Molecular structure and function of CD4 on murine egg plasma membrane.
In the present study, the expression of the CD4 molecule on murine egg plasma membrane was confirmed by the indirect immunofluorescence (IIF) method. The full-length CD4 cDNA from murine eggs was synthesised by the reverse transcriptase-polymerase chain reaction (RT-PCR) method and its authenticity verified by Southern blot hybridisation using an end-labelled internal oligonucleotide. The results of DNA sequencing showed that the nucleotide sequence of the cDNA of CD4 from murine egg mRNA was identical to that of immune T cells. To demonstrate the direct interaction of CD4 from murine egg with murine sperm cells bearing MHC (major histocompatibility complex) class II molecule, we employed a baculovirus expression system to generate CD4 on the surface of Spodoptera frugiperda (Sf9) cells. Expression of CD4 on Sf9 cells infected with Autographa californica nuclear polyhedrosis virus (AcNPV)-CD4 was demonstrated by IIF and immunoblotting. The CD4-expressing Sf9 cells adhered to MHC class II-bearing sperm cells since the adhesion was specifically blocked by anti-CD4 monoclonal antibody (mAb) or anti-monomorphic region of MHC class II mAb. Taking our previous and present experimental results together, they strongly suggest that intercellular membrane adhesion between two gametes at the fusion step in fertilisation is mediated by the MHC class II molecule located on the posterior region of the sperm head and the CD4 molecule on egg plasma membrane.
Guo
M W
MW
Department of Immunology and Pathology, University of Tokyo, Japan.
Watanabe
T
T
Mori
E
E
Mori
T
T
D000818:Animals; D001483:Base Sequence; D015704:CD4 Antigens / Q000737:chemistry* / Q000502:physiology*; D002448:Cell Adhesion; D002462:Cell Membrane / Q000737:chemistry* / Q000276:immunology; D018076:DNA, Complementary / Q000138:chemical synthesis / Q000737:chemistry; D005260:Female; D015870:Gene Expression; D005822:Genetic Vectors / Q000737:chemistry; D006801:Humans; D008285:Major Histocompatibility Complex; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D015394:Molecular Structure; D017924:Nucleopolyhedroviruses / Q000235:genetics; D010063:Ovum / Q000648:ultrastructure*; D016133:Polymerase Chain Reaction / Q000379:methods; D051381:Rats; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D013094:Spermatozoa / Q000737:chemistry / Q000378:metabolism; D018411:Spodoptera / Q000737:chemistry / Q000235:genetics / Q000821:virology; D013601:T-Lymphocytes / Q000737:chemistry / Q000502:physiology; D015044:Zona Pellucida
D015704:CD4 Antigens; D018076:DNA, Complementary