Identification of Sialyl-Lewis(x)-Interacting Protein on Human Spermatozoa

Identification of Five NK Cell-Related Hub Genes in COPD Using Single-Cell RNA Sequencing Analysis

Background

COPD is a healthcare problem. However, the underlying mechanism remains unclear. Our study aimed to explore the key genes involved in immune infiltration in COPD using bioinformatic tools.

Methods

In this study, scRNA-seq analysis was utilized to explore specific marker genes of each immune cell subtype in COPD. TSNE analysis was used to evaluate the relationship between each immune cell cluster. Lasso regression identified 21 genes as characteristics of COPD modulated by the single-cell NK cell subpopulation. The "limma" package was used for differentially expressed analysis. The pseudotime analysis reveals the continuous changes of NK cells along their developmental trajectory. Further, we constructed a hub gene network to examine the correlation between hub genes and immune factors, transcriptional regulation factors, and potential therapeutic drugs. GO and KEGG enrichment analysis revealed the biological functions of the hub genes. RT-qPCR was used for validation of the five hub in COPD patients.

Results

NK cell subtypes are closely related to other immune cell subtypes and considered as the most important immune cells in the immune microenvironment of COPD patients. LASSO regression identified 21 genes as NK cells-characteristic genes for COPD. The GSE57148 as the training set has a AUC of 0.9489 and GSE8581 as the validation set has a AUC of 0.7303. The GO semantic similarity further confirmed five NK cell-related hub genes, C1orf56, S100A6, IGFBP7, ANXA1, and PTPN7. RT-qPCR experiment revealed that the mRNA expression of five hub genes in the normal group was lower than that in the disease group. We also found that five hub genes correlated with immune cell infiltration. The potential therapeutic agents for COPD may be zalcitabine, PP-2, PD-98059, and TGX-221 based on the CMap database prediction.

Conclusion

We proposed that peripheral NK cells may play a role in the pathogenesis of COPD through bioinformatic analysis. These hub genes may provide insights into mechanistic research and new targets for new therapies in patients with COPD.

The Sweet Relationship between the Endometrium and Protein Glycosylation

The endometrium is an important part of women's bodies for menstruation and pregnancy. Various proteins are widely expressed on the surface of endometrial cells, and glycosylation is an important post-translational modification of proteins. Glycosylation modification is closely related not only to endometrial receptivity but also to common diseases related to endometrial receptivity. Glycosylation can improve endometrial receptivity, promote embryo localization and trophoblast cell adhesion and invasion, and contribute to successful implantation. Two diseases related to endometrial receptivity include endometriosis and endometrial cancer. As a common benign disease in women, endometriosis is often accompanied by an increased menstrual volume, prolonged menstrual periods, progressive and aggravated dysmenorrhea, and may be accompanied by infertility. Protein glycosylation modification of the endometrial surface indicates the severity of the disease and may be an important pathogenesis of endometriosis. In cancer, glycosylation modifications on the surface of tumor cells can be a marker to distinguish the type and severity of endometrial cancer. This review highlights the role of protein glycosylation in embryo-maternal endometrial dialogue and explores its potential mechanisms in diseases related to endometrial receptivity, which could provide a new clinical approach for their diagnosis and treatment.

Spermatogenic cell-specific SPACA4 is essential for efficient sperm-zona pellucida binding in vitro

Fertilization is a complex and highly regulated process that involves a series of molecular interactions between sperm and oocytes. However, the mechanisms of proteins involved in human fertilization, such as that of testis-specific SPACA4, remain poorly understood. Here we demonstrated that SPACA4 is a spermatogenic cell-specific protein. SPACA4 is expressed during spermatogenesis, upregulated in early-stage spermatids, and downregulated in elongating spermatids. SPACA4 is an intracellular protein that locates in the acrosome and is lost during the acrosome reaction. Incubation with antibodies against SPACA4 inhibited the binding of spermatozoa to zona pellucida. SPACA4 protein expression levels across different semen parameters were similar but varied significantly among patients. A prospective clinical study found no association between SPACA4 protein levels and fertilization or cleavage rates. Thus, the study suggests a novel function for SPACA4 in human fertilization in a non-dose-dependent manner. However, a larger clinical trial is required to evaluate the potential use of sperm SPACA4 protein levels to predict fertilization potential.

The role of spermatozoa-zona pellucida interaction in selecting fertilization-competent spermatozoa in humans

Human fertilization begins when a capacitated spermatozoon binds to the zona pellucida (ZP) surrounding a mature oocyte. Defective spermatozoa-ZP interaction contributes to male infertility and is a leading cause of reduced fertilization rates in assisted reproduction treatments (ARTs). Human ejaculate contains millions of spermatozoa with varying degrees of fertilization potential and genetic quality, of which only thousands of motile spermatozoa can bind to the ZP at the fertilization site. This observation suggests that human ZP selectively interacts with competitively superior spermatozoa characterized by high fertilizing capability and genetic integrity. However, direct evidence for ZP-mediated sperm selection process is lacking. This study aims to demonstrate that spermatozoa-ZP interaction represents a crucial step in selecting fertilization-competent spermatozoa in humans. ZP-bound and unbound spermatozoa were respectively collected by a spermatozoa-ZP coincubation assay. The time-course data demonstrated that ZP interacted with a small proportion of motile spermatozoa. Heat shock 70 kDa protein 2 (HSPA2) and sperm acrosome associated 3 (SPACA 3) are two protein markers associated with the sperm ZP-binding ability. Immunofluorescent staining indicated that the ZP-bound spermatozoa had significantly higher expression levels of HSPA2 and SPACA3 than the unbound spermatozoa. ZP-bound spermatozoa had a significantly higher level of normal morphology, DNA integrity, chromatin integrity, protamination and global methylation when compared to the unbound spermatozoa. The results validated the possibility of applying spermatozoa-ZP interaction to select fertilization-competent spermatozoa in ART. This highly selective interaction might also provide diagnostic information regarding the fertilization potential and genetic qualities of spermatozoa independent of those derived from the standard semen analysis.

Diversity of sialic acids and sialoglycoproteins in gametes and at fertilization

Sialic acids are a family of 9-carbon monosaccharides with particular physicochemical properties. They modulate the biological functions of the molecules that carry them and are involved in several steps of the reproductive process. Sialoglycoproteins participate in the balance between species recognition and specificity, and the mechanisms of these aspects remain an issue in gametes formation and binding in metazoan reproduction. Sialoglycoproteins form a specific coat at the gametes surface and specific polysialylated chains are present on marine species oocytes. Spermatozoa are submitted to critical sialic acid changes in the female reproductive tract facilitating their migration, their survival through the modulation of the female innate immune response, and the final oocyte-binding event. To decipher the role of sialic acids in gametes and at fertilization, the dynamical changes of enzymes involved in their synthesis and removal have to be further considered.