Cellular organization is based on a complex series of events involving gene expression, signal transduction, membrane traffic and the function of dynamic cytoskeletal networks. We have used antibodies in immunofluorescence microscopy to understand the distribution and function of the two ubiquitous filament systems - microfilaments and microtubules – that have as their major proteins actin and tubulin respectively. Antibodies also allowed us to show that intermediate filaments in different cell types are built from distinct but related proteins. Applying this knowledge we showed that intermediate filament proteins are useful markers in differential tumor diagnosis, where they can distinguish the major tumor types and provide additional information relevant to patient treatment.
Certain antibodies also allow a particular cytoskeletal organisation to be manipulated. When microinjected into live cells they not only find their target but also disturb the organization creating a new phenotype which can be detected by immunofluorescence microscopy. Fine analyses of complexes within particular supermolecular organizations have been helped by the use of recombinantly expressed proteins or their individual domains. These can be analyzed in vivo by transfecting the corresponding cDNA constructs into cultured cells. One example of this approach is work on NuMA. NuMA is an insoluble protein during interphase and translates 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. Other studies were directed towards understanding how NuMA functions at the molecular level, as well as to seeing whether it has a role in the interphase nuclear matrix. In addition RNA interference (RNAi) was used as a tool to study gene function.
Thus my scientific interests are in the general area of cell biology and pathology - more specifically in the cytoskeleton, in certain proteins of the cell nucleus and in the use of antibodies in cancer diagnosis. I have published more than 280 scientific papers in these areas, and have been an invited speaker and chairperson at many international meetings e.g plenary lectures at the ComBio2005 meeting in Australia and at the Portugese Biochemical Society Meeting in 2006. I stopped running an active lab at the end of 2005.