instituto de biologia molecular e celular | institute for molecular and cell biology
Previous research results:
Our research group has been for a number of years involved in studying the
molecular mechanisms required for maintenance of genomic stability during cell division. Towards this aim we have used Drosophila melanogaster as our model organism resorting to classical genetics, biochemistry and cell biobogy to identify and characterize genes that are essential for this process. During these studies we identified, characterized and performed functional studies of proteins involved in a number of events that take place during cell division. We were involved in the identification of the founding member of the Polo-like kinase family and demonstrated its role in mitotic progression and centrosome maturation. Subsequently we identified mutations for γ-tubulin and showed that although it was involved in microtubule nucleation from centrosomes, partly functional spindles could be made in its absence. During subsequent years we concentrated our work on the proteins required for mitotic chromosome organization and demonstrated that the condensin complex is not required for overall chromosome architecture but is essential for sister chromatid individualization. During the last few years our attention has turned to the functional analysis of proteins involved in the Spindle Assembly Checkpoint that monitors proper attachment of chromosomes to the mitotic spindle. We have shown that some of these proteins like Bub3 and BubR1 have essential roles in mitosis that are additional to their roles in the checkpoint. Also we demonstrated that the kinase activity of BubR1 plays a major role during regulating meiotic recombination.
IMAGE: A Drosophila S2 tissue culture cell during early anaphase in which the kinetochore protein involved in microtubule binding Ndc80 was depleted by RNAi. The image shows kinetochores (green), spindle microtubules (red) and DNA (blue).
The work in progress to uncover the molecular mechanisms that integrate the signals that result after microtubules bind the kinetochore with those involved in checkpoint signalling. For this we are studying at the biochemical level the role BubR1 and the kinase Mps1 play in signal transduction. In parallel we are continuing to study the role of BubR1 in meiotic progression and have identified Polo as an important genetic interactor to supress nondisjunction. Moreover, we have started two new lines of research designed to study 1) the molecular requirements for SAC deficient cells to become tumorigenic and 2) the role os SAC proteins and other mitotic regulators in cell division within well-defined epithelia and its relation to Apico-Basal polarity. We continue to use tissue culture cells, dsRNAi, in vivo fluorescence imaging and biochemical approaches to develop models for microtubule attachment and checkpoint function. In parallel we are designing experiments that will test the models derived from these studies in different cell types within the whole organism including mitotic. With these approaches we aim to determine the possible contribution of chromosome missegregation in tumour development.
Takeo S, Lake CM, Morais-de-Sa E, Sunkel CE and Hawley RS. (2011) A Synaptonemal Complex-Dependent Process of Centromeric Clustering Is Coupled to the Initiation of Synapsis in Drosophila Oocytes. Curr.Biol. 21:1845-51.
Martins T, Maia A, Steffensen S and Sunkel CE (2009) “Sgt1, a co-chaperone of Hsp90 stabilizes Polo and is required for centrosome rganization.” EMBO Journal 28, 234-47.
Coelho PA, Queiroz-Machado J, Carmo AM, Moutinho-Pereira A, Maiato H and Sunkel CE (2008) “Dual role of Topoisomerase II in centromere resolution and Aurora B activity.” PlosBiology 6, 1758-1777.
Malmanche N, Owen S, Gegick S, Steffensen S, Tomkiel JE and Sunkel CE (2007). “BubR1 is essential to maintain sister chromatid cohesion and the Synaptonemal Complex during Drosophila meiosis.” Current Biology 17, 1489-1497.
Orr B, Bousbaa H and Sunkel CE (2007). “Mad2-independent spindle assembly checkpoint activation and controlled metaphase-anaphase transi¬tion in Drosophila S2 cells.” Molecular Biology of the Cell 18, 850-863.
Oliveira RA, Coelho PA and Sunkel CE (2005) “The condensin I subunit Barren/CAP-H is essential for the structural integrity of centromeric heterochromatin during mitosis.” Molecular Biology of the Cell 25, 8971-8984.
Morais de Sá, Eurico
Rodrigues Amorim, João
Costa Osswald, Mariana
Raquel Rocha Moreira, Sofia
Bastos Ventura, Guilherme
Brás, Ana Rita
Cunha Silva, Ana Sofia
Moreira Monteiro, Augusta
Branco Teixeira, Ana Pinto
Machado Leça, Nelson
Miguel Pinto Basto Alves, Pedro
Santos, Ana Filipa