium

    The CEP55-binding motif was repurposed as a tool, showing GPPX3Y-containing TEX14 peptides inhibit proliferation and induce apoptosis in cancer cells, indicating the motif is biologically active out of context.

    Evidence Proliferation and apoptosis assays with TEX14 partial peptides in cancer cell lines

    PMID:41219627

    Open questions at the time

    • Single study/lab
    • Endogenous TEX14 role in cancer not established
    • Mechanism of apoptosis induction not defined
11. 2026 High

    A mouse knock-in plus matching patient confirmed frameshift TEX14 variants ablate protein and bridge formation, and ICB proteomics revealed enrichment of RNA-processing and RNP biogenesis factors, hinting at a broader bridge cargo function.

    Evidence Exome sequencing, mouse knock-in, Western blot, IF, histology, and mass spectrometry of purified ICBs

    PMID:41603674

    Open questions at the time

    • Functional role of bridge-associated RNA machinery not tested
    • Mechanism connecting TEX14 to RNP transport unknown

• How TEX14's mitotic kinetochore activity, its germ cell bridge-stabilizing role, and the RNA-processing cargo of intercellular bridges are mechanistically integrated remains unresolved.
• No unified model linking somatic and germ cell functions
• Function of TEX14 kinase domain untested
• Role of ICB-associated RNP machinery undefined