PRSS50 is a testis protease responsible for proper sperm tail formation and function

A novel sorting method for the enrichment of early human spermatocytes from clinical biopsies

OBJECTIVE

To determine if early spermatocytes can be enriched from a human testis biopsy using fluorescence-activated cell sorting (FACS).

DESIGN

Potential surface markers for early spermatocytes were identified using bioinformatics analysis of single-cell RNA-sequenced human testis tissue. Testicular sperm extraction samples from three participants with normal spermatogenesis were digested into single-cell suspensions and cryopreserved. Two to four million cells were obtained from each and sorted by FACS as separate biologic replicates using antibodies for the identified surface markers. A portion from each biopsy remained unsorted to serve as controls. The sorted cells were then characterized for enrichment of early spermatocytes.

SETTING

A laboratory study.

PATIENTS

Three men with a diagnosis of obstructive azoospermia (age range, 30-40 years).

INTERVENTION

None.

MAIN OUTCOME MEASURES

Sorted cells were characterized for RNA expression of markers encompassing the stages of spermatogenesis. Sorting markers were validated by their reactivity on human testis formalin-fixed paraffin-embedded tissue.

RESULTS

Serine protease 50 (TSP50) and SWI5-dependent homologous recombination repair protein 1 were identified as potential surface proteins specific for early spermatocytes. After FACS sorting, the TSP50-sorted populations accounted for 1.6%-8.9% of total populations and exhibited the greatest average-fold increases in RNA expression for the premeiotic marker stimulated by retinoic acid (STRA8), by 23-fold. Immunohistochemistry showed the staining pattern for TSP50 to be strong in premeiotic undifferentiated embryonic cell transcription factor 1-/doublesex and Mab-3 related transcription factor 1-/STRA8+ spermatogonia as well as SYCP3+/protamine 2- spermatocytes.

CONCLUSION

This work shows that TSP50 can be used to enrich early STRA8-expressing spermatocytes from human testicular biopsies, providing a means for targeted single-cell RNA sequencing analysis and in vitro functional interrogation of germ cells during the onset of meiosis. This could enable investigation into details of the regulatory pathways underlying this critical stage of spermatogenesis, previously difficult to enrich from whole tissue samples.

Exploring the role of the ovary-serine protease gene in the female fertility of the diamondback moth using CRISPR/Cas9

BACKGROUND

Oogenesis is a complex pathway necessary for proper female reproduction in insects. Ovary-serine protease (Osp) is a homologous gene of serine protease Nudel (SpNudel) and plays an essential role in the oogenesis and ovary development of Drosophila melanogaster. However, the function of Osp is not determined in Plutella xylostella, a highly destructive pest of cruciferous crops.

RESULTS

The PxOsp gene comprises a 5883-bp open-reading frame that encodes a protein consisting of 1994 amino acids, which contain four conserved domains. PxOsp exhibited a high relative expression in adult females with a specific expression in the ovary. Through the utilization of CRISPR/Cas9 technology, homozygous mutants of PxOsp were generated. These homozygous mutant females produced fewer eggs (average of 56 eggs/female) than wild-type (WT) females (average of 97 eggs/female) when crossed with WT males, and these eggs failed to hatch. Conversely, mutant males produced normal progeny when crossed with WT females. The ovarioles in homozygous mutant females were significantly shorter (5.02 mm in length) and contained fewer eggs (average of 3 eggs/ovariole) than WT ovarioles (8.09 mm in length with an average of 8 eggs/ovariole). Moreover, eggs laid by homozygous mutant females were fragile, with irregular shapes, and were unable to maintain structural integrity due to eggshell ruptures. However, no significant differences were observed between WT and mutant individuals regarding developmental duration, pupal weight, and mating behavior.

CONCLUSION

Our study suggesteds that PxOsp plays a vital role in female reproduction, particularly in ovary and egg development. Disrupting PxOsp results in recessive female sterility while leaving the male reproductive capability unaffected. This report represents the first study of a haplosufficient gene responsible for female fertility in lepidopteran insects. Additionally, these findings emphasize PxOsp as a potential target for genetically-based pest management of P. xylostella. © 2024 Society of Chemical Industry.

Knockout of ovary serine protease Leads to Ovary Deformation and Female Sterility in the Asian Corn Borer, Ostrinia furnacalis

Oogenesis in insects is a carefully orchestrated process, facilitating the formation of female gametes, which is regulated by multiple extrinsic and intrinsic factors, including ovary serine protease (Osp). As a member of the serine protease family, Osp is a homolog of Nudel, a maternally required protease defining embryonic dorsoventral polarity in Drosophila. In this study, we used CRISPR/Cas9-mediated mutagenesis to functionally characterize Osp in the Asian corn borer, Ostrinia furnacalis, a devastating maize pest throughout Asia and Australia. Building on previous knowledge, we hypothesized that knockout of Osp would disrupt embryonic development in O. furnacalis females. To examine this overarching hypothesis, we (1) cloned and characterized Osp from O. furnacalis, (2) designed target sites on exons 1 and 4 to construct a CRISPR/Cas9 mutagenesis system, and (3) documented phenotypic impacts among O. furnacalis Osp mutants. As a result, we (1) examined the temporal-spatial expression profiles of OfOsp, which has an open reading frame of 5648 bp in length and encodes a protein of 1873 amino acids; (2) established O. furnacalis Osp mutants; and (3) documented recessive, female-specific sterility among OfOspF mutants, including absent or deformed oviducts and reduced fertility in female but not male mutants. Overall, the combined results support our initial hypothesis that Osp is required for embryonic development, specifically ovarian maturation, in O. furnacalis females. Given its substantial impacts on female sterility, Osp provides a potential target for the Sterile Insect Technique (SIT) to manage Lepidoptera pests in general and the species complex Ostrinia in particular.

Proteasome-Associated Proteins, PA200 and ECPAS, Are Essential for Murine Spermatogenesis

Proteasomes are highly sophisticated protease complexes that degrade non-lysosomal proteins, and their proper regulation ensures various biological functions such as spermatogenesis. The proteasome-associated proteins, PA200 and ECPAS, are predicted to function during spermatogenesis; however, male mice lacking each of these genes sustain fertility, raising the possibility that these proteins complement each other. To address this issue, we explored these possible roles during spermatogenesis by producing mice lacking these genes (double-knockout mice; dKO mice). Expression patterns and quantities were similar throughout spermatogenesis in the testes. In epididymal sperm, PA200 and ECPAS were expressed but were differentially localized to the midpiece and acrosome, respectively. Proteasome activity was considerably reduced in both the testes and epididymides of dKO male mice, resulting in infertility. Mass spectrometric analysis revealed LPIN1 as a target protein for PA200 and ECPAS, which was confirmed via immunoblotting and immunostaining. Furthermore, ultrastructural and microscopic analyses demonstrated that the dKO sperm displayed disorganization of the mitochondrial sheath. Our results indicate that PA200 and ECPAS work cooperatively during spermatogenesis and are essential for male fertility.

Divergence of X-linked trans regulatory proteins and the misexpression of gene targets in sterile Drosophila pseudoobscura hybrids

BACKGROUND

The genetic basis of hybrid incompatibilities is characterized by pervasive cases of gene interactions. Sex chromosomes play a major role in speciation and X-linked hybrid male sterility (HMS) genes have been identified. Interestingly, some of these genes code for proteins with DNA binding domains, suggesting a capability to act as trans-regulatory elements and disturb the expression of a large number of gene targets. To understand how interactions between trans- and cis-regulatory elements contribute to speciation, we aimed to map putative X-linked trans-regulatory elements and to identify gene targets with disrupted gene expression in sterile hybrids between the subspecies Drosophila pseudoobscura pseudoobscura and D. p. bogotana.

RESULTS

We find six putative trans-regulatory proteins within previously mapped X chromosome HMS loci with sequence changes that differentiate the two subspecies. Among them, the previously characterized HMS gene Overdrive (Ovd) had the largest number of amino acid changes between subspecies, with some substitutions localized within the protein's DNA binding domain. Using an introgression approach, we detected transcriptional responses associated with a sterility/fertility Ovd allele swap. We found a network of 52 targets of Ovd and identified cis-regulatory effects among target genes with disrupted expression in sterile hybrids. However, a combined analysis of polymorphism and divergence in non-coding sequences immediately upstream of target genes found no evidence of changes in candidate regulatory proximal cis-elements. Finally, peptidases were over-represented among target genes.

CONCLUSIONS

We provide evidence of divergence between subspecies within the DNA binding domain of the HMS protein Ovd and identify trans effects on the expression of 52 gene targets. Our results identify a network of trans-cis interactions with possible effects on HMS. This network provides molecular evidence of gene × gene incompatibilities as contributors to hybrid dysfunction.