ERC FUNDED PROJECTS

Serotonin (5-HT) is implicated in a wide spectrum of brain functions and disorders. However, its functions remain controversial and enigmatic. We suggest that past work on the 5-HT system have been significantly hampered by technical limitations in the selectivity and temporal resolution of the conventional pharmacological and electrophysiological methods that have been applied. We therefore propose to apply novel optogenetic methods that will allow us to overcome these limitations and thereby gain new insight into the biological functions of this important molecule. In preliminary studies, we have demonstrated that we can deliver exogenous proteins specifically to 5-HT neurons using viral vectors. Our objectives are to (1) record, (2) stimulate and (3) silence the activity of 5-HT neurons with high molecular selectivity and temporal precision by using genetically-encoded sensors, activators and inhibitors of neural function. These tools will allow us to monitor and control the 5-HT system in real-time in freely-behaving animals and thereby to establish causal links between information processing in 5-HT neurons and specific behaviors. In combination with quantitative behavioral assays, we will use this approach to define the role of 5-HT in sensory, motor and cognitive functions. The significance of the work is three-fold. First, we will establish a new arsenal of tools for probing the physiological and behavioral functions of 5-HT neurons. Second, we will make definitive tests of major hypotheses of 5-HT function. Third, we will have possible therapeutic applications. In this way, the proposed work has the potential for a major impact in research on the role of 5-HT in brain function and dysfunction.

2 318 636 €

Start date: 2010-07-01, End date: 2015-12-31

When faced with a threat, an animal must decide whether to freeze, reducing its chances of being noticed, or to flee to the safety of a refuge. Animals from fish to primates choose between these two alternatives when confronted by an attacking predator, a choice that largely depends on the context in which the threat occurs. Recent work has made strides identifying the pre-motor circuits, and their inputs, which control freezing behavior in rodents, but how contextual information is integrated to guide this choice is still far from understood. We recently found that fruit flies in response to visual looming stimuli, simulating a large object on collision course, make rapid freeze/flee choices that depend on the social and spatial environment, and the fly’s internal state. Further, identification of looming detector neurons was recently reported and we identified the descending command neurons, DNp09, responsible for freezing in the fly. Knowing the sensory input and descending output for looming-evoked freezing, two environmental factors that modulate its expression, and using a genetically tractable system affording the use of large sample sizes, places us in an unique position to understand how a information about a threat is integrated with cues from the environment to guide the choice of whether to freeze (our goal). To assess how social information impinges on the circuit for freezing, we will examine the sensory inputs and neuromodulators that mediate this process, mapping their connections to DNp09 neurons (Aim 1). We ask whether learning is required for the spatial modulation of freezing, which cues flies are using to discriminate different places and which brain circuits mediate this process (Aim 2). Finally, we will study how activity of DNp09 neurons drives freezing (Aim 3). This project will provide a comprehensive understanding of the mechanism of freezing and its modulation by the environment, from single neurons to behaviour.

1 969 750 €

Start date: 2019-02-01, End date: 2024-01-31

The brain evolves, develops, and operates in the context of animal movements. As a consequence, fundamental brain functions such as spatial perception and motor control critically depend on the precise knowledge of the ongoing body motion. An accurate internal estimate of self-movement is thought to emerge from sensorimotor integration; nonetheless, which circuits perform this internal estimation, and exactly how motor-sensory coordination is implemented within these circuits are basic questions that remain to be poorly understood. There is growing evidence suggesting that, during locomotion, motor-related and visual signals interact at early stages of visual processing. In mammals, however, it is not clear what the function of this interaction is. Recently, we have shown that a population of Drosophila optic-flow processing neurons —neurons that are sensitive to self-generated visual flow, receives convergent visual and walking-related signals to form a faithful representation of the fly’s walking movements. Leveraging from these results, and combining quantitative analysis of behavior with physiology, optogenetics, and modelling, we propose to investigate circuit mechanisms of self-movement estimation during walking. We will:1) use cell specific manipulations to identify what cells are necessary to generate the motor-related activity in the population of visual neurons, 2) record from the identified neurons and correlate their activity with specific locomotor parameters, and 3) perturb the activity of different cell-types within the identified circuits to test their role in the dynamics of the visual neurons, and on the fly’s walking behavior. These experiments will establish unprecedented causal relationships among neural activity, the formation of an internal representation, and locomotor control. The identified sensorimotor principles will establish a framework that can be tested in other scenarios or animal systems with implications both in health and disease.

1 500 000 €

Start date: 2017-11-01, End date: 2022-10-31

The formation of a functional patterned vascular network is essential for development, tissue growth and organ physiology. Several human vascular disorders arise from the mis-patterning of blood vessels, such as arteriovenous malformations, aneurysms and diabetic retinopathy. Although blood flow is recognised as a stimulus for vascular patterning, very little is known about the molecular mechanisms that regulate endothelial cell behaviour in response to flow and promote vascular patterning. Recently, we uncovered that endothelial cells migrate extensively in the immature vascular network, and that endothelial cells polarise against the blood flow direction. Here, we put forward the hypothesis that vascular patterning is dependent on the polarisation and migration of endothelial cells against the flow direction, in a continuous flux of cells going from low-shear stress to high-shear stress regions. We will establish new reporter mouse lines to observe and manipulate endothelial polarity in vivo in order to investigate how polarisation and coordination of endothelial cells movements are orchestrated to generate vascular patterning. We will manipulate cell polarity using mouse models to understand the importance of cell polarisation in vascular patterning. Also, using a unique zebrafish line allowing analysis of endothelial cell polarity, we will perform a screen to identify novel regulators of vascular patterning. Finally, we will explore the hypothesis that defective flow-dependent endothelial polarisation underlies arteriovenous malformations using two genetic models. This integrative approach, based on high-resolution imaging and unique experimental models, will provide a unifying model defining the cellular and molecular principles involved in vascular patterning. Given the physiological relevance of vascular patterning in health and disease, this research plan will set the basis for the development of novel clinical therapies targeting vascular disorders.

1 618 750 €

Start date: 2016-09-01, End date: 2021-08-31

A great deal is known about the neural basis of associative fear learning. However, many animal species are able to use social cues to recognize threats, a defence mechanism that may be less costly than learning from self-experience. We have previously shown that rats perceive the cessation of movement-evoked sound as a signal of danger and its resumption as a signal of safety. To study transmission of fear between rats we assessed the behavior of an observer while witnessing a demonstrator rat display fear responses. With this paradigm we will take advantage of the accumulated knowledge on learned fear to investigate the neural mechanisms by which the social environment regulates defense behaviors. We will unravel the neural circuits involved in detecting the transition from movement-evoked sound to silence. Moreover, since observer rats previously exposed to shock display observational freezing, but naive observer rats do not, we will determine the mechanism by which prior experience contribute to observational freezing. To this end, we will focus on the amygdala, crucial for fear learning and expression, and its auditory inputs, combining immunohistochemistry, pharmacology and optogenetics. Finally, as the detection of and responses to threat are often inherently social, we will study these behaviors in the context of large groups of individuals. To circumvent the serious limitations in using large populations of rats, we will resort to a different model system. The fruit fly is the ideal model system, as it is both amenable to the search for the neural mechanism of behavior, while at the same time allowing the study of the behavior of large groups of individuals. We will develop behavioral tasks, where conditioned demonstrator flies signal danger to other naïve ones. These experiments unravel how the brain uses defense behaviors as signals of danger and how it contributes to defense mechanisms at the population level.

1 412 376 €

Start date: 2013-12-01, End date: 2018-11-30

The molecular mechanisms that mediate cell competition, cell fitness and cell selection is gaining interest. With innovative approaches, molecules and ground-breaking hypothesis, this field of research can help understand several biological processes such as development, cancer and tissue degeneration. The project has 3 clear and ambitious objectives: 1. We propose to identify all the key genes mediating cell competition and their molecular mechanisms. In order to reach this objective we will use data from two whole genome screens in Drosophila where we have identified 7 key genes. By the end of this CoG grant, we should have no big gaps in our knowledge of how slow dividing cells are recognised and eliminated in Drosophila. 2. In addition, we will explore how general the cell competition pathways are and how they can impact biomedical research, with a focus in cancer and tissue degeneration. The interest in cancer is based on experiments in Drosophila and mice where we and others have found that an active process of cell selection determines tumour growth. Preliminary results suggest that the pathways identified do not only play important roles in the elimination of slow dividing cells, but also during cancer initiation and progression. 3. We will further explore the role of cell competition in neuronal selection, specially during neurodegeneration, development of the retina and adult brain regeneration in Drosophila. This proposal is of an interdisciplinary nature because it takes a basic cellular mechanism (the genetic pathways that select cells within tissues) and crosses boundaries between different fields of research: development, cancer, regeneration and tissue degeneration. In this ERC CoG proposal, we are committed to continue our efforts from basic science to biomedical approaches. The phenomena of cell competition and its participating genes have the potential to discover novel biomarkers and therapeutic strategies against cancer and tissue degeneration.

1 968 062 €

Start date: 2014-06-01, End date: 2019-05-31

Centrioles are essential for the formation of several microtubule organizing structures including cilia, flagella and centrosomes. These structures are involved in a variety of functions, from cell motility to division. Centrosome defects are seen in many cancers, while abnormalities in cilia and flagella can lead to a variety of human diseases, such as polycystic kidney disease. The molecular mechanisms regulating centriole biogenesis have only recently started to be unravelled, opening new ways to answer a wide range of questions that have fascinated biologists for more than a century. In this grant we are asking two fundamental questions that are central to human disease: how is centriole structure and number established and regulated in the eukaryotic cell? To address these questions we propose to identify new molecular players, and to test the role of these and known players in the context of specific mechanistic hypothesis, using in vitro and in vivo models. We propose to develop novel assays for centriole structure and regulation in order to address mechanistic problems not accessible with today s assays. In our search for novel components we will use a multidisciplinary approach combining bioinformatics with high throughput screening. The use of in vitro systems will permit the quantitative dissection of molecular mechanisms, while the study of those mechanisms in Drosophila will allow us to understand them at the whole organism level. Furthermore, this analysis, together with studies in human tissue culture cells, will allow us to understand the consequences of misregulation of these fundamental centriole properties for human disease, such as ciliopathies and cancer. My group is already collaborating with medical doctors in the study of centriole aberrations in human disease (cancer and ciliopathies), which will be invaluable to bringing the results of this study to the translational level.

1 500 000 €

Start date: 2011-01-01, End date: 2016-12-31

Over the next 35 years, antibiotic resistant bacteria are expected to kill more than 300 million people. The need to find alternative strategies for antimicrobial therapies remains a global challenge with several bottlenecks in the antibiotic discovery process. Using Staphylococcus aureus, the most common multidrug-resistant bacterium in the European Union and an excellent model organism for cell division in cocci, we propose: (i) to find new pathways to re-sensitize resistant bacteria. Bacteria undergo major morphology changes during the cell cycle. We hypothesize that these changes generate windows of opportunity during which bacteria are more susceptible or more tolerant to the action of antibiotics. We will identify key regulators of the cell cycle in order to manipulate the duration of windows of opportunity for the action of existing antibiotics. (ii) to develop new fluorescence-based reporters for whole-cell screenings of antimicrobial compounds with new modes of action, including compounds that arrest or delay the cell cycle; compounds that target non-essential pathways that are required for expression of resistance against existing antibiotics and therefore can be used as synergistic drugs for combination therapies; compounds that inhibit the production of virulence factors and compounds that revert persister states that are phenotypically resistant to antibiotics. (iii) to unravel new modes of action of antibiotics by using the constructed reporter strains as powerful tools to learn how antibiotics act at the single cell level. Over the past years, my group has become expert on the biology of S. aureus, has constructed powerful biological tools to study cell division and synthesis of the cell surface and has studied mechanisms of action of various antimicrobial compounds. We are therefore in a privileged position to quickly unravel the function of new players in the bacterial cell cycle and simultaneously contribute to accelerate antibiotic discovery.

2 533 500 €

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

This project is about the racialization of migrant labourers across political boundaries, with a main focus on impoverished Europeans who served in huge numbers as indentured labourers in nineteenth-century Guianese, Caribbean and Hawaiian sugar plantations and in the workforce of late nineteenth and early twentieth century New England cotton mills. With this project I aim to provide major, innovative contributions on three fronts: (i) theory-making, by working the concepts of race, racism, racialization, embodiment and memory in association with migrant work across political boundaries and imperial classifications; (ii) social relevance of basic research, by linking an issue of pressing urgency in contemporary Europe to substantive, broad-scope, and multi-sited anthropological/historical research on the wider structures of domination, rather than to targeted problem-solving research of immediate applicability; (iii) disciplinary scope, by proposing to unsettle historical anthropology and ethnographic history from within the boundaries of a single empire, and to overcome the limitations of existing comparative studies, by inquiring into the flows and interactions between competing empires. I will also: (iv) strengthen the methodology for multi-sited, multi-period research in anthropology; (v) contribute to an anthropology of global connections and trans-local approaches; (vi) promote the multidisciplinary and combined-methods approach to complex subjects; (vii) narrate a poorly known set of historical situations of labour racializations involving Europeans and document the ways they reverberate through generations; and (viii) make the analysis available to both academic audiences and the different communities involved in the research.

2 161 397 €

Start date: 2016-09-01, End date: 2021-08-31