Protein Kinase C in Mitosis

Abstract

In fission yeast, mitotic commitment (irreversibly entering M-phase) is controlled by mitosis-promoting factor (MPF). The activity of MPF is regulated by the mitotic inhibitor kinase Wee1 and the mitotic inducer phosphatase Cdc25. Cells have evolved mechanisms that can check cell size, DNA integrity and the environment in order to regulate the activity of Wee1 and/or Cdc25 to ensure cell divide at appropriate time and conditions. Protein kinases are the key signaling factors that regulate cell cycle progression. In this report, I have used a chemical-genetics approach to demonstrate that protein kinase C (Pck1/2) in Schizosaccharomyces pombe (S.pombe) is involved in the control of mitotic commitment. Cells showed delay in entering M-phase after ATP analogue inhibition of Pck2-As (analog sensitive); and after releasing cells from Pck2-As inhibition, a burst of mitosis was observed at 25°C. At 36°C this burst of mitosis is delayed by 80 mins. Epstatic gene interaction tests showed that Pck2 regulates mitotic entry through Wee1, but not via Cdc25, nor the Pom1 regulated cell tip extension pathway or via the Plo1 regulated cell stress pathway. The Pmk1 regulated cell integrity pathway might not be directly involved in Pck2 regulated mitotic entry, but it did influence the timing of Pck2 regulated mitotic entry. I also observed that some of pck2::kanMX6 cells have defects in interphase microtubule dynamics. Many pck2::kanMX6 cells also have defects in polarized cell growth, suggesting Pck2 is involved new end take off (NETO).

Date of Award	31 Dec 2011
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Iain Hagan (Supervisor)