Raffaele Di Agostino

Bio: Raffaele Di Agostino is an academic researcher from University of Teramo. The author has contributed to research in topics: Biomedical text mining & Sperm-egg recognition. The author has an hindex of 2, co-authored 2 publications receiving 20 citations.

Network Analyses of Sperm–Egg Recognition and Binding: Ready to Rethink Fertility Mechanisms?

Abstract: The rapid growth of published literature makes biomedical text mining increasingly invaluable for unpacking implicit knowledge hidden in unstructured text. We employed biomedical text mining and biological networks analyses to research the process of sperm egg recognition and binding (SERB). We selected from the literature the molecules expressed either on spermatozoa or on oocytes thought to be involved in SERB and, using an automated literature search software (Agilent Literature Search), we realized a network, SERBN, characterized by a hierarchical scale free and a small world topology. We used an integrated approach, either based on selection of hubs or by a cluster analysis, to discern the key molecules of SERB. We found that in most cases some of them are not directly situated on spermatozoa and oocyte, but are dispersed in oviductal fluid or embedded in exosomes present in the perivitelline space. To confirm and validate our results, we performed further analyses using STRING and Reactome FI software. Our findings underscore that the fertility is not a property of gametes in isolation, but rather depends on the functional integrity of the entire reproductive system. These observations collectively underscore the importance of integrative biology in exploring biological systems and in rethinking of fertility mechanisms in the light of this innovative approach.

The maturation of murine spermatozoa membranes within the epididymis, a computational biology perspective.

Abstract: To become fertile, mammalian spermatozoa require completing a complex biochemical maturation that begins in the testis and ends within the female oviduct. Here, we paid attention to the events occurring at the membrane level during the epididymal transit. Indeed, in the epididymis, the molecular composition and the physical-chemical proprieties of sperm membranes markedly change, with functional cross talking among the spermatozoa, the epithelium, and the luminal content (particularly the epididymosomes). To study this process, we undertook a biological networks study, representing the involved molecules as nodes and their interactions as links. The analysis of network topology revealed that it has a scale free and small world architecture and it is robust against random failure. That assures a fast and efficient transmission of information and it leads to identifying the molecules exerting a higher level of control on the system, among which cholesterol plays a pivotal role. The reactome enrichment analysis allowed the reconstruction of the biochemical pathways involved in sperm epididymal maturation and STRING analysis permitted the identification of molecular events possibly involved in that process. In conclusion, this approach allows inferring interesting information, thus contributing to the knowledge on this process and suggesting staring points for further research.

Impact of male fertility status on the transcriptome of the bovine epididymis.

Abstract: Study question Can region-specific transcriptional profiling of the epididymis from fertile and sub-fertile bulls predict the etiology of fertility/sub-fertility in males? Summary answer The highly regulated gene expression along the bovine epididymis is affected by the fertility status of bulls used for artificial insemination. What is known already In mammals, sperm maturation and storage occur in the epididymis. Each epididymal segment has his own transcriptomic signature that modulates the intraluminal composition and consequently governs sequential modifications of the maturing male gamete. Study design, size, duration Epididymides from six Holstein bulls with documented fertility were used. These bulls were divided into two groups: high fertility (n = 3), and medium-low fertility (n = 3) and their epididymal transcriptomic profiles were analyzed. Participants/materials, setting, methods Bovine cDNA microarray probing and bioinformatic tools were used to identify genes that are differentially expressed in caput, corpus and cauda epididymidal tissues of bulls with the documented fertility index. Main results and the role of chance Hierarchical clustering and principal component analysis revealed a clear separation between caput, corpus and cauda epididymides. Some transcripts characterize a particular anatomical segment, whereas others are expressed in two out of three epididymal segments. Gene ontology analysis allowed deduction of specific functions played by each epididymal segment. The transcriptional profiles between fertile versus sub-fertile conditions clustered most closely in the corpus and cauda segments, whereas the profiles in the caput segment were distinct between fertile and sub-fertile bulls. Of the differently expressed genes, 10 (AKAP4, SMCP, SPATA3, TCP11, ODF1, CTCFL, SPATA18, ADAM28, SORD and FAM161A) were found to exert functions related to reproductive systems and 5 genes (DEAD, CYST11, DEFB119, DEFB124 and MX1) were found to be associated with the defense response. Large scale data The GEO number for public access of bovine epididymis microarray data is GSE96602. Limitations, reasons for caution Further work is required to link these modulations of epididymal functions with sperm fertilizing ability in order to understand the etiology of certain cases of idiopathic infertility in livestock and men. Wider implications of the findings As fertility can be quantified in bulls used for artificial insemination, this species is a unique model to aid in the understanding of male fertility/sub-fertility in man. Our data provide a molecular characterization that will facilitate advances in understanding the involvement of epididymal physiology in sub/infertility etiology. Study funding/competing interest(s) This work was supported by a grant to R.S. from the Natural Sciences and Engineering Research Council (NSERC) of Canada. C.L., A.A., E.C. and R.S. have no conflict of interest to declare. P.B. is R&D director at Alliance Boviteq Inc., a bovine artificial insemination company.

Heat Shock Protein member A2 forms a stable complex with angiotensin converting enzyme and protein disulfide isomerase A6 in human spermatozoa

Abstract: Study hypothesis Given the importance of the chaperone Heat Shock Protein A2 (HSPA2) in the regulation of male fertility, this study aimed to identify and characterize additional proteins that may rely on the activity of this chaperone in human spermatozoa. Study finding In view of the findings in this study we propose that angiotensin converting enzyme (ACE) and protein disulfide isomerase A6 (PDIA6) are novel interacting proteins of HSPA2 and that this multimeric complex may participate in key elements of the fertilization cascade. What is known already The molecular chaperone HSPA2 plays a pivotal role in the remodelling of the sperm surface during capacitation. Indeed, human spermatozoa that are deficient in HSPA2 protein expression lack the ability to recognize human oocytes, resulting in repeated IVF failure in a clinical setting. Moreover, our recent work has shown that defective HSPA2 function induced by oxidative stress leads to the aberrant surface expression of one of its interacting proteins, arylsulfatase A, and thus contributes to a loss of sperm-zona pellucida adhesion. Study design, samples/materials, methods Human spermatozoa were collected from fertile donors, capacitated and prepared for Blue Native Polyacrylamide Gel Electrophoresis (BN-PAGE) analysis. Protein complexes resolved via BN-PAGE were excised and their constituents were identified using mass spectrometry. The interactions between ACE, PDIA6 and HSPA2 were then confirmed using immunoprecipitation and proximity ligation assays and the localization of these proteins was assessed in isolated spermatozoa and commercially available human testis tissue sections. Finally, pharmacological inhibition of ACE was performed to assess the role of ACE in human sperm capacitation. Main results and the role of chance Herein we have identified ACE and PDIA6 as potential HSPA2-interacting proteins and shown that this assemblage resides in membrane raft microdomains located in the peri-acrosomal region of the sperm head. Additionally, the surface expression of PDIA6, but not ACE, was shown to be dynamically regulated during sperm capacitation and, like that of previously characterized HSPA2-interacting proteins, this surface expression proved vulnerable to oxidative stress. In terms of the functional significance of this protein complex, pharmacological inhibition of ACE significantly reduced the ability of human spermatozoa to undergo an agonist induced acrosome reaction (P Limitations, reasons for caution While these results provide a descriptive analysis of the PDIA6/ACE/HSPA2 complex, this study provides the impetus for further investigation into the role of PDIA6 and ACE in human sperm function. Wider implications of the findings As our research group, and others, have shown that HSPA2 is compromised in the spermatozoa of men with oocyte recognition defects, the characterization of these HSPA2-interacting proteins provides important insight into the complexity of the cellular pathways that may be affected in the spermatozoa of infertile individuals. Large scale data Large scale proteomics data can be accessed through the Proteomics Identifications Database (PRIDE). Study funding/competing interests This work was supported by the National Health and Medical Research Council. Grant # APP1046346. The authors have no competing interests to declare.

Female-induced remote regulation of sperm physiology may provide opportunities for gamete-level mate choice.

Abstract: In sedentary externally fertilizing species, direct interactions between mating partners are limited and prefertilization communication between sexes occurs largely at the gamete level. Certain combinations of eggs and sperm often have higher fertilization success than others, which may be contingent on egg-derived chemical factors that preferentially attract sperm from compatible males. Here, we examine the mechanisms underlying such effects in the marine mussel Mytilus galloprovincialis, where differential sperm attraction has recently been shown to be associated with variation in offspring viability. Specifically, we focus on the sperm surface glycans, an individually unique layer of carbohydrates that moderate self-recognition and other cellular-level interactions. In many species egg-derived factors trigger remarkable changes in the sperm's glycan layer, physiology, and swimming behavior, and thus potentially moderate mate choice at the gamete level. Here, we show that sperm glycan modifications and the strength of acrosome reaction are both dependent on specific male–female interactions (male–female combination). We also find associations between female-induced sperm glycan changes and the Ca2+ influx into sperm–-a key regulator of fertilization processes from sperm capacitation to gamete fusion. Together, our results suggest that female-induced remote regulation of sperm physiology may constitute a novel mechanism of gamete-level mate choice.

Male Infertility: Shining a Light on Lipids and Lipid-Modulating Enzymes in the Male Germline.

Abstract: Despite the prevalence of male factor infertility, most cases are defined as idiopathic, thus limiting treatment options and driving increased rates of recourse to assisted reproductive technologies (ARTs). Regrettably, our current armory of ARTs does not constitute therapeutic treatments for male infertility, thus highlighting an urgent need for novel intervention strategies. In our attempts to fill this void, we have come to appreciate that the production of pathological levels of oxygen radicals within the male germline are a defining etiology of many idiopathic infertility cases. Indeed, an imbalance of reactive oxygen species can precipitate a cascade of deleterious sequelae, beginning with the peroxidation of membrane lipids and culminating in cellular dysfunction and death. Here, we shine light on the importance of lipid homeostasis, and the impact of lipid stress in the demise of the male germ cell. We also seek to highlight the utility of emerging lipidomic technologies to enhance our understanding of the diverse roles that lipids play in sperm function, and to identify biomarkers capable of tracking infertility in patient cohorts. Such information should improve our fundamental understanding of the mechanistic causes of male infertility and find application in the development of efficacious treatment options.