DNAH3

DNAH3 is an axonemal dynein heavy chain that functions as a structural component of the inner dynein arm (IDA) in sperm flagella, where it is required for proper axonemal assembly and sperm motility (PMID:39503742, PMID:38312775). DNAH3 forms a protein complex with the inner dynein arm light intermediate chain DNALI1, an interaction necessary for IDA assembly and motility (PMID:41731497). Biallelic loss-of-function variants in humans, and knockout in mice, produce asthenoteratozoospermia: IDA deficiency accompanied by loss of co-resident IDA proteins DNAH1, DNAH6, and DNALI1, abnormal flagellar morphology including central-pair, mitochondrial-sheath, and fibrous-sheath defects, and male infertility that can be overcome by ICSI (PMID:39503742, PMID:38312775). DNAH3's residence in the IDA is corroborated by its dependence on DNAH7 integrity, as DNAH7 loss markedly reduces flagellar DNAH3 (PMID:40810911). Beyond its structural role, DNAH3 deficiency perturbs sperm energy metabolism, reducing L-palmitoylcarnitine and glycocholic acid levels (PMID:39774634). This timeline establishes a sperm-flagellar IDA function as the dominant, well-evidenced role of human DNAH3.

1. 2024 High

   Established DNAH3 as a bona fide inner dynein arm component whose loss disrupts the axonemal machinery, answering whether DNAH3 has a causal role in sperm motility and male fertility.

   Evidence Whole-exome sequencing of infertile men plus Dnah3 knockout mice analyzed by TEM, immunofluorescence, and CASA, with ICSI rescue

   PMID:38312775 PMID:39503742

   Open questions at the time

   • Atomic/structural placement of DNAH3 within the IDA not resolved
   • Whether loss of DNAH1/DNAH6/DNALI1 is due to direct interaction or secondary destabilization not dissected
   • Mechanism linking IDA loss to specific flagellar morphological defects (central pair, sheaths) not defined
2. 2024 Medium

   Extended the human phenotypic spectrum to oligoasthenoteratozoospermia with fibrous sheath dysplasia and confirmed that pathogenic variants reduce DNAH3 protein, addressing the molecular consequence of the variants.

   Evidence Whole-exome sequencing, electron microscopy, RT-qPCR, and Western blotting in a human patient cohort

   PMID:39588341

   Open questions at the time

   • No mouse model in this study to confirm causality
   • Which flagellar proteins are altered and by what mechanism not fully resolved
3. 2025 Medium

   Revealed a metabolic dimension to DNAH3 function by showing its loss disturbs sperm energy metabolism independent of overt structural defects, broadening the mechanistic picture beyond axonemal architecture.

   Evidence Dnah3 knockout mice analyzed by CASA, TEM, and sperm metabolomics with ICSI rescue

   PMID:39774634

   Open questions at the time

   • Metabolomics finding novel and not independently replicated
   • Causal link between DNAH3 loss and specific metabolite changes not established
   • Apparent absence of morphological abnormality conflicts with structural defects reported elsewhere; reconciliation unclear
4. 2025 Medium

   Independently corroborated DNAH3's IDA localization by demonstrating its flagellar abundance depends on DNAH7 integrity, placing DNAH3 within an interdependent network of IDA dynein heavy chains.

   Evidence Immunofluorescence and TEM of sperm from patients with DNAH7 loss-of-function variants

   PMID:40810911

   Open questions at the time

   • Whether DNAH3-DNAH7 dependence reflects direct interaction or shared assembly pathway not determined
   • Single-lab observation in human patients only
5. 2026 High

   Identified DNALI1 as a direct DNAH3 binding partner required for IDA assembly, providing the first defined molecular interaction underpinning DNAH3's structural role.

   Evidence Co-immunoprecipitation and mass spectrometry with comparative proteomics, scRNA-seq, CRISPR/Cas9 knockout mice, and electron microscopy

   PMID:41731497

   Open questions at the time

   • Stoichiometry and structural architecture of the DNAH3-DNALI1 complex unresolved
   • Whether DNALI1 binding is required for DNAH3 stability or vice versa not separated

• How DNAH3 mechanically couples to the axoneme to generate motility, and how its structural role connects to the observed energy-metabolism disturbances, remain unresolved.
• No high-resolution structure of DNAH3 within the assembled IDA
• Mechanistic basis of metabolic phenotype not connected to axonemal function
• Generality of findings beyond sperm flagella (e.g., motile cilia) not characterized