Specific regulation of CENP-E and kinetochores during meiosis I/meiosis II transition in pig oocytes.
To understand the mechanisms which regulate meiosis-specific cell cycle and chromosome distribution in mammalian oocytes, the level and the localization of CENP-E and the kinetochore number and direction on a half bivalent were examined during pig oocyte maturation. CENP-E is a kinetochore motor protein whose intracellular level and localization are strictly regulated in the somatic cell cycle. The localizations of CENP-E on meiotic chromosomes from diakinesis stage to anaphase I and at the spindle midzone at telophase I were shown by immunofluorescent confocal microscopy to be similar to those in somatic cells of pig and other species. Further, ultrastructural analysis revealed the presence of CENP-E on fibrous corona and outer plate of kinetochores of the meiotic chromosomes. However, unlike mitosis, CENP-E staining was continuously detected either at the spindle midzone or on the kinetochores of segregated chromosomes during the first polar body emission. Consistent with this, immunoblot analysis revealed that CENP-E level remained high during meiosis I/meiosis II (MI/MII) transition and that some of CENP-E survived through the transition even in cycloheximide-treated oocytes in which cyclin B1 was completely degraded. Furthermore, examinations of CENP-E signals in confocal microscopy and kinetochores in electron microscopy in MI and MII oocytes provide the cytological evidence in mammalian oocytes which suggests that each sister chromatid in a pair has its own kinetochore which localizes side-by-side so that two sister chromatids on a half bivalent are oriented toward and connected to the same pole in MI.
Lee
J
J
Laboratory of Protein Function, The Babraham Institute, Cambridge, United Kingdom. 950d951n@ipc.kobe-u.ac.jp
Miyano
T
T
Dai
Y
Y
Wooding
P
P
Yen
T J
TJ
Moor
R M
RM
D000818:Animals; D002478:Cells, Cultured; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D005260:Female; D006801:Humans; D018386:Kinetochores / Q000378:metabolism; D008540:Meiosis / Q000502:physiology*; D008938:Mitosis / Q000502:physiology; D009865:Oocytes / Q000378:metabolism; D013552:Swine
D002868:Chromosomal Proteins, Non-Histone; C068688:centromere protein E