Differential regulation of cyclin B1 degradation between the first and second meiotic divisions of bovine oocytes
Differential regulation of cyclin B1 degradation between the first and second meiotic divisions of bovine oocytes
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 ?M, but higher doses (200 ?M) 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.
cyclin B1, securin, mpf, meiosis, bovine, oocytes
1171-1181.e1
Liu, W
622f6d44-225b-4d4e-9ed9-839e234e7163
Yin, J
a4a0d155-c3d8-4a74-915a-cbbfe683b737
Zhao, G
9d57225c-e8af-4e26-8075-e92b91fac36c
Yun, Y
aaa5ab77-a61c-4dcb-910b-76996272c6c8
Wu, S
eb84cc5f-a0b1-494c-bac8-f99c998adc19
Jones, KT
73e8e2b5-cd67-4691-b1a9-4e7bc9066af4
Lei, A
25530a17-3bb2-49fd-81e6-575a635321cd
1 October 2012
Liu, W
622f6d44-225b-4d4e-9ed9-839e234e7163
Yin, J
a4a0d155-c3d8-4a74-915a-cbbfe683b737
Zhao, G
9d57225c-e8af-4e26-8075-e92b91fac36c
Yun, Y
aaa5ab77-a61c-4dcb-910b-76996272c6c8
Wu, S
eb84cc5f-a0b1-494c-bac8-f99c998adc19
Jones, KT
73e8e2b5-cd67-4691-b1a9-4e7bc9066af4
Lei, A
25530a17-3bb2-49fd-81e6-575a635321cd
Liu, W, Yin, J, Zhao, G, Yun, Y, Wu, S, Jones, KT and Lei, A
(2012)
Differential regulation of cyclin B1 degradation between the first and second meiotic divisions of bovine oocytes.
Theriogenology, 78 (6), .
(doi:10.1016/j.theriogenology.2012.06.006).
(PMID:22901768)
Abstract
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 ?M, but higher doses (200 ?M) 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.
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e-pub ahead of print date: 15 August 2012
Published date: 1 October 2012
Keywords:
cyclin B1, securin, mpf, meiosis, bovine, oocytes
Organisations:
Centre for Biological Sciences
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Local EPrints ID: 349643
URI: http://eprints.soton.ac.uk/id/eprint/349643
ISSN: 0093-691X
PURE UUID: 619546e3-e04b-4bc1-ac5a-625f1e97bc97
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Date deposited: 07 Mar 2013 16:30
Last modified: 14 Mar 2024 13:16
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Author:
W Liu
Author:
J Yin
Author:
G Zhao
Author:
Y Yun
Author:
S Wu
Author:
KT Jones
Author:
A Lei
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