Sperm plasma membrane

About: Sperm plasma membrane is a research topic. Over the lifetime, 1016 publications have been published within this topic receiving 49964 citations.

Adhesion molecules in human sperm-oocyte interaction: relevance to infertility.

Abstract: Fertilization involves cell-cell fusion of a sperm with the oocyte. This fusion restores the diploid genome, activates the oocyte, and initiates embryonic development. The identification of proteins mediating the fusion of sperm with oocyte plasma membrane (oolemma) is important to a deeper knowledge of fertilization. Defects in sperm-oocyte fusion may account for some form of human infertility. The hypothesis that sperm plasma membrane and oolemma carry complementary molecules involved in multistep fusion process has been validated by studies of cell adhesion molecules (integrins) in sperm-oocyte interaction in a number of animal models and human in vitro fertilization assays. Integrins or integrin-like molecules and complement proteins present on the surface of mammalian gametes, might be involved in the interaction between oocyte and sperm at fertilization. This review will provide an overview of the interaction of human sperm membrane with the oolemma, the nature of cell adhesion molecules, their expression profiles and their possible involvement in adhesive and fusogenic events in human fertilization. Unraveling the unique molecules involved in human sperm plasma membrane-oolemma fusion will be an important component for the development of a new set of contraceptive vaccines.

Lipid Peroxidation in Human Spermatozoa

Abstract: Oxidation of lipids can be a blessing or a curse as far as spermatozoa are concerned. Beatitudes are conferred via the oxidative generation of oxysterols, which then drive sperm capacitation by promoting the removal of cholesterol from the sperm plasma membrane. Conversely, the anathema involves peroxidation of polyunsaturated fatty acids (PUFA) to generate lipid peroxides that have a detrimental effect on spermatozoa, disrupting DNA integrity and limiting their competence for fertilization. Spermatozoa actively detoxify and remove toxic lipid peroxides from the sperm plasma membrane, but once these defense mechanisms have been overwhelmed, lipid peroxidation spreads rapidly through the cell leading to membrane damage, leakage of ATP, and a rapid loss of sperm motility and viability. The excessive presence of unesterified PUFA may be instrumental in the genesis of oxidative stress through the ability of these amphiphiles to interfere with the mitochondrial electron transport chain and promote cellular generation of superoxide anion.

Ion channels from the mouse sperm plasma membrane in planar lipid bilayers.

Abstract: Fusion of purified mouse sperm plasma membranes to planar lipid bilayers resulted in the insertion of three ion channel types. They could be discerned on the basis of their selectivity, conductance, gating and voltage-dependent properties. The presence of a previously reported large, Ca2+ -selective channel was confirmed. Here, it is reported that the Ca2+ -selective channel from mouse sperm plasma membrane displayed a PNa+/PK+ = 1.6 +/- 0.2 (n = 4) and was blocked by micromolar concentrations of ruthenium red. Fusion yielded also a cation-selective channel (PNa+/PK+ = 2.5 +/- 0.3, n = 3) with a main open conductance substate of 103 pS and a smaller open substate of 51 pS (600 mM K+ cis/100 mM Na+ trans). The channel inserted into bilayers in two stable fashions: a high-activity mode (open probability = 0.57 +/- 0.02, n = 3), and a low activity mode (open probability < 1%, n = 4). In high mode, the channel displayed bursting kinetics and burst length was voltage independent. In addition, a perfectly anion-selective channel, with a slope conductance of 83 pS (600 KCl cis/100 KCl trans), was identified. It displayed a high, nearly constant open probability (approximately 0.90) in the 0 to -80 mV range.

Testase 1 (ADAM 24) a sperm surface metalloprotease is required for normal fertility in mice.

Abstract: ADAM family members play important roles in various physiological and pathological processes, for example, fertilization, embryogenesis, neurogenesis, and development of asthma and arthritis (Primakoff and Myles, 2000. Trends Genet 16: 83-87; Edwards et al., 2008. Mol Aspects Med 29: 258-289). We previously reported that testase 1 (ADAM 24) is the first identified metalloprotease present on the surface of mature sperm. To investigate a potential role of testase 1 in fertilization, we generated testase 1 deficient mice. Testase 1 null male mice showed reduced fertility, producing only half the number of offspring when compared to wild-type littermates. In a standard in vitro fertilization assay, we found that sperm lacking testase 1 gave rise to polyspermic fertilization, a phenotypic feature that might contribute to failure of normal embryo development due to polyaneuploidy. Furthermore, in vivo, we found that testase 1 null males produced a higher number of polyspermic embryos at the pronuclear stage. These findings suggest that testase 1 is a sperm plasma membrane component which contributes to the prevention of polyspermy at the level of the oocyte plasma membrane.