ERC FUNDED PROJECTS

Ageing is accompanied by ectopic white adipose tissue depositions in skeletal muscle and other anatomical locations, such as brown adipose tissue and the bone marrow. Ectopic fat accrual contributes to organ dysfunction, systemic insulin resistance, and other perturbations that have been implicated in metabolic diseases. This research proposal aims to identify the regulatory cues that control the development of ectopic progenitor cells that give rise to this type of fat. It is hypothesized that an age-related dysfunction of the stem cell niche leads to an imbalance between (1) tissue-specific stem cells and (2) fibroblast-like, primarily adipogenic progenitors that reside within many tissues. Novel methodologies that assess stem/progenitor cell characteristics on the single cell level will be combined with animal models of lineage tracing to determine the developmental origin of these adipogenic progenitors and processes that regulate their function. Notch signalling is a key signalling pathway that relies on direct physical interaction to control stem cell fate. It is proposed that impaired Notch activity contributes to the phenotypical shift of precursor cell distribution in aged tissues. Lastly, the role of the stem cell niche in ectopic adipocyte progenitor formation will be analyzed. External signals originating from the surrounding niche cells regulate the developmental fate of stem cells. Secreted factors and their role in the formation of ectopic adipocyte precursors during senescence will be identified using a combination of biochemical and systems biology approaches. Accomplishment of these studies will help to understand the basic processes of stem cell ageing and identify mechanisms of age-related functional decline in tissue regeneration. By targeting the population of tissue-resident adipogenic progenitor cells, therapeutic strategies could be developed to counteract metabolic complications associated with the ageing process.

1 496 444 €

Start date: 2013-03-01, End date: 2018-02-28

Acute Myeloid Leukemia (AML), the most common leukemia diagnosed in adults, represents the paradigm of resistance to front-line therapies in hematology. Indeed, AML is so genetically complex that only few targeted therapies are currently tested in this disease and chemotherapy remains the only standard treatment for AML since the past four decades. Despite an initial sustained remission achieved by chemotherapeutic agents, almost all patients relapse with a chemoresistant minimal residual disease (MRD). The goal of my proposal is to characterize the still poorly understood biological mechanisms underlying persistence and emergence of MRD. MRD is the consequence of the re-expansion of leukemia-initiating cells that are intrinsically more resistant to chemotherapy. This cell fraction may be stochastically more prone to survive front-line therapy regardless of their mutational status (the stochastic model), or genetically predetermined to resist by virtue of a collection of chemoprotective mutations (the mutational model). I have already generated in mice, by consecutive rounds of chemotherapy, a stochastic MLL-AF9-driven chemoresistance model that I examined by RNA-sequencing. I will pursue the comprehensive cell autonomous and cell non-autonomous characterization of this chemoresistant AML disease using whole-exome and ChIP-sequencing. To establish a mutationally-induced chemoresistant mouse model, I will conduct an innovative in vivo screen using pooled mutant open reading frame and shRNA libraries in order to predict which combinations of mutations, among those already known in AML, actively promote chemoresistance. Finally, by combining genomic profiling and in vivo shRNA screening experiments, I will decipher the molecular mechanisms and identify the functional effectors of these two modes of resistance. Ultimately, I will then be able to firmly establish the fundamental relevance of the stochastic and/or the mutational model of chemoresistance for MRD genesis.

1 500 000 €

Start date: 2018-03-01, End date: 2023-02-28

New neurons are continuously generated in certain regions of adult mammalian brain. One of those regions is the dentate gyrus, a subregion of hippocampus, which is essential for memory formation. Although these new neurons in the adult dentate gyrus are thought to have an important role in learning and memory, it is largely unclear how new neurons are involved in information processing and storage underlying memory. Because new neurons constitute a minor portion of intermingled local neuronal population, simple application of conventional techniques such as multi-unit extracellular recording and pharmacological lesion are not suitable for the functional analysis of new neurons. In this proposed research program, I will combine multi-unit recording and behavioral analysis with virus mediated, cell-type-specific genetic manipulation of neuronal activity, to investigate computational roles of new neurons in learning and memory. Specifically, I will determine: 1) specific memory processes that require new neurons, 2) dynamic patterns of activity that new neurons express during memory-related behavior, 3) influence of new neurons on their downstream structure. Further, based on the information obtained by these three lines of studies, we will establish causal relationship between specific memory-related behavior and specific pattern of activity in new neurons. Solving these issues will cooperatively provide important insight into the understanding of computational roles performed by adult neurogenesis. The information on the function of new neurons in normal brain could contribute to future development of efficient therapeutic strategy for a variety of brain disorders.

1 991 743 €

Start date: 2009-01-01, End date: 2013-12-31

Blood and lymphatic vessels have been the subject of intense investigation due to their important role in cancer development and in cardiovascular diseases. The significant advance in the methods used to modify and analyse gene function have allowed us to obtain a much better understanding of the molecular mechanisms involved in the regulation of the biology of blood vessels. However, there are two key aspects that significantly diminish our capacity to understand the function of gene networks and their intersections in vivo. One is the long time that is usually required to generate a given double mutant vertebrate tissue, and the other is the lack of single-cell genetic and phenotypic resolution. We have recently performed an in vivo comparative transcriptome analysis of highly angiogenic endothelial cells experiencing different VEGF and Notch signalling levels. These are two of the most important molecular mechanisms required for the adequate differentiation, proliferation and sprouting of endothelial cells. Using the information generated from this analysis, the overall aim of the proposed project is to characterize the vascular function of some of the previously identified genes and determine how they functionally interact with these two signalling pathways. We propose to use novel inducible genetic tools that will allow us to generate a spatially and temporally regulated fluorescent cell mosaic matrix for quantitative analysis. This will enable us to analyse with unprecedented speed and resolution the function of several different genes simultaneously, during vascular development, homeostasis or associated diseases. Understanding the genetic epistatic interactions that control the differentiation and behaviour of endothelial cells, in different contexts, and with high cellular definition, has the potential to unveil new mechanisms with high biological and therapeutic relevance.

1 481 375 €

Start date: 2015-03-01, End date: 2020-02-29

Angiogenesis research has focused on the sprouting of new capillaries. The mechanisms of vessel maturation are much less well understood. Yet, the maintenance of a mature, quiescent, and organotypically-differentiated layer of endothelial cells (ECs) lining the inside of all blood vessels is vital for human health. The goal of ANGIOMATURE is to identify, validate, and implement novel mechanisms of vascular maturation and organotypic EC differentiation that are active during development, maintenance of vascular stability in adults, and undergo changes in aging. We recently identified previously unrecognized gene expression signatures of vascular maturation in a genome-wide screen of ECs isolated from newborn and adult mice. Epigenetic mechanisms were identified that control the EC transcriptome through gain and loss of DNA methylation as well as EC differentiation and signaling specification. These findings pave the way for groundbreaking novel opportunities to study vascular maturation. By characterizing functionally diverse types of blood vessels, including continuous ECs in lung and brain and sinusoidal ECs in liver and bone marrow, the ANGIOMATURE project will (1) determine up to single cell resolution the transcriptional and epigenetic program(s) of vascular maturation and organotypic differentiation during adolescence, (2) analyze the functional consequences of such program(s) in differentiated ECs and their adaptation to challenge, and (3) study changes of maturation and differentiation program(s) and vascular responses during aging. We will towards this end employ an interdisciplinary matrix of approaches involving omics, systems biology, conditional gene targeting, organoid cell culture, and experimental pathology to create a high-resolution structural and functional organotypic angioarchitectural map. The project will thereby yield transformative mechanistic insights into vital biological processes that are most important for human health and healthy aging.

2 338 918 €

Start date: 2018-08-01, End date: 2023-07-31

Despite improved therapy, cardiovascular diseases remain the most prevalent diseases in the European Union and the incidence is rising due to increased obesity and ageing. The fine-tuned regulation of vascular functions is essential not only for preventing atherosclerotic diseases, but also after tissue injury, where the coordinated growth and maturation of new blood vessels provides oxygen and nutrient supply. On the other hand, excessive vessel growth or the generation of immature, leaky vessels contributes to pathological angiogenesis. Thus, the regulation of the complex processes governing vessel growth and maturation has broad impacts for several diseases ranging from tumor angiogenesis, diabetic retinopathy, to ischemic cardiovascular diseases. MicroRNAs (miRs) are small noncoding RNAs, which play a crucial role in embryonic development and tissue homeostasis. However, only limited information is available regarding the role of miRs in the vasculature. MiRs regulate gene expression by binding to the target mRNA leading either to degradation or to translational repression. Because miRs control patterns of target genes, miRs represent an attractive and promising therapeutic target to interfere with complex processes such as neovascularization and repair of ischemic tissues. Therefore, the present application aims to identify miRs in the vasculature, which regulate vessel growth and vessel remodelling and may, thus, serve as therapeutic targets in ischemic diseases. Since ageing critically impairs endothelial function, neovascularization and vascular repair, we will specifically identify miRs, which are dysregulated during ageing in endothelial cells and pro-angiogenic progenitor cells, in order to develop novel strategies to rescue age-induced impairment of neovascularization. Beyond the specific scope of the present application, the principle findings may have impact for other diseases, where deregulated vessel growth causes or accelerates disease states.

2 375 394 €

Start date: 2009-03-01, End date: 2014-02-28

Dysregulation of capillary permeability is a severe problem in critically ill patients, but the mechanisms involved are poorly understood. Further, there are no targeted therapies to stabilize leaky vessels in various common, potentially fatal diseases, such as systemic inflammation and sepsis, which affect millions of people annually. Although a multitude of signals that stimulate opening of endothelial cell-cell junctions leading to permeability have been characterized using cellular and in vivo models, approaches to reverse the harmful process of capillary leakage in disease conditions are yet to be identified. I propose to explore a novel autocrine endothelial permeability regulatory system as a potentially universal mechanism that antagonizes vascular stabilizing ques and sustains vascular leakage in inflammation. My group has identified inflammation-induced mechanisms that switch vascular stabilizing factors into molecules that destabilize vascular barriers, and identified tools to prevent the barrier disruption. Building on these discoveries, my group will use mouse genetics, structural biology and innovative, systematic antibody development coupled with gene editing and gene silencing technology, in order to elucidate mechanisms of vascular barrier breakdown and repair in systemic inflammation. The expected outcomes include insights into endothelial cell signaling and permeability regulation, and preclinical proof-of-concept antibodies to control endothelial activation and vascular leakage in systemic inflammation and sepsis models. Ultimately, the new knowledge and preclinical tools developed in this project may facilitate future development of targeted approaches against vascular leakage.

1 999 770 €

Start date: 2018-05-01, End date: 2023-04-30

Deregulated apoptotic signaling in hematopoietic stem and progenitor cells (HSPCs) strongly contributes to the pathogenesis and phenotypes of congenital bone marrow failure and myelodysplastic syndromes (MDS) and their progression to acute myeloid leukemia (AML). HSPCs are highly susceptible to apoptosis during bone marrow failure and early MDS, but AML evolution selects for apoptosis resistance. Little is known about the main apoptotic players and their regulators. ApoptoMDS will investigate the impact of apoptotic deregulation for pathogenesis, correlate apoptotic susceptibility with the kinetics of disease progression and characterize the mechanism by which apoptotic susceptibility turns into resistance. ApoptoMDS will draw on a large collection of patient-derived samples and genetically engineered mouse models to investigate disease progression in serially transplanted and xenotransplanted mice. How activated DNA damage checkpoint signaling contributes to syndrome phenotypes and HSPC hypersusceptibility to apoptosis will be assessed. Checkpoint activation confers a competitive disadvantage, and HSPCs undergoing malignant transformation are under high selective pressure to inactivate it. Checkpoint abrogation mitigates the hematological phenotype, but increases the risk of AML evolution. ApoptoMDS aims to analyze if inhibiting apoptosis in HSPCs from bone marrow failure and early-stage MDS can overcome the dilemma of checkpoint abrogation. Whether inhibiting apoptosis is sufficient to improve HSPC function will be tested on several levels and validated in patient-derived samples. How inhibiting apoptosis in the presence of functional checkpoint signaling influences malignant transformation kinetics will be assessed. If, as hypothesized, inhibiting apoptosis both mitigates hematological symptoms and delays AML evolution, ApoptoMDS will pave the way for novel therapeutic approaches to expand the less severe symptomatic period for patients with these syndromes.

1 372 525 €

Start date: 2015-06-01, End date: 2020-05-31

Atherosclerosis is characterized by chronic inflammation of the arterial wall. Mononuclear cell recruitment is driven by chemokines that can be deposited e.g. by activated platelets on inflamed endothelium. Chemokines require oligomerization and immobilization for efficient function, and recent evidence supports the notion that heterodimer formation between chemokines constitutes a new regulatory principle amplifying specific chemokine activities while suppressing others. Although crucial to inflammatory disease, this has been difficult to prove in vivo, primarily as chemokine heterodimers exist in equilibrium with their homodimer counterparts. We introduce the paradigm that heteromerization of chemokines provides the combinatorial diversity for functional plasticity and fine-tuning, coining this interactome. Given the relevance of chemokine heteromers in vivo, we aim to exploit this in an anti-inflammatory approach to selectively target vascular disease. In a multidisciplinary project, we plan to generate covalently-linked heterodimers to establish their biological significance. Obligate heterodimers of CC and CXC chemokines will be designed using computer-assisted modeling, chemically synthesized and cross-linked, structurally assessed using NMR spectroscopy and crystallography, and subjected to functional characterization in vitro and reconstitution in vivo. Conversely, we will develop cyclic beta-sheet-based peptides binding chemokines to specifically disrupt heteromers and we will generate mice with conditional deletion or knock-in of chemokine mutants with defects in heteromerization or proteoglycan binding to be analyzed in models of atherosclerosis. Peptides will be used for molecular imaging and chemokine heteromers will be quantified in cardiovascular patients.

2 500 000 €

Start date: 2010-04-01, End date: 2016-03-31