ERC FUNDED PROJECTS

Cytokinesis completes cell division by partitioning the contents of the mother cell to the two daughter cells. This process is accomplished through the assembly and constriction of a contractile ring, a complex actomyosin network that remains poorly understood on the molecular level. Research in cytokinesis has overwhelmingly focused on signaling mechanisms that dictate when and where the contractile ring is assembled. By contrast, the research I propose here addresses fundamental questions about the structural and functional properties of the contractile ring itself. We will use the nematode C. elegans to exploit the power of quantitative live imaging assays in an experimentally tractable metazoan organism. The early C. elegans embryo is uniquely suited to the study of the contractile ring, as cells dividing perpendicularly to the imaging plane provide a full end-on view of the contractile ring throughout constriction. This greatly facilitates accurate measurements of constriction kinetics, ring width and thickness, and levels as well as dynamics of fluorescently-tagged contractile ring components. Combining image-based assays with powerful molecular replacement technology for structure-function studies, we will 1) determine the contribution of branched and non-branched actin filament populations to contractile ring formation; 2) explore its ultra-structural organization in collaboration with a world expert in electron microcopy; 3) investigate how the contractile ring network is dynamically remodeled during constriction with the help of a novel laser microsurgery assay that has uncovered a remarkably robust ring repair mechanism; and 4) use a targeted RNAi screen and phenotype profiling to identify new components of actomyosin contractile networks. The results from this interdisciplinary project will significantly enhance our mechanistic understanding of cytokinesis and other cellular processes that involve actomyosin-based contractility.

1 499 989 €

Start date: 2015-07-01, End date: 2020-06-30

Autophagy is a fundamental cellular catabolic process deputed to the degradation and recycling of a variety of intracellular materials. Autophagy plays a significant role in multiple human physio-pathological processes and is now emerging as a critical regulator of skeletal development and homeostasis. We have discovered that during postnatal development in mice, the growth factor FGF18 induces autophagy in the chondrocyte cells of the growth plate to regulate the secretion of type II collagen, a major component of cartilaginous extracellular matrix. The FGF signaling pathways play crucial roles during skeletal development and maintenance and are deregulated in many skeletal disorders. Hence our findings may offer the unique opportunity to uncover new molecular mechanisms through which FGF pathways regulate skeletal development and maintenance and to identify new targets for the treatment of FGF-related skeletal disorders. In this grant application we propose to study the role played by the different FGF ligands and receptors on autophagy regulation and to investigate the physiological relevance of these findings in the context of skeletal growth, homeostasis and maintenance. We will also investigate the intracellular machinery that links FGF signalling pathways to the regulation of autophagy. In addition, we generated preliminary data showing an impairment of autophagy in chondrocyte models of Achondroplasia (ACH) and Thanathoporic dysplasia, two skeletal disorders caused by mutations in FGFR3. We propose to study the role of autophagy in the pathogenesis of FGFR3-related dwarfisms and explore the pharmacological modulation of autophagy as new therapeutic approach for achondroplasia. This application, which combines cell biology, mouse genetics and pharmacological approaches, has the potential to shed light on new mechanisms involved in organismal development and homeostasis, which could be targeted to treat bone and cartilage diseases.

1 586 430 €

Start date: 2017-01-01, End date: 2021-12-31

The key organizing principles that characterize neuronal systems include asymmetric, parallel, and topographic connectivity of the neural circuits. The main aim of my research is to elucidate the key principles underlying functional development of neural circuits by focusing on those organizing principles. I choose mouse visual system as my model since it contains all of these principles and provides sophisticated genetic tools to label and manipulate individual circuit components. My research is based on the central hypothesis that the mechanisms of brain development cannot be fully understood without first identifying individual functional cell types in adults, and then understanding how the functions of these cell types become established, using cell-type-specific molecular and synaptic mechanisms in developing animals. Recently, I have identified several transgenic mouse lines in which specific cell types in a visual center, the superior colliculus, are labeled with Cre recombinase in both developing and adult animals. Here I will take advantage of these mouse lines to ask fundamental questions about the functional development of neural circuits. First, how are distinct sensory features processed by the parallel topographic neuronal pathways, and how do they contribute to behavior? Second, what are the molecular and synaptic mechanisms that underlie developmental circuit plasticity for forming parallel topographic neuronal maps in the brain? Third, what are the molecular mechanisms that set up spatially asymmetric circuit connectivity without the need for sensory experience? I predict that my insights into the developmental mechanism of asymmetric, parallel, and topographic connectivity and circuit plasticity will be instructive when studying other brain circuits which contain similar organizing principles.

1 500 000 €

Start date: 2015-04-01, End date: 2020-03-31

Acute myeloid leukemia (AML) is a group of hematologic malignancies which, due to their molecular and clinical heterogeneity, have been traditionally difficult to classify and treat. Recently, next-generation, whole-genome sequencing has uncovered several recurrent somatic mutations that better define the landscape of AML genomics. Despite these advances in deciphering AML molecular subsets, there have been no concurrent improvements in AML therapy which still relies on the ‘antracycline+cytarabine’ scheme. Hereto, only about 40-50% of adult young patients are cured whilst most of the elderly succumb to their disease. Therefore, new therapeutic approaches which would take advantage of the new discoveries are clearly needed. In the past years, we discovered and characterized nucleophosmin (NPM1) mutations as the most frequent genetic alteration (about 30%) in AML, and today NPM1-mutated AML is a new entity in the WHO classification of myeloid neoplasms. However, mechanisms of leukemogenesis and a specific therapy for this leukemia are missing. Here, I aim to unravel the complex network of molecular interactions that take place in this distinct genetic subtype, and find their vulnerabilities to identify new targets for therapy. To address this issue, I will avail of relevant pre-clinical models developed in our laboratories and propose two complementary strategies: 1) a screening-based approach, focused either on the target, by analyzing synthetic lethal interactions through CRISPR-based genome-wide interference, or on the drug, by high-throughput chemical libraries screenings; 2) a hypothesis-driven approach, based on our recent gained novel insights on the role of specific intracellular pathways/genes in NPM1-mutated AML and on pharmacological studies with ‘old’ drugs, which we have revisited in the specific AML genetic context. I expect our discoveries will lead to find novel therapeutic approaches and make clinical trials available to patients as soon as possible.

1 883 750 €

Start date: 2017-04-01, End date: 2022-03-31