Several strands of research as outlined below.
Mechanism of Mitotic Chromosome Condensation
Mitotic chromosome segregation requires proper chromosome assembly and the phosphorylation of a number of chromosomal proteins. The Aurora B protein kinase and its binding partners INCENP and survivin have a critical role in this process. We are using both biochemical and imaging based approaches to study the function and regulation of the Aurora B protein complex.
Dynamics of the Interphase Nucleus
The interphase nucleus is a dynamic, yet surprisingly tightly-packed organelle. As a model for intranuclear mobility, we are studying the dynamics of the Cajal body. Cajal bodies (CBs) are subnuclear organelles that contain factors required for splicing, ribosome biogenesis, and transcription. CBs are localised in the nucleoplasm and are often found at the nucleolar periphery. In a collaboration with the Lamond lab, we used a stable HeLa cell line, HeLaGFP-coilin, that expresses the CB marker protein, p80 coilin, fused to the Green Fluorescent Protein (GFP-coilin) to study CB dynamics in living cells. Time lapse recordings on 63 nuclei of HeLaGFP-coilin cells showed that all CBs move within the nucleoplasm. Movements included translocations through the nucleoplasm, joining of bodies to form larger structures and separation of smaller bodies from larger CBs. The GFP-coilin protein is dynamically associated with CBs as shown by changes in their fluorescence intensity over time (Platani et al, 2001).
Cell Cycle Chromatin Proteomics
The events of the cell cycle have profound effects on nuclei and chromosomes. Chromosome replication, nuclear disassembly and reassembly, chromosome condensation and apoptosis all involve proteins that directly interact with chromatin. This project combines a powerful cell-free system based on Xenopus egg extracts with proteomic analysis using mass spectrometry to identify proteins associated with chromatin at different cell cycle states. While many chromatin-associated proteins will show no changes throughout the cell cycle, differences in abundance or modification are likely to reflect proteins with cell cycle-specific function. This proteomic screen will therefore identify new factors important for cell cycle dynamics and provide novel details about the post-translational modifications of known ones. The project is a collaboration between the Swedlow Lab and the Blow Lab.
Image Informatics in Biological Microscopy
Digital fluorescence imaging is used in functional genomics, genetic and chemical screens, and cell biology for assays of molecular localization, interaction and mobility. However, there is no solution for systematically managing and analyzing this data. We and our collaborators have developed several tools and a standard image format as part of the Open Microscopy Environment (OME) Project.