Molecular and immunological approaches to mammalian fertilization.
By means of hybridoma technology, we obtained six hydriboma cell lines producing monoclonal antibody (mAb) to porcine zona pellucid (ZP), two of which recognizes the steric structure of common antigens between porcine ZP and humans. Furthermore, we have analyzed all or partial structures of N- and O-linked sugar chains of ZP glycprotein from porcine or murine oocytes. Then, we have clarified that beta-galactose and Le(X) residues on ZP played the binding roles to sperm cells in porcine and murine fertilization. We have also succeeded Sp38 cDNA cloning from cDNA library of porcine testis. We found that Sp38 protein bind to porcine ZP2 and expressed in murine and human sperm cells. Corresponding to the presence of major histocompatibility complex (MHC) class II on murine sperm, CD4 on the murine egg plasma membrane was clearly shown by indirect IIF and immunoprecipitation test. Furthermore, the transcriptional expression of CD4/p56(lck) in eggs was confirmed by RT-PCR method. In addition, the p56(lck) associated with CD4 underneath the plasma membrane of eggs was autophosphorylated after cross-linking of CD4 with anti CD4 mAb. The binding between eggs or Sf9-CD4 cells labeled with anti-CD4 mAb and sperm cells labeled with anti-monomorphic region of class II mAb was completely blocked. Considering these findings together with the fact that an interspecies' heterogeneity is present in CD4 amino acid sequence at the interactive site with class II, we elucidated that one of species' specific intercellular adhesions between two gametes at the fusion step in fertilization is definitely mediated by class II located on the posterior region of sperm head and CD4/p56(lck) complex on the plasma membrane of egg.
Institute of Medical Science, University of Tokyo, Japan.
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Mori
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Guo
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Sato
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Baba
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Takasaki
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Mori
D000595:Amino Acid Sequence; D000818:Animals; D015704:CD4 Antigens; D002240:Carbohydrate Sequence; D002352:Carrier Proteins; D004527:Egg Proteins; D005260:Female; D005306:Fertilization / Q000276:immunology*; D000949:Histocompatibility Antigens Class II; D006801:Humans; D016256:Lewis X Antigen; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D008297:Male; D008562:Membrane Glycoproteins; D051379:Mice; D008969:Molecular Sequence Data; D013552:Swine
D015704:CD4 Antigens; D002352:Carrier Proteins; D004527:Egg Proteins; D000949:Histocompatibility Antigens Class II; D016256:Lewis X Antigen; D008562:Membrane Glycoproteins; C093236:Sp38 protein, Sus scrofa; C094916:zona pellucida protein, 55-kDa, Oryctolagus cuniculus; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck)