Ignaz L. Lieben-Preis 2017

Iva Tolić has been granted the award for her outstanding achievements in the field of molecular cell biology, especially for her work on the microtubule cytoskeleton.

Field of research

Inside cells there are tiny motor engines that ride on thin rods called microtubules. Without this, cells would not be able to grow, reproduce or communicate. Iva Tolić and her team are interested in how motor proteins and microtubules self-organize to produce fascinating assemblies such as the mitotic spindle with its orchestrated movements of chromosomes. In their interdisciplinary approach, they combine cell and molecular biology, molecular genetics, biophysical tools including laser microsurgery, optical engineering, computer science and theoretical physics. With her team and collaborators Iva Tolić aims at quantitative descriptions and development of theoretical models that help to understand the self-organization processes in the cell.

Recent Research
Cell division is one of the most fundamental processes in the living world. At the onset of division the cell assembles a spindle, a fascinating and complex micro-machine made of microtubules and the accompanying proteins (Pavin and Tolić, Annu Rev Biophys 2016). Spindle microtubules bundled together into fibers attach to chromosomes via kinetochores, protein complexes on the chromosome. The critical task of the spindle is accurate chromosome segregation, but forces driving this process in human cells are not well understood. Iva Tolić and her team have discovered that non-kinetochore microtubules, which they termed bridging fibers, balance the tension between sister kinetochores by bridging sister kinetochore fibers (Kajtez, Solomatina, Novak et al., Nat Commun 2016). Their finding challenges the prevailing view that the forces acting on kinetochores are generated by molecular events occurring only at the ends of the kinetochore fibers. The team showed that each chromosome in a spindle has its associated bridging fiber (Polak, Risteski et al., EMBO Rep 2017). By combining laser ablation, photoactivation and theory, the team showed that sliding apart of microtubules within the bridging fiber pushes the attached kinetochore fibers and their kinetochores apart, being able to segregate chromosomes independently of the spindle pole  (Vukušić, Buđa et al., Dev Cell 2017). This result, which is unexpected because according to the current view kinetochore separation requires kinetochores to be linked with the spindle pole, revealed a role of the bridging fiber in chromosome segregation.

Previously, Tolić team has discovered a new mechanism of kinetochore capture during mitosis, based on the rotation of microtubules around the spindle pole (Kalinina et al., Nat. Cell Biol. 2013). This concept challenges the current ‘search-and-capture’ model introduced in the 1980s, centered on direct growth of microtubules towards kinetochores. The Tolić team has also pioneered single-molecule observation and quantification of the motor protein dynein in living yeast cells, which allowed them to discover a new mechanism for how dynein targets cortical anchor sites, by diffusing along the microtubule (Ananthanarayanan et al., Cell 2013). Finally, they have demonstrated that fission yeast does not undergo replicative aging, which challenges the view that all organisms, including microorganisms, are susceptible to aging (Coelho et al., Curr. Biol. 2013; Coelho et al., PLOS Biol. 2014).

The Prize Winner

Iva Tolić became Full Professor and Senior Research Group Leader at Ruđer Bošković Institute, Zagreb, in 2014. From 2005 – 2014 she worked as a Research Group Leader at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, being promoted into a Senior Research Group Leader in 2010. In 1996 she graduated in molecular biology (diploma) at the University of Zagreb, where she also obtained her PhD in 2002 for her work completed at the Ruđer Bošković Institute and at the Harvard School of Public Health in Boston. She was a post-doctoral researcher at the Niels Bohr Institute, Copenhagen (2001-2002) and at the European Laboratory for Non-Linear Spectroscopy (LENS) in Florence (2003-2004).

Research Grants and Awards (choice):
2015-2020: Research grant from the European Research Council (ERC Consolidator Grant); 2015-2019: Research grant from the Croatian Science Foundation (HRZZ); 2015-2016: Grant from the European Social Fund (ESF), together with Igor Weber, Ruđer Bošković Institute; 2013-2016: Research grant from the German Research Foundation (DFG), together with Nenad Pavin, University of Zagreb.

Prizes (choice):
2016: National Science Award of the Republic of Croatia and Croatian Women of Influence Award; 2015: European Biophysical Societies Association (EBSA) Young Investigators Medal and Prize

The Award

The Ignaz L. Lieben Award is granted to scientists who have been working in Austria, Bosnia-Herzegowina, Croatia, the Czech Republic, Hungary, Slovakia or Slovenia for the last 3 years. Eligible candidates should not be older than 40, have competed their doctorate and have made outstanding achievements in scientific research in the fields of molecular biology, chemistry or physics. The Award amounts to USD 36.000,-