Speaker: Dr. Anna Santamaria
Biozentrum , University of Basel
Basel, Switzerland

Host

Dr. Joan Roig, IRB Barcelona and Dr. Jens Lüders, IRB Barcelona

Friday 12 March 2010, 12.00 h Aula Fèlix Serratosa

Abstract

Eukaryotic cell division is captivating when observed through a microscope. Before embarking on mitosis, a cell duplicates its chromosomes, producing pairs of sister chromatids that later become arranged in the middle of the cell. Then each pair is separated into chromatids that are segregated to each side, so that when the cell divides, each daughter cell receives an identical set of genes. This formidable feat is achieved by the mitotic spindle, a precise machine made from a bipolar array of microtubules, focused at each end of the spindle by a centrosome or spindle pole body. A spindle is necessary for both meiosis, the form of cell division that produces gametes for sexual reproduction, and mitosis, cell division for growth. Without the spindle, cell division would be unfeasible, and subtle defects in its function are likely to be involved in the genomic instability associated with cancer.Despite major progress in deciphering the temporal and spatial regulation of mitotic spindle formation, its composition and function are not fully understood. In the first part of my talk, I will summarize the work on the characterization of a number of novel spindle components originally identified in a proteomics survey of the human mitotic spindle; namely CHICA, hSpindly and the Ska complex, all involved in chromosome congression at the spindle equator. Several mechanisms orchestrate assembly of the mitotic spindle and phospho-regulation of spindle components by mitotic kinases has proven to be a key mechanism for regulating spindle assembly during mitosis. Despite this, the full rangeof targets and phosphorylation sites remains to be explored. In the second part of my talk, I will summarize the work carried out recently in our laboratory in relation to the regulation of the mitotic spindle by phosphorylation. I will show our results from a phospho-proteomic screen that aimed at defining the Plk1-dependent phosphoproteome of the early mitotic spindle and discuss the intricate link between Plk1 and Aurora A that brings about centrosome maturation and spindle assembly at the onset of mitosis.

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