生物谷报道：使得哺乳动物精子和卵子能够相互认识、然后融合形成一个胚胎的分子事件正在逐渐被揭示出来。卵细胞膜上的一种分子，即与Integrin相关的蛋白CD9，最近被发现对于精子和卵子的融合来说是非常重要的，而现在研究人员已在小鼠身上发现了第一个与精子相关的融合因子。该分子是免疫球蛋白这一超级蛋白家族的一个成员，是在NCBI数据库中被发现的。这种被命名为Izumo（该名称源自Izumo Taisha，它是日本的一个与婚姻有关的神社）的蛋白也存在于人精子中，在那里抗Izumo的抗体阻止精卵融合。随着与精卵融合有关的更多分子被发现，研究人员有可能找到受孕和治疗不育症的新方法。该文发表在： Nature 434, 234 - 238 (10 March 2005); doi:10.1038/nature03362
The immunoglobulin superfamily protein Izumo is required for sperm to fuse with eggs
NAOKAZU INOUE1, MASAHITO IKAWA2, AYAKO ISOTANI1,3 & MASARU OKABE1,2,3
1 Genome Information Research Center,
2 Research Institute for Microbial Diseases,
3 Faculty of Pharmaceutical Sciences, Osaka University, Yamadaoka 3-1, Suita, Osaka 565-0871, Japan
Correspondence and requests for materials should be addressed to M.O. (e-mail: okabe@gen-info.osaka-u.ac.jp).
Sequences have been deposited with GenBank under accession numbers AB195681 for mouse Izumo, AB195682 for human Izumo and AB195683 for rat Izumo.
Representing the 60 trillion cells that build a human body, a sperm and an egg meet, recognize each other, and fuse to form a new generation of life. The factors involved in this important membrane fusion event, fertilization, have been sought for a long time. Recently, CD9 on the egg membrane was found to be essential for fusion, but sperm-related fusion factors remain unknown. Here, by using a fusion-inhibiting monoclonal antibody and gene cloning, we identify a mouse sperm fusion-related antigen and show that the antigen is a novel immunoglobulin superfamily protein. We have termed the gene Izumo and produced a gene-disrupted mouse line. Izumo-/- mice were healthy but males were sterile. They produced normal-looking sperm that bound to and penetrated the zona pellucida but were incapable of fusing with eggs. Human sperm also contain Izumo and addition of the antibody against human Izumo left the sperm unable to fuse with zona-free hamster eggs.
