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CENP-E is an essential kinetochore motor in maturing oocytes and is masked during mos-dependent, cell cycle arrest at
N S Duesbery1, T Choi, K D Brown
1ABL-Basic Research Program, National Cancer Institute-Frederick Cancer Research and Development Center, P.O. Box B, Frederick, MD 21702-1201, USA.
Abstract:
CENP-E, a kinesin-like protein that is known to associate with kinetochores during all phases of mitotic chromosome movement, is shown here to be a component of meiotic kinetochores as well. CENP-E is detected at kinetochores during metaphase I in both mice and frogs, and, as in mitosis, is relocalized to the midbody during telophase. CENP-E function is essential for meiosis I because injection of an antibody to CENP-E into mouse oocytes in prophase completely prevented progression of those oocytes past metaphase I. Beyond this, CENP-E is modified or masked during the natural, Mos-dependent, cell cycle arrest that occurs at metaphase II, although it is readily detectable at the kinetochores in metaphase II oocytes derived from mos-deficient (MOS-/-) mice that fail to arrest at metaphase II. This must reflect a masking of some CENP-E epitopes, not the absence of CENP-E, in meiosis II because a different polyclonal antibody raised to the tail of CENP-E detects CENP-E at kinetochores of metaphase II-arrested eggs and because CENP-E reappears in telophase of mouse oocytes activated in the absence of protein synthesis.
Insights
Centromere protein E (CENP-E) is crucial for meiosis I chromosome segregation. Its function is masked during metaphase II arrest, indicating a regulatory role in female meiosis.
Area of Science:
- Cell Biology
- Molecular Biology
- Reproductive Biology
Background:
- Centromere protein E (CENP-E) is a kinesin-like protein vital for kinetochore function during mitosis.
- Kinetochores are protein structures on chromosomes essential for proper segregation.
- Meiosis involves specialized cell divisions for sexual reproduction.
Purpose of the Study:
- To investigate the role of CENP-E in meiotic kinetochores and chromosome segregation.
- To determine if CENP-E is present and functional during mammalian oogenesis.
- To elucidate CENP-E's behavior during meiotic arrest and progression.
Main Methods:
- Immunodetection of CENP-E at kinetochores in mouse and frog oocytes.
- Microinjection of anti-CENP-E antibodies into prophase mouse oocytes.
- Analysis of CENP-E localization in wild-type and mos-deficient mouse oocytes.
- Assessment of CENP-E reappearance during oocyte activation without protein synthesis.
Main Results:
- CENP-E localizes to meiotic kinetochores during metaphase I and telophase in mice and frogs.
- Anti-CENP-E antibody injection blocks oocyte progression past metaphase I.
- CENP-E is masked or modified during the metaphase II arrest, detectable in mos-deficient oocytes.
- CENP-E reappears in telophase oocytes even without protein synthesis, suggesting epitope masking.
Conclusions:
- CENP-E is essential for accurate chromosome segregation during meiosis I.
- CENP-E function is regulated during the metaphase II arrest, likely through epitope masking.
- CENP-E plays a significant role in the fidelity of female meiosis.