TEX11

TEX11 is a meiosis-specific protein that regulates genome-wide crossover formation and meiotic double-strand break (DSB) repair during spermatogenesis (PMID:18369460, PMID:26136358). It was first identified as an NBS1-interacting partner whose loss in male mice delays DSB repair (reduced DMC1 resolution) and reduces crossovers (decreased MLH1 foci), producing achiasmate chromosomes at meiosis I and establishing TEX11 as a functional collaborator of the Mre11/NBS1 complex (PMID:18369460). TEX11 acts as a component of the trimeric ZZS complex together with SHOC1 and SPO16, binding recombination intermediates after strand invasion to stabilize them and promote crossover formation; recruitment of TEX11 to these intermediates depends on the SHOC1 XPF-like domain [PMID:bio_10.1101_2025.05.28.656576]. TEX11 protein levels set genome-wide recombination rates, and an intronless autosomal Tex11 transgene rescues the X-linked knockout, providing evidence for retrotransposition (PMID:26136358). In men, loss-of-function TEX11 mutations cause meiotic arrest and azoospermia, with TEX11 normally expressed in late spermatocytes and spermatids and absent in affected patients (PMID:25970010). Beyond its meiotic role, TEX11 modulates cell proliferation in somatic/cultured-cell contexts: it competes with estrogen receptor β (ERβ) for HPIP binding, enhancing ERβ nuclear transcriptional activity while suppressing its cytoplasmic AKT/ERK signaling (PMID:22383461), and in colorectal cancer cells it inhibits proliferation through a FOXO3a→COP1→c-Jun→p21 axis (PMID:36258021). Multiple knock-in mouse studies show that the meiotic requirement is variant- and species-specific, as several human-mimicking SPO22-domain and missense alleles do not disrupt mouse spermatogenesis (PMID:41300722, PMID:41756962, PMID:39231187).

1. 2005 Low

   Before functional data, the question was what type of protein TEX11/Spo22 is and where it acts; bioinformatics predicted a 22-unit TPR architecture functioning at crossover-designated recombination sites alongside Zip2 and Zip3.

   Evidence Bioinformatic repeat annotation (ABRA) and structural domain prediction of the yeast Spo22/Zip4 ortholog

   PMID:16314568

   Open questions at the time

   • Purely computational; no experimental validation of TPR structure or of any ubiquitin-labeling activity
   • Inferred only from yeast ortholog, not mammalian TEX11
2. 2008 High

   It was unknown how TEX11 connects to the DSB repair machinery; identifying it as an NBS1 interactor whose knockout delays DSB repair and reduces crossovers placed it functionally within meiotic recombination and crossover control.

   Evidence Yeast two-hybrid screen, Zip4h−/Y mouse knockout with DMC1 and MLH1 cytology in spermatocytes

   PMID:18369460

   Open questions at the time

   • Did not define how TEX11 acts biochemically on recombination intermediates
   • Did not establish the larger complex in which TEX11 operates
3. 2012 Medium

   Whether TEX11 has functions outside meiosis was unaddressed; competition with ERβ for HPIP and modulation of ERβ signaling and proliferation revealed a somatic, hormone-signaling-linked activity.

   Evidence Yeast two-hybrid, co-IP/binding competition, ERβ translocation and AKT/ERK phosphorylation assays, proliferation assays in GC-1/GC-2 cells

   PMID:22383461

   Open questions at the time

   • No structural basis for HPIP/ERβ competition
   • Physiological relevance of this somatic pathway in vivo not established
4. 2015 Medium

   Whether TEX11 disruption causes human infertility and whether its dosage controls recombination were open; human mutation analyses and transgenic mouse rescue showed loss-of-function causes azoospermia/meiotic arrest and that TEX11 levels set genome-wide recombination rates.

   Evidence Human genetic screening and testis IHC; transgenic mouse complementation and recombination rate quantification

   PMID:25970010 PMID:26136358

   Open questions at the time

   • Molecular mechanism by which TEX11 dosage tunes recombination not resolved
   • Did not define the protein complex mediating crossover stabilization
5. 2025 Medium

   The biochemical mechanism by which TEX11 promotes crossovers was clarified by placing it in the trimeric ZZS complex with SHOC1 and SPO16 that binds and stabilizes post-strand-invasion recombination intermediates.

   Evidence Mouse CRISPR/Cas9 models, co-IP/complex assembly, ChIP, and meiotic spread cytology (preprint)

   PMID:bio_10.1101_2025.05.28.656576

   Open questions at the time

   • TEX11 role inferred from a SHOC1 XPF-domain variant disrupting recruitment rather than direct TEX11 perturbation
   • Preprint, single study
   • Structure of the ZZS complex bound to intermediates not resolved
6. 2025 Medium

   Whether specific human TEX11 variants are truly pathogenic was tested; an in-frame deletion variant produced truncated protein but did not perturb modeled ZZS structure and the corresponding mouse was fertile, indicating species-specific functional differences.

   Evidence HEK293 expression with qPCR/Western blot, in silico structural modeling, CRISPR/Cas9 mouse model

   PMID:41300722

   Open questions at the time

   • Pathogenicity of the variant in humans remains unresolved by the negative mouse result
   • Structural modeling not experimentally validated
7. 2024 Medium

   Whether a SPO22-domain exon 9-11 deletion mimicking a human variant disrupts function was tested; the mouse showed normal spermatogenesis, fertility, and transcriptome, reinforcing species-specific differences in TEX11 requirements.

   Evidence CRISPR/Cas9 Tex11Ex9-11del/Y mouse with sperm analysis, fertility assays, and testis RNA-seq

   PMID:39231187

   Open questions at the time

   • Does not exclude pathogenicity of the orthologous human variant
   • Mechanistic basis of species difference unknown
8. 2026 Medium

   How distinct human-derived TEX11 alleles map to phenotypic severity was examined; knock-in mice showed allele-specific outcomes ranging from complete maturation arrest to normal fertility to partial, incompletely penetrant defects.

   Evidence CRISPR/Cas9 knock-in mouse models (Tex11D, Tex11A, Tex11L) with testis weight, sperm counts, histology, and breeding assays (preprint)

   PMID:41756962

   Open questions at the time

   • Molecular reason for allele-specific severity not defined
   • Preprint, single study
   • Direct translation of mouse allele phenotypes to human patients uncertain

• How TEX11 biochemically recognizes and stabilizes recombination intermediates within the ZZS complex, and how its dosage quantitatively controls genome-wide crossover designation, remain unresolved.
• No experimentally determined structure of the TEX11-containing ZZS complex on DNA
• Mechanism linking TEX11 abundance to recombination rate undefined
• Reconciliation of human pathogenicity with species-specific mouse phenotypes incomplete