Loss of Axdnd1 causes sterility due to impaired spermatid differentiation in mice

Abstract

Purpose Spermiogenesis, the process of deformation of sperm head morphology and flagella formation, is a phenomenon unique to sperm. Axonemal dynein light chain proteins are localized to sperm flagella and are known to be involved in sperm motility. Here, we focused on the gene axonemal dynein light chain domain containing 1 ( Axdnd1 ) with the aim to determine the function of its protein product AXDND1. Methods To elucidate the role of AXDND1 in spermatogenesis, we generated Axdnd1 knockout (KO) mice using the CRISPR/Cas9 system. The generated mice were subjected to fertility tests and analyzed by immunohistochemistry. Result The Axdnd1 KO mouse exhibited sterility caused by impaired spermiogenesis during the elongation step as well as abnormal nuclear shaping and manchette, which are essential for spermiogenesis. Moreover, AXDND1 showed enriched testicular expression and was localized from the mid‐pachytene spermatocytes to the early spermatids. Conclusion Axdnd1 is essential for spermatogenesis in the mouse testes. These findings improve our understanding of spermiogenesis and related defects. According to a recent report, deleterious heterozygous mutations in AXDND1 were found in non‐obstructive azoospermia (NOA) patients. Therefore, Axdnd1 KO mice could be used as a model system for NOA, which will greatly contribute to future NOA treatment studies.

AXDND1 is required to balance spermatogonial commitment and for sperm tail formation in mice and humans

“…Objective sperm head shaping analysis revealed a reduction in the percentage of sperm heads classified as most normal (cluster 1, p = 0.0033) and an increase in the abnormal clustering (cluster 3, p = 0.023). This finding is in support of a critical role of AXDND1 in manchette dynamics (22, 23) and its localisation to the manchette.…”

“…Herein where we describe AXDND1 localises to the manchette, and in previous studies, it is clear that AXDND1 is required for normal manchette structure and thus sperm head shaping (22). Taken together these data point to a direct role for AXDND1 at the manchette.…”

“…To make things worse, while mice are still relatively young, the absence of AXDND1 leads to a loss of blood-testis barrier patency and the recruitment of immune cells into the testis and seminiferous epithelium further exacerbating pathology. While previous studies have identified AXDND1 to be essential for male fertility in mice, they failed to identify the evolving phenotype of Axdnd1 -/- mice, which exacerbates with age (22, 23).…”

Transgenerational impact of grand‐paternal lifetime exposures to both folic acid deficiency and supplementation on genome‐wide DNA methylation in male germ cells

“…This gene has been found to be essential for spermiogenesis, with homozygous knockout mice demonstrating sterility. 39,40 Similarly, sperm-tail PG-rich repeat containing 4, Stpg4, was found as the largest hypomethylated DMR, with seven DMCs. This gene has been predicted to aid in chromatin/histone binding activity, as well as possible involvement in DNA demethylation of the male pronucleus following fertilization.…”

“…In the current study, axonemal dynein light chain domain containing 1, Axdnd1 , contained 5 hypermethylated CpG sites and was identified as a DMR in the 20FS diet group of F1 sperm. This gene has been found to be essential for spermiogenesis, with homozygous knockout mice demonstrating sterility 39,40 . Similarly, sperm‐tail PG‐rich repeat containing 4, Stpg4 , was found as the largest hypomethylated DMR, with seven DMCs.…”