scholarly journals Partition of the organochlorine insecticide lindane into the human sperm surface induces membrane depolarization and Ca2+ influx

1997 ◽  
Vol 321 (3) ◽  
pp. 691-698 ◽  
Author(s):  
Leopoldo SILVESTRONI ◽  
Roberto FIORINI ◽  
Simonetta PALLESCHI
Keyword(s):  
Plasma Membrane ◽  
Human Sperm ◽  
Membrane Depolarization ◽  
Organochlorine Insecticide ◽  
Dipole Potential ◽  
Membrane Dipole Potential ◽  
High K ◽  
Voltage Dependent ◽  
Sperm Plasma Membrane ◽  
Influx Pathways

The effects of the insecticide lindane (the γ-isomer of 1,2,3,4,5,6-hexachlorocyclohexane) on membrane potential, cytosolic free Ca2+ concentration ([Ca2+]i) and surface biophysical properties were studied in human spermatozoa. The insecticide induces rapid, transient and reproducible membrane depolarization and opening of voltage-dependent Ca2+ channels leading to an increase in [Ca2+]i. In contrast with the effect in somatic cells, lindane did not affect γ-aminobutyric acid receptor-linked Cl- currents. Ca2+ and K+ currents were found to drive lindane-induced membrane depolarization and repolarization respectively, whereas Na+ and Cl- fluxes appear not to have a role in the phenomenon. The insecticide was still able to produce membrane depolarization both in the combined absence of extracellular Ca2+ and Na+ and in high-K+ buffer, suggesting that lindane alters the membrane dipole potential. In agreement with this, Laurodan and Prodan fluorescence spectroscopy revealed that lindane partition into the sperm plasma membrane lowers water molecular dynamics in the uppermost region of the membrane external leaflet, probably as the result of reordering of water dipoles. We propose that the first effect of lindane partitioning into the sperm plasma membrane is a change in the membrane dipole potential, which results in the activation of membrane-located Ca2+-influx pathways.

Mechanism of human sperm activation by extracellular ATP

1996 ◽  
Vol 270 (6) ◽  
pp. C1709-C1714 ◽  
Author(s):  
C. Foresta ◽  
M. Rossato ◽  
P. Chiozzi ◽  
F. Di Virgilio
Keyword(s):  
Plasma Membrane ◽  
Acrosome Reaction ◽  
Human Sperm ◽  
Extracellular Atp ◽  
Effective Concentration ◽  
Na Channel ◽  
Monovalent Cations ◽  
Sperm Activation ◽  
Gated Channel ◽  
Sperm Plasma Membrane

We have identified the mechanism whereby extracellular ATP (ATPe) triggers the acrosome reaction in human spermatozoa. This nucleotide opens a ligand-gated ion channel expressed on the sperm plasma membrane. ATPe threshold and 50% effective concentration calculated on the total added ATPe are 0.1 and 2 mM, respectively, corresponding to a free ATP concentration (ATP4-) of 3 and 200 microM, respectively. The ATPe-gated channel is selective for monovalent cations (Na+, choline, and methylglucamine), whereas on the contrary, permeability to Ca2+ is negligible. Isosmolar replacement of extracellular Na+ with sucrose fully blocked ATPe-dependent sperm activation, thus suggesting a mandatory role for Na+ influx. These results show that human sperm express an ATPe-gated Na+ channel that might have an important role in sperm activation before egg fertilization.

scholarly journals Glycodelin-A interacts with fucosyltransferase on human sperm plasma membrane to inhibit spermatozoa-zona pellucida binding

2006 ◽  
Vol 120 (1) ◽  
pp. 33-44 ◽  
Author(s):  
P. C. N. Chiu ◽  
M.-K. Chung ◽  
R. Koistinen ◽  
H. Koistinen ◽  
M. Seppala ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Zona Pellucida ◽  
Human Sperm ◽  
Sperm Plasma Membrane ◽  
Glycodelin A

Characterization of human sperm plasma membrane: Glycolipids and polypeptides

1987 ◽  
Vol 243 (2) ◽  
pp. 339-346 ◽  
Author(s):  
S. R. Mack ◽  
L. J. D. Zaneveld ◽  
R. N. Peterson ◽  
W. Hunt ◽  
L. D. Russell
Keyword(s):  
Plasma Membrane ◽  
Human Sperm ◽  
Sperm Plasma Membrane

scholarly journals Pharmacology of a Ca2+-influx pathway activated by emptying the intracellular Ca2+ stores in HL-60 cells: evidence that a cytochrome P-450 is not involved

1994 ◽  
Vol 302 (1) ◽  
pp. 187-190 ◽  
Author(s):  
B D Koch ◽  
G F Faurot ◽  
M V Kopanitsa ◽  
D C Swinney
Keyword(s):  
Plasma Membrane ◽  
Selective Inhibitors ◽  
High Affinity ◽  
Voltage Dependent ◽  
Influx Pathways ◽  
Subsequent Activation ◽  
Cytochrome P 450 ◽  
Haem Iron ◽  
Dependent Pathway ◽  
Ca2 Channels

In HL-60 cells, inhibition of the endoplasmic-reticular Ca2+ pump by thapsigargin leads to the emptying of this intracellular Ca2+ store and a subsequent activation of plasma-membrane Ca2+ influx through a non-voltage-dependent pathway. The elevated intracellular free Ca2+ concentration ([Ca2+]i) produced and maintained by this Ca2+ inflow was used to examine the potency of various compounds to inhibit this influx mechanism. As expected, specific blockers of known Ca2+ channels, such as nifedipine, omega-conotoxin GVIA and ryanodine were without effect. The less selective inhibitors La3+, SKF-96365 and L-651,582, which are thought to inhibit both voltage-dependent and voltage-independent Ca2+ channels, decreased [Ca2+]i back to resting levels, with pIC50 values of 5.2, 5.9 and 6.2 respectively. It has been proposed that a cytochrome P-450 is involved in activating Ca(2+)-influx pathways in thymocytes, neutrophils and platelets. Consistent with this idea, the imidazole cytochrome P-450 inhibitors miconazole, econazole, clotrimazole and ketoconazole inhibited the thapsigargin-elevated [Ca2+]i with pIC50 values of 7.1, 7.1, 7.1 and 5.8 respectively. The high affinity of imidazoles for cytochromes P-450 is due to co-ordinate binding to the haem. This interaction is greatly decreased in 2-substituted imidazoles. We examined whether the inhibition of Ca2+ influx was due to an interaction of the inhibitor imidazole nitrogen with the haem iron of the putative cytochrome P-450 by comparing the activity of two compounds, identical except that one was methylated at the imidazole 2-position. They were found to block thapsigargin-activated Ca2+ influx with equal potency. These results strongly suggest that a cytochrome P-450 is not involved in the activation of the Ca2+ influx produced by emptying the intracellular Ca2+ stores.

scholarly journals A mouse sperm decapacitation factor receptor is phosphatidylethanolamine-binding protein 1

Reproduction ◽  
2005 ◽  
Vol 130 (4) ◽  
pp. 497-508 ◽  
Author(s):  
Rachel Gibbons ◽  
Susan A Adeoya-Osiguwa ◽  
Lynn R Fraser
Keyword(s):  
Plasma Membrane ◽  
Binding Protein ◽  
Human Sperm ◽  
Surface Proteins ◽  
Mouse Sperm ◽  
Fertility Treatments ◽  
State Dependent ◽  
Sperm Plasma Membrane ◽  
Associated Proteins ◽  
Functional Consequences

Capacitation is a pivotal event for mammalian spermatozoa, involving the loss of surface proteins known as decapacitation factors (DF) and consequent acquisition of fertilizing ability. Earlier studies showed that a mouse sperm DF binds to a receptor, DF-R, whose attachment to the sperm plasma membrane appears to involve a glycosylphosphatidylinositol (GPI) anchor. In the present study, purification and subsequent sequencing of DF-R has identified this ~23 kDa protein as phosphatidyletha-nolamine-binding protein 1 (PEBP 1). To obtain functional evidence that supports sequence homology data, purified recombinant PEBP 1 and PEBP 2 were evaluated for biological activity. While PEBP 1 was able to remove DF activity in solution at concentrations above ~1 nmol/l, PEBP 2 was ineffective, even at 600 nmol/l; this confirmed that DF-R is PEBP 1. Anti-PEBP 1 antiserum recognized recombinant PEBP 1 and a ~23 kDa protein in both mouse and human sperm lysates. Immunolocalization studies revealed that DF-R/PEBP 1 is located on the acrosomal cap, the post-acrosomal region and the flagellum of both mouse and human spermatozoa, with epitope accessibility being capacitation state-dependent and reversible. Treatment of cells with a phospholipase able to cleave GPI anchors essentially abolished immunostaining, thus confirming the extracellular location of DF-R/PEBP 1. We suggest that DF-R/PEBP 1 plays its fundamental role in capacitation by causing alterations in the sperm plasma membrane in both head and flagellum, with functional consequences for membrane-associated proteins. Obtaining more detail about DF ↔ DF-R interactions could lead to useful applications in both fertility treatments and new contraceptive approaches.

scholarly journals Identification of calcium-binding proteins associated with the human sperm plasma membrane

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Soren Naaby-Hansen ◽  
Alan Diekman ◽  
Jagathpala Shetty ◽  
Charles J Flickinger ◽  
Anne Westbrook ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Calcium Binding ◽  
Binding Proteins ◽  
Human Sperm ◽  
Calcium Binding Proteins ◽  
Sperm Plasma Membrane

Effect of sperm immobilisation and demembranation on the oocyte activation rate in the mouse

Zygote ◽  
1999 ◽  
Vol 7 (3) ◽  
pp. 187-193 ◽  
Author(s):  
T. Kasai ◽  
K. Hoshi ◽  
R. Yanagimachi
Keyword(s):  
Plasma Membrane ◽  
Plasma Membranes ◽  
Human Sperm ◽  
Sperm Head ◽  
The State ◽  
Human Spermatozoa ◽  
Oocyte Activation ◽  
Activation Rate ◽  
Sperm Plasma Membrane ◽  
Triton X

To analyse the effect of the state of the sperm plasma membrane on oocyte activation rate following intracytoplasmic sperm injection (ICSI), three types of human and mouse spermatozoa (intact, immobilised and Triton X-100 treated) were individually injected into mouse oocytes. At 30, 60 and 120 min after injection, maternal chromosomes and sperm nuclei within oocytes were examined. Following human sperm injection, the fastest and the most efficient oocyte activation and sperm head decondensation occurred when the spermatozoa were treated with Triton X-100. Intact spermatozoa were the least effective in activating oocytes. Thus, the rate of mouse oocyte activation following human sperm injection is greatly influenced by the state of the sperm plasma membrane during injection. When mouse spermatozoa were injected into mouse oocytes, the rates of oocyte activation and sperm head decondensation within activated oocytes were the same irrespective of the type of sperm treatment prior to injection. We witnessed that live human spermatozoa injected into moue oocytes often kept moving very actively within the ooplasm for more than 60 min, whereas motile mouse spermatozoa usually became immotile within 20 min after injection into the ooplasm. In 0.002% Triton X-100 solution, mouse spermatozoa are immobilised faster than human spermatozoa. These facts seem to suggest that human sperm plasma membranes are physically and biochemically more stable than those of mouse spermatozoa. Perhaps the physical and chemical properties of the sperm plasma membrane vary from species to species. For those species whose spermatozoa have ‘stable’ plasma membranes, prior removal or ‘damage’ of sperm plasma membranes would increase the success rate of ICSI.

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