Academics

Welcome

This page gives a summary of my research interests. For more details see my lab web pages.

Research Interests

Regulation of the eukaryotic cell cycle, particularly control of DNA replication. Most of my work uses the model organism fission yeast (Schizosaccharomyces pombe).

Current research is focused on proteins that regulate the initiation of DNA replication. DNA replication starts from thousands of origins in eukaryotic genomes. This process must be tightly regulated so that each origin functions only once per cell cycle, otherwise re-replication of some chromosomal regions would occur, leading to genome instability. This tight regulation is ensured by  regulating the activity of initiation proteins, which can only function during a narrow window of the cell cycle.

We can study the function of initiation proteins by tagging them with fluorescent proteins (originally derived from marine organisms), allowing the location and levels of these proteins to be monitored in single cells.

Here two proteins (Cdt1 and Cdc45) involved in initiation of DNA replication have been tagged using different  fluorescent tags. Cdt1 is degraded before Cdc45 binds to DNA, and this helps to ensure a single round of DNA replication. For more details see this DNA replication website.

Recent Publications

• T. Tvegard et al., 'A novel checkpoint mechanism regulating the G1/S transition' in Genes and Development, 21 (2007), 649-54
• Jurag Gregan et al., 'The kinetochore proteins pcs1 and mde4 and heterochromatin are required to prevent merotelic orientation' in Current Biology, 17 (2007), 1190-200
• SE Kearsey, AL Stevenson, T Toda, SW Wang, 'Fission yeast Cut8 is required for the repair of DNA double-strand breaks, ribosomal DNA maintenance, and cell survival in the absence of Rqh1 helicase' in Molecular and Cellular Biology, 27 (2007), 1558-67
• Emma Ralph, Erik Boye, Stephen Kearsey, 'DNA damage induces Cdt1 proteolysis in fission yeast through a pathway dependent on Cdt2 and Ddb1.' in EMBO Reports, 7 (2006), 1134-9
• Mandana Namdar and Stephen E Kearsey, 'Analysis of Mcm2-7 chromatin binding during anaphase and in the transition to quiescence in fission yeast' in Exp. Cell Res., 312 (2006), 3360-9
• Stephen Kearsey, Sue Cotterill, 'Enigmatic variations: divergent modes of regulating eukaryotic DNA replication' in Molecular Cell, 12 (2003), 1067-1075
• Juraj Gregan, Karola Lindner, Lydia Brimage Roger Franklin, Mandana Namdar, Elizabeth Hart, Stephen Aves, Stephen Kearsey, 'Fission yeast Cdc23/Mcm10 functions after pre-replicative complex formation to promote Cdc45 chromatin binding' in Molecular Biology of the Cell, 14 (2003), 3876-3887
• Karola Lindner, Juraj Gregan, Stuart Montgomery, Stephen Kearsey, 'Essential role of MCM proteins in pre-meiotic DNA replication' in Molecular Biology of the Cell, 13 (2002), 435-444
• Stephen Kearsey, Stuart Montgomery, Karim Labib, Karola Lindner, 'Chromatin binding of the fission yeast replication factor Mcm4 occurs during anaphase and requires ORC and Cdc18' in EMBO Journal, 19 (2000), 1681-1690
• Karim Labib, John Diffley, Stephen Kearsey, 'G1 and B-type cyclins exclude the DNA replication factor Mcm4 from the nucleus' in Nature Cell Biology, 1 (1999), 415-422

Academic Biography

• Ciba Visiting Fellow, EMBL Heidelberg (1991 - 1992)
• University Lecturer in Cell and Developmental Biology; Fellow of Keble College (1985 - present)
• Beit Memorial Research Fellow, Dept of Zoology, University of Cambridge (1983 - 1985)
• Beit Memorial Research Fellow, MRC Laboratory of Molecular Biology, Cambridge (1981 - 1983)
• Graduate Student, University of Oxford (Supervisor: Dr Ian Craig) (1979 - 1981)
• Graduate Student, University of California, Santa Barbara (Supervisor: Dr Ian Craig) (1978 - 1979)