Former Department of Biochemistry and Cell Biology
Cellular organisation is based on a complex series of events combining gene expression, signal transduction, membrane traffic and the function of dynamic cytoskeletal networks. This laboratory is interested in cytoskeletal elements of mammalian cells and networks governing either cellular architecture in general or particular aspects of certain differentiated cell types. This laboratory has used antibodies in immunofluorescence microscopy to understand the two general cytoskeletal filament systems - the microfilaments and microtubules - which are based on actin and tubulin and their associated proteins respectively (top figure). Antibodies also allowed us to demonstrate that intermediate filaments arise in different cell types from distinct but related proteins (second figure). Translating this knowledge this laboratory has established that intermediate filament proteins are useful markers to identify different cell types in tissues (third figure) and in differential tumor diagnosis.
A few antibodies also open a way to manipulate a certain cytoskeletal organisation. When microinjected into live cells they not only dock on their target but also disturb the organisation creating a phenotype visible in the microscope. Fine analysis of complexes within a supermolecular organisation has been greatly helped by the use of recombinantly expressed proteins or their individual domains. These can be analysed by their biochemical and molecular properties and some aspects can readily be analysed in vivo by transfecting the corresponding cDNA constructs into cultured cells. One example of this approach is work on NuMA. NuMA is an insoluble nuclear protein during interphase (fourth figure) and translocates to the spindle poles at mitosis. Microinjection of a particular NuMA antibody causes the formation of aberrant spindles and mitotic arrest, as well as of micronuclei. Our in vivo and in vitro results also suggest that NuMA may be involved in the architecture of the interphase nucleus.
Research interests included:
- structure, function and evolution of the metazoan multigene family of intermediate filament proteins which covers about 60 members in man. This work covers organisms as diverse as Hydra and Amphioxus and also leads into molecular phylogeny.
- general coiled-coil architecture.
- enzymology and function of three posttranslational modifications unique to tubulins (polyglutamylation, polyglycylation and tyrosination).
- the function of NuMA in the mitotic and interphase cell.
- use of antibodies as diagnostic markers in pathology.