Helfrid Hochegger (Genome Damage and Stability Center, School of Life Sciences University of Sussex)

2016. 02. 23 (Tue) 16:00 ~ 17:00

Conf. Room, Myodaiji (111)

Stem Cell Biology, Tomomi Tsubouchi (7693)

Entry into mitosis is thought to be triggered by activation of Cdk1/cyclinB, its translocation into the nucleus and the inactivation of the Cdk1 counteracting phosphatases PP2A/B55.  There are two major questions to be addressed to fully understand this complex cellular transition.  Firstly, the switch system itself remains poorly understood and the contribution of individual players remains to be investigated.  Secondly, the downstream targets of Cdk1　whose phosphorylation triggers the ordered and highly orchestrated transition into mitosis remain largely elusive. 

New work from my lab on both of these questions will be addressed in this seminar.  I will describe a novel assay system to analyse the individual components of the complex G2/M switch system based on CrispR-mediated chemical genetics and degron tags in mammalian cell lines. To address the 2nd question, I will also present work on the mechanism of centrosome separation, one of the earliest events that occur following Cdk1 activation.  This study has revealed a novel actin-dependent force generation mechanism that counteracts centrosome separation in G2.  We have undertaken a detailed characterization of this mechanism and are now investigating how it is subjected to cell cycle control.