Localisation and function of voltage-dependent anion channels (VDAC) in bovine spermatozoa

Abstract

Sperm motility, regulation of cell volume, sperm capacitation, acrosome reaction and tight binding of spermatozoa to the zona pellucida are crucial events in the process of fertilisation. Voltage-dependent anion channels (VDAC) are highly conserved pore-forming proteins implicated in apoptosis, metabolite transport between mitochondria and cytosol, energy metabolism, and cell volume regulation in somatic cells. Several studies have demonstrated the presence of VDAC in cell compartments other than mitochondria. In previous studies using immunofluorescence, we were able to localise VDAC2 and VDAC3 in outer dense fibres of the bovine sperm flagellum. Furthermore, we described the presence of VDAC2 in the head of bovine sperm. In the present study, we confirm the localisation of VDAC2 in the acrosomal region of bovine spermatozoa using immunoelectron microscopy. After incubation with anti-VDAC antibodies raised against each VDAC isoform, bovine spermatozoa showed an increased loss of the acrosomal cap, noticeable changes in the surface of the head, coiled tails and an increased cell volume. The incubation of bovine spermatozoa with anti-VDAC antibodies might lead to alteration of the intracellular ion concentration that causes changes in the cell volume, followed by destabilization of the cytoskeleton and, finally, to loss of the acrosomal cap.

Analysis and difference of voltage-dependent anion channel mRNA in ejaculated spermatozoa from normozoospermic fertile donors and infertile patients with idiopathic asthenozoospermia

“…VDAC2 in the mitochondrial sheath of sperm flagellum can provide required energy for sperm motility via participating in ATP transport and sperm energy metabolism. VDAC2 is also identified in the plasma membrane of sperm head and might be implicated in acrosomal reaction [35]. VDAC, as a channel protein, has been validated to mediate ions transport such as Na + , Ca 2+ , Cl − and HCO 3 − .…”

Co-Incubation of Human Spermatozoa with Anti-VDAC Antibody Reduced Sperm Motility

“…Although VDAC has been studied extensively in somatic cells, little is known about VDAC in male germ cells. Few recent studies have shown that VDAC exists in mammalian spermatozoa and participates in spermatogenesis, maturation, and fertilization [9,10,11,12,13,14]. However, the exact distribution and function of VDAC in mammalian spermatozoa, especially in human spermatozoa, remain unclear.…”

“…VDAC in somatic cells participates in transmembrane transport of Ca 2+ and ATP [2,20,21,22]. Co-incubation of bull spermatozoa with anti-VDAC antibody impairs normal cell morphology and function when the concentration of intracellular ions changes [11]. A previous series of studies performed by the present team focused on the existence and function of VDAC in human spermatozoa.…”

Establishment of human sperm-specific voltage-dependent anion channel 3 recombinant vector for the production of a male contraceptive vaccine

“…Anti-VDAC antibodies against VDAC isoforms functionally lead to a loss of the acrosomal cap, surface alterations of the sperm head, coiled sperm tails and sperm cell volume disturbances. 9,21 In our preliminary study anti-VDAC2 antibody decreased bovine sperm motility, but these results were statistically not significant.…”