Institute of Molecular and Cell Biology (IMCB), A∗STAR (Agency for Science, Technology and Research), 61 Biopolis Drive, Proteos #3-09, Singapore 138673, Republic of Singapore
Radoslaw Szmyd
Institute of Molecular and Cell Biology (IMCB), A∗STAR (Agency for Science, Technology and Research), 61 Biopolis Drive, Proteos #3-09, Singapore 138673, Republic of Singapore
Diana Low
Institute of Molecular and Cell Biology (IMCB), A∗STAR (Agency for Science, Technology and Research), 61 Biopolis Drive, Proteos #3-09, Singapore 138673, Republic of Singapore
M. Kasim Diril
Institute of Molecular and Cell Biology (IMCB), A∗STAR (Agency for Science, Technology and Research), 61 Biopolis Drive, Proteos #3-09, Singapore 138673, Republic of Singapore
Heng-Yu Chang
Department of Biochemistry and Molecular Cell Biology, School of Medicine, Taipei Medical University, Taipei 11031, Taiwan
Vincenzo Coppola
Mouse Cancer Genetics Program, National Cancer Institute, NCI-Frederick, Building 560, 1050 Boyles Street, Frederick, MD 21702-1201, USA
Kui Liu
Department of Chemistry and Molecular Biology, University of Gothenburg, SE-405 30 Gothenburg, Sweden
Lino Tessarollo
Mouse Cancer Genetics Program, National Cancer Institute, NCI-Frederick, Building 560, 1050 Boyles Street, Frederick, MD 21702-1201, USA
Ernesto Guccione
Institute of Molecular and Cell Biology (IMCB), A∗STAR (Agency for Science, Technology and Research), 61 Biopolis Drive, Proteos #3-09, Singapore 138673, Republic of Singapore
Ans M.M. van Pelt
Center for Reproductive Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands
Philipp Kaldis
Institute of Molecular and Cell Biology (IMCB), A∗STAR (Agency for Science, Technology and Research), 61 Biopolis Drive, Proteos #3-09, Singapore 138673, Republic of Singapore
The meiotic functions of Emi2, an inhibitor of the APC/C complex, have been best characterized in oocytes where it mediates metaphase II arrest as a component of the cytostatic factor. We generated knockout mice to determine the in vivo functions of Emi2—in particular, its functions in the testis, where Emi2 is expressed at high levels. Male and female Emi2 knockout mice are viable but sterile, indicating that Emi2 is essential for meiosis but dispensable for embryonic development and mitotic cell divisions. We found that, besides regulating cell-cycle arrest in mouse eggs, Emi2 is essential for meiosis I progression in spermatocytes. In the absence of Emi2, spermatocytes arrest in early diplotene of prophase I. This arrest is associated with decreased Cdk1 activity and was partially rescued by a knockin mouse model of elevated Cdk1 activity. Additionally, we detected expression of Emi2 in spermatids and sperm, suggesting potential post-meiotic functions for Emi2.
