ERC FUNDED PROJECTS

The centriole is the largest evolutionary conserved macromolecular structure responsible for building centrosomes and cilia or flagella in many eukaryotes. Centrioles are critical for the proper execution of important biological processes ranging from cell division to cell signaling. Moreover, centriolar defects have been associated to several human pathologies including ciliopathies and cancer. This state of facts emphasizes the importance of understanding centriole biogenesis. The study of centriole formation is a deep-rooted question, however our current knowledge on its molecular organization at high resolution remains fragmented and limited. In particular, exquisite details of the overall molecular architecture of the human centriole and in particular of its central core region are lacking to understand the basis of centriole organization and function. Resolving this important question represents a challenge that needs to be undertaken and will undoubtedly lead to groundbreaking advances. Another important question to tackle next is to develop innovative methods to enable the nanometric molecular mapping of centriolar proteins within distinct architectural elements of the centriole. This missing information will be key to unravel the molecular mechanisms behind centriolar organization. This research proposal aims at building a cartography of the human centriole by elucidating its molecular composition and architecture. To this end, we will combine the use of innovative and multidisciplinary techniques encompassing spatial proteomics, cryo-electron tomography, state-of-the-art microscopy and in vitro assays and to achieve a comprehensive molecular and structural view of the human centriole. All together, we expect that these advances will help understand basic principles underlying centriole and cilia formation as well as might have further relevance for human health.

1 498 965 €

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

DNA repair pathways evolved as an intricate network that senses DNA damage and resolves it in order to minimise genetic lesions and thus preventing tumour formation. Gaining in recognition the last few years, the alternative end-joining (alt-EJ) DNA repair pathway was recently shown to be up-regulated and required for cancer cell viability in the absence of homologous recombination-mediated repair (HR). Despite this integral role, the alt-EJ repair pathway remains poorly characterised in humans. As such, its molecular composition, regulation and crosstalk with HR and other repair pathways remain elusive. Additionally, the contribution of the alt-EJ pathway to tumour progression as well as the identification of a mutational signature associated with the use of alt-EJ has not yet been investigated. Moreover, the clinical relevance of developing small-molecule inhibitors targeting players in the alt-EJ pathway, such as the polymerase Pol Theta (Polθ), is of importance as current anticancer drug treatments have shown limited effectiveness in achieving cancer remission in patients with HR-deficient (HRD) tumours. Here, we propose a novel, multidisciplinary approach that aims to characterise the players and mechanisms of action involved in the utilisation of alt-EJ in cancer. This understanding will better elucidate the changing interplay between different DNA repair pathways, thus shedding light on whether and how the use of alt-EJ contributes to the pathogenic history and survival of HRD tumours, eventually paving the way for the development of novel anticancer therapeutics. For all the abovementioned reasons, we are convinced this project will have important implications in: 1) elucidating critical interconnections between DNA repair pathways, 2) improving the basic understanding of the composition, regulation and function of the alt-EJ pathway, and 3) facilitating the development of new synthetic lethality-based chemotherapeutics for the treatment of HRD tumours.

1 498 750 €

Start date: 2017-07-01, End date: 2022-06-30

The evolutionary pressures exerted by viruses on their host cells constitute a major force that drives the evolution of cellular antiviral mechanisms. The proposed research is motivated by our interest in the roles of protein-RNA interactions in both prokaryotic and eukaryotic antiviral pathways and will proceed in two directions. The first project stems from our current work on the CRISPR pathway, a recently discovered RNA-guided adaptive defense mechanism in bacteria and archaea that silences mobile genetic elements such as viruses (bacteriophages) and plasmids. CRISPR systems rely on short RNAs (crRNAs) that associate with CRISPR-associated (Cas) proteins and function as sequence-specific guides in the detection and destruction of invading nucleic acids. To obtain molecular insights into the mechanisms of crRNA-guided interference, we will pursue structural and functional studies of DNA-targeting ribonuceoprotein complexes from type II and III CRISPR systems. Our work will shed light on the function of these systems in microbial pathogenesis and provide a framework for the informed engineering of RNA-guided gene targeting technologies. The second proposed research direction centres on RNA-targeting antiviral strategies employed by the human innate immune system. Here, our work will focus on structural studies of major interferon-induced effector proteins, initially examining the allosteric activation mechanism of RNase L and subsequently focusing on other antiviral nucleases and RNA helicases, as well as mechanisms by which RNA viruses evade the innate immune response of the host. In our investigations, we plan to approach these questions using an integrated strategy combining structural biology, biochemistry and biophysics with cell-based functional studies. Together, our studies will provide fundamental molecular insights into RNA-centred antiviral mechanisms and their impact on human health and disease.

1 467 180 €

Start date: 2013-11-01, End date: 2018-10-31

Telomeres are heterochromatic nucleoprotein complexes located at the end of linear eukaryotic chromosomes. Contrarily to a longstanding dogma, we have recently demonstrated that mammalian telomeres are transcribed into TElomeric Repeat containing RNA (TERRA) molecules. TERRA transcripts contain telomeric RNA repeats and are produced at least in part by DNA-dependent RNA polymerase II-mediated transcription of telomeric DNA. TERRA molecules form discrete nuclear foci that co-localize with telomeric heterochromatin in both interphase and transcriptionally inactive metaphase cells. This indicates that TERRA is an integral component of telomeres and suggests that TERRA might participate in maintaining proper telomere heterochromatin. We will use a variety of biochemistry, cell biology, molecular biology and microscopy based approaches applied to cultured mammalian cells and to the yeast Schizosaccharomyces pombe, to achieve four distinct major goals: i) We will over-express or deplete TERRA in mammalian cells in order to characterize the molecular details of putative TERRA-associated functions in maintaining normal telomere structure and function; ii) We will locate TERRA promoter regions on different human chromosome ends; iii) We will generate mammalian cellular systems in which to study artificially seeded telomeres that can be transcribed in an inducible fashion; iv) We will identify physiological regulators of TERRA by analyzing it in mammalian cultured cells where the functions of candidate factors are compromised. In parallel, taking advantage of the recent discovery of TERRA also in fission yeast, we will systematically analyze TERRA levels in fission yeast mutants derived from a complete gene knockout collection. The study of TERRA regulation and function at chromosome ends will strongly contribute to our understanding of how telomeres are maintained and will help to clarify the general functions of mammalian non-coding RNAs.

1 602 600 €

Start date: 2009-10-01, End date: 2014-09-30