The expression of nuclear lamin A and C epitopes is regulated by the developmental stage of the cytoplasm in mouse oocytes or embryos.
The cytoplasmic regulation of changes of nuclear lamin antigens was examined by transferring 16-cell stage blastomeres into mouse oocytes. Sixteen-cell stage blastomeres were transferred to either pronuclear eggs, enucleated pronuclear eggs or metaphase II oocytes, which were subsequently activated. Pronuclei react with a monoclonal antibody to A/C lamins (J9), whereas nuclei from 16-cell stage blastomeres do not react with J9. However, after transfer of 16-cell stage nuclei to activated metaphase II oocytes, the transferred nuclei acquire the antigen. This is in contrast to 16-cell nuclei that were transferred to intact or enucleated pronuclear eggs; i.e., the nuclei only faintly acquired the A/C epitope. These results suggest that the developmental stage of the cytoplasm regulates the exposure of nuclear lamina epitopes, perhaps by limiting the supply of lamin A/C in the oocyte or because nuclear lamina assembly can only occur at the telophase transition. Furthermore, it appears that there is some exchange of the A/C epitope between (pro)nuclei within the same cell but that the majority of the A/C lamin epitope can be removed from a cell with (pro)nuclear removal.
Department of Zoology, University of Wisconsin, Madison 53706.
R S
RS
Prather
J
J
Kubiak
G G
GG
Maul
N L
NL
First
G
G
Schatten
D000818:Animals; D000911:Antibodies, Monoclonal; D002459:Cell Fusion; D002467:Cell Nucleus / Q000276:immunology; D003593:Cytoplasm / Q000502:physiology*; D004622:Embryo, Mammalian / Q000276:immunology* / Q000378:metabolism; D005314:Embryonic and Fetal Development; D000939:Epitopes / Q000096:biosynthesis*; D034904:Lamin Type A; D034882:Lamins; D051379:Mice; D008813:Mice, Inbred ICR; D009687:Nuclear Proteins / Q000096:biosynthesis* / Q000276:immunology; D053652:Nuclear Transfer Techniques; D009865:Oocytes / Q000276:immunology* / Q000378:metabolism
D000911:Antibodies, Monoclonal; D000939:Epitopes; D034904:Lamin Type A; D034882:Lamins; D009687:Nuclear Proteins