Integration of omics studies indicates that species-dependent molecular mechanisms govern male fertility

Abstract

Background: Comparative and comprehensive omics studies have recently been conducted to provide a comprehensive understanding of the biological mechanisms underlying infertility. However, because these huge omics datasets often contain irrelevant information, editing strategies for summarizing and filtering the data are necessary prerequisite steps for identifying biomarkers of male fertility. Here, we attempted to integrate omics data from spermatozoa with normal and below-normal fertility from boars and bulls, including transcriptomic, proteomic, and metabolomic data. Pathway enrichment analysis was conducted and visualized using g:Profiler, Cytoscape, EnrichmentMap, and AutoAnnotation to determine fertility-related biological functions according to species.

Results: In particular, gamete production and protein biogenesis-associated pathways were enriched in bull spermatozoa with below-normal fertility, whereas mitochondrial-associated metabolic pathways were enriched in boar spermatozoa with normal fertility. These results indicate that below-normal fertility may be determined by aberrant regulation of protein synthesis during spermatogenesis, and the modulation of reactive oxygen species generation to maintain capacitation and the acrosome reaction governs boar sperm fertility.

Conclusion: Overall, this approach demonstrated that distinct molecular pathways drive sperm fertility in mammals in a species-dependent manner. Moreover, we anticipate that searching for species-specific signaling pathways may aid in the discovery of fertility-related biomarkers within large omics datasets.

Keywords: Integrated signaling pathways; Male fertility; Metabolomics; Proteomics; Spermatozoa transcriptomics.

Fig. 1

Signaling pathways from transcripts differentially expressed between bull and boar spermatozoa with normal and below-normal fertility. A Enrichment map created based on the differentially expressed transcripts in bull and boar spermatozoa with normal and below-normal fertility. Blue and yellow, enrichment in bovine and porcine spermatozoa with normal fertility, respectively; green and pink, enrichment in bovine spermatozoa with below-normal fertility. Biological Process GO terms based on the differentially expressed transcripts in (B) bovine and (C) porcine spermatozoa with normal and below-normal fertility. Blue, enrichment in spermatozoa with normal fertility; pink, enrichment in spermatozoa with below-normal fertility. Enrichment maps were created using g:Profiler, Cytoscape, EnrichmentMap, and ClueGO with FDR Q < 0.05

Fig. 2

Important signaling pathway-related to proteins differentially expressed between bull or boar spermatozoa with normal and below-normal fertility. A Integration of an enrichment map of differentially expressed proteins in spermatozoa from bulls and boars with normal and below-normal fertility. Blue, enrichment in bull spermatozoa with normal fertility; green, enrichment in bull spermatozoa with below-normal fertility; yellow, enrichment in boar spermatozoa with normal fertility; pink, enrichment in boar spermatozoa with below-normal fertility. B Biological Process GO terms based on the differentially expressed proteins in (B) bovine and (C) porcine spermatozoa with normal and below-normal fertility. Blue, enrichment in spermatozoa with normal fertility; pink, enrichment in spermatozoa with below-normal fertility. The enrichment map was created using g:Profiler, Cytoscape, and EnrichmentMap with FDR Q < 0.01

Fig. 3

Enrichment signaling pathway related protein expression in the spermatozoa. Different expression patterns of proteins annotated with enrichment signaling pathways in (A) bovine and (B) porcine spermatozoa between normal and below-normal fertility group were analyzed by western blot. Data represent the mean of three experiments ± standard error of the mean (SEM)

Fig. 4

Metabolite set enrichment analysis of metabolites differentially expressed between bull spermatozoa with normal and below-normal fertility. Functional enrichment analysis of pathways from bull spermatozoa with normal (A) and below-normal (B) fertility. MetaboAnalyst 4.0 was used to examine and interpret the enrichment pathways. The color depth and column length indicate the degree of disturbance