ZMYND12

ZMYND12 is a structural subunit of the axonemal inner dynein arm (IDA) complex that forms a complex with TTC29, DNAH1, and PRKACA to support flagellar and ciliary assembly and motility (PMID:37934199, PMID:39066891). Loss of ZMYND12 disrupts axonemal localization of IDA-associated proteins including DNAH1, DNALI1, WDR66, and TTC29 in human sperm, and ZMYND12 knockout mice exhibit reduced sperm motility, impaired capacitation, and decreased PRKACA levels, establishing a mechanistic link between ZMYND12 and cAMP-dependent signaling during sperm function (PMID:39066891, PMID:37934199). Zebrafish crispants targeting zmynd12 recapitulate ciliary phenotypes, confirming a conserved role in cilia function beyond spermatogenesis (PMID:36533556). Biallelic loss-of-function variants in ZMYND12 cause male infertility due to multiple morphological abnormalities of the sperm flagella (PMID:37934199).

1. 2022 Medium

   Whether ZMYND12 is required for cilia function in vivo was unknown; zebrafish F0 crispants targeting zmynd12 displayed ciliary phenotypes, establishing ZMYND12 as a cilia-associated gene with a conserved functional requirement.

   Evidence Multiple-guide CRISPR/Cas9 F0 crispant screen in zebrafish with ciliary phenotype readout

   PMID:36533556

   Open questions at the time

   • No mechanistic resolution beyond a general requirement for cilia function
   • Molecular partners and subciliary localization were not identified
   • F0 crispant mosaicism limits quantitative phenotypic interpretation
2. 2023 High

   The molecular context of ZMYND12 within the axoneme was undefined; co-immunoprecipitation, proteomics, and expansion microscopy demonstrated that ZMYND12 forms a complex with TTC29 and DNAH1, localizes to the axoneme, and is required for proper localization of multiple IDA subunits (DNAH1, DNALI1, WDR66, TTC29), with RNAi knockdown of the Trypanosoma ortholog confirming a conserved role in flagellar motility.

   Evidence Co-IP, comparative proteomics (Trypanosoma and Ttc29 KO mice), RNAi knockdown in T. brucei, ultrastructure expansion microscopy, immunofluorescence in human patient sperm, whole-exome sequencing

   PMID:37934199

   Open questions at the time

   • Direct structural position of ZMYND12 within the IDA repeat was not resolved
   • The MYND zinc-finger domain's specific molecular function (e.g., protein–protein interaction interface) was not dissected
   • Signaling pathways downstream of ZMYND12 loss were not explored
3. 2024 High

   How ZMYND12 influences flagellar beating beyond structural assembly was unclear; knockout mice revealed that ZMYND12 interacts with PRKACA and is required for maintaining PRKACA levels in sperm, linking ZMYND12 to cAMP-dependent signaling during capacitation and explaining the motility defect.

   Evidence CRISPR/Cas9 knockout mouse model with sperm motility and capacitation assays, co-immunoprecipitation, mass spectrometry

   PMID:39066891

   Open questions at the time

   • Whether ZMYND12 directly scaffolds PRKACA or stabilizes it indirectly is unresolved
   • Downstream PKA substrates affected in the absence of ZMYND12 have not been mapped
   • Whether the ZMYND12–PRKACA interaction is relevant in motile cilia beyond sperm flagella is unknown

• The structural basis for ZMYND12's integration into the IDA complex, the specific function of its MYND zinc-finger domain, and whether its role in PKA signaling extends to other motile-ciliated tissues remain to be determined.
• No high-resolution structural model of ZMYND12 within the IDA repeat
• MYND domain binding partners or histone/protein substrates not identified
• Role in airway or ependymal motile cilia not tested in mammalian models