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General Comment |
Ki-67 is a commercially available monoclonal antibody that reacts with a nuclear antigen expressed in proliferating
cells but not in quiescent cells. Expression of this antigen occurs preferentially during late G1, S, G2, and M phases of
the cell cycle, while in cells in G0 phase the antigen cannot be detected. Consequently, the antibody is used in tumor
pathology to detect proliferating cells in neoplastic diseases. In cultured cells an antigen in the nucleolus of interphase
cells stains with Ki-67, which, furthermore, reacts with an interchromatinous network during mitosis.Sequence analysis predicted that the short-lived 2,896- and 3,256-amino acid protein isoforms contain potential nuclear
targeting signals, over 200 potential phosphorylation sites, 19 N-myristoylation sites, 3 amidation sites, and numerous
PEST sites. Antisense oligonucleotides inhibited cellular proliferation in a dose-dependent manner, suggesting that
Ki-67 protein expression may be an absolute requirement for cell proliferation.
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Comment |
Chaffin CL, et al 2001 reported the gonadotropin and steroid control of granulosa cell
proliferation during the periovulatory interval in rhesus
monkeys.
Granulosa cells or ovaries were obtained
from macaques undergoing controlled ovarian stimulation either before (0 h) or
as long as 36 h following the administration of an ovulatory hCG bolus with or
without a 3 beta -hydroxysteroid dehydrogenase inhibitor with or without a
nonmetabolizable progestin. The percentage of cells staining positive for
Ki-67, a nuclear marker for cell proliferation, decreased (P < 0.05) within 12
h of hCG administration in a steroid-independent manner. Levels of cyclin D2
and E mRNA did not decline during the periovulatory interval; however, cyclin
BI mRNA was reduced significantly by 12 h. Steroid depletion increased (P <
0.05) cyclin B1 mRNA at both 12 and 36 h post-hCG and was reversible by
progestin replacement at 36 h. The cyclin-dependent kinase inhibitor p21(Cip1)
was transiently increased 12 h post-hCG, whereas p27(Kip1) mRNA levels
increased at 36 h in a steroid-independent fashion. These data suggest that a
gonadotropin bolus inhibits mitosis in granulosa cells early (12 h) in the
periovulatory interval, whereas progesterone may play a later,
antiproliferative role in luteinized cells of primates.
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