The fusing ability of sperm is bestowed by CD9-containing vesicles released from eggs in mice.
نویسندگان
چکیده
Membrane fusion is an essential step in the encounter of two nuclei from sex cells-sperm and egg-in fertilization. However, aside from the involvement of two molecules, CD9 and Izumo, the mechanism of fusion remains unclear. Here, we show that sperm-egg fusion is mediated by vesicles containing CD9 that are released from the egg and interact with sperm. We demonstrate that the CD9(-/-) eggs, which have a defective sperm-fusing ability, have impaired release of CD9-containing vesicles. We investigate the fusion-facilitating activity of CD9-containing vesicles by examining the fusion of sperm to CD9(-/-) eggs with the aid of exogenous CD9-containing vesicles. Moreover, we show, by examining the fusion of sperm to CD9(-/-) eggs, that hamster eggs have a similar fusing ability as mouse eggs. The CD9-containing vesicle release from unfertilized eggs provides insight into the mechanism required for fusion with sperm.
منابع مشابه
Residues SFQ (173-175) in the large extracellular loop of CD9 are required for gamete fusion.
Gamete fusion is the fundamental first step initiating development of a new organism. Female mice with a gene knockout for the tetraspanin CD9 (CD9 KO mice) produce mature eggs that cannot fuse with sperm. However, nothing is known about how egg surface CD9 functions in the membrane fusion process. We found that constructs including CD9's large extracellular loop significantly inhibited gamete ...
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Acquisition of fertilization ability by spermatozoa during epididymal transit occurs in part by the transfer of molecules from membranous vesicles called epididymosomes. Epididymosomes are heterogeneous in terms of both size and molecular composition. Exosomes and other related small membranous vesicles (30-120 nm) containing tetraspanin proteins on their surface are found in many biological fl...
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Background: Fertilization and fecundation obviously are the phenomenon in which several factors are involved. Sperm membranous proteins are a series of these important elements. CD9, an inner acrosomal membrane protein, is one of the tetraspanin members that involved in sperm-egg fusion. CD52, is a GPI anchor protein which is expressed in the epididymal cells and during passage of sperms throug...
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Fertilization process is a very clever and unique process comprising some essential steps resulting in formation of zygote. Tetraspanin CD9 is considered to be a serious candidate molecule participating in these events. The importance of CD9 has been discussed in relation to acrosome reaction, sperm-binding, sperm-penetration, sperm-egg fusion and eventually, egg activation. The abundant expres...
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Changes occurring as the prophase I oocyte matures to metaphase II are critical for the acquisition of competence for normal egg activation and early embryogenesis. A prophase I oocyte cannot respond to a fertilizing sperm as a metaphase II egg does, including the ability to prevent polyspermic fertilization. Studies here demonstrate that the competence for the membrane block to polyspermy is d...
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ورودعنوان ژورنال:
- Proceedings of the National Academy of Sciences of the United States of America
دوره 105 35 شماره
صفحات -
تاریخ انتشار 2008