ERC FUNDED PROJECTS

Most of the lymphomas diagnosed in the western world are originated from mature B cells. The hallmark of these malignancies is the presence of recurrent chromosome translocations that usually involve the immunoglobulin loci and a proto-oncogene. As a result of the translocation event the proto-oncogene becomes deregulated under the influence of immunoglobulin cis sequences thus playing an important role in the etiology of the disease. Upon antigen encounter mature B cells engage in the germinal center reaction, a complex differentiation program of critical importance to the development of the secondary immune response. The germinal center reaction entails the somatic remodelling of immunoglobulin genes by the somatic hypermutation and class switch recombination reactions, both of which are triggered by Activation Induced Deaminase (AID). We have previously shown that AID also initiates lymphoma-associated c-myc/IgH chromosome translocations. In addition, the germinal center reaction involves a fine-tuned balance between intense B cell proliferation and program cell death. This environment seems to render B cells particularly vulnerable to malignant transformation. We aim at studying the molecular events responsible for B cell susceptibility to lymphomagenesis from two perspectives. First, we will address the role of AID in the generation of lymphomagenic lesions in the context of AID specificity and transcriptional activation. Second, we will approach the regulatory function of microRNAs of AID-dependent, germinal center events. The proposal aims at the molecular understanding of a process that lies in the interface of immune regulation and oncogenic transformation and therefore the results will have profound implications both to basic and clinical understanding of lymphomagenesis.

1 596 000 €

Start date: 2008-12-01, End date: 2014-11-30

The discovery of adult neural stem cells (NSCs) has broaden our view of the physiological plasticity of the nervous system, and has opened new perspectives on the possibility of tissue regeneration and repair in the brain. NSCs reside in specialized niches in the adult mammalian nervous system, where they are exposed to specific paracrine signals regulating their behavior. These neural progenitors are generally in a quiescent state within their niche, and they activate their proliferation depending on tissue regenerative and growth needs. Understanding the mechanisms by which NSCs enter and exit the quiescent state is crucial for the comprehension of the physiology of the adult nervous system. In this project we will study the behavior of a specific subpopulation of adult neural stem cells recently described by our group in the carotid body (CB). This small organ constitutes the most important chemosensor of the peripheral nervous system and has neuronal glomus cells responsible for the chemosensing, and glia-like sustentacular cells which were thought to have just a supportive role. We recently described that these sustentacular cells are dormant stem cells able to activate their proliferation in response to a physiological stimulus like hypoxia, and to differentiate into new glomus cells necessary for the adaptation of the organ. Due to our precise experimental control of the activation and deactivation of the CB neurogenic niche, we believe the CB is an ideal model to study fundamental questions about adult neural stem cell physiology and the interaction with the niche. We propose to study the cellular and molecular mechanisms by which these carotid body stem cells enter and exit the quiescent state, which will help us understand the physiology of adult neurogenic niches. Likewise, understanding this neurogenic process will improve the efficacy of using glomus cells for cell therapy against neurological disease, and might help us understand some neural tumors.

1 476 000 €

Start date: 2010-11-01, End date: 2015-10-31

The mammalian brain is assembled from thousands of neuronal cell types that are organized into distinct circuits to perform behaviourally relevant computations. To gain mechanistic insights about brain function and to treat specific diseases of the nervous system it is crucial to understand what these local circuits are computing and how they achieve these computations. By examining the structure and function of a few genetically identified and experimentally accessible neural circuits we plan to address fundamental questions about the functional architecture of neural circuits. First, are cell types assigned to a unique functional circuit with a well-defined function or do they participate in multiple circuits (“multitasking cell types”), adjusting their role depending on the state of these circuits? Second, does a neural circuit perform “a single computation” or depending on the information content of its inputs can it carry out radically different functions? Third, how, among the large number of other cell types, do the cells belonging to the same functional circuit connect together during development? We use the mouse retina as a model system to address these questions. Finally, we will study the structure and function of a specialised neural circuit in the human fovea that enables humans to read. We predict that our insights into the mechanism of multitasking, network switches and the development of selective connectivity will be instructive to study similar phenomena in other brain circuits. Knowledge of the structure and function of the human fovea will open up new opportunities to correlate human retinal function with human visual behaviour and our genetic technologies to study human foveal function will allow us and others to design better strategies for restoring vision for the blind.

1 499 000 €

Start date: 2010-11-01, End date: 2015-10-31

With the availability of the essentially complete sequence of the human genome, as well as a rapid development of massive sequencing techniques, the research efforts to understand genetics and disease from a cis standpoint will soon reach an endpoint. However, our emerging knowledge of gene regulation networks reveals that epigenetic regulation of the hereditary information plays crucial roles in various biological events through its influence on processes such as transcription, DNA replication and chromosome architecture. Another scenario in which the control of chromatin structure is crucial is the repair of lesions in genomic DNA. There is mounting evidence, particularly from model organisms such as Saccharomyces cerevisiae, that histone modifying enzymes (acetylases, deacetylases, kinases, …) are essential components of the machinery that maintains genome integrity and thereby guards against cancer, degenerative diseases and ageing. However, little is known about the specific “code” of histone tail modifications that coordinate DNA repair, and the impact that an aberrant “histone code” may have on human health. In CHROMOREPAIR we will systematically analyze the chromatin remodelling process that undergoes at DNA lesions and evaluate the impact that chromatin alterations have on the access, signaling and repair of DNA damage. Furthermore, we propose to translate our in vitro knowledge to the development of mouse models that help us evaluate how modulation of chromatin status impinges on genome maintenance and therefore on cancer and aging. As a provocative line of research and based on our preliminary data, we propose that certain chromatin alterations could not only impair but also in some cases promote a more robust response to DNA breaks, which could be a novel and not yet explored way to potentiate the elimination of pre-cancerous cells.

948 426 €

Start date: 2008-12-01, End date: 2013-11-30