Slc26a1 is not essential for spermatogenesis and male fertility in mice.

Thousands of genes are expressed in the testis of mice. However, the details about their roles during spermatogenesis have not been well-clarified for most genes. The purpose of this study was to examine the effect of Slc26a1 deficiency on mouse spermatogenesis and male fertility. Slc26a1-knockout (KO) mice were generated using CRISPR/Cas9 technology on C57BL/6J background. We found no obvious differences between Slc26a1-KO and Slc26a1-WT mice in fertility tests, testicular weight, sperm concentrations, or morphology. Histological analysis found that Slc26a1-KO mouse testes had normal germ cell types and mature sperm. These findings indicated that Slc26a1 was dispensable for male fertility in mice. Our results may save time and resources by allowing other researchers to focus on genes that are more meaningful for fertility studies. We also found that mRNAs of two Slc26a family members (Slc26a5 and Slc26a11) were expressed on higher mean levels in Slc26a1-KO total mouse testes, compared to Slc26a1-WT mice. This effect was not found in mouse GC-1 and GC-2 germ cell lines with the Slc26a1 gene transiently knocked down. This result may indicate that a gene compensation phenomenon was present in the testes of Slc26a1-KO mice.

Drug transport across the blood-testis barrier.

The blood-testis barrier transfers nutrients to spermatogenic tubules to ensure the normal physiological function of the testes. It also restricts the "entry and exit" of biological macromolecules in the testicular lumen and provides a unique microenvironment for spermatogenesis. This makes the testes a safe place for some viruses and tumors, as immune factors cannot function and drugs fail to reach therapeutic concentrations in the testes. This review aimed to describe the factors regulating the structure and physiological function of the blood-testis barrier. By understanding therapeutic mechanisms of action, drugs can be developed to function in the testicles.

Identification of bi-allelic KIF9 loss-of-function variants contributing to asthenospermia and male infertility in two Chinese families.

Introduction: Asthenozoospermia (AZS) is a leading cause of male infertility, affecting an estimated 18% of infertile patients. Kinesin proteins function as molecular motors capable of moving along microtubules. The highly conserved kinesin family member 9 (KIF9) localizes to the central microtubule pair in the flagella of Chlamydomonas cells. The loss of KIF9 expression in mice has been linked to AZS phenotypes. Methods: Variant screening was performed by whole exome sequencing from 92 Chinese infertile patients with AZS. Western blot was used to was used for analyzing of candidate proteins expression. Patients' sperm samples were stained with immunofluorescent to visualise proteins localization and were visualised by transmission electron microscopy (TEM) to determine axoneme structures. Co-immunoprecipitation assay was used to verify the binding proteins of KIF9. In vitro fertilization (IVF) was used to evaluate the efficiency of clinical treatment. Results: Bi-allelic KIF9 loss-of-function variants were identified in two unrelated Chinese males exhibiting atypical sperm motility phenotypes. Both of these men exhibited typical AZS and suffered from infertility together with the complete absence of KIF9 expression. In contrast to these KIF9-deficient patients, positive KIF9 staining was evident throughout the flagella of sperm from normal control individuals. KIF9 was able to interact with the microtubule central pair (CP) component hydrocephalus-inducing protein homolog (HYDIN) in human samples. And KIF9 was undetectable in spermatozoa harboring CP deletions. The morphologicy of KIF9-deficient spermatozoa appeared normal under gross examination and TEM. Like in mice, in vitro fertilization was sufficient to overcome the fertility issues for these two patients. Discussion: These findings indicate that KIF9 associates with the central microtubules in human sperm and that it functions to specifically regulate flagellar swinging. Overall, these results offer greater insight into the biological functions of KIF9 in the assembly of the human flagella and its role in male fertility.