ANKRD31

ANKRD31 is a meiosis-specific scaffold protein that controls the timing, number, and genomic distribution of programmed DNA double-strand breaks (DSBs) by anchoring DSB-promoting factors to chromosome axes. It directly binds the pleckstrin homology domain of REC114 through a structurally defined interface that is competitively shared with IHO1 and TOPOVIBL, and this interaction is essential for ANKRD31 function, as structure-guided mutations that specifically disrupt REC114 binding phenocopy the null mutant (PMID:31003867, PMID:37976262, PMID:37431931). ANKRD31 is indispensable for the hyperaccumulation of DSB machinery and the specialized axis elongation at pseudoautosomal regions (PARs), and its loss abolishes the uniquely high PAR DSB rates required for obligate sex-chromosome crossovers, causing meiotic arrest in spermatocytes (PMID:31000436, PMID:32461690). Heterozygous variants in ANKRD31 that disrupt REC114 binding have been identified as a cause of primary ovarian insufficiency (POI) in humans, consistent with dosage-sensitive requirements for meiotic DSB formation (PMID:34257419).

1. 2019 High

   The discovery that ANKRD31 directly binds REC114 via a PH-domain interface and that its loss delays DSBs genome-wide while abolishing PAR-targeted DSBs established ANKRD31 as the first identified scaffold specifically targeting DSB-promoting complexes to defined chromosomal locations during meiosis.

   Evidence Crystal structure of REC114 PH domain–ANKRD31 complex, Ankrd31 knockout mouse with cytological and immunofluorescence analysis of DSB markers

   PMID:31000436 PMID:31003867

   Open questions at the time

   • How ANKRD31 recognizes PAR-specific genomic features was unknown
   • Whether the REC114 interaction is sufficient for all ANKRD31 functions was untested
   • Relationship to other DSB-promoting factors such as MEI4 and IHO1 was undefined
2. 2020 High

   Demonstrating that ANKRD31 and MEI4 are jointly required for PAR axis elongation, sister chromatid separation, and hyperaccumulation of DSB factors at the PAR—independently of REC8 and HORMAD1—revealed that ANKRD31 shapes higher-order chromosome architecture to create a recombination-permissive environment.

   Evidence Super-resolution and structured illumination microscopy of PAR ultrastructure in Ankrd31, Mei4, Rec8, and Hormad1 knockout mice with genetic epistasis analysis

   PMID:32461690

   Open questions at the time

   • Whether ANKRD31 directly mediates axis structural changes or acts indirectly through DSB-factor recruitment was unresolved
   • The molecular basis of the ANKRD31–MEI4 functional interaction was not defined
3. 2021 Medium

   Identification of heterozygous ANKRD31 variants in POI patients that disrupt REC114 binding provided the first evidence that ANKRD31 haploinsufficiency causes human meiotic disease, extending its role from mouse genetics to human reproductive pathology.

   Evidence Exome sequencing in POI patients combined with functional interaction assays for ANKRD31-REC114 binding with patient-derived variants

   PMID:34257419

   Open questions at the time

   • Number of patients is limited; independent replication in larger cohorts is lacking
   • Whether the variants cause meiotic DSB defects in human oocytes was not directly shown
   • Potential additional functions of ANKRD31 in oogenesis beyond DSB formation were not explored
4. 2023 High

   Structure-informed in vivo mutagenesis showed that the REC114-binding interface is the essential functional output of ANKRD31: truncation alleles eliminating REC114 contact phenocopy nulls, and partial-disruption alleles produce dosage-dependent intermediate phenotypes, separating REC114 binding from other potential ANKRD31 activities.

   Evidence Genome-edited mice carrying Ankrd31 missense and truncation alleles targeting the REC114-interaction surface, with cytological recombination and DSB marker analysis

   PMID:37976262

   Open questions at the time

   • Whether ANKRD31 has REC114-independent functions in specific genomic contexts remained untested
   • Structural basis of ANKRD31 interactions with partners other than REC114 was unknown
5. 2023 High

   Showing that IHO1 and TOPOVIBL compete with ANKRD31 for the same REC114 PH-domain surface reframed ANKRD31 as one component of a mutually exclusive interaction network, positioning REC114 as a regulatory hub rather than a passive ANKRD31 partner.

   Evidence AlphaFold2 structural modeling validated by pulldowns and SEC-MALS competition assays in vitro

   PMID:37431931

   Open questions at the time

   • The temporal order and regulatory logic of partner switching on REC114 in vivo was not determined
   • Whether competition is regulated by post-translational modifications was unknown
6. 2024 High

   Genetic epistasis between IHO1 interaction mutants and ANKRD31 revealed that ANKRD31 provides a complementary, partially redundant pathway for seeding and growing DSB-machinery clusters on axes, explaining residual DSB activity when the primary IHO1-HORMAD1 seeding mechanism is lost.

   Evidence Mouse genetic epistasis combining IHO1 interaction mutants with Ankrd31 analysis, quantitative immunofluorescence of DSB-factor clusters

   PMID:38580643

   Open questions at the time

   • Molecular mechanism by which ANKRD31 seeds clusters independently of IHO1-HORMAD1 is undefined
   • Whether other scaffold proteins contribute to a third pathway remains unknown

• The mechanism by which ANKRD31 specifically recognizes PAR sequences or PAR-associated chromatin features to create a uniquely recombination-permissive environment, and the in vivo dynamics of competitive partner switching on the REC114 PH domain, remain unresolved.
• No DNA-binding or chromatin-recognition domain in ANKRD31 has been identified
• In vivo partner switching kinetics on REC114 have not been measured
• Whether ANKRD31 has meiosis-independent functions in somatic tissues requires systematic investigation