Infertility of CD9-deficient mouse eggs is reversed by mouse CD9, human CD9, or mouse CD81; polyadenylated mRNA injection developed for molecular analysis of sperm-egg fusion.
CD9 is a membrane protein belonging to the tetraspanin family. Despite CD9's broad tissue distribution, the only abnormality observed in CD9-deficient mice was infertility of females, which was responsible for a defect in the sperm-egg fusion process. However, the function of CD9 in sperm-egg fusion is not clear at all because the technique to analyze the activity of molecules in sperm-egg fusion has not been established. We demonstrated that the exogenous mouse CD9, expressed by polyadenylated mRNA injection at the germinal-vesicle stage oocytes, was precisely localized to the egg plasma membrane, and the expression reversed the infertility of CD9(-/-) eggs. Then, two other tetraspanins, human CD9 and mouse CD81, overexpressed with this technique on CD9(-/-) eggs restored the fertilization rate up to approximately 90 and approximately 50% against that of wild type eggs, respectively. Moreover, in the presence of an anti-mouse CD9 mAb, which blocks sperm-egg fusion, expression of human CD9 or mouse CD81 on eggs also rescued the fusibility. These results suggested that human CD9 plays a crucial role in human fertilization, and mouse CD81 has the potential to compensate for CD9 function in sperm-egg fusion. In addition, the polyadenylated mRNA injection is effective for molecular analysis of sperm-egg fusion.
Kaji
Keisuke
K
Department of Life Science, Tokyo Institute of Technology, Yokohama, 226-8501, Japan.
Oda
Shoji
S
Miyazaki
Shunichi
S
Kudo
Akira
A
D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D005298:Fertility; D005306:Fertilization; D005307:Fertilization in Vitro; D005838:Genotype; D006801:Humans; D007150:Immunohistochemistry; D007267:Injections; D008561:Membrane Fusion; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D051379:Mice; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D010063:Ovum / Q000254:growth & development; D010957:Plasmids; D026723:Polyadenylation; D012333:RNA, Messenger / Q000008:administration & dosage; D013084:Sperm-Ovum Interactions; D060225:Tetraspanin 28; D060245:Tetraspanin 29; D013997:Time Factors
D015703:Antigens, CD; C554798:CD81 protein, human; C554869:CD9 protein, human; C554799:Cd81 protein, mouse; C554870:Cd9 protein, mouse; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D060225:Tetraspanin 28; D060245:Tetraspanin 29