Novel axonemal protein ZMYND12 interacts with TTC29 and DNAH1, and is required for male fertility and flagellum function

Abstract

Male infertility is common and complex, presenting a wide range of heterogeneous phenotypes. Although about 50% of cases are estimated to have a genetic component, the underlying cause often remains undetermined. Here, from whole-exome sequencing on samples from 168 infertile men with severe sperm flagellum defects, we identified homozygous ZMYND12 variants in four unrelated patients. In sperm cells from these individuals, immunofluorescence revealed altered localization of DNAH1, DNALI1, WDR66 and TTC29. Axonemal localization of ZMYND12 ortholog TbTAX-1 was confirmed using the Trypanosoma brucei model. RNAi knock-down of TbTAX-1 dramatically affected flagellar motility, with a phenotype similar to ZMYND12-variant-bearing human sperm. Co-immunoprecipitation and ultrastructure expansion microscopy in T. brucei revealed TbTAX-1 to form a complex with TTC29. Comparative proteomics with samples from Trypanosoma and Ttc29 KO mice identified a third member of this complex: DNAH1. The data presented revealed the axonemal ZMYND12/TTC29/DNAH1 trio to critically contribute to flagellum function and assembly in humans and Trypanosoma. ZMYND12 is thus a new asthenoteratozoospermia-associated gene, bi-allelic variants of which cause severe flagellum malformations and primary male infertility.

ZMYND12 serves as an IDAd subunit that is essential for sperm motility in mice

“…Coutton et al recently found that 3 of 167 patients with MMAF harbored variants in the ZMYND12 gene [21]. In line with its possible functional role in this context, knockdown of the ZMYND12 ortholog TbTAX-1 in Trypanosoma brucei had a pronounced effect on sperm motility [21,22]. These results suggest a potential role for ZMYND12 de ciency in human AZS.…”

“…Prior studies identi ed p38 in Chlamydomonas as an IDAdspeci c accessory subunit [20]. Coutton et al recently found that 3 of 167 patients with MMAF harbored variants in the ZMYND12 gene [21]. In line with its possible functional role in this context, knockdown of the ZMYND12 ortholog TbTAX-1 in Trypanosoma brucei had a pronounced effect on sperm motility [21,22].…”

FBXO24 modulates mRNA alternative splicing and MIWI degradation and is required for normal sperm formation and piRNA production

“…Of note, many genetic changes identified in this study have been closely associated with sperm formation. For example, Zmynd12 (29), Bbs7 (30), and Ube2j2 (18) were required for flagellum function and male fertility. Map7d1 facilitates microtubule stabilization (31) and Mfn1 deficiency leads to defects in mitochondrial activity and male infertility (32).…”

Loss of an extensive ciliary connectome induces proteostasis and cell fate switching in a severe motile ciliopathy

“…Many proteins with unknown roles and locations are also depleted or reduced (Figure 2C). Inspection of single particle cryo-EM reconstructions shows that at least 13 of the missing proteins are in direct contact with the CCDC39/40 heterodimer (Figure 2C) [7][8][9][10][11][12]14,[45][46][47][48][49][50][51][52][53][54][55] . Each of these 13 missing proteins, plus MORN3, which is not present in our proteomics, is linked to a major cilia complex (Figure 2D).…”

“…Notably, 14 of the missing proteins directly contact CCD39/40 and are likely to be the ciliary address recognition proteins (CARPs) for IDA, the N-DRC, and the RSs. CARPs attach to specific amino acid sequences of CCDC39/40 (the addresses) (Figure 2D, 2E) [7][8][9][10][11][12]14,[45][46][47][48][49][50][51][52][53][54][55] . During assembly, CARPs enter cilia coincident with CCDC39/40.…”