Miwa N (2015), Protein-Carbohydrate Interaction between Sperm ...

XB-ART-50723

Molecules 2015 May 22;205:9468-86. doi: 10.3390/molecules20059468.

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Protein-Carbohydrate Interaction between Sperm and the Egg-Coating Envelope and Its Regulation by Dicalcin, a Xenopus laevis Zona Pellucida Protein-Associated Protein.

Miwa N .

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Protein-carbohydrate interaction regulates multiple important processes during fertilization, an essential biological event where individual gametes undergo intercellular recognition to fuse and generate a zygote. In the mammalian female reproductive tract, sperm temporarily adhere to the oviductal epithelium via the complementary interaction between carbohydrate-binding proteins on the sperm membrane and carbohydrates on the oviductal cells. After detachment from the oviductal epithelium at the appropriate time point following ovulation, sperm migrate and occasionally bind to the extracellular matrix, called the zona pellucida (ZP), which surrounds the egg, thereafter undergoing the exocytotic acrosomal reaction to penetrate the envelope and to reach the egg plasma membrane. This sperm-ZP interaction also involves the direct interaction between sperm carbohydrate-binding proteins and carbohydrates within the ZP, most of which have been conserved across divergent species from mammals to amphibians and echinoderms. This review focuses on the carbohydrate-mediated interaction of sperm with the female reproductive tract, mainly the interaction between sperm and the ZP, and introduces the fertilization-suppressive action of dicalcin, a Xenopus laevis ZP protein-associated protein. The action of dicalcin correlates significantly with a dicalcin-dependent change in the lectin-staining pattern within the ZP, suggesting a unique role of dicalcin as an inherent protein that is capable of regulating the affinity between the lectin and oligosaccharides attached on its target glycoprotein.

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Species referenced: Xenopus laevis
Genes referenced: fubp1 s100a11 zp3

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	Figure 1. Dicalcin-mediated change in RCA-I reactivity of the zona pellucida (ZP). (a) Blots of the vitelline envelope (VE) were treated with rhodamine-labeled RCA-I. RCA-I recognizes ZPC (arrowhead); (b) Representative confocal images of a Xenopus laevis egg treated with rhodamine-labeled RCA-I. Unfertilized eggs were pretreated with bovine serum albumin (BSA) or dicalcin, followed by RCA-I staining. Insets: higher magnification images. The egg plasma membrane is indicated (arrow). Scale bar: 50 μm; (c) Averaged line scans of RCA-I staining across the frog ZP under lower-sensitivity detection. The position where the RCA-I signal starts to increase is designated as 0 μm in the x-axis; (d) Averaged line scans of RCA-I staining across the frog ZP under higher sensitivity detection. An increase in RCA-I signal at the interface between VE and egg plasma membrane is indicated (arrow). Reproduced from Miwa et al., (2010) [12] with permission of the publisher.
	Figure 2. Dicalcin-binding to frog ZPC increases the RCA-I reactivity of ZPC. (a) Blots of frog ZP proteins were preincubated in the presence or absence of dicalcin, followed by incubation with rhodamine-labeled RCA-I (upper). The normalized intensity is also shown (lower, n = 8; , p = 0.06; *, p = 0.002); (b) Isolation of frog ZPC. Silver, silver-stained frog ZP proteins and isolated ZPC; RCA-I, blot with RCA-I; (c) Schematic representation of the fluorescent signal measurement. A fluorescent signal of the diffusing molecule (red) was detected within a small defined confocal volume (yellow) of the well. Autocorrelation analysis of the fluctuating fluorescent signal estimates the diffusion time of fluorescent molecules and distinguishes small fast-diffusing (i.e., free fluorescent molecules) and large slow-moving (target-bound molecules) molecules; this enabled us to investigate the stoichiometry of the binding; (d) The normalized binding activity of isolated fluorescently labeled ZPC to RCA-I. Reproduced from Miwa et al., (2010) [12] with permission of the publisher.
	Figure 3. Dicalcin-binding to frog ZPC changes the three-dimensional structure of the entire ZP (a) Schematic representation of in vivo labeling of the frog ZP with fluorescent dye; (b) After preincubation either with bovine serum albumin (BSA) or dicalcin, labeled ZP proteins were electrophoresed and fluorescent images were obtained, followed by quantification of the amount of each ZP protein (asterisks); (c) The ratio of the molar amount of labeled protein to the total amount existing in the preparation was calculated for each frog ZP protein (n = 8–10; , p < 0.02; *, p = 0.002). Reproduced from Miwa et al., (2010) [12] with permission of the publisher.

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Baba, Sperm from mice carrying a targeted mutation of the acrosin gene can penetrate the oocyte zona pellucida and effect fertilization. 1994, Pubmed