Following cell division
Drosophila S2 cells in culture, stably expressing Histone2Av-GFP (green) and Tubulin-Cherry (red). In mitosis, chromosomes condense and align a microtubule-based spindle. The segregation of sister chromatids marks the beginning of mitotic exit. Cytokinesis completes the division process.
The cell cycle is finely regulated in time and space. This process involves spatial coordination of key regulators including kinases and phosphatases. We are interested in this fundamental aspect of cell biology. The movies below show the dynamic localization of Polo and Gwl kinases in Drosophila cells in culture (acquired on a Spinning Disk Confocal microscope). The behavior of the human orthologs is nearly identical. We are interested in the functions and molecular mechanisms of these changes in localization.
Dynamic localization of kinases during cell division
Polo-GFP in a D-Mel cell in culture.
In order to regulate several processes in mitosis and cytokinesis, the Polo kinase localizes to various discrete structures during the cell cycle. In early mitosis, Polo is on centrosomes and kinetochores. At anaphase, Polo appears on the central spindle and the midbody. Polo strongly localizes to microtubules in interphase and cytokinesis but not in early mitosis. See Archambault et al 2008.
Gwl-GFP in a D-Mel cell in culture.
Gwl is nuclear in interphase and becomes cytoplasmic and excluded from the nucleus in prophase, before nuclear envelope breakdown. Why? How? See Wang et al 2013.
GFP-Polo (green) and Histone2Av-RFP (red) in a syncytial embryo
After being laid, the fertilized egg completes meiosis and the first zygotic nucleus enters mitosis. Thirteen rapid rounds of mitosis and DNA replication take place in a syncytium before cellularization of the blastoderm. Nuclei divide synchronously every few minutes, without Gap phases. In the last syncytial cycles (10-13) the nuclei are positioned near the surface of the embryo and they can be imaged on a Spinning Disk Confocal microscope.
