Dr Benjamin Curry

© Cambridge University Press 2011. Introduction apoptosis and DNA damage in human spermatozoa Apoptosis, a physiological process for the controlled deletion of cells, is critical for the regulation of cell numbers, the management of morphogenesis during embryonic development and the orchestration of many cellular processes in the adult. Spermatogenesis, the production of functional spermatozoa from spermatogonial stem cells is no exception. It appears that a functional apoptotic pathway is necessary for normal spermatogenesis to develop and without it infertility ensues. Apoptosis also plays a crucial role in the maintenance of the testis and its response to external toxicants as well as in the programmed senescence of terminally differentiated spermatozoa. This chapter will focus specifically on how apoptosis affects sperm quality and function, and the implications of this process for both embryonic development and the health and well-being of the offspring. A great deal of data has accumulated in recent years suggesting that human spermatozoa can exhibit some of the hallmarks of apoptosis including activation of caspases 1, 3, 8 and 9 [1, 2], annexin-V binding [3, 4], mitochondrial generation of reactive oxygen species (ROS) [5] and DNA fragmentation [6¿8]. The latter is potentially extremely important because DNA damage in the male germ line has been associated with a wide variety of adverse biological and clinical outcomes. Thus DNA damage in human spermatozoa has been correlated with poor fertilization and impaired embryonic development to the blastocyst stage [9, 10] as well as with the incidence of subsequent miscarriage [11¿13].

© 2018 American Society of Andrology and European Academy of Andrology Background and Objectives: Serine proteases are emerging as important players in the spermatozoon's acquisition of functional competence. This study aimed to characterize the serine protease testisin (PRSS21) in stallion spermatozoa, examining its surface expression, possible origins in the testis and epididymis, and changes in response to capacitation and acrosome reaction, as well as its capacity to form high molecular weight complexes and interact with other proteins. Materials and Methods: The role of serine proteases in spontaneous capacitation and acrosome reaction of stallion spermatozoa was established using the serine protease inhibitor, AEBSF. Testisin localization, before and after exposure of stallion spermatozoa to capacitating conditions and calcium ionophore, was examined using live cell immunofluorescence and flow cytometry. Immunohistochemistry of testicular and epididymal tissues was used to further dissect the origins of sperm testisin. Testisin's participation in high molecular weight protein complexes and identification of its interacting partner proteins were investigated using Blue Native PAGE, co-immunoprecipitation, and mass spectrometry, with interrogation of protein¿protein interaction databases and gene ontology analysis of partner proteins used to further explore the potential roles of the testisin-containing complex in sperm function. Results: Testisin surface expression increased significantly in capacitated spermatozoa (p¿<¿0.001), increased further following acrosome reaction (p¿<¿0.01), and was localized to the equatorial region of the sperm head. Testisin was also detected in luminal fluid within the caput and corpus regions of the epididymis, epididymal spermatozoa, and epididymal epithelial cells. Testisin formed several multiprotein complexes; co-immunoprecipitation revealed interactions of testisin with a multitude of zona pellucida-binding proteins, including ZPBP, ZAN, acrosin, several heat-shock proteins, and components of the TCP1 complex. Conclusion: Testisin appears to form part of the zona pellucida-binding complex in stallion spermatozoa and may be involved in the proteolytic cascade that prepares the sperm surface for interaction with the oocyte.

© 2015 Society for Reproduction and Fertility. Stallion spermatozoa continue to present scientific and clinical challenges with regard to the biological mechanisms responsible for their survival and function. In particular, deeper understanding of sperm energy metabolism, defence against oxidative damage and cell-cell interactions should improve fertility assessment and the application of advanced reproductive technologies in the equine species. In this study, we used highly sensitive LC-MS/MS technology and sequence database analysis to identify and characterise the proteome of Percoll-isolated ejaculated equine spermatozoa, with the aim offurthering our understanding of this cell's complex biological machinery. We were able to identify 9883 peptides comprising 1030 proteins, which were subsequently attributed to 975 gene products. Gene ontology analysis for molecular and cellular processes revealed new information about the metabolism, antioxidant defences and receptors of stallion spermatozoa. Mitochondrial proteins and those involved in catabolic processes constituted dominant categories. Several enzymes specific to ß-oxidation of fatty acids were identified, and further experiments were carried out to ascertain their functional significance. Inhibition of carnitine palmitoyl transferase 1, a rate-limiting enzyme of ß-oxidation, reduced motility parameters, indicating that b-oxidation contributes to maintenance of motility in stallion spermatozoa.