Polyspermy, or fertilization of an egg by more than 1 sperm, is believed to be the cause of at least 5% of spontaneous pregnancy loss in humans. To inhibit fertilization by additional sperm, eggs have developed preventative mechanisms known as blocks to polyspermy. The block at the level of the egg extra cellular coat has been well characterized in many different animal species, and the block at the level of the egg plasma membrane is understood in some non-mammalian species. However, virtually nothing is known about the membrane block to polyspermy in mammalian eggs, despite data dating back 50-90 years that provide evidence for its existence. Our recent data demonstrates that sperm-induced Ca2+ signaling and the egg actin cytoskeleton are 2 components involved in this post-fertilization change that transforms the egg membrane from a form that supports fertilization to 1 that prevents it. The broad, long-term goal of this project is elucidating the mechanism of the membrane block to polyspermy, from the fertilization-associated signaling that initiates membrane block establishment to the changes in the egg membrane and cortex that prevent additional fertilization. To make progress toward this goal and to build on our recent published and preliminary data, our studies in this proposal will address the following specific aims.
Specific Aim 1 will determine the mechanisms by which sperm and sperm-induced Ca2+ signaling induce the establishment of the membrane block.
This aim will identify what sperm component(s) is involved in membrane block establishment and how sperm-induced Ca2+ signaling affects characteristics of the membrane block.
Specific Aim 2 will characterize the next step in the pathway following Ca2+ by identifying the Ca2+-dependent effector molecules that are involved in the establishment of the membrane block to polyspermy. Finally, Specific Aim 3 will focus on the later steps of the pathway culminating in the membrane block to polyspermy, examining specific changes in the egg membrane and cortex.
This aim will test the hypotheses that cortical granule exocytosis, endocytosis, and post-fertilization changes in cortex composition and membrane order contribute to the down-regulation of egg membrane receptivity to sperm that follows fertilization. These inquiries into sperm-induced signaling, calcium, and post-fertilization membrane and cortical dynamics will provide important insights into the cellular and molecular mechanisms underlying the mammalian membrane block to polyspermy, advancing our knowledge of this fundamental question in reproductive and developmental biology.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD045671-03
Application #
7209724
Study Section
Cellular, Molecular and Integrative Reproduction Study Section (CMIR)
Program Officer
Rankin, Tracy L
Project Start
2005-04-20
Project End
2010-03-31
Budget Start
2007-04-01
Budget End
2008-03-31
Support Year
3
Fiscal Year
2007
Total Cost
$260,268
Indirect Cost
Name
Johns Hopkins University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
001910777
City
Baltimore
State
MD
Country
United States
Zip Code
21218
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Mackenzie, Amelia C L; Kyle, Diane D; McGinnis, Lauren A et al. (2016) Cortical mechanics and myosin-II abnormalities associated with post-ovulatory aging: implications for functional defects in aged eggs. Mol Hum Reprod 22:397-409
Kryzak, Cassie A; Moraine, Maia M; Kyle, Diane D et al. (2013) Prophase I mouse oocytes are deficient in the ability to respond to fertilization by decreasing membrane receptivity to sperm and establishing a membrane block to polyspermy. Biol Reprod 89:44
Evans, Janice P; Robinson, Douglas N (2011) The spatial and mechanical challenges of female meiosis. Mol Reprod Dev 78:769-77
Marcello, Matthew R; Jia, Weitao; Leary, Julie A et al. (2011) Lack of tyrosylprotein sulfotransferase-2 activity results in altered sperm-egg interactions and loss of ADAM3 and ADAM6 in epididymal sperm. J Biol Chem 286:13060-70
Larson, Stephanie M; Lee, Hyo J; Hung, Pei-hsuan et al. (2010) Cortical mechanics and meiosis II completion in mammalian oocytes are mediated by myosin-II and Ezrin-Radixin-Moesin (ERM) proteins. Mol Biol Cell 21:3182-92
Glazar, Amanda I; Evans, Janice P (2009) Immunoglobulin superfamily member IgSF8 (EWI-2) and CD9 in fertilisation: evidence of distinct functions for CD9 and a CD9-associated protein in mammalian sperm-egg interaction. Reprod Fertil Dev 21:293-303
Evans, Janice P (2009) Egg integrins: back in the game of mammalian fertilization. ACS Chem Biol 4:321-3
Dalo, Diane T; McCaffery, J Michael; Evans, Janice P (2008) Ultrastructural analysis of egg membrane abnormalities in post-ovulatory aged eggs. Int J Dev Biol 52:535-44
Vjugina, Ulyana; Evans, Janice P (2008) New insights into the molecular basis of mammalian sperm-egg membrane interactions. Front Biosci 13:462-76

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