Membrane Dynamics of Spermatozoa during Capacitation: New Insight in Germ Cells Signalling

Abstract

The study of germline stem cells and of germline cells has deep implications for the understanding of fertility, development and cancer. Nowadays, we are experiencing the very fascinating challenge of application of -OMICS technologies to this issue, which is opening new and unexpected horizons in virtually all the branches of biology. Here, we carried out a review of signalling systems involved in maturation of male germ cells and in the process that leads them to become fully fertile. In particular, we discuss the control mechanisms involved in capacitation and acrosome reaction that act at membrane level. Indeed, spermatozoa membranes play key roles in determining the achievement of fertility: they are the interface with the surrounding environment, they locate the signal transduction systems and they are active in recognizing and binding the oocyte. In addition, we discuss the effect of several compounds that could exert a negative effect on reproductive activity, by interfering with the endocrine axis, the so-called endocrine disruptors.

Disruption of bovine sperm functions in the presence of aplastic midpiece defect

“…It was reported as suitable to detect early membrane degeneration due to the apoptotic process (Muratori et al, 2004). Besides, it has been proposed that the capacitation-dependent lipid remodeling of sperm plasma membrane and the apoptotic pathway could be interconnected Bernab o et al, 2018).…”

FE-SEM Characterization of α-Mannose Density and Surface Mapping Changes in Human Sperm Head During In Vitro Capacitation

“…The sperm membrane suffers structural remodeling during in vitro capacitation inducing responses that evoke significant changes in glycocalyx components (Liu, 2016; De Jonge, 2017) and also increases their fusogenicity (Bernabó et al, 2018). By using FE-SEM, we determined that α -mannose residues density decreases and develops significant distribution changes in the human spermatozoa plasma membrane during in vitro capacitation.…”

“…Otherwise, the decreasing α -mannose registered in this study during both in vitro capacitation times indicates a noticeable removal of spermatozoa glycocomponents. Surface carbohydrates and other membrane components removing,, such as cholesterol (Gadella & Boerke, 2016), have been described as a mechanism related to the molecular and structural properties that favor posterior fusion and secretory processes during acrosome reaction (Bernabó et al, 2018).…”

“…In turn, the specific location of α -mannose residues in the apical spermatozoa head membrane could suggest the progressive formation of nucleation points during the early steps of acrosome reaction. Nucleation points are described as limited areas where the ionic obstacle present on the membrane surface is surpassed, favoring membrane fusion (Bernabó et al, 2018). Thereby, the physicochemical membrane characteristics acquired during the capacitation process would allow the formation of acrosomal granules whose content will be released in the last stages of acrosome reaction (Sosa et al, 2015).…”

Graphene oxide: A glimmer of hope for Assisted Reproductive Technology

“…In that way, we started our analysis evaluating the sperm membrane state. It is well accepted (although controversial [52,53]) that spermatozoa are transcriptionally silent and with a limited lipid metabolism, with virtually no cytosol (thus numerous molecules involved in sperm signaling are localized in the membrane), pointing out the central role of the membrane during the process of acrosome reaction [54]. During capacitation, numerous membrane lipids are displaced, increasing the membrane fluidity and modulating the activity of several enzymes and proteins, leading to a deep remodeling of the membranes.…”