fusing ability of sperm is bestowed by CD9-containing vesicles released from eggs in mice

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 105; no. 35; pp. 12921 - 12926
• Main Authors: Miyado, Kenji, Yoshida, Keiichi, Yamagata, Kazuo, Sakakibara, Keiichi, Okabe, Masaru, Wang, Xiaobiao, Miyamoto, Kiyoko, Akutsu, Hidenori, Kondo, Takahiko, Takahashi, Yuji, Ban, Tadanobu, Ito, Chizuru, Toshimori, Kiyotaka, Nakamura, Akihiro, Ito, Masahiko, Miyado, Mami, Mekada, Eisuke, Umezawa, Akihiro
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 02.09.2008; National Acad Sciences
• Subjects: Animals; Antigens, CD - metabolism; Biological Sciences; Cell membranes; Cells; Eggs; Exosomes; Female; Female animals; Fertilization; Green Fluorescent Proteins - metabolism; Incubation; Male; Membrane Glycoproteins - deficiency; Membrane Glycoproteins - metabolism; Membranes; Mice; Microvilli; Molecules; Ova; Ovum - cytology; Ovum - metabolism; Ovum - ultrastructure; Recombinant Fusion Proteins - metabolism; Rodents; Secretory Vesicles - metabolism; Secretory Vesicles - ultrastructure; Sperm-Ovum Interactions - physiology; Spermatozoa; Spermatozoa - cytology; Tetraspanin-29; Zona pellucida
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0710608105

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.