Ultrastructural localization of the prostasome - an organelle in human seminal plasma

Applications of Urinary Extracellular Vesicles in the Diagnosis and Active Surveillance of Prostate Cancer

Prostate cancer is the most common non-cutaneous cancer among men in the UK, causing significant health and economic burdens. Diagnosis and risk prognostication can be challenging due to the genetic and clinical heterogeneity of prostate cancer as well as uncertainties in our knowledge of the underlying biology and natural history of disease development. Urinary extracellular vesicles (EVs) are microscopic, lipid bilayer defined particles released by cells that carry a variety of molecular cargoes including nucleic acids, proteins and other molecules. Urine is a plentiful source of prostate-derived EVs. In this narrative review, we summarise the evidence on the function of urinary EVs and their applications in the evolving field of prostate cancer diagnostics and active surveillance. EVs are implicated in the development of all hallmarks of prostate cancer, and this knowledge has been applied to the development of multiple diagnostic tests, which are largely based on RNA and miRNA. Common gene probes included in multi-probe tests include PCA3 and ERG, and the miRNAs miR-21 and miR-141. The next decade will likely bring further improvements in the diagnostic accuracy of biomarkers as well as insights into molecular biological mechanisms of action that can be translated into opportunities in precision uro-oncology.

Expression of CD13 and CD26 on extracellular vesicles in canine seminal plasma: preliminary results

Canine seminal plasma is a complex fluid containing proteins, peptides, enzymes, hormones as well as extracellular vesicles that are involved in many physiological and pathological processes including reproduction. We examined the expression of the extracellular vesicles surface antigens Aminopeptidase-N (CD13) and Dipeptidyl peptidase IV (CD26) by flow cytometry. For this study, third fraction of the ejaculate, from fertile adult male German Shepherd dogs, was manually collected twice, two days apart. FACS analyses revealed that CD13 and CD26 are co-expressed on the 69.3 ± 3.7% of extracellular vesicles and only a 2.0 ± 0.5% of extracellular vesicles express CD26 alone. On the other hand, 28.6 ± 3.6% of seminal EVs express CD13 alone. Our results agree with the hypothesis that CD26 needs to be co-expressed with other signal-transducing molecules, while CD13, can perform functions independently of the presence or co-expression of CD26. The results obtained in normal fertile dogs could represent physiological expression of these enzymes. Therefore, it would be interesting to carry out further studies to evaluate the expression of CD13 and CD26 on extracellular vesicles as biomarker for prostate pathological condition in dogs.

Differentiation of large extracellular vesicles in oral fluid: Combined protocol of small force centrifugation and sedimentation pattern analysis

Extracellular vesicles (EVs) in biofluids are highly heterogeneous entities in terms of their origins and physicochemical properties. Considering the application of EVs in diagnostic and therapeutic fields, it is of extreme importance to establish differentiating methods by which focused EV subclasses are operationally defined. Several differentiation protocols have been proposed; however, they have mainly focused on smaller types of EVs, and the heterogeneous nature of large EVs has not yet been fully explored. In this report, to classify large EVs into subgroups based on their physicochemical properties, we have developed a protocol, named EV differentiation by sedimentation patterns (ESP), in which entities in the crude large EV fraction are first moved through a density gradient of iodixanol with small centrifugation forces, and then the migration patterns of molecules through the gradients are analysed using a non-hierarchical data clustering algorithm. Based on this method, proteins in the large EV fractions of oral fluids clustered into three groups: proteins shared with small EV cargos and enriched in immuno-related proteins (Group 1), proteins involved in energy metabolism and protein synthesis (Group 2), and proteins required for vesicle trafficking (Group 3). These observations indicate that the physiochemical properties of EVs, which are defined through low-speed gradient centrifugation, are well associated with their functions within cells. This protocol enables the detailed subclassification of EV populations that are difficult to differentiate using conventional separation methods.

The effects of boar seminal plasma extracellular vesicles on sperm fertility

Extracellular vesicles (EVs) are abundant in body fluid and are critical in cell interaction. Seminal plasma contains numerous EVs which affecting sperm function via transferring regulatory cargoes to the sperm. However, the mechanism of seminal plasma extracellular vesicles (SP-EVs) is still not clear. The present study aimed to isolate the boar SP-EVs and explore its potential function, then identify the key protein involved in SP-EVs and sperms interaction, and elucidate mechanism of SP-EVs protein on sperms. Here, we successfully isolated and concentrated boar SP-EVs, the SP-EVs showed a typical vesicle structure under transmission electron microscopy, most of their diameters range between 50 and 200 nm and express EVs biomarkers CD9 and CD63. We proved that SP-EVs could inhibit sperm acrosome reaction and in vitro fertility. Through a data-independent acquisition analysis of protein profiles of noncapacitated sperms, normal capacitated sperms and SP-EVs treated capacitated sperms, we identified that EZRIN was one of the active proteins that participated in SP-EVs and sperms interaction. Furthermore, we tested that the inhibition of EZRIN could promote boar sperm fertility, which is in consistence with the function of SP-EVs. The results may facilitate future research of SP-EVs on sperm function and male infertility.

Clinical Significance of Extracellular Vesicles in Prostate and Renal Cancer

Extracellular vesicles (EVs)-including apoptotic bodies, microvesicles, and exosomes-are released by almost all cell types and contain molecular footprints from their cell of origin, including lipids, proteins, metabolites, RNA, and DNA. They have been successfully isolated from blood, urine, semen, and other body fluids. In this review, we discuss the current understanding of the predictive value of EVs in prostate and renal cancer. We also describe the findings supporting the use of EVs from liquid biopsies in stratifying high-risk prostate/kidney cancer and advanced disease, such as castration-resistant (CRPC) and neuroendocrine prostate cancer (NEPC) as well as metastatic renal cell carcinoma (RCC). Assays based on EVs isolated from urine and blood have the potential to serve as highly sensitive diagnostic studies as well as predictive measures of tumor recurrence in patients with prostate and renal cancers. Overall, we discuss the biogenesis, isolation, liquid-biopsy, and therapeutic applications of EVs in CRPC, NEPC, and RCC.

Microfluidics facilitating the use of small extracellular vesicles in innovative approaches to male infertility

Sperm are transcriptionally and translationally quiescent and, therefore, rely on the seminal plasma microenvironment for function, survival and fertilization of the oocyte in the oviduct. The male reproductive system influences sperm function via the binding and fusion of secreted epididymal (epididymosomes) and prostatic (prostasomes) small extracellular vesicles (S-EVs) that facilitate the transfer of proteins, lipids and nucleic acids to sperm. Seminal plasma S-EVs have important roles in sperm maturation, immune and oxidative stress protection, capacitation, fertilization and endometrial implantation and receptivity. Supplementing asthenozoospermic samples with normospermic-derived S-EVs can improve sperm motility and S-EV microRNAs can be used to predict non-obstructive azoospermia. Thus, S-EV influence on sperm physiology might have both therapeutic and diagnostic potential; however, the isolation of pure populations of S-EVs from bodily fluids with current conventional methods presents a substantial hurdle. Many conventional techniques lack accuracy, effectiveness, and practicality; yet microfluidic technology has the potential to simplify and improve S-EV isolation and detection.

Extracellular vesicles in seminal fluid and effects on male reproduction. An overview in farm animals and pets

Extracellular vesicles (EVs) are lipid bilayer nanovesicles released by most functional cells to body fluids, containing bioactive molecules, mainly proteins, lipids, and nucleic acids having actions at target cells. The EVs have essential functions in cell-to-cell communication by regulating different biological processes in target cells. Fluids from the male reproductive tract, including seminal plasma, contain many extracellular vesicles (sEVs), which have been evaluated to a lesser extent than those of other body fluids, particularly in farm animals and pets. Results from the few studies that have been conducted indicated epithelial cells of the testis, epididymis, ampulla of ductus deferens and many accessory sex glands release sEVs mainly via apocrine mechanisms. The sEVs are morphologically heterogeneous and bind to functional cells of the male reproductive tract, spermatozoa, and cells of the functional tissues of the female reproductive tract after mating or insemination. The sEVs encapsulate proteins and miRNAs that modulate sperm functions and male fertility. The sEVs, therefore, could be important as reproductive biomarkers in breeding sires. Many of the current findings regarding sEV functions, however, need experimental confirmation. Further studies are particularly needed to characterize both membranes and contents of sEVs, as well as the interaction between sEVs and target cells (spermatozoa and functional cells of the internal female reproductive tract). A priority for conducting these studies is development of methods that can be standardized and that are scalable, cost-effective and time-saving for isolation of different subtypes of EVs present in the entire population of sEVs.

Extracellular vesicles as a source of prostate cancer biomarkers in liquid biopsies: a decade of research

Prostate cancer is a global cancer burden and considerable effort has been made through the years to identify biomarkers for the disease. Approximately a decade ago, the potential of analysing extracellular vesicles in liquid biopsies started to be envisaged. This was the beginning of a new exciting area of research investigating the rich molecular treasure found in extracellular vesicles to identify biomarkers for a variety of diseases. Vesicles released from prostate cancer cells and cells of the tumour microenvironment carry molecular information about the disease that can be analysed in several biological fluids. Numerous studies document the interest of researchers in this field of research. However, methodological issues such as the isolation of vesicles have been challenging. Remarkably, novel technologies, including those based on nanotechnology, show promise for the further development and clinical use of extracellular vesicles as liquid biomarkers. Development of biomarkers is a long and complicated process, and there are still not many biomarkers based on extracellular vesicles in clinical use. However, the knowledge acquired during the last decade constitutes a solid basis for the future development of liquid biopsy tests for prostate cancer. These are urgently needed to bring prostate cancer treatment to the next level in precision medicine.

Advanced Nanotechnologies for Extracellular Vesicle-Based Liquid Biopsy

Extracellular vesicles (EVs) are emerging as a new source of biomarkers in liquid biopsy because of their wide presence in most body fluids and their ability to load cargoes from disease-related cells. Owing to the crucial role of EVs in disease diagnosis and treatment, significant efforts have been made to isolate, detect, and analyze EVs with high efficiency. A recent overview of advanced EV detection nanotechnologies is discussed here. First, several key challenges in EV-based liquid biopsies are introduced. Then, the related pivotal advances in nanotechnologies for EV isolation based on physical features, chemical affinity, and the combination of nanostructures and chemical affinity are summarized. Next, a summary of high-sensitivity sensors for EV detection and advanced approaches for single EV detection are provided. Later, EV analysis is introduced in practical clinical scenarios, and the application of machine learning in this field is highlighted. Finally, future opportunities for the development of next-generation nanotechnologies for EV detection are presented.

The Role of Extracellular Vesicles in Sperm Function and Male Fertility

Within the reproductive tract, distinct cell types must have precisely controlled communication for complex processes such as gamete production, fertilisation and implantation. Intercellular communication in many physiological processes involves extracellular vesicles (EVs). In reproductive systems, EVs have been implicated in many aspects, from gamete maturation to embryo development. Sperm develop within the testis and then exit into the epididymis in an immature form, lacking motility and fertilising capabilities. Due to their small size, compact nature of the nucleus and the lack of specific organelles, sperm are unable to perform de novo protein synthesis, and thus rely on extrinsic signals delivered from the external milieu to gain full function. Mounting evidence points to EVs as being a major provider of these signals, not just within the male reproductive tract but also within the female as the sperm make their way through a seemingly hostile environment to the oocyte. In this chapter, we review the current knowledge on EVs as mediators of sperm maturation and function and highlight their potential roles in male fertility.

Tetraspanins, More than Markers of Extracellular Vesicles in Reproduction

The participation of extracellular vesicles in many cellular processes, including reproduction, is unquestionable. Although currently, the tetraspanin proteins found in extracellular vesicles are mostly applied as markers, increasing evidence points to their role in extracellular vesicle biogenesis, cargo selection, cell targeting, and cell uptake under both physiological and pathological conditions. In this review, we bring other insight into the involvement of tetraspanin proteins in extracellular vesicle physiology in mammalian reproduction. We provide knowledge regarding the involvement of extracellular vesicle tetraspanins in these processes in somatic cells. Furthermore, we discuss the future direction towards an understanding of their functions in the tissues and fluids of the mammalian reproductive system in gamete maturation, fertilization, and embryo development; their involvement in mutual cell contact and communication in their complexity.

A urine-based biomarker for chronic prostatitis/chronic pelvic pain syndrome: a retrospective multi-center study

Background

Chronic prostatitis (CP) or chronic pelvic pain syndrome (CPPS) is one of the most common diseases in young and middle-aged men, accounting for 30% of outpatient men in urology OPD. There are no definitive diagnostic criteria for CP or CPPS and no accepted therapies that cure the disease.

Methods

We identified 372 patients with CP diagnosed from 2015 to 2018 and collect the information of age, routine urinary test, express prostatic secretion (EPS), and NIH-Chronic Prostatitis Symptom Index (NIH-CPSI).

Results

Our study proved a correlation between the increase of prostatic exosomal proteins (PSEPs) level and NIH-CPSI scores. Spearman’s correlation coefficient showed a significant level correlation between NIH-CPSI and PSEP level (rs=0.194, P=0.0035). In the meantime, the correlation was found between the PSEP level and EPS-white blood cells. Spearman’s correlation coefficient showed that there was a significant hierarchical correlation between EPS-white blood cells and PSEP level (rs=0.183, P=0.001).

Conclusions

These findings highlight the potential of PSEP is a practical indicator of the symptomatic progression of CP/CPPS. Applications of PSEP assay may guide drug discovery and lead to better treatment to improve the patient’s quality of life.All in all, PSEP detection in urine is safe and effective, and it is worthy of further promotion and application in clinical practice.

Roles of male reproductive tract extracellular vesicles in reproduction

Extracellular vesicles (EVs) are secreted cell-derived membrane structures present in all organisms across animal, bacterial, and plant phyla. These vesicles play important roles in cell-cell communication in many processes integral to health and disease. Recent studies demonstrate that EVs and their cargo have influential and conserved roles in male reproduction. While EVs have been isolated from virtually all specialized tissues comprising the male reproductive tract, they are best characterized in the epididymis (epididymosomes) and seminal fluid (seminal fluid extracellular vesicles or prostasomes). Broadly speaking, EVs promote reproductive success through supporting sperm development and function, as well as influencing the physiology of female reproductive tract cells after mating. In this review, we present current knowledge on the composition and function of male reproductive tract EV populations in both normal physiology and pathology, and argue that their functions identify them as critical regulators of fertility and fecundity.

Exosomes of male reproduction

Exosomes are nanosized membrane vesicles secreted by wide variety of cells and found in abundance in biological fluids including semen. They contain cargo of lipids, proteins, microRNAs and mRNAs, and are known to play a major role in intracellular communication. Seminal exosomes mainly include epididymosomes and prostasomes. Most of the proteins associated with the epididymosomes are transferred to the sperm subcellular or membranous domains during their epididymal transit and are involved in the acquisition of fertilizing ability, modulation of motility and protection against oxidative stress. Proteins associated with prostasomes stimulate sperm motility and regulate the timing of capacitation to avoid premature induction of acrosome reaction. Furthermore, prostasomes protect the sperm from immune responses within the female reproductive tract. Overall, exosome-associated proteins play an indispensable role in maturation of spermatozoa and therefore, serve as an excellent biomarker in early diagnosis of male infertility.

Human prostasomes an extracellular vesicle - Biomarkers for male infertility and prostrate cancer: The journey from identification to current knowledge

Extracellular vesicles (EVs) are gaining attention among the cell biologists and researchers over the last two decades. Prostasomes are considered to be (Evs) secreted by prostate epithelial cells into the semen during emission or ejaculation. Prostasomes contain various proteins required for immune regulation namely, amino and dipeptidyl peptidase; endopeptidase (neutral); decay accelerating factor; angiotensin-converting enzyme. Sperm cells need a few prerequisites in order to fertilize the egg. The role of prostasomes in enhancing the male fertility was reviewed extensively throughout the manuscript. Also, prostasomes have an immunosuppressive, immunomodulatory, antibacterial role in the female reproductive tract, and in some cases they can be used as immunocontraceptive agent to regulate the fertility status. This review will give insights to many active researchers in the field of prostasomal research and male infertility/fertility research. This review will open many unanswered mechanisms of prostasomes with respect to structure-function analysis, fatty acids patterns in diagnosis as well as prognosis of male infertility/fertility. More scientific reports are in need to support the mechanism of prostasomes and its role in immunomodulation. The development of prostasomes as a biomarker for the prostate cancer is still miserable with a lot of controversial results by various researchers.

Microfluidic Technology for Clinical Applications of Exosomes

Exosomes, a type of nanovesicle, are distinct cellular entities specifically capable of carrying various cargos between cells. It has been hypothesized that exosomes, as an enriched source of biomolecules, may serve as biomarkers for various diseases. This review introduces general aspects of exosomes, presents the challenges in exosome research, discusses the potential of exosomes as biomarkers, and describes the contribution of microfluidic technology to enable their isolation and analysis for diagnostic and disease monitoring. Additionally, clinical applications of exosomes for diagnostic purposes are also summarized.

In vitro decidualisation of human endometrial stromal cells is enhanced by seminal fluid extracellular vesicles

Extracellular vesicles are highly abundant in seminal fluids and have a known role enhancing sperm function. Clinical pregnancy rates after IVF treatment are improved after female exposure to seminal fluid. Seminal fluid extracellular vesicles (SF-EVs) are candidate enhancers, however, whether SF-EVs interact with cells from the endometrium and modulate the implantation processes is unknown. Here, we investigated whether SF-EVs interact with endometrial stromal cells (ESCs) and enhance decidualisation, a requisite for implantation. SF-EVs, isolated from human seminal fluid (n = 11) by ultracentrifugation, were characterised by nanoparticle tracking analysis and Western blotting, and purified using size exclusion chromatography. Non-decidualised and decidualised primary ESCs (n = 5) were then treated with SF-EVs. Binding of bio-maleimide-labelled SF-EVs was detected by flow cytometry and fluorescence microscopy. Prolactin and IGFBP-1 protein levels in culture media were also analysed after single and multiple SF-EV exposure. SF-EVs size ranged from 50 to 300 nm, and they expressed exosomal markers (ALIX, SYNTENIN-1, CD9 and CD81). SF-EVs bound to non-decidualised and decidualised ESCs at similar levels. ESCs prolactin secretion was increased after single (p = 0.0044) and multiple (p = 0.0021) SF-EV exposure. No differences were found in IGFBP-1 protein levels. In conclusion, SF-EVs enhance in vitro ESC decidualisation and increase secretion of prolactin, an essential hormone in implantation. This elucidates a novel role of SF-EVs on endometrial receptivity. Abbreviations: ECACC: European Collection of Authenticated Cell Cultures; ESCs: endometrial stromal cells; EVs: extracellular vesicles; FCS: foetal calf serum; HRP: horse-radish peroxidase; IFNγ: interferon-gamma; IGF: insulin-like growth factor; IGFBP-1: insulin-like growth factor binding protein 1; IVF: in vitro fertilisation; MVB: multivesicular bodies; NTA: nanoparticle tracking analysis; PRLR^−/−: homozygous prolactin receptor knockout; RT: room temperature; SF-EVs: seminal fluid extracellular vesicles; STR: short tandem repeat; TGFβ: transforming growth factor β; uNK: uterine natural killer

Extracellular vesicles and energy metabolism

Glycolytic enzymes are among the most frequently identified proteins in proteomics of exosomes/extracellular vesicles. This review brings up the possibility that exosomes/extracellular vesicles during their life-time in bodily fluids power important energy-consuming functions by glycolytic conversion of glucose or fructose into ATP. It was seen that prostasomes (exosomes of the prostate) could produce ATP by glycolysis and that the produced ATP quickly was consumed by adjacent prostasomal ATPases. The glycolytic ATP production appeared to be coupled to self-sustaining energy requirements. It will also be discussed how a failure in this machinery (lowered activity of ATPases) with a resultant polluting leakage of extracellular ATP could affect cancer development.

Extracellular vesicles in cancer immune responses: roles of purinergic receptors

Extracellular vesicles (EVs) are nano- to micro-scale membrane-enclosed vesicles that are released from presumably all cell types. Tumor cells and immune cells are prodigious generators of EVs often with competing phenotypes in terms of immune suppression versus immune stimulation. Purinergic receptors, proteins that bind diverse purine nucleotides and nucleosides (ATP, ADP, AMP, adenosine), are widely expressed across tissues and cell types, and are prominent players in immune and tumor cell nucleotide metabolism. The effects of purinergic receptor stimulation or agonism tend to produce inflammatory responses that may aid immune stimulation but may also provoke various immune suppression mechanisms, particularly in the tumor microenvironment. EVs released by cells following receptor stimulation are frequently pro-inflammatory, but often also pro-thrombolytic; these EVs may generate an environment that favors tumor progression at the cost of an effective immune response. Purinergic signaling pathways are becoming more recognized as valuable targets in various therapeutic scenarios, including cancer. It is possible that some of those clinically relevant compounds might also impact EV secretion and/or phenotype, which would hopefully capitalize on the immune stimulatory properties of purinergic signaling while minimizing the immune suppressive consequences. This review covers a relatively understudied area in EV biology, but even so, focuses almost exclusively on the purinergic receptors in a very limited capacity. There is much more to evaluate and incorporate into our understanding of extracellular nucleotides in EV biology, and we hope this work prompts further discovery.

Induction of immune-related gene expression by seminal exosomes in the porcine endometrium

Seminal plasma (SP) is considered as a vehicle to carry sperm into female reproductive tract, of which functions have not been completely understood. This study aimed to identify the function of seminal exosomes on porcine endometrium. Exosomes were isolated from the sperm-rich fraction of boar semen and were confirmed by the expression of exosome marker HSP70 and size distribution using nano-sight tracking analysis. Porcine endometrial epithelial cells (EECs) were then treated with seminal exosomes, and RNA extracted were subjected to global expression analysis. Transcripts related to "immune response", "inflammatory response" and their associated signaling pathways were up-regulated in EECs treated with seminal exosome, whereas those associated with "steroid biosynthesis", "metabolic pathways" and "T cell differentiation" were down-regulated. The decrease in PMVK, SC5D, INSIG1, HSD17B7, NSDHL, HMGCR, SQLE and FDFT1, and increase in CCL20, TNFSF15, AMCFII, CXCL2 and CXCL8 were also found in the endometrium from the naturally mated pigs. Moreover, changes in exosome-induced CYP24A1, EBP, CCL20, AMCFII and IL1A expression were not regulated by the exosome removed SP. These observations indicated that exosomes present in SP are involved in the immune-related gene regulation in the uterus, which could pave the passage for sperm and possibly fertilized eggs.

Extracellular vesicles are integral and functional components of the extracellular matrix

Extracellular vesicles (EV) are small plasma membrane-derived particles released into the extracellular space by virtually all cell types. Recently, EV have received increased interest because of their capability to carry nucleic acids, proteins, lipids and signaling molecules and to transfer their cargo into the target cells. Less attention has been paid to their role in modifying the composition of the extracellular matrix (ECM), either directly or indirectly via regulating the ability of target cells to synthesize or degrade matrix molecules. Based on recent results, EV can be considered one of the structural and functional components of the ECM that participate in matrix organization, regulation of cells within it, and in determining the physical properties of soft connective tissues, bone, cartilage and dentin. This review addresses the relevance of EV as specific modulators of the ECM, such as during the assembly and disassembly of the molecular network, signaling through the ECM and formation of niches suitable for tissue regeneration, inflammation and tumor progression. Finally, we assess the potential of these aspects of EV biology to translational medicine.

Proceedings of the ISEV symposium on "HIV, NeuroAIDS, drug abuse & EVs"

Extracellular vesicles (EVs) are globular, membrane bound nanovesicles (30-100 nm range) that are shed both during normal cellular functioning and under pathological conditions by most cell types. In recent years, there has been significant interest in the study of these vesicles as conduits for the delivery of information between cells from both analogous and disparate tissues. Their ability to carry specialised cargo including signalling mediators, proteins, messenger RNA and miRNAs characterises these vesicles as primary facilitators of cell-to-cell communication and regulation. EVs have also been demonstrated to play important roles in the field of cancer biology and metastasis. However, significant knowledge gaps exist in the role these vesicles play in the context of HIV infection and drug abuse. To foster discussion in this area a satellite symposium on "HIV, NeuroAIDS, Drug Abuse & EVs", was held in conjunction with the annual meeting of the International Society for Extracellular Vesicles (ISEV) in Bethesda, in April 2015. Experts in HIV and drug abuse fields were invited to share their findings on the role of EVs in HIV-1 infection and drug addiction. Additional discussion included current areas of research in EV biology in HIV infection and drug abuse.

Glycome complexity of human seminal plasma high molecular mass components: Evaluation of the contribution of acid-soluble glycoproteins/mucins and extracellular vesicles

This study was aimed at evaluation of the contribution of acid-soluble glycoproteins (ASG)/mucins and extracellular vesicles (EVs), yet unexplored components of human seminal plasma (hSP) to the complexity of its glycome. Gaining insight into the native presentation and distribution of glycans across hSP could help establish molecular environments supporting specific biological activities based on unique ligand capacities. Soluble and particulate fractions of hSP from healthy subjects were analyzed by gel filtration, electrophoresis, ion-exchange chromatography and a solid phase assay with immobilized charge-resolved glycospecies to test their reactivity with plant lectins, carbohydrate-binding antibodies and selected human lectins. Common O- and N-glycosylated species were detected on mixed or overlapped underlying protein scaffolds in both soluble and particulate fractions of hSP. Siaα2,6Gal and N-glycans were concentrated on EVs, whereas Siaα2,3Gal, T and Tn antigens were selectively associated with distinct glycospecies of ASG/mucins. Accessible ligands for the lectins, DC-SIGN and Siglec-9, were detected in all hSP components, but they preferentially bound to EVs glycospecies. Insight into the complexity of hSP glycans as recognition signals under normal physiological conditions could be of interest for regulation and possible modulation of its biological activity, as well as for biomarker potential related to male health.

Extending gene ontology in the context of extracellular RNA and vesicle communication

Background

To address the lack of standard terminology to describe extracellular RNA (exRNA) data/metadata, we have launched an inter-community effort to extend the Gene Ontology (GO) with subcellular structure concepts relevant to the exRNA domain. By extending GO in this manner, the exRNA data/metadata will be more easily annotated and queried because it will be based on a shared set of terms and relationships relevant to extracellular research.

Methods

By following a consensus-building process, we have worked with several academic societies/consortia, including ERCC, ISEV, and ASEMV, to identify and approve a set of exRNA and extracellular vesicle-related terms and relationships that have been incorporated into GO. In addition, we have initiated an ongoing process of extractions of gene product annotations associated with these terms from Vesiclepedia and ExoCarta, conversion of the extracted annotations to Gene Association File (GAF) format for batch submission to GO, and curation of the submitted annotations by the GO Consortium. As a use case, we have incorporated some of the GO terms into annotations of samples from the exRNA Atlas and implemented a faceted search interface based on such annotations.

Results

We have added 7 new terms and modified 9 existing terms (along with their synonyms and relationships) to GO. Additionally, 18,695 unique coding gene products (mRNAs and proteins) and 963 unique non-coding gene products (ncRNAs) which are associated with the terms: “extracellular vesicle”, “extracellular exosome”, “apoptotic body”, and “microvesicle” were extracted from ExoCarta and Vesiclepedia. These annotations are currently being processed for submission to GO.

Conclusions

As an inter-community effort, we have made a substantial update to GO in the exRNA context. We have also demonstrated the utility of some of the new GO terms for sample annotation and metadata search.

Diversity of extracellular vesicles in human ejaculates revealed by cryo-electron microscopy

Human ejaculates contain extracellular vesicles (EVs), that to a large extent are considered to originate from the prostate gland, and are often denominated “prostasomes.” These EVs are important for human fertility, for example by promoting sperm motility and by inducing immune tolerance of the female immune system to the spermatozoa. So far, the EVs present in human ejaculate have not been studied in their native state, inside the seminal fluid without prior purification and isolation procedures. Using cryo-electron microscopy and tomography, we performed a comprehensive inventory of human ejaculate EVs. The sample was neither centrifuged, fixed, filtered or sectioned, nor were heavy metals added. Approximately 1,500 extracellular structures were imaged and categorized. The extracellular environment of human ejaculate was found to be diverse, with 5 major subcategories of EVs and 6 subcategories of extracellular membrane compartments, including lamellar bodies. Furthermore, 3 morphological features, including electron density, double membrane bilayers and coated surface, are described in all subcategories. This study reveals that the extracellular environment in human ejaculate is multifaceted. Several novel morphological EV subcategories are identified and clues to their cellular origin may be found in their morphology. This inventory is therefore important for developing future experimental approaches, and to interpret previously published data to understand the role of EVs for human male fertility.

Prostasomes: extracellular vesicles from the prostate

The term 'prostasomes' is generally used to classify the extracellular vesicles (EVs) released into prostatic fluid by prostate epithelial cells. However, other epithelia within the male reproductive tract also release EVs that mix with 'true' prostasomes during semen emission or ejaculation. Prostasomes have been proposed to regulate the timing of sperm cell capacitation and induction of the acrosome reaction, as well as to stimulate sperm motility where all three are prerequisite processes for spermatozoa to attain fertilising capacity. Other proposed functions of prostasomes include interfering with the destruction of spermatozoa by immune cells within the female reproductive tract. On the other hand, it is unclear whether the distinct presumed functions are performed collectively by a single type of prostasome or by separate distinct sub-populations of EVs. Moreover, the exact molecular mechanisms through which prostasomes exert their functions have not been fully resolved. Besides their physiological functions, prostasomes produced by prostate tumour cells have been suggested to support prostate cancer spread development, and prostasomes in peripheral blood plasma may prove to be valuable biomarkers for prostate cancer.

Prostasomes are heterogeneous regarding size and appearance but affiliated to one DNA-containing exosome family

BACKGROUND

Prostate acinar epithelial cells release microvesicles (prostasomes) that possess pleiotropic biological effects relevant for successful fertilization. Prostasomes are formed in a similar way as exosomes but are heterogeneous as regards size and appearance. Like exosomes they are thought to be mediators of intercellular communication.

METHODS

We prepared seminal prostasomes in accordance with the prevailing protocol for exosome preparation including passage through a 0.2 µm filter and centrifugation in a sucrose gradient.

RESULTS

We compared the "filterable prostasomes" with those trapped on the filter ("nonfilterable prostasomes") and, qualitatively, no conspicuous differences were apparent regarding ultrastructure and SDS-PAGE banding pattern. Moreover, both types of prostasomes contained DNA fragments and Western blot revealed presence of prostate specific membrane antigen (PSMA), CD38, and annexin A1.

CONCLUSIONS

Reasonably, prostasomes could be included in the exosome family and be regarded as one entity containing chromosomal DNA.

Role of exosomes/microvesicles in the nervous system and use in emerging therapies

Extracellular membrane vesicles (EMVs) are nanometer sized vesicles, including exosomes and microvesicles capable of transferring DNAs, mRNAs, microRNAs, non-coding RNAs, proteins, and lipids among cells without direct cell-to-cell contact, thereby representing a novel form of intercellular communication. Many cells in the nervous system have been shown to release EMVs, implicating their active roles in development, function, and pathologies of this system. While substantial progress has been made in understanding the biogenesis, biophysical properties, and involvement of EMVs in diseases, relatively less information is known about their biological function in the normal nervous system. In addition, since EMVs are endogenous vehicles with low immunogenicity, they have also been actively investigated for the delivery of therapeutic genes/molecules in treatment of cancer and neurological diseases. The present review summarizes current knowledge about EMV functions in the nervous system under both physiological and pathological conditions, as well as emerging EMV-based therapies that could be applied to the nervous system in the foreseeable future.

Secretion patterns and effect of prostate-derived granules on the sperm acrosome reaction of rabbit buck

There is increasing evidence that the particulate fraction of seminal plasma plays an important role in reproduction of several mammalian species. However, the origin and role of these granules in the physiology of rabbit spermatozoa is partially unknown. The aim of this study was to investigate the implication of prostate gland in the production and secretion of granules into the rabbit semen and the role of prostate-derived granules in the sperm acrosome reaction. Light and electron microscopy of the prostate gland showed that the anterior and middle tracts of the prostate (namely the proprostate and prostate, respectively) are chiefly implicated in the secretion of granules of different size: smaller granules (SG; 0.5 μm) and large granules (LG; 4 μm). Two major patterns of secretion were identified, based on electron microscope views: storage granules (large granules) seem to empty inner smaller granules directly into the duct by exocytosis, or the storage vesicle itself is released in toto into the ducts (diacytosis). In vitro experiments using granules from vasectomized rabbits, to exclude testicular origin of granules, showed that granules reduce the acrosome reaction of Percoll-selected spermatozoa, independently of the size. Interestingly, spermatozoa incubated with heat-treated granules showed a higher sperm acrosome reaction rate, suggesting a potential role of granule-derived proteins in this process. Inhibition of the acrosome reaction is a crucial event in rabbit reproduction; ejaculated spermatozoa have to wait for a long time (8-16 h) for egg availability in the female tract after mating. Taking together, our results demonstrate that prostate granules secreted either by exocytosis or diacytosis can preserve spermatozoa fertilizing ability, by preventing sperm acrosome reaction. The type of granule-derived proteins or other macromolecules implicated in this process should be further investigated.

Prostasomes are mediators of intercellular communication: from basic research to clinical implications

Prostasomes are nanosized microvesicles secreted by acinar epithelial cells of the prostate gland. Furthermore, they are intracellular microvesicles inside another larger vesicle, a so-called storage vesicle, equivalent to multivesicular bodies of late endosomal origin. Prostasomes are thought to play an important role in intercellular communication by direct interaction primarily between the immobile acinar cells of the prostate gland and the mobile spermatozoa. Prostasomes transfer not only membrane components but also genetic material to spermatozoa. They are rich in various transferable bioactive molecules (e.g., receptors and enzymes) that promote the fertilizing ability of spermatozoa. In this review, the pleiotropic biological effects of prostasomes that are relevant for successful fertilization will be discussed. The ability to synthesize and export prostasomes to the extracellular space is observed not only in normal prostate epithelial cells but also in malignant prostate cells. Release of prostasomes by prostate cancer cells suggests a role in malignant cell growth and proliferation. These findings may provide new therapeutic and diagnostic strategies.

Proteomic analysis of microvesicles released by the human prostate cancer cell line PC-3

Cancer biomarkers are invaluable tools for cancer detection, prognosis, and treatment. Recently, microvesicles have appeared as a novel source for cancer biomarkers. We present here the results from a proteomic analysis of microvesicles released to the extracellular environment by the metastatic prostate cancer cell line PC-3. Using nanocapillary liquid chromatography-tandem mass spectrometry 266 proteins were identified with two or more peptide sequences. Further analysis showed that 16% of the proteins were classified as extracellular and that intracellular proteins were annotated in a variety of locations. Concerning biological processes, the proteins found in PC-3 cell-released microvesicles are mainly involved in transport, cell organization and biogenesis, metabolic process, response to stimulus, and regulation of biological processes. Several of the proteins identified (tetraspanins, annexins, Rab proteins, integrins, heat shock proteins, cytoskeletal proteins, 14-3-3 proteins) have previously been found in microvesicles isolated from other sources. However, some of the proteins seem to be more specific to the vesicular population released by the metastatic prostate cancer PC-3 cell line. Among these proteins are the tetraspanin protein CD151 and the glycoprotein CUB domain-containing protein 1. Interestingly, our results show these proteins are promising biomarkers for prostate cancer and therefore candidates for clinical validation studies in biological fluids.

Identification of distinct populations of prostasomes that differentially express prostate stem cell antigen, annexin A1, and GLIPR2 in humans

In addition to sperm cells, seminal fluid contains various small membranous vesicles. These include prostasomes, membrane vesicles secreted by prostate epithelial cells. Prostasomes have been proposed to perform a variety of functions, including modulation of (immune) cell activity within the female reproductive tract and stimulation of sperm motility and capacitation. How prostasomes mediate such diverse functions, however, remains unclear. In many studies, vesicles from the seminal plasma have been categorized collectively as a single population of prostasomes; in fact, they more likely represent a heterogeneous mixture of vesicles produced by different reproductive glands and secretory mechanisms. We here characterized membranous vesicles from seminal fluid obtained from vasectomized men, thereby excluding material from the testes or epididymides. Two distinct populations of vesicles with characteristic sizes (56 ± 13 nm vs. 105 ± 25 nm) but similar equilibrium buoyant density (∼1.15 g/ml) could be separated by using the distinct rates with which they floated into sucrose gradients. Both types of vesicle resembled exosomes in terms of their buoyant density, size, and the presence of the ubiquitous exosome marker CD9. The protein GLIPR2 was found to be specifically enriched in the lumen of the smaller vesicles, while annexin A1 was uniquely associated with the surface of the larger vesicles. Prostate stem-cell antigen (PSCA), a prostate-specific protein, was present on both populations, thereby confirming their origin. PSCA was, however, absent from membrane vesicles in the seminal fluid of some donors, indicating heterogeneity of prostasome characteristics between individuals.

Secretions from seminal vesicles lack characteristic markers for prostasomes

BACKGROUND

Prostasomes are suggested to be produced in the prostate gland. Although biochemical studies support this, some immunohistochemical findings indicate that also the seminal vesicles could be a source of prostasomes. Therefore, we have compared the secretion of the vesicles with that of the prostate using biochemical and ultrastructural techniques.

METHODS

Ultracentrifuged pellets of substance from seminal vesicle secretions were analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and flow cytometry. The secretory cells of the seminal vesicles were examined with transmission electron microscopy. These findings were then compared with published results from similar studies of the prostate secretory cells.

RESULTS

In SDS-PAGE, the seminal vesicle pellets lacked the three prostasome-characteristic CD-markers, namely CD10, CD13, and CD26, but expressed two proteins of about 55 kDa and 70 kDa, corresponding to clusterin and heat shock protein (HSP70). Flow cytometry showed the presence of secretion particles in the seminal pellet, although of a smaller size than that of the prostasomes. Electron microscopy of the luminal part of the cells in the seminal vesicles demonstrated many secretion granules, each enclosed in a vesicle with a size of about 1 microm.

CONCLUSIONS

Pelleted seminal vesicle secretion is different to prostate secretion in several ways. No prostasome characteristics were detected in the pelleted seminal vesicle secretion.

Structural heterogeneity and protein composition of exosome-like vesicles (prostasomes) in human semen

BACKGROUND

Human seminal fluid contains small exosome-like vesicles called prostasomes. Prostasomes have been reported previously to play an important role in the process of fertilization by boosting survivability and motility of spermatozoa, in addition to modulating acrosomal reactivity. Prostasomes have also been reported to present with sizes varying from 50 to 500 nm and to have multilayered lipid membranes; however, the fine morphology of prostasomes has never been studied in detail.

METHODS

Sucrose gradient-purified prostasomes were visualized by cryo-electron microscopy (EM). Protein composition was studied by trypsin in-gel digestion and liquid chromatography/mass spectrometry.

RESULTS

Here we report for the first time the detailed structure of seminal prostasomes by cryo-EM. There are at least three distinct dominant structural types of vesicles present. In parallel with the structural analysis, we have carried out a detailed proteomic analysis of prostasomes, which led to the identification of 440 proteins. This is nearly triple the number of proteins identified to date for these unique particles and a number of the proteins identified previously were cross-validated in our study.

CONCLUSION

From the data reported herein, we hypothesize that the structural heterogeneity of the exosome-like particles in human semen reflects their functional diversity. Our detailed proteomic analysis provided a list of candidate proteins for future structural and functional studies.

Seminal thrombin-activatable fibrinolysis inhibitor: a regulator of liquefaction

Several active components of the haemostatic system have been identified in human semen. Here we investigated the presence of thrombin-activatable fibrinolysis inhibitor (TAFI) in seminal plasma. Using an enzyme-linked immunosorbent assay, TAFI levels were measured in 36 semen specimens obtained from subfertile, normally fertile, fertile sperm donor and vasectomized individuals. TAFI was detectable in human semen. Its levels were highest in vasectomized individuals compared with the other groups, including a pooled normal semen parameter stratification group (by World Health Organization criteria). This elevation in the vasectomy group was found to be statistically significant in comparison with the normally fertile (P < 0.01) and the pooled normal semen parameter groups (P < 0.05). Seminal TAFI levels showed a significant positive correlation with total sperm count and sperm density. In contrast, a negative association was observed with semen volume, days of sexual abstinence and liquefaction time. The highly motile sperm group showed low TAFI levels. Our results establish the presence of TAFI in seminal plasma with a probable role in the protection of the seminal clot against lysis. It also suggests a downstream (post-testicular) source for its production. This reinforces the involvement of the conventional haemostatic system in the coagulation and liquefaction properties of human semen.

Seminal factor VII and factor VIIa: supporting evidence for the presence of an active tissue factor-dependent coagulation pathway in human semen

Human semen spontaneously coagulates into a semisolid mass and then wholly liquefies in a process that may have some similarity to that of normal blood. This well described phenomenon is referred to as coagulation and liquefaction of semen. Besides other active components of the haemostatic system, semen contains a significant amount of functional tissue factor (TF). However, TF needs factor (F)VII in order to exert it actions. In this study, we assessed human semen for the presence of FVII and FVIIa, and related their levels to conventional fertility parameters. Using a functional, one stage, clotting assay based upon the prolongation of the prothrombin clotting time, using the ACL 300R analyser and an Imubind FVIIa ELISA assay, FVII and FVIIa levels were measured in 97 semen specimens obtained from sub-fertile (sperm counts <20 x 10(6)/mL), normally fertile (sperm counts >or=20 x 10(6) but <60 x 10(6)/mL), fertile sperm donors (sperm counts >or=60 x 10(6)/mL), vasectomized subjects and in a pooled normal semen parameters group (categorization into groups was based on the World Health Organization guidelines on fertility criteria). In addition, conventional semen parameters were analysed on all semen samples. Both FVII and FVIIa were quantifiable in human semen. The mean levels of FVII and FVIIa were 4.4 IU/dL and 12 ng/mL respectively. Despite the observed variations of FVIIa levels in the studied groups they did not meet statistical significance when the groups were tested against each other. However, seminal FVIIa levels showed a significant positive association with semen liquefaction time, sperm motility and semen volume. The anti-sperm antibodies and sperm-agglutination groups were also associated with raised seminal FVIIa levels. We observed no significant relationship between FVIIa levels and total sperm concentration, sperm count per mL (sperm density), sperm progression and days of sexual abstinence. This study demonstrates that human semen contains appreciable amounts of FVII and FVIIa. It is possible to quantify these using commercially available assays. There also appears to be a direct correlation between the levels of these factors and certain seminal parameters. This finding reinforces the concept of an active clotting system in human semen, by establishing the missing link in the activation of a TF-dependent pathway.

The origin of membrane vesicles in ram seminal plasma

The hypothesis tested in this study was that the membrane vesicles present in ram seminal plasma are of testicular origin, rather than being secreted by the accessory sex glands as has been previously reported for a number of species. Membrane vesicles were present in cellular extracts from reproductive organs and accessory sex glands of six rams, and in the seminal plasma of a further eight rams. When four of the latter rams were subjected to vasectomy, to isolate ejaculate contents to only the secretions of the accessory sex glands, the vesicles were largely eliminated from their ejaculates, while vesicles were still present in the ejaculates of the four control rams. The constituents of the cytoplasmic droplets and membrane vesicles derived from the seminal plasma were compared by transmission electron microscopy (TEM). Vesicles present in the cytoplasmic droplets were similar in morphology but smaller on average than those in the seminal plasma. It was concluded that the membrane vesicles in ram seminal plasma originate from either the cytoplasmic droplets, or a combination of vesicles from the droplets and the epididymis.

Mycophenolic acid-induced replication arrest, differentiation markers and cell death of androgen-independent prostate cancer cells DU145

Inosine 5'-monophosphate dehydrogenase inhibitors including mycophenolic acid (MPA) are effective inducers of terminal differentiation in a variety of distinct human tumor cell types. Here, we report that MPA also induces such a differentiation in the androgen-independent prostate cancer derived cell line DU145. MPA evoked replication arrest and accumulation of the DU145 cells in the S-phase of the cell cycle. The inhibitor also induced the expression of CD55, clusterin, granulophysin, glucose-regulated protein 78, vasoactive intestinal polypeptide and prostate-specific transglutaminase, which are differentiation markers associated with the phenotype of normal prostate cells. We suggest that inosine 5'-monophosphate dehydrogenase inhibitors, which are already used for the treatment of other diseases, may be used as potential differentiation therapy drugs to control prostate cancer.

Seminal tissue factor revisited

Studies of seminal tissue factor (TF) are few and mostly based on small numbers. Due to the reported lack of factor (F) X in semen, it has been suggested that TF may not have a role in seminal coagulum formation. However, recent identification of a number of haemostatic factors in semen justifies a re-evaluation of its occurrence. Semen specimens were collected from sub-fertile (n = 19), normally fertile (n = 33), semen donors (n = 30) and vasectomized subjects (n = 62), some fractionated into sperm, a prostasome-rich fraction and seminal plasma. Functional and antigenic TF levels were measured and related to conventional fertility parameters. Semen contains high concentration of functional and antigenic TF. Most TF was found in seminal plasma prepared by low-speed centrifugation. When further fractionated by ultracentrifugation much of this may reside in the pellet (prostasomal fraction). It was also detectable on sperm. TF antigen levels were higher in vasectomized subjects than sub-fertile, normally fertile, donor (p = 0.02) and a 'pooled normal semen parameters' (PNSP) stratification (derived from a combination of measurements) (p = 0.06). The sub-fertile group showed a wider variation than normal, donor or the PNSP subjects. Seminal TF antigen levels correlated significantly with sperm agglutination (p = 0.03) and abnormal sperm morphology (p = 0.04). Subjects with anti-sperm antibodies also showed high TF antigen levels. In conclusion, semen contains functional and antigenic TF at high concentrations. A full complement of clotting factors probably exists in semen, so some pro-coagulant role for TF should not be excluded. Decreased seminal TF levels appear to be associated with seminal parameters that are known to favour male fertility.

Role of exosomes in sperm maturation during the transit along the male reproductive tract

Even tough differentiated spermatozoa are unable of transcriptional or translational activity; the sperm surface undergoes major modifications in macromolecules composition during the transit along the male reproductive tract. This is the result of sequential, well orchestrated interactions between the male reproductive tract secretions and the transiting male gamete. This is particularly true when spermatozoa transit along the epididymis. The epididymis is a long convoluted tubules in which the spermatozoa leaving the testis have to transit. The unraveled epididymal tubule can be as long as 80 m in stallion, and the transit time of spermatozoa is of 3-12 days depending on the species. The epididymis is usually divided in three segments: the caput (proximal part), the corpus, and cauda. While the cauda epididymides acts as a sperm reservoir, the caput and corpus are responsible for sperm maturation. This means that, under androgen control, the epididymal epithelium secretes proteins that will interact sequentially with sperm surface. Some of the sperm proteins acquired during maturation along the excurrent duct behave as integral membrane proteins. In fact, some epididymal originating proteins are glycosylphosphatidylinositol (GPI)-anchored to the sperm plasma membrane. Our laboratory has shown that some of these proteins are secreted in an apocrine manner by the epididymal epithelium and are associated to exosomes, called epididymosomes. Epididymosomes are rich in sphingomyelin and are characterized by a high cholesterol/phospholipids ratio. Many proteins are associated to epididymosomes, some of which are selectively transferred to spermatozoa during the epididymal transit. We have identified some of these exosomes associated proteins transferred to the maturing spermatozoa. These include two enzymes involved in the polyol pathway: an aldose reductase and a sorbitol dehydrogenase. A cytokine named MIF (macrophage migration inhibitory factor) is another protein associated to exosomes who is transferred to spermatozoa during the epididymal transit. We hypothesized that both the polyol pathway and MIF secreted in an apocrine fashion by the epididymal epithelium modulate sperm motility during the transit along the male reproductive tract. Finally, P25b, belonging to a family of sperm surface proteins (P26h/P34H) necessary for the binding to the surface of the egg, is also acquired through the interaction between epididymosomes and the male gamete. In vitro studies have defined the conditions of protein transfer when epididymal spermatozoa are co-incubated with epididymosomes. The transfer of selected proteins to specific membrane domains of spermatozoa is saturable, temperature and pH-dependent, being optimal at pH 6.5. The presence of zinc in the incubation medium, but not of calcium neither magnesium, significantly increases the efficiency of protein transfer. These results show that exosomes play a role in sperm epididymal maturation which is an essential event to produce male gametes with optimal fertilizing ability.

Differentiation of human prostate cancer PC-3 cells induced by inhibitors of inosine 5'-monophosphate dehydrogenase

To establish a system to study differentiation therapy drugs, we used the androgen-independent human prostate PC-3 tumor cell line as a target and mycophenolic acid (MPA), tiazofurin, or ribavirin, which are inhibitors of IMP dehydrogenase, as inducers. These inhibitors evoked replication arrest, caused an increase in cell size, and triggered vacuolization of the cytoplasm. By Northern and Western blotting and immunostaining, we demonstrated MPA-induced expression of 12 proteins reported to reside in prostasomes, organelles released by secretory luminal prostate cells. Additional MPA-induced proteins were identified by two-dimensional gel electrophoresis. Among these was keratin 17, a prostate cell differentiation marker. By Northern blotting, we also demonstrated the constitutive expression of keratins 8 and 18 and induced expression of keratin 19, three other prostate cell differentiation markers. In addition, we established that cells were committed to differentiate after the 2nd day of MPA treatment using guanosine, which can abrogate the effects of MPA. Based on the expression patterns of prostasomal proteins and keratins and the presence of tentative secretory vacuoles, we hypothesize that IMP dehydrogenase inhibitors induce androgen-independent PC-3 cells to mature into cells with a phenotype that resembles normal prostate luminal cells, but at their intermediate state of differentiation.

Identification, proteomic profiling, and origin of ram epididymal fluid exosome-like vesicles

Small membranous vesicles, between 25- and 75-nm diameter, were collected by high-speed centrifugation from the ram cauda epididymal fluid and were found to be normal constituents of this fluid and of the seminal plasma. The SDS-PAGE protein pattern of these vesicles was specific and very different from that of the caudal fluid, seminal plasma, sperm extract, and cytoplasmic droplets. After two-dimensional electrophoresis separation and mass spectrometry analysis, several proteins were identified and grouped into i) membrane-linked enzymes, such as dipeptidyl peptidase IV (DPP-IV), neprilysin (NEP), phosphodiesterase-I (E-NPP3), and protein G-beta; ii) vesicle-associated proteins, such as lactadherin (MFEG8-PAS6/7) and vacuolar ATPase; iii) several cytoskeleton-associated proteins, such as actin, ezrin and annexin; and iv) metabolic enzymes. The presence of some of these proteins as well as several different hydrophobic proteins secreted by the epididymis was further confirmed by immunoblotting. These markers showed that the majority of the vesicles originated from the cauda epididymal region. The physical and biochemical characteristics of these vesicles suggest they are the equivalent of the exosomes secreted by several cell types and epithelium. The main membrane-linked proteins of the vesicles were not retrieved in the extract from cauda or ejaculated sperm, suggesting that these vesicles did not fuse with sperm in vivo.

Pyroglutamyl peptidase I and prolyl endopeptidase in human semen: increased activity in necrozoospermia

Thyrotropin-releasing hormone (TRH) and its analogues have been reported to have important functions in human semen. In the present paper, we have characterized the activity of the TRH-degrading enzymes pyroglutamyl peptidase I and prolyl endopeptidase in the fluid and prostasomes of human semen and in subcellular fractions of the corresponding sperm. Enzymatic activities were measured fluorimetrically using beta-naphthylamine derivatives as substrate. Activity associated with both enzymes was detected in seminal fluid and in the prostasome fraction, as well as in soluble and particulate sperm subcellular fractions. Pyroglutamyl-peptidase I activity presented highest levels in the particulate sperm fraction, whereas the activity of prolyl endopeptidase was maximal in the soluble sperm fraction. In addition, we compared the activity of both enzymes in different seminal fractions in normozoospermic, fertile men and in subfertile patients with different abnormalities revealed by spermiogram analysis (astenozoospermia, necrozoospermia and teratozoospermia). The activities of pyroglutamyl peptidase I and prolyl endopeptidase in necrozoospermia were found to be higher in the corresponding soluble and particulate sperm fractions, respectively, with respect to those measured in normozoospermic semen. The results of the present study indicate that these enzymes may participate in regulating the levels of seminal TRH analogues and in mediating sperm death associated with necrozoospermia.

Characterization and Localization of Membrane Vesicles in Ejaculate Fractions from the Ram, Boar and Stallion

Membrane vesicles, separated by differential centrifugation from the seminal plasma, were detected in the sperm-rich ejaculate fractions of four boars and three stallions, and in the whole ejaculates of seven rams. The volume and percentage of vesicles, determined by a stereological technique, were higher in the sperm-rich than in the post-sperm-rich fractions of the boar and stallion ejaculates, and no vesicles were detected in the pre sperm-rich fractions. Vesicles were examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). For boar, stallion and ram semen, the mean (+/- s.e.m.) vesicle diameters were 130.9 +/- 3.22 (range 18-577), 164.1 +/- 4.42 (range 15-671) and 159.7 +/- 2.92 nm (range 22-986), respectively, although they were not significantly different (p = 0.709). The vesicles had approximately round (TEM) or spherical shape (SEM), were surrounded by single, double or multi-laminar membranes, and were trapped within ample amorphous material, sometimes containing short, flattened membranous elements. The majority of the vesicles had a clear interior but some contained granule-dense material. Ram membrane vesicles, purified from ultracentrifuged plasma by size exclusion chromatography, kept their round shape and the amorphous material was less evident compared with the sections taken before purification. This is the first report to identify seminal plasma membrane vesicles in the different fractions of ejaculated semen in the boar and stallion, and confirms their presence in ram seminal plasma. The origin and function of these vesicles are yet to be elucidated.