- Title
- Differential regulation of cyclin B1 degradation between the first and second meiotic divisions of bovine oocytes
- Creator
- Liu, W.; Yin, J.; Zhao, G.; Yun, Y.; Wu, S.; Jones, K. T.; Lei, A.
- Relation
- Theriogenology Vol. 78, Issue 6, p. 1171.e1-1181.e1
- Publisher Link
- http://dx.doi.org/10.1016/j.theriogenology.2012.06.006
- Publisher
- Elsevier
- Resource Type
- journal article
- Date
- 2012
- Description
- During mammalian oocyte maturation, two consecutive meiotic divisions are required to form a haploid gamete. For each meiotic division, oocytes must transfer from metaphase to anaphase, but maturation promoting factor (cyclin-dependent kinase 1/cyclin B1) activity would keep the oocytes at metaphase. Therefore, inactivation of maturation promoting factor is needed to finish the transition and complete both these divisions; this is provided through anaphase-promoting complex/cyclosome-dependent degradation of cyclin B1. The objective of this study was to examine meiotic divisions in bovine oocytes after expression of a full length cyclin B1 and a nondegradable N-terminal 87 amino acid deletion, coupled with the fluorochrome Venus, by microinjecting their complementary RNA (cRNA). Overexpression of full-length cyclin B1-Venus inhibited homologue disjunction and first polar body formation in maturing oocytes (control 70% vs. overexpression 16%; P < 0.05). However at the same levels of expression, it did not block second meiotic metaphase and cleavage of eggs after parthenogenetic activation (control: 82% pronuclei and 79% cleaved; overexpression: 91% pronuclei and 89% cleaved). The full length cyclin B1 and a nondegradable N-terminal 87 amino acid deletion caused metaphase arrest in both meiotic divisions, whereas degradation of securin was unaffected. Roscovitine, a potent cyclin-dependent kinase 1 (CDK1) inhibitor, overcame this metaphase arrest in maturing oocytes at 140 μM, but higher doses (200 μM) were needed to overcome arrest in eggs. In conclusion, because metaphase I (MI) blocked by nondegradable cyclin B1 was distinct from metaphase II (MII) in their different sensitivities to trigger CDK1 inactivation, we concluded that mechanisms of MI arrest differed from MII arrest.
- Subject
- cyclin B1; securin; MPF; meiosis; bovine; oocytes
- Identifier
- http://hdl.handle.net/1959.13/1324737
- Identifier
- uon:25109
- Identifier
- ISSN:0093-691X
- Language
- eng
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