Differential Proteomic Analysis of Human Sperm: A Systematic Review to Identify Candidate Targets to Monitor Sperm Quality

Receptor accessory protein 6, a novel ferroptosis suppressor, drives oral squamous cell carcinoma by maintaining endoplasmic reticulum hemostasis

Increasing evidence suggests a close association between endoplasmic-reticulum (ER) stress and ferroptosis. Receptor accessory protein 6 (REEP6) is known to play a crucial role in maintaining ER homeostasis. However, its involvement in ferroptosis remains unknown. In this study, we found that REEP6 was overexpressed, and its overexpression showed a significant association with tumor size and poor survival in OSCC patients. Besides, in vitro and in vivo assays together showed that REEP6 plays an oncogenic role in OSCC progression. The GO/KEGG, and GSEA analysis showed that REEP6 overexpression leads to the inactivation of ferroptosis signaling in OSCC. Moreover, REEP6 overexpression conferred resistance to RSL3, a ferroptosis inducer, whereas REEP6 knockdown sensitized OSCC cells to RSL3. Overexpression of REEP6 decrease the accumulation of iron ions, ROS production, but increase the number of mitochondrial cristae in OSCC cells. More importantly, we confirmed that REEP6 inhibited ferroptosis in OSCC cells by maintaining ER homeostasis via regulating ACSL4 expression. In addition, we identified promoter DNA hypomethylation as the underlying cause of REEP6 overexpression in OSCC. Taken together, REEP6 acts as a novel suppressor of ferroptosis, with its overexpression driven by promoter hypomethylation contributing to OSCC progression by ER stress-mediated ferroptosis via ACSL4.

The role of HnrnpF/H as a driver of oligoteratozoospermia

Male subfertility or infertility is a common condition often characterized by men producing a low number of sperm with poor quality. To gain insight into this condition, we performed a quantitative proteomic analysis of semen samples obtained from infertile and fertile men. At least 6 proteins showed significant differences in regulation of alternatively spliced isoforms. To investigate this link between aberrant alternative splicing and production of poor-quality spermatozoa, we overexpressed the hnrnpH/F-orthologue Glorund (Glo) in Drosophila, which was also found to be abundant in poor quality human sperm. Transgenic animals produced low numbers of morphologically defective spermatozoa and aberrant formation of the "dense body," an organelle akin to the mammalian manchette. Furthermore, fertility trials demonstrated that transgenic flies were either completely infertile or highly subfertile. These findings suggest that dysregulation of hnrnpH/F is likely to result in the production of low-quality semen, leading to subfertility or infertility in men.

The Application of Ejaculate-Based Shotgun Proteomics for Male Infertility Screening

Problems with the male reproductive system are of both medical and social significance. As a rule, spermatozoa and seminal plasma proteomes are investigated separately to assess sperm quality. The current study aimed to compare ejaculate proteomes with spermatozoa and seminal plasma protein profiles regarding the identification of proteins related to fertility scores. A total of 1779, 715, and 2163 proteins were identified in the ejaculate, seminal plasma, and spermatozoa, respectively. Among these datasets, 472 proteins were shared. GO enrichment analysis of the common proteins enabled us to distinguish biological processes such as single fertilization (GO:0007338), spermatid development (GO:0007286), and cell motility (GO:0048870). Among the abundant terms for GO cellular components, zona pellucida receptor complex, sperm fibrous sheath, and outer dense fiber were revealed. Overall, we identified 139 testis-specific proteins. For these proteins, PPI networks that are common in ejaculate, spermatozoa, and seminal plasma were related to the following GO biological processes: cilium movement (GO:0003341), microtubule-based movement (GO:0007018), and sperm motility (GO:0097722). For ejaculate and spermatozoa, they shared 15 common testis-specific proteins with spermatogenesis (GO:0007283) and male gamete generation (GO:0048232). Therefore, we speculated that ejaculate-based proteomics could yield new insights into the peculiar reproductive physiology and spermatozoa function of men and potentially serve as an explanation for male infertility screening.