Epidermal growth factor receptor mRNA and protein increase after the four-cell preimplantation stage in murine development.
Epidermal growth factor receptors (EGF-Rs) are expressed at increasing levels on mouse preimplantation embryos. Immunofluorescence assays were used to show that unfertilized eggs and 2-cell embryos have a very low level of reactivity to antimouse EGF-R antibodies, but by the 4-cell stage and later the reactivity increases. The synthesis of EGF-R protein was verified at the blastocyst stage by immunoprecipitation of a 170-kDa metabolically labeled protein. The EGF-R protein is expressed on cell plasma membrane surfaces, but after compaction at the 8-cell stage concentrates on the apical cell surfaces. We also find a low level of expression of EGF-R protein on inner cell mass cells; thus, all cell lineages express receptors from the beginning of gestation. The receptor protein synthesized by the 8-cell embryo and later is probably translated from embryonic transcription, since reverse transcription-polymerase chain reaction indicates increasing levels of mRNA starting after the 4-cell stage. However, we also detected maternal mRNA in zygotes and 2-cell embryos. The pervasive nature of EGF-R expression throughout development suggests important roles for these receptors which could include autocrine and paracrine stimulation.
Wiley
L M
LM
La Jolla Cancer Research Foundation, California 92037.
Wu
J X
JX
Harari
I
I
Adamson
E D
ED
D000818:Animals; D001483:Base Sequence; D001755:Blastocyst / Q000378:metabolism*; D015139:Blotting, Southern; D004622:Embryo, Mammalian / Q000378:metabolism*; D047108:Embryonic Development; D004815:Epidermal Growth Factor / Q000378:metabolism; D066246:ErbB Receptors / Q000096:biosynthesis / Q000235:genetics*; D005260:Female; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D012333:RNA, Messenger; D004815:Epidermal Growth Factor; D066246:ErbB Receptors