DICER1 regulates antibacterial function of epididymis by modulating transcription of β-defensins

β-Defensin gene copy number variation in cattle

β-Defensins are peptides with antimicrobial roles, characterized by a conserved tertiary structure. Beyond antimicrobial functions, they exhibit diverse roles in both the immune response and fertility, including involvement in sperm maturation and function. Copy number variation (CNV) of β-defensin genes is extensive across mammals, including cattle, with possible implications for reproductive traits and disease resistance. In this study, we comprehensively catalogue 55 β-defensin genes in cattle. By constructing a phylogenetic tree to identify human orthologues and lineage-specific expansions, we identify 1 : 1 human orthologues for 35 bovine β-defensins. We also discover extensive β-defensin gene CNV across breeds, with DEFB103, in particular, showing extensive multi-allelic CNV. By comparing β-defensin expression levels in testis from calves and adult bulls, we find that 14 β-defensins, including DEFB103, increase in expression during sexual maturation. Analysis of β-defensin gene expression levels in the caput of adult bull epididymis, and β-defensin gene copy number, in 94 matched samples shows expression levels of four β-defensins are correlated with genomic copy numbers, including DEFB103. We therefore demonstrate extensive CNV in bovine β-defensin genes, in particular DEFB103, with potential functional consequences for fertility.

Epididymal acquired sperm microRNAs modify post-fertilization embryonic gene expression

Sperm small RNAs have emerged as important non-genetic contributors to embryogenesis and offspring health. A subset of sperm small RNAs is thought to be acquired during epididymal transit. However, the identity of the specific small RNAs transferred remains unclear. Here, we employ Cre/Lox genetics to generate germline- and epididymal-specific Dgcr8 knockout (KO) mice to investigate the dynamics of sperm microRNAs (miRNAs) and their functions post-fertilization. Testicular sperm from germline Dgcr8 KO mice has reduced levels of 116 miRNAs. Enthrallingly, following epididymal transit, the abundance of 72% of these miRNAs is restored. Conversely, sperm from epididymal Dgcr8 KO mice displayed reduced levels of 27 miRNAs. This loss of epididymal miRNAs in sperm was accompanied by transcriptomic changes in embryos fertilized by this sperm, which was rescued by microinjection of epididymal miRNAs. These findings ultimately demonstrate the acquisition of miRNAs from the soma by sperm during epididymal transit and their subsequent regulation of embryonic gene expression.

Loss of DIS3L in the initial segment is dispensable for sperm maturation in the epididymis and male fertility

DIS3L, a catalytic exoribonuclease associated with the cytoplasmic exosome complex, degrades cytoplasmic RNAs and is implicated in cancers and certain other diseases in humans. Epididymis plays a pivotal role in the transport, maturation, and storage of sperm required for male fertility. However, it remains unclear whether DIS3L-mediated cytoplasmic RNA degradation plays a role in epididymis biology and functioning. Herein, we fabricated a Dis3l conditional knockout (Dis3l cKO) mouse line in which DIS3L was ablated from the principal cells of the initial segment (IS). Morphological analyses showed that spermatogenesis and IS differentiation occurred normally in Dis3l cKO mice. Additionally, the absence of DIS3L had no dramatic influence on the transcriptome of IS. Moreover, the sperm count, morphology, motility, and acrosome reaction frequency in Dis3l cKO mice were comparable to that of the control, indicating that the Dis3l cKO males had normal fertility. Collectively, our genetic model demonstrates that DIS3L inactivation in the IS is nonessential for sperm maturation and male fertility.

Epididymal DIS3 exosome ribonuclease is not necessary for mouse sperm maturation or fertility

DIS3 is an RNA exosome associated ribonuclease that degrades a wide range of transcripts that can be essential for cell survival and development. The proximal region of the mouse epididymis (initial segment and caput) plays a pivotal role in sperm transport and maturation required for male fertility. However, whether DIS3 ribonuclease mediates RNA decay in proximal epididymides remains unclear. Herein, we established a conditional knockout mouse line by crossing a floxed Dis3 allele with Lcn9-cre mice in which the recombinase is expressed in the principal cells of initial segment as early as post-natal day 17. Morphological and histological analyses, immunofluorescence, computer-aided sperm analysis and fertility were used for functional analyses. We document that DIS3 deficiency in the initial segment had no effect on male fertility. Dis3 cKO males had normal spermatogenesis and initial segment development. In cauda epididymides of Dis3 cKO mice, sperm abundance, morphology, motility, and the frequency of acrosome exocytosis were comparable to controls. Collectively, our genetic model demonstrates that loss of DIS3 in the initial segment of the epididymis is not essential for sperm maturation, motility, or male fertility.

Antibacterial effects of nano-decoction iron polysulfide in epididymitis and the systematic evaluation of its toxicity on the reproductive health of male mice

Ferrous iron and polysulfide (Fe(II)S_n aq) is a nano-decoction. It is usually prepared from the suspension of iron sulfide nanomaterial, using autoclave and centrifugation. A previous study conducted in our laboratory revealed that Fe(II)S_n aq was highly antibacterial, and it could efficiently kill more than 90% population of Escherichia coli and Staphylococcus aureus, within 5 min of the treatment. Our study reported that the intravenous administration of Fe(II)S_n aq provided effective treatment against epididymis infection, caused by S. aureus. The results of the study further highlighted its potential for clinical application. However, its effects on the reproductive system and overall health of mammals have not been investigated earlier. The present study assessed the impacts of Fe(II)S_n aq on reproductive health and other aspects of male mice. Briefly, male mice were exposed to Fe(II)S_n aq, either intravenously at the dose of 0.7 mM, 1.4 mM, and 2.8 mM of Fe²⁺or orally at the dose of 1.4 mM, 2.8 mM, and 5.6 mM of Fe²⁺. Following this, body weight, organs index, quality of sperm, blood biochemical markers, histopathology of organs, oxidative stress and apoptosis were evaluated, after 1 day and 30 days of exposure. In addition, male reproductivity was evaluated in terms of mating with female mice, and the body weight of the resulting offspring was recorded. Our results showed that the mice processed with Fe(II)S_n aq exhibited normal physiological status and reproductive capability. The present study illustrated the short- and long-term influences of Fe(II)S_n aq on the fertility of male mice for the first time. The findings of the study provided a valuable reference for the application of Fe(II)S_n aq, particularly in terms of reproductive safety.