DNAH12 (dynein axonemal heavy chain 12, also known as DHC3/DNHD2) is an inner dynein arm (IDA) heavy chain of the sperm flagellar axoneme. It is the shortest member of the axonemal dynein heavy chain family (3092 aa): it keeps the N-terminal stem and the ATP-binding AAA1-AAA4 modules, but lacks a typical microtubule-binding domain at the tip of the stalk. It is expressed in human trachea and testis; human testis single-cell RNA data place its expression mainly in spermatocytes and early spermatids. In mice, Dnah12 is expressed most highly in testis and at lower levels in lung, trachea and oviduct. The protein lies along the sperm flagellum. Rather than acting as an independent force-generating motor, DNAH12 is needed to assemble the sperm IDA. It binds the IDA components DNALI1 and DNAH1 and recruits them to the axoneme. It also binds the radial spoke head proteins RSPH1, RSPH9 and DNAJB13 and helps keep the central pair stable. DNAH12 sits near radial spoke 1, because it is depleted from sperm when the RS1 protein IQUB is lost. The recruitment hierarchy is not fully settled: one patient studied by another group lost DNAH12 and the central-pair protein SPAG6 but kept DNAH1 in the flagellum. Biallelic loss-of-function variants cause asthenoteratozoospermia with multiple morphological abnormalities of the sperm flagella (MMAF), IDA loss and central-pair loss (spermatogenic failure 100, SPGF100). Dnah12 knockout and knock-in mice reproduce this male infertility. In these mouse models, tracheal ciliary beating and morphology were preserved; knockout mice also retained tracheal axonemal ultrastructure and comparable DNALI1 and DNAH1 abundance and localization in trachea and oviduct. The affected men reported no primary ciliary dyskinesia symptoms. These observations support a preferential requirement for DNAH12 in sperm flagella. Affected men and mice can achieve fertilization and offspring by ICSI. The mouse ortholog Dnah12 (MGI:107720, Q3V0Q1, 3086 aa) has the same domain layout. DNAH12 belongs to the inner-arm dynein heavy chain group with DNAH1, DNAH2, DNAH3, DNAH6, DNAH7, DNAH10 and DNAH14. One exome study describes it as the closest paralog of DNAH1 (PMID:34089056). Its established relationship with DNAH1 is physical: DNAH12 binds DNAH1 and is needed to recruit it.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005524 ATP binding | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: InterPro-based ATP binding. UniProt annotates intact ATP-binding P-loop motifs in AAA1-AAA4 of DNAH12, so nucleotide binding by the motor head is plausible even though the protein lacks a canonical microtubule-binding domain. Reason: The P-loops are retained, so the inference is structurally reasonable, but ATP binding alone is uninformative and has not been tested experimentally for DNAH12. Its physiological role is assembly of the sperm inner dynein arm, not catalysis on its own. Supporting Evidence: file:human/DNAH12/DNAH12-uniprot.txt FT BINDING 1253..1260 |
| GO:0007018 microtubule-based movement | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: Generic dynein heavy chain family mapping. DNAH12 lacks the microtubule-binding domain that couples ATP hydrolysis to translocation along microtubules. The experimental data show that it assembles other inner dynein arm components rather than acting as a motor itself. Reason: With no microtubule-binding domain, there is no evidence that DNAH12 itself performs microtubule-based movement. Its contribution to sperm motility is through IDA assembly and central-pair stability, as the authors themselves conclude ("DNAH12 likely collaborates with other members to carry out its functions"). Supporting Evidence: PMID:40146200 Notably, it is the shortest member and lacks a typical microtubule-binding domain (MTBD) in the DNAH family. PMID:40146200 Therefore, DNAH12 likely collaborates with other members to carry out its functions. |
| GO:0007286 spermatid development | IMP PMID:40146200 Deficiency in DNAH12 causes male infertility by impairing DN... | KEEP AS NON CORE | Summary: Biallelic DNAH12 variants in six families, and two mouse models (Dnah12-/- and Dnah12mut/mut), cause asthenoteratozoospermia with axonemal defects and compromised sperm development. Reason: The annotation is correct but broad. The defect is specifically in flagellar axoneme organization, which is captured more precisely by the sperm axoneme assembly IMP annotation from the same paper. Supporting Evidence: PMID:40146200 disruption of DNAH12 leads to failed recruitment of DNALI1 and DNAH1 to IDAs and compromised sperm development |
| GO:0007288 sperm axoneme assembly | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA prediction. It agrees with the experimental IMP annotation from PMID:40146200. Reason: Consistent with the direct experimental evidence for DNAH12. Supporting Evidence: PMID:40146200 DNAH12 plays a crucial role in the proper organization of axoneme in sperm flagella, but not cilia, by recruiting DNAH1 and DNALI1 in both humans and mice. |
| GO:0007288 sperm axoneme assembly | IMP PMID:40146200 Deficiency in DNAH12 causes male infertility by impairing DN... | ACCEPT | Summary: Patient and mouse sperm show IDA impairment and central-pair loss. DNAH12 is required to recruit DNAH1 and DNALI1 into the flagellar axoneme. Reason: This is the core biological process. Two independent groups report the same axonemal phenotype: IDA and central-pair defects in human patients and in knockout mice. Supporting Evidence: PMID:40146200 Transmission electron microscopy (TEM) revealed pronounced axonemal abnormalities, including inner dynein arms (IDAs) impairment and central pair (CP) loss in sperm flagella of the patients. PMID:42321500 DNAH12 deficiency in patient sperm was accompanied by loss of DNAH1, DNALI1, RSPH9, and SPAG6 and disruption of the classical "9 + 2" axonemal structure. |
| GO:0008569 minus-end-directed microtubule motor activity | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: Family-level InterPro mapping from the dynein heavy chain P-loop domain. DNAH12 is unusual in the family: it ends after AAA5 (3092 aa) and lacks the microtubule-binding domain needed for ATP-sensitive microtubule binding and motor direction. Reason: Directional microtubule motor activity needs a microtubule-binding domain. DNAH12 lacks one, and no motility assay has been done on it. PAINT places this activity at a deep dynein heavy chain node (PTN000743491, PANTHER 19 family PTHR10676), and mouse Dnah12 inherits it by IBA. The argument here is therefore one of lineage-specific loss: DNAH12 lost the microtubule-binding domain after that node, so the inherited function does not apply. Human DNAH12 itself carries no IBA for this term, because PANTHER 19 classifies it in a different family (PTHR46532) from its mouse ortholog. The term is inherited from the family rather than demonstrated, and it probably misstates what DNAH12 does. Not marked REMOVE because the authors describe an "MT-like" region in their domain diagram, so residual microtubule contact cannot be ruled out without biochemistry. Supporting Evidence: PMID:40146200 we found that DNAH12 is a distinctive IDA lacking the microtubule-binding domain (MTBD), which is crucial for ATP-sensitive microtubule binding and motor direction control |
| GO:0030286 dynein complex | IEA GO_REF:0000002 | MODIFY | Summary: Correct but very general. DNAH12 is an inner dynein arm heavy chain that interacts with the IDA components DNAH1 and DNALI1. Reason: The specific complex is the axonemal inner dynein arm. Phylogenetic classification and co-immunoprecipitation with DNAH1 and DNALI1 place DNAH12 there. Proposed replacements: inner dynein arm Supporting Evidence: PMID:40146200 Mechanistically, DNAH12 was confirmed to interact with two other IDA components DNALI1 and DNAH1 |
| GO:0031514 motile cilium | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: Mapped from the UniProt subcellular location "Cell projection, cilium, flagellum". The sperm flagellum is a motile cilium in GO; mouse tracheal cilia also show DNAH12 staining. The broad location is retained as non-core alongside the specific sperm flagellum annotations. Reason: This location term encompasses the sperm flagellum and does not by itself assert a requirement for somatic cilium function. PMID:40146200 reports preserved mouse tracheal ciliary beating and morphology, comparable knockout tracheal axonemal ultrastructure, and comparable DNALI1/DNAH1 abundance and localization in knockout trachea and oviduct. The human patients reported no PCD symptoms; this is clinical history, not a human ciliary-beat assay. These observations distinguish the demonstrated sperm assembly role from the tested somatic cilia without claiming that every possible ciliary function is unaffected. Supporting Evidence: PMID:40146200 Noteworthy, DNAH12 deficiency did not show effects on cilium organization and function. |
| GO:0036126 sperm flagellum | IDA PMID:40146200 Deficiency in DNAH12 causes male infertility by impairing DN... | ACCEPT | Summary: Immunofluorescence shows DNAH12 along the sperm flagellum, and the staining is lost in patient sperm. Reason: Direct experimental localization; this is the core cellular location. Supporting Evidence: PMID:40146200 DNAH12 plays a crucial role in the proper organization of axoneme in sperm flagella |
| GO:0036126 sperm flagellum | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA prediction, consistent with the IDA annotation. Reason: Consistent with the direct experimental localization. |
| GO:0045505 dynein intermediate chain binding | IEA GO_REF:0000002 | UNDECIDED | Summary: Family-level mapping from the dynein heavy chain N-terminal region. No DNAH12 interaction with a dynein intermediate chain has been reported; the partners shown are DNAH1, DNALI1 and radial spoke head proteins. Reason: Inner dynein arm heavy chains differ in whether they assemble with intermediate chains, and no DNAH12 data address this. The IP/MS interactome in PMID:40146200 could settle it, but its supplementary tables are not in our cache. The case against the term is substantial. The PAINT IBD for this term at PTN000743491 is seeded only by a Dictyostelium cytoplasmic dynein heavy chain (dictyBase:DDB_G0276355), so the family-level inference traces to cytoplasmic-dynein intermediate chain biology. DNAH12 partners with DNALI1 (p28), which is characteristic of the single-headed IDA species that lack the I1/f intermediate chain complex. Left UNDECIDED rather than marked as an over-annotation until the IP/MS data are checked. |
| GO:0051959 dynein light intermediate chain binding | IEA GO_REF:0000002 | ACCEPT | Summary: DNAH12 interacts with the IDA light intermediate chain DNALI1 (p28). Loss of DNAH12 abolishes DNALI1 recruitment to the sperm axoneme. Reason: Co-immunoprecipitation from mouse testis supports the family-level inference, and UniProt maps the interaction to the stem region. A second group independently recovered DNAH12 with DNALI1 by IP-MS from human sperm. Binding DNALI1 is the molecular basis of DNAH12's role in IDA assembly. Supporting Evidence: PMID:36792588 MS identified both DNAH1 and DNAH12 as potential interacting proteins of DNALI1 PMID:40146200 further in vitro Co-IP assays validated that the Stem domain of DNAH12 indeed mediates interactions with DNALI1 PMID:40146200 DNAH12 interacts with other IDA components like DNALI1 and DNAH1 in mouse testes, and disruption of DNAH12 impaired the recruitment of dynein components into sperm flagella. |
| GO:0036159 inner dynein arm assembly | IMP PMID:40146200 Deficiency in DNAH12 causes male infertility by impairing DN... | NEW | Summary: Proposed new annotation. DNAH12 is required to incorporate DNAH1 and DNALI1 into the sperm inner dynein arm. Without it, IDAs are impaired in patient and mouse sperm. Reason: DNAH12 does part of the work of this process: it is itself an IDA heavy chain and binds the subunits it recruits. It is not an upstream regulator or a substrate. The term is more specific than sperm axoneme assembly and states the mechanism. PAINT already asserts this term at node PTN008951089, and mouse Dnah12 (Q3V0Q1) carries it by IBA. Human DNAH12 lacks it only because PANTHER 19 places the human protein in PTHR46532 rather than PTHR10676, so the NEW annotation fills a classification gap rather than making a new claim. The comparator check passes: the PTN008951089 IBD is seeded by DNAH3 (Q8TD57), DNAH7 (Q8WXX0) and MGI:2683040, all structural IDA heavy chains rather than assembly factors (interpro/panther/PTHR10676/PTHR10676-paint.tsv). Supporting Evidence: PMID:40146200 disruption of DNAH12 leads to failed recruitment of DNALI1 and DNAH1 to IDAs and compromised sperm development |
Loading supporting content…
Download this section (compressed HTML)Q: Should PANTHER reunite the DNAH12 orthologs? In PANTHER 19, human DNAH12 (Q6ZR08) sits in subfamily PTHR46532:SF11 of family PTHR46532 ("male fertility factor kl5"), where no PAINT annotation reaches it, whereas mouse Dnah12 (Q3V0Q1) sits in subfamily PTHR10676:SF255 of family PTHR10676. Both subfamilies are correctly named "dynein axonemal heavy chain 12", so PANTHER identifies the protein correctly; only the family-level placement differs. As a result, mouse inherits IBAs for inner dynein arm, inner dynein arm assembly, sperm flagellum assembly and dynein light intermediate chain binding, and human inherits none. InterPro and UniProt cross-references put both proteins in PTHR22878:SF70, so the two PANTHER classification routes also disagree with each other.
Q: Is DNAH1 recruitment strictly dependent on DNAH12? The eLife study (PMID:40146200) reports loss of DNAH1 from DNAH12-deficient sperm, but patient AY0749 (PMID:39071892) kept flagellar DNAH1 while losing DNAH12 and SPAG6, and DNAH12 persists in DNALI1-mutant sperm that lack DNAH1 (PMID:36792588). Do allele type, assay or species account for the difference?
Q: Does DNAH12 hydrolyse ATP, and does its "MT-like" stalk region contact the microtubule at all, or is it purely a structural scaffold within the sperm IDA?
Q: Why are the tested mouse tracheal ciliary readouts preserved despite DNAH12 expression there, while sperm flagellar assembly is impaired? Do differences in inner-arm composition or compensatory assembly explain this contrast, and are additional human ciliary-function measurements consistent with the reported absence of PCD symptoms?
Q: Two papers report sperm head abnormalities as well as flagellar defects (PMID:42321500). Do these reflect a separate role in manchette or head shaping, or a secondary effect of failed flagellar assembly?
Experiment: Cryo-ET of wild-type and Dnah12-/- mouse sperm axonemes to place DNAH12 within the 96-nm repeat and identify which IDA species it belongs to.
Type: cryo-electron tomography
Experiment: Express recombinant DNAH12 motor head and test ATPase activity and microtubule co-sedimentation, to decide whether the motor-activity annotations should be removed.
Type: biochemical ATPase and microtubule-binding assays
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)