Annexin A2 and S100A10 in the mammalian oviduct

Phosphatidylserine on sperm head interact with Annexin A5 on oviduct luminal cilia to form a sperm reservoir in pigs

After insemination, a subpopulation of sperm reaches the oviducts and binds to isthmic epithelial cells to form a "sperm reservoir". Our objective was to explore the role of annexin A5 (ANXA5), a protein that binds with high affinity to phosphatidylserine (PS), in the formation of the sperm reservoir in pigs. Phosphatidylserine was detected on the head of approximately 10 % of boar sperm at ejaculation. Porcine ANXA5 was immunodetected with a strong signal on luminal cilia in the isthmus and in derived isthmic epithelial spheroids (IES). Exogenous PS between 0.01 and 0.1 µg/mL and recombinant porcine ANXA5 (rpANXA5) above 0.1 µg/mL inhibited sperm binding to IES without reducing sperm motility. Pre-incubation of sperm, but not IES, with rpANXA5 inhibited sperm binding to IES. Under capacitating conditions, the proportion of live sperm with head PS exposure and the ability of sperm to bind to rpANXA5 and IES cilia increased within 30 min. Conversely, the acrosome reaction decreased the ability of sperm to bind rpANXA5 and prevented sperm binding to IES. In conclusion, sperm membrane remodelling during capacitation enhanced head PS exposure in motile sperm, resulting in increased interaction with ciliary ANXA5 on isthmic epithelial spheroids. These findings support a role for PS-ANXA5 interaction in the formation of the sperm reservoir in mammalian females.

Unveiling the role of protein kinase A (PKA) activity in bovine oviductal epithelial cells: implications on apoptotic signaling pathways during the estrous cycle

The complex interactome crucial for successful pregnancy is constituted by the intricate network of endocrine and paracrine signaling pathways, involving gametes, embryos, and the female reproductive tract. Specifically, the oviduct exhibits distinct responses to gametes and early embryos during particular phases of the estrus cycle, a process tightly regulated by reproductive hormones. Moreover, these hormones play a pivotal role in orchestrating cyclical changes within oviductal epithelial cells. To unravel the molecular mechanisms underlying these dynamic changes, our study aimed to investigate the involvement of protein kinase A (PKA) in oviductal epithelial cells throughout the estrus cycle and in advanced pregnancy, extending our studies to oviductal epithelial cell in primary culture. By a combination of 2D-gel electrophoresis, Western blotting, and mass spectrometry, we identified 17 proteins exhibiting differential phosphorylation status mediated by PKA. Among these proteins, we successfully validated the phosphorylation status of heat shock 70 kDa protein (HSP70), aconitase 2 (ACO2), and lamin B1 (LMNB1). Our findings unequivocally demonstrate the dynamic regulation of PKA throughout the estrus cycle in oviductal epithelial cells. Also, analysis by bioinformatics tools suggest its pivotal role in mediating cyclical changes possibly through modulation of apoptotic pathways. This research sheds light on the intricate molecular mechanisms underlying reproductive processes, with implications for understanding fertility and reproductive health.

Recent Advances in Molecular and Cellular Functions of S100A10

S100A10 (p11, annexin II light chain, calpactin light chain) is a multifunctional protein with a wide range of physiological activity. S100A10 is unique among the S100 family members of proteins since it does not bind to Ca2+, despite its sequence and structural similarity. This review focuses on studies highlighting the structure, regulation, and binding partners of S100A10. The binding partners of S100A10 were collated and summarized.

Grouper annexin A2 affects RGNNV by regulating the host immune response

Annexin A2 (AnxA2) is ubiquitous in vertebrates and has been identified as a multifunctional protein participating in a series of biological processes, such as endocytosis, exocytosis, signal transduction, transcription regulation, and immune responses. However, the function of AnxA2 in fish during virus infection still remains unknown. In this study, we identified and characterized AnxA2 (EcAnxA2) in Epinephelus coioides. EcAnxA2 encoded a 338 amino acids protein with four identical annexin superfamily conserved domains, which shared high identity with other AnxA2 of different species. EcAnxA2 was widely expressed in different tissues of healthy groupers, and its expression was significantly increased in grouper spleen cells infected with red-spotted grouper nervous necrosis virus (RGNNV). Subcellular locatio n analyses showed that EcAnxA2 diffusely distributed in the cytoplasm. After RGNNV infection, the spatial distribution of EcAnxA2 was unaltered, and a few EcAnxA2 co-localized with RGNNV during the late stage of infection. Furthermore, overexpression of EcAnxA2 significantly increased RGNNV infection, and knockdown of EcAnxA2 reduced RGNNV infection. In addition, overexpressed EcAnxA2 reduced the transcription of interferon (IFN)-related and inflammatory factors, including IFN regulatory factor 7 (IRF7), IFN stimulating gene 15 (ISG15), melanoma differentiation related gene 5 (MDA5), MAX interactor 1 (Mxi1) laboratory of genetics and physiology 2 (LGP2), IFN induced 35 kDa protein (IFP35), tumor necrosis factor receptor-associated factor 6 (TRAF6) and interleukin 6 (IL-6). The transcription of these genes was up-regulated when EcAnxA2 was inhibited by siRNA. Taken together, our results showed that EcAnxA2 affected RGNNV infection by down-regulating the host immune response in groupers, which provided new insights into the roles of AnxA2 in fish during virus infection.

Transcriptome sequencing reveals ovarian immune response and development during female sperm storage in viviparous black rockfish (Sebastes schlegelii)

Black rockfish (Sebastes schlegelii) is a viviparous teleost fish whose spermatozoa were transferred into the female ovary cavity and stored for up to five months and then fertilized with the matured eggs. There is no clarity about the molecular characteristics of ovarian follicles during female sperm storage in Sebastes schlegelii. In this study, histological observation, transcriptomic analysis and hormone level detection were performed in ovaries at stages of pre-mating (PRM), post-mating (POM) and pre-fertilization (PRF). Histological observation displayed that oocytes developed from the primary growth (PG) stage to the mature stage during the three stages. Furthermore, somatic cells around the oocyte were proliferated and spermatozoa were found near the layer of epithelial cells. Transcriptomic analysis showed that there were 437 and 747 differentially expressed genes (DEGs) in ovarian comparison of PRM-vs-POM and POM-vs-PRF, respectively. GO enrichment and KEGG analysis revealed that lots of DEGs from PRM-vs-POM were linked to immune-related pathways, such as antigen processing and presentation, immune response, and complement and coagulation cascade. Meanwhile, seven DEGs associated with immune response were differentially expressed after spermatozoa treatment in ovarian tissue in vitro. While the DEGs from POM-vs-PRF were mostly enriched in the pathways related to homeostasis maintenance and cellular junction and metabolism. In addition, we found increased estrogen (E2) and 11-ketotestosterone (11-KT) level and decreased testosterone level in ovarian follicles during the sperm storage period by ELISA, suggesting that sex hormones are involved in the dynamic change of ovarian follicles. In total, this study could provide new hints for understanding the immune adaption and developmental signatures of ovarian follicles post copulation in black rockfish and other viviparous fish.

The stallion sperm acrosome: Considerations from a research and clinical perspective

During the fertilization process, the interaction between the sperm and the oocyte is mediated by a process known as acrosomal exocytosis (AE). Although the role of the sperm acrosome on fertilization has been studied extensively over the last 70 years, little is known about the molecular mechanisms that govern acrosomal function, particularly in species other than mice or humans. Even though subfertility due to acrosomal dysfunction is less common in large animals than in humans, the evaluation of sperm acrosomal function should be considered not only as a complementary but a routine test when individuals are selected for breeding potential. This certainly holds true for stallions, which might display lower levels of fertility in the face of "acceptable" sperm quality parameters determined by conventional sperm assays. Nowadays, the use of high throughput technologies such as flow cytometry or mass spectrometry-based proteomic analysis is commonplace in the research arena. Such techniques can also be implemented in clinical scenarios of males with "idiopathic" subfertility. The current review focuses on the sperm acrosome, with particular emphasis on the stallion. We aim to describe the physiological events that lead to the acrosome formation within the testis, the role of very specific acrosomal proteins during AE, the methods to study the occurrence of AE under in vitro conditions, and the potential use of molecular biology techniques to discover new markers of acrosomal function and subfertility associated with acrosomal dysfunction in stallions.

Identification of nucleotide polymorphisms in the key promoter region of chicken annexins A2 gene associatied with egg laying traits

Annexin A2 (ANXA2) is a member of the A subfamily of a multifunctional calcium dependent membrane phospholipid binding protein family. The mRNA expression of ANXA2 is consistent with ovary function and egg laying in chickens. In this study, six nucleotide polymorphisms in the key promoter region of chicken ANXA2 gene (-2861 bp to -1394 bp), i.e.,: g.-2337 indel (GT), g.-2255 C > T, g. -2248 A > G, g.-2188 A > G, g.-2169 G > A, g.-2160 A > C, were identified. Their distributions in populations of Xinyang Brown, Recessive White Rock, Wenchang and Wenshang Barred chickens were analyzed. In the Recessive White Rock chicken population, CAA, CAG and TGG were three major haplotypes. Association analysis indicated that the individuals with diplotype TGG/TGG laid more eggs at 32 weeks, and the individual with diplotype CAG/TGG laid at the earlier age. Luciferase activity assay showed that mutation from C to T at -2255 increased trascriptional activity of chicken ANXA2, which is consistent with its effect on egg laying traits.

Simulating nature in sperm selection for assisted reproduction

Sperm selection in the female reproductive tract (FRT) is sophisticated. Only about 1,000 sperm out of millions in an ejaculate reach the fallopian tube and thus have a chance of fertilizing an oocyte. In assisted reproduction techniques, sperm are usually selected using their density or motility, characteristics that do not reflect their fertilization competence and, therefore, might result in failure to fertilize the oocyte. Although sperm processing in in vitro fertilization (IVF) and intrauterine insemination (IUI) bypasses many of the selection processes in the FRT, selection by the cumulus mass and the zona pellucida remain intact. By contrast, the direct injection of a sperm into an oocyte in intracytoplasmic sperm injection (ICSI) bypasses all natural selection barriers and, therefore, increases the risk of transferring paternal defects such as fragmented DNA and genomic abnormalities in sperm to the resulting child. Research into surrogate markers of fertilization potential and into simulating the natural sperm selection processes has progressed. However, methods of sperm isolation - such as hyaluronic acid-based selection and microfluidic isolation based on sperm tactic responses - use only one or two parameters and are not comparable with the multistep sperm selection processes naturally occurring within the FRT. Fertilization-competent sperm require a panel of molecules, including zona pellucida-binding proteins and ion channel proteins, that enable them to progress through the FRT to achieve fertilization. The optimal artificial sperm selection method will, therefore, probably need to use a multiparameter tool that incorporates the molecular signature of sperm with high fertilization potential, and their responses to external cues, within a microfluidic system that can replicate the physiological processes of the FRT in vitro.

ANXA2 is a potential marker for the diagnosis of human cervical cancer

Aim: The aim is to study ANXA2 biomarkers for early diagnosis of cervical cancer. Materials & methods: The study used bioinformatics analysis and experimental verification of ANXA2 expression in cervical cancer. Results:ANXA2 expression was higher in cancer tissues than in non-cancer tissues (p = 0.002). ANXA2 was expressed in cell membranes of non-cancer tissues, whereas in cancer tissues it was expressed in both the cell membranes and the cytoplasm. Moreover, ANXA2 expression was more pronounced in squamous cell carcinomas. ANXA2 expression decreased overall survival of patients, and the data suggested that protein expression was associated with invasion and migration of tumors. Conclusion:ANXA2 has high specificity and sensitivity as a detection marker for cervical cancer and can assist in the diagnosis of cervical cancer.

Porcine model for the study of sperm capacitation, fertilization and male fertility

Mammalian fertilization remains a poorly understood event with the vast majority of studies done in the mouse model. The purpose of this review is to revise the current knowledge about semen deposition, sperm transport, sperm capacitation, gamete interactions and early embryonic development with a focus on the porcine model as a relevant, alternative model organism to humans. The review provides a thorough overview of post-ejaculation events inside the sow's reproductive tract including comparisons with humans and implications for human fertilization and assisted reproductive therapy (ART). Porcine methodology for sperm handling, preservation, in vitro capacitation, oocyte in vitro maturation, in vitro fertilization and intra-cytoplasmic sperm injection that are routinely used in pig research laboratories can be successfully translated into ART to treat human infertility. Last, but not least, new knowledge about mitochondrial inheritance in the pig can provide an insight into human mitochondrial diseases and new knowledge on polyspermy defense mechanisms could contribute to the development of new male contraceptives.

Hormone-regulated PKA activity in porcine oviductal epithelial cells

The oviduct is a dynamic organ that suffers changes during the oestrous cycle and modulates gamete and embryo physiology. We analyse the possible existence of Protein kinase A (PKA)-dependent hormone-regulated pathways in porcine ampulla and primary cell cultures by 2D-electrophoresis/Western blot using anti-phospho PKA substrate antibodies. Differential phosphorylation was observed for ten proteins that were identified by mass spectrometry. The results were validated for five of the proteins: Annexin A5, Calumenin, Glyoxalase I and II and Enolase I. Immunofluorescence analyses show that Calumenin, Glyoxalase II and Enolase I change their localisation in the oviductal epithelium through the oestrus cycle. The results demonstrate the existence of PKA hormone-regulated pathways in the ampulla epithelium during the oestrus cycle.

Sperm Proteome Analysis and Identification of Fertility-Associated Biomarkers in Unexplained Male Infertility

Up to 30% of men with normal semen parameters suffer from infertility and the reason for this is unknown. Altered expression of sperm proteins may be a major cause of infertility in these men. Proteomic profiling was performed on pooled semen samples from eight normozoospermic fertile men and nine normozoospermic infertile men using LC-MS/MS. Furthermore, key differentially expressed proteins (DEPs) related to the fertilization process were selected for validation using Western blotting. A total of 1139 and 1095 proteins were identified in normozoospermic fertile and infertile men, respectively. Of these, 162 proteins were identified as DEPs. The canonical pathway related to free radical scavenging was enriched with upregulated DEPs in normozoospermic infertile men. The proteins associated with reproductive system development and function, and the ubiquitination pathway were underexpressed in normozoospermic infertile men. Western blot analysis revealed the overexpression of annexin A2 (ANXA2) (2.03 fold change; P = 0.0243), and underexpression of sperm surface protein Sp17 (SPA17) (0.37 fold change; P = 0.0205) and serine protease inhibitor (SERPINA5) (0.32 fold change; P = 0.0073) in men with unexplained male infertility (UMI). The global proteomic profile of normozoospermic infertile men is different from that of normozoospermic fertile men. Our data suggests that SPA17, ANXA2, and SERPINA5 may potentially serve as non-invasive protein biomarkers associated with the fertilization process of the spermatozoa in UMI.

S100A10 and Cancer Hallmarks: Structure, Functions, and its Emerging Role in Ovarian Cancer

S100A10, which is also known as p11, is located in the plasma membrane and forms a heterotetramer with annexin A2. The heterotetramer, comprising of two subunits of annexin A2 and S100A10, activates the plasminogen activation pathway, which is involved in cellular repair of normal tissues. Increased expression of annexin A2 and S100A10 in cancer cells leads to increased levels of plasmin—which promotes the degradation of the extracellular matrix—increased angiogenesis, and the invasion of the surrounding organs. Although many studies have investigated the functional role of annexin A2 in cancer cells, including ovarian cancer, S100A10 has been less studied. We recently demonstrated that high stromal annexin A2 and high cytoplasmic S100A10 expression is associated with a 3.4-fold increased risk of progression and 7.9-fold risk of death in ovarian cancer patients. Other studies have linked S100A10 with multidrug resistance in ovarian cancer; however, no functional studies to date have been performed in ovarian cancer cells. This article reviews the current understanding of S100A10 function in cancer with a particular focus on ovarian cancer.

Regulation of the bovine oviductal fluid proteome

Our objective was to investigate the regulation of the proteome in the bovine oviductal fluid according to the stage of the oestrous cycle, to the side relative to ovulation and to local concentrations of steroid hormones. Luminal fluid samples from both oviducts were collected at four stages of the oestrous cycle: pre-ovulatory (Pre-ov), post-ovulatory (Post-ov), and mid- and late luteal phases from adult cyclic cows (18–25 cows/stage). The proteomes were assessed by nanoLC–MS/MS and quantified by label-free method. Totally, 482 proteins were identified including a limited number of proteins specific to one stage or one side. Proportions of differentially abundant proteins fluctuated from 10 to 24% between sides at one stage and from 4 to 20% among stages in a given side of ovulation. In oviductal fluids ipsilateral to ovulation, Annexin A1 was the most abundant protein at Pre-ov compared with Post-ov while numerous heat shock proteins were more abundant at Post-ov compared with Pre-ov. Among differentially abundant proteins, seven tended to be correlated with intra-oviductal concentrations of progesterone. A wide range of biological processes was evidenced for differentially abundant proteins, of which metabolic and cellular processes were predominant. This work identifies numerous new candidate proteins potentially interacting with the oocyte, spermatozoa and embryo to modulate fertilization and early embryo development.

Matrix-assisted laser desorption/ionization imaging mass spectrometry for the spatial location of feline oviductal proteins

With the purpose of identifying factors involved in early stages of embryo development in the domestic cat, matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) was used for the first time to describe the spatial localization of proteins in the oviducts of queens. Oviducts were obtained from two 2 and 4 years old cross-bred queens, divided into three segments, snap-frozen in liquid nitrogen and then stored at -80°C until use. Next, they were sectioned in a cryostat, fixed on ITO (indium tin oxide) conductive glass slides for MALDI-IMS and serial sections were collected on microscope slides for histology. As confirmed by histology, MALDI-IMS was able to show contrasting protein distributions in the oviductal infundibulum, ampulla and isthmus. Mass spectra were characterized by abundant ions of m/z 1,259, 4,939, 4,960 and 10,626, which have been tentatively attributed to keratin, thymosin β10, thymosin β4 and S100, respectively. Keratin and thymosins are involved in the biological response to tissue damage. S100 proteins are calcium-modulated proteins implicated in a variety of cellular activities, including cell differentiation and regulation of cell motility. These results suggest that protein composition differs between segments of the cat oviduct, which corresponds to morphological changes within these sections. Further functional studies could elucidate the effects of these proteins on feline reproductive physiology.

Extracellular Vesicles in the Intrauterine Environment: Challenges and Potential Functions

Extracellular vesicles (EVs), including exosomes (30–150 nm) and microvesicles (100–1500 nm), play important roles in mediating cell-cell communication. Such particles package distinct cargo elements, including lipids, proteins, mRNAs, microRNAs, and DNA, that vary depending on the cell of origin and its phenotype. This cargo can be horizontally transferred to target cells where its components can reprogram the recipient cell to modify its function. EVs have been identified within the uterine cavity of women, sheep, and mice, where they contribute to the microenvironment of sperm transport, and of blastocyst and endometrial preparation for implantation. It is likely that exosomes and microvesicles carry different cargo and coordinate different roles in this intrauterine environment. Understanding and defining these subtypes of EVs is important for future functional studies and clinical translation. Here we critically review the various purification and validation procedures for extracellular vesicle analysis and discuss what is known of endometrial-derived exosome cargo and of their hormonal regulation. The current knowledge of the functions of uterine exosomes, with respect to sperm transport and function, and of their actions on trophectodermal cells to promote implantation are summarized and evaluated in their physiological context. Given the potential importance of this form of cell-cell interactions within the reproductive tract, the critical issues discussed will guide new insights in this rapidly expanding field.