Sperm-egg fusion occurs at a critical moment in fertilization at which the zygote is formed. In recent progress key proteins on the gamete surfaces have been implicated in membrane fusion. Current evidence indicates: (1) sperm ADAMs may have a role in fusion and (2) the egg tetraspanin CD9 and egg GPI-anchored proteins are required for fusion. ADAM proteins potentially have either cell-cell adhesion activity or protease activity and we propose that each of these is required for normal fertilization. Although gene knockout studies have shown that ADAMs 1, 2 and 3 are not required for fusion, it is possible that other ADAM family members have a role. We will test if a different ADAM acts in fusion of the sperm and egg plasma membranes. We will also test if a known protease, ADAM 24, acts to create the membrane block to polyspermy. Since gene deletion studies have shown that egg CD9 is required for fusion, we focus on CD9's mechanism of action and its localization to lipid microdomains. CD9 is known to have a soluble ligand and we will test if sperm have a related transmembrane ligand to which CD9 binds. In tissue culture lines, CD9 associates with many other proteins on the surface of a CD9-expressing cell. We will test if an egg CD9-associated protein binds to the sperm surface. Gene knockout studies have also shown that egg GPI-anchored proteins are required for fusion. We propose to identify the critical GPl-anchored protein(s) and analyze its mode of action. Since multiple proteins appear to play a role in fusion, we ask how their activities are coordinated. We propose that to function in fusion the active egg molecules must be organized into lipid microdomains. Thus, these studies are designed to combine molecular and cellular levels to bring new insight into the process of gamete membrane fusion.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37HD016580-27
Application #
7414427
Study Section
Reproductive Biology Study Section (REB)
Program Officer
Moss, Stuart B
Project Start
1996-05-01
Project End
2010-03-31
Budget Start
2008-04-01
Budget End
2010-03-31
Support Year
27
Fiscal Year
2008
Total Cost
$308,285
Indirect Cost
Name
University of California Davis
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
047120084
City
Davis
State
CA
Country
United States
Zip Code
95618
Nishimura, Hitoshi; Gupta, Surabhi; Myles, Diana G et al. (2011) Characterization of mouse sperm TMEM190, a small transmembrane protein with the trefoil domain: evidence for co-localization with IZUMO1 and complex formation with other sperm proteins. Reproduction 141:437-51
He, Zhi-Yong; Gupta, Surabhi; Myles, Diana et al. (2009) Loss of surface EWI-2 on CD9 null oocytes. Mol Reprod Dev 76:629-36
Zhu, Guo-Zhang; Gupta, Surabhi; Myles, Diana Gold et al. (2009) Testase 1 (ADAM 24) a sperm surface metalloprotease is required for normal fertility in mice. Mol Reprod Dev 76:1106-14
Gupta, Surabhi; Primakoff, Paul; Myles, Diana G (2009) Can the presence of wild-type oocytes during insemination rescue the fusion defect of CD9 null oocytes? Mol Reprod Dev 76:602
Nishimura, Hitoshi; Myles, Diana G; Primakoff, Paul (2007) Identification of an ADAM2-ADAM3 complex on the surface of mouse testicular germ cells and cauda epididymal sperm. J Biol Chem 282:17900-7
Runge, Kathryn E; Evans, James E; He, Zhi-Yong et al. (2007) Oocyte CD9 is enriched on the microvillar membrane and required for normal microvillar shape and distribution. Dev Biol 304:317-25
Ellerman, Diego A; Myles, Diana G; Primakoff, Paul (2006) A role for sperm surface protein disulfide isomerase activity in gamete fusion: evidence for the participation of ERp57. Dev Cell 10:831-7
Stein, Kathryn K; Go, Jowell C; Primakoff, Paul et al. (2005) Defects in secretory pathway trafficking during sperm development in Adam2 knockout mice. Biol Reprod 73:1032-8
He, Zhi-Yong; Brakebusch, Cord; Fassler, Reinhard et al. (2003) None of the integrins known to be present on the mouse egg or to be ADAM receptors are essential for sperm-egg binding and fusion. Dev Biol 254:226-37
Alfieri, Jennifer A; Martin, Arlan D; Takeda, Junji et al. (2003) Infertility in female mice with an oocyte-specific knockout of GPI-anchored proteins. J Cell Sci 116:2149-55

Showing the most recent 10 out of 46 publications