Enucleation of human endometrial cells: nucleo-cytoplasmic distribution of DNA polymerase alpha and estrogen receptor.
Nucleo-cytoplasmic distribution of estrogen receptors and DNA polymerase alpha activity in human endometrial adenocarcinoma cells (HEC-50 line) was evaluated after separation of nuclei following either homogenization or enucleation with cytochalasin B. About 30% of the estrogen receptor was found in the nuclear fraction after homogenization whereas 86% was found in the karyoplasts after enucleation. The total amounts of estrogen receptor per cell after homogenization and enucleation were not significantly different (14,000-17,000 binding sites/cell). Receptor measurements were carried out using the hydroxylapatite method after labeling with [3H]estradiol (5 nM [3H]E2 +/- 500 nM E2) at 30 degrees C for 3 h. About 20% of the DNA polymerase alpha activity was found in the nuclear fraction after homogenization, whereas 96% was found in the karyoplasts after enucleation. The average total activity (0.84 Units/10(6) cells) in homogenized cells was about 1/8 of the activity in karyoplasts. These results indicate that estrogen receptor and DNA polymerase alpha activity reside in the nucleus in intact HEC-50 cells. DNA polymerase alpha is translocated to the cytoplasmic fraction and inactivated after homogenization.
A
A
Gravanis
E
E
Gurpide
D000230:Adenocarcinoma; D002458:Cell Fractionation / Q000379:methods; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000201:enzymology / Q000378:metabolism*; D004257:DNA Polymerase II / Q000378:metabolism*; D004717:Endometrium / Q000378:metabolism* / Q000648:ultrastructure; D005260:Female; D006801:Humans; D011960:Receptors, Estrogen / Q000378:metabolism*; D014594:Uterine Neoplasms
D011960:Receptors, Estrogen; D004257:DNA Polymerase II