A cell free system reveals that capacitation is a prerequisite for membrane fusion during the acrosome reaction

Spungin, Ben; Levinshal, T.; Rubinstein, Sara; Breitbart, Haim

doi:10.1016/0014-5793(92)81388-3

Cited by 51 publications

(36 citation statements)

References 42 publications

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“…Albumin is the major protein in the female genital tract secretions and is an important component during in vivo and in vitro capacitation. Indeed, the acrosomal and PMs isolated from bovine sperm can fuse in vitro only if the membranes were prepared from capacitated sperm, a result consistent with the suggestion that the loss of cholesterol during capacitation promotes membrane priming and membrane fusion (Spungin et al 1992). The loss of cholesterol has been suggested to effect the sperm PM lipid bilayer and make it "fusogenic" (for review see Cross 1998).…”

Section: Introductionsupporting

confidence: 63%

Evidence for the capacitation-associated membrane priming of mouse spermatozoa

Abou-Haïla

Tulsiani

2003

Histochem Cell Biol

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An important feature of male fertility is the physiological priming of mammalian spermatozoa by a multifaceted process referred to as capacitation. It is a prerequisite event before spermatozoa can bind to the egg's extracellular coat, the zona pellucida, and undergo a signal transduction cascade. The net result is the fusion of the plasma membrane (PM) and underlying outer acrosomal membrane at multiple sites and the release of acrosomal contents (i.e., glycohydrolases, proteinases, etc.) at the site of sperm-zona binding. In this study, we have used an indirect immunofluorescence (IIF) assay and other staining approaches to examine capacitation-associated membrane priming of mouse spermatozoa. For IIF studies, we used affinity-purified antibodies against two glycohydrolases that cross-reacted with the acrosomal enzymes only when the uncapacitated spermatozoa were permeabilized. Incubation of spermatozoa in a medium that favors in vitro capacitation induced membrane priming that allowed the antibodies to cross-react with the acrosomal enzymes in capacitating acrosome-intact spermatozoa without permeabilization, as revealed by the appearance of several distinct fluorescent patterns, including an initial immunopositive lining over the acrosome cap to an intense immunopositive reaction throughout the acrosome. These early immunopositive patterns were followed by the appearance of intense fluorescent spots (droplets) that seem to establish contact with the PM in a time-dependent manner. Inclusion of calmodulin, a 17-kDa Ca 2+ -binding protein which promotes capacitation, in the incubation medium did not alter the overall rate of capacitation; however, its presence accelerated the initial stages of membrane priming. The potential similarities between sperm capacitation and early events of Ca 2+ -triggered membrane fusion among eukaryotes and among various stations of the secretory and endocytotic pathways are discussed.

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Section: Introductionsupporting

confidence: 63%

Evidence for the capacitation-associated membrane priming of mouse spermatozoa

Abou-Haïla

Tulsiani

2003

Histochem Cell Biol

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“…We have recently shown [19] that remodelling of sperm membranes which takes place during capacitation is a prerequisite for membrane fusion during the acrosome reaction. PAGE analysis of sperm membrane proteins indicates that major remodelling of the protein phase does not occur (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…This vesiculation releases the acrosomal contents, including a variety of hydrolytic enzymes, and is required if fertilization is to proceed further. We have recently shown [19] that membrane remodelling, which occurs during capacitation, is required for the membrane fusion event during the acrosome reaction.…”

Section: Introductionmentioning

confidence: 99%

A 70 kDa protein is transferred from the outer acrsomal to the plasma membrane during capacitation

1995

Self Cite

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Bull sperm plasma and outer acrosomal membranes were analyzed by SDS-PAGE. Analysis of the plasma membrane proteins revealed the presence of a 70 kDa band the prominence of which is enhanced after capacitation. This protein was found to bind to zona pellucida intact oocytes. PAGE analysis of outer acrosomal membrane proteins also reveals the presence of a 70 kDa band, but its prominence decreases after capacitation. This protein also binds to zona pellucida intact oocytes. Futhermore, the 70 kDa outer acrosomal membrane protein is recognized in Western blot analysis by antibodies to plasma membrane proteins and vice versa. The results indicate that the 70 kDa acrosomal and plasma membrane proteins are the same. This 70 kDa protein would thus be a zona pellucida binding protein which is initially stored in the outer acrosomal membrane and transferred to the plasma membrane during capacitation, enabling it to function in egg-sperm binding.

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“…Aromatic sulfonates can serve as important materials in detecting specific organic anion binding proteins in the liver plasma membrane (Yachi et al, 1989), as well as in many other fields (Narayanan & Krakow, 1983;Jiang et al, 1990;Alford et al, 1991;Tharakan et al, 1992;Spungin et al, 1992). The crystal structures of several aromatic sulfonates have been reported (Vembu et al, 2004a,b).…”

Section: Commentmentioning

confidence: 99%