ERC FUNDED PROJECTS

"Blood vessels pervade all tissues in the body to supply nutrients and oxygen. Aberrant vessel growth and function are hallmarks of cancer and cardiovascular diseases and they contribute to disease pathogenesis. Antiangiogenic therapeutics have reached the clinic, but limited efficacy and resistance raise unresolved challenges. The current limitations of angiogenic medicine call for a more integrated understanding of the angiogenic process that focuses not only on the instigators of vessel branching but also on mechanisms that sustain vessel growth. Recent insights into fundamental aspects of cell growth move metabolism into spotlight and establish how proliferating cells reprogram their metabolism to provide energy and building blocks for cell replication. During angiogenesis, endothelial cells (ECs) also convert between growth states: although mostly quiescent in adult tissues, ECs divide and migrate rapidly upon angiogenic stimulation. To allow growth of new vessel branches, ECs therefore need to adjust their metabolism to increase energy production and biosynthetic activity. However, the molecular mechanisms that coordinate EC metabolism with angiogenic signalling are not known to date. In this proposal, we put forth the hypothesis that metabolic regulation is a key component of the endothelial angiogenic machinery that is required to sustain vessel growth. Thus, this proposal aims (I) to define transcriptional circuits that link EC growth with metabolism, (II) to explore the regulation of these transcriptional networks by lysine acetylation, a nutrient-regulated protein modification with key functions in metabolism, and (III) to assess the role of sirtuin deacetylases for sensing endothelial energetics during vascular growth. Understanding the principles of angiogenesis-metabolism crosstalk will not only yield novel insights into the basic mechanisms of vessel formation but will also provide unprecedented opportunities for future drug development."

1 487 920 €

Start date: 2012-09-01, End date: 2017-08-31

The proteins of the Bcl-2 family function as key regulators of apoptosis by controlling the permeabilization of the mitochondrial outer membrane. They form an intricate, fine-tuned interaction network which is altered in cancer cells to avoid cell death. Currently, we do not understand how signaling within this network, which combines events in cytosol and membranes, is orchestrated to decide the cell fate. The main goal of this proposal is to unravel how apoptosis signaling is integrated by the Bcl-2 network by determining the quantitative Bcl-2 interactome and building with it a mathematical model that identifies which interactions determine the overall outcome. To this aim, we have established a reconstituted system for the quantification of the interactions between Bcl-2 proteins not only in solution but also in membranes at the single molecule level by fluorescence correlation spectroscopy (FCS). (1) This project aims to quantify the relative affinities between an reconstituted Bcl-2 network by FCS. (2) This will be combined with quantitative studies in living cells, which include the signaling pathway in its entirety. To this aim, we will develop new FCS methods for mitochondria. (3) The structural and dynamic aspects of the Bcl-2 network will be studied by super resolution and live cell microscopy. (4) The acquired knowledge will be used to build a mathematical model that uncovers how the multiple interactions within the Bcl-2 network are integrated and identifies critical steps in apoptosis regulation. These studies are expected to broaden the general knowledge about the design principles of cellular signaling as well as how cancer cells alter the Bcl-2 network to escape cell death. This systems analysis will allow us to predict which perturbations in the Bcl-2 network of cancer cells can switch signaling towards cell death. Ultimately it could be translated into clinical applications for anticancer therapy.

1 462 900 €

Start date: 2013-04-01, End date: 2019-03-31

Chromatin undergoes fascinating structural and functional changes during the metazoan cell cycle. It massively condenses at the beginning of mitosis with a degree of compaction up to fiftyfold higher than in interphase. At the end of mitosis, mitotic chromosomes decondense to re-establish their interphase chromatin structure. This process is indispensable for reinitiating transcription and treplication, and is thus of central importance in the cellular life cycle. Despite its significance to basic research as well as its potential medical implications, postmitotic chromatin decondensation is only poorly understood. It has been well described cytologically, but we lack an understanding of the underlying molecular events. We are ignorant about the proteins that mediate chromatin decondensation, the distinct steps in this multi-step procedure and their regulation. Using a novel in vitro assay, which recapitulates the process in the simplicity of a cell free reaction, we will identify the molecular machinery mediating postmitotic chromatin decondensation and define the different steps of the process. The cell free assay offers the unique possibility to isolate and purify activities responsible for individual steps in chromatin decondensation, to identify their molecular composition and to analyse the molecular changes they induce on chromatin. Accompanied by live cell imaging in mammalian tissue culture cells, the proposed approach will not only facilitate the elucidation of the factors involved in chromatin decondensation, but will also provide insight into how this process is integrated into mitotic exit and nuclear reformation and linked to other concomitant processes such as nuclear envelope assembly or nuclear body formation. Thus, using an unprecedented approach to study the ill-defined but important cell biological process of postmitotic chromatin decondensation, we aim to expand the frontiers in our knowledge on this topic.

1 499 880 €

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

Human epithelia are permanently challenged by microorganisms. In the gut, the fraction of strict anaerobic bacteria increases from proximal to distal, reaching 99% of bacterial species in the colon. Moreover, microbial metabolism causes a reduction of the environment to a low redox potential of only –200 mV to –300 mV. Defensins, characterised by three intramolecular disulfide-bridges, are key effector molecules of innate immunity that protect the host from infectious microbes. Human β-defensin 1 (hBD-1) is one of the most prominent peptides of its class but comparison with other defensins suggested only minor antibiotic killing activity. We could recently show that hBD-1 becomes a potent antimicrobial peptide against C. albicans and anaerobic, Gram-positive commensals of the human normal flora in a reducing environment (Nature 2011). The effect was attributable to the linear, reduced hBD-1 peptide. Here we aim to investigate the antimicrobial activity of reduced hBD-1 in more detail. We will study the mechanism of its reduction by cell-culture experiments and in vitro reduction assays. The molecular details of its antibiotic action will be investigated by using bacterial mutants and further in vitro assays. Additionally we aim to characterise the antibiotic spectrum of reduced hBD-1 by using different antimicrobial assays. Also, we plan to systematically test human defensins under reducing conditions and different pH values that occur in the gut Besides we will screen extracts of human intestinal tissue and stool samples for antimicrobial substances by using the conditions described above. Extracts will be purified by HPLC and antimicrobially active fractions will be examined by MALDI-TOF peptide mass fingerprint technique. We hope to identify novel peptides which have been overlooked due to standardized testing methods. Resembling the natural conditions as close as possible will help to better understand antibiotic mucosal host defense in the intestinal tract.

1 500 000 €

Start date: 2013-02-01, End date: 2018-01-31

How important are environmental barriers between species and populations now and in the future? Currently, environmental barriers to movement across habitats that have persisted since the last ice age are breaking down, resulting in gene flow among previously isolated populations and even hybridization between species. What are the consequences of this gene flow? Local genetic adaptations to the specific conditions of a habitat are though to be threatened when gene flow occurs, but we know little about the long-term evolutionary effects such events have on species. Recent ancient DNA work on polar and brown bears even suggests that gene flow may be beneficial, rather than detrimental for the adaptation and survival of species during times of rapid climate change. This project aims to investigate the extent of gene flow among and its effect upon the survival, adaptation and evolutionary history of temporarily isolated populations of animal species during periods of rapid climate change. This goal will be achieved by looking back into the late Pleistocene, when our world experienced repeated and rapid periods of massive climatic change to which species had to adapt. The project will target the evolutionary history of four species (mammoth, spotted hyena, cave bear, and grey wolf) by sequencing large parts of the nuclear genome of each species across both time and space. In each species conflicting evolutionary histories are provided by morphological and mitochondrial DNA analyses, suggesting that (so far undetected) gene flow of nuclear DNA must have occurred. Undetected gene flow may explain aspects of their evolutionary history, and also the way these species adapted to the rapidly changing environmental conditions of the late Pleistocene.

1 449 380 €

Start date: 2012-12-01, End date: 2017-11-30

This proposal presents an unconventional method for the stimulation of the outer and middle ear that may change the current concept of hearing aids. Photons of the visible light are known to activate the visual sensory cells through photoreceptors. However, when the so-called stress-confinement condition is fulfilled, laser light can induce an acoustic signal through an optoacoustic effect. We demonstrated previously that these light induced sound waves, the optoacoustic waves, can be used to activate the inner ear, the cochlea. Unexpectedly, we found that not just the inner ear but also the middle and outer ear are responsive to laser pulses. However, simple activation of the auditory system is not a sufficient therapy in hearing impaired people. A controlled frequency specific activation of the complete audible frequency spectrum is mandatory to make speech and complex sounds of daily life perceptible and intelligible. The overall objective of this project is to establish methods for frequency specific activation of the complete audible spectrum using monochrome laser pulses. The frequency modulation is a well known process in physics that has to be proven as valid for biological systems as well. Successfull development of parameters for frequency modulation and speech coding resulting will create / provide the basis for a novel non-contact stimulation method that will revolutionize the implantable and non-implantable hearing aids by replacing the speaker or the sound transducer (force mass transducer, the Bone Anchored Hearing Aid screw) with the non contact and focused laser pulses. We expect that the development of these novel stimulation-strategy and stimulation-devices will ameliorate patients’ quality of life by significantly improving their aided hearing and comfort using the hearing device as well as reducing medical health care expenses determined through device related complications.

1 276 698 €

Start date: 2012-10-01, End date: 2018-05-31

Mutational heterogeneity bestows tumors with the phenotypic plasticity and adaptability required for expansion. On the other hand, mutations destabilize proteins – lower stability (metastability) of the tumor proteome must be the inevitable consequence. We set out to systematically investigate this biochemical aspect of metastasis aiming to uncover and therapeutically exploit specific vulnerabilities resulting from protein destabilization. We will approach this goal by cataloging associations between metastasis-promoting proteins and molecular chaperones. Chaperones are obvious candidates to stabilize the proteome, therefore we will prepare a BAC-based mouse model of metastasis, where the contribution of 63 chaperones, comprising the entire murine HSP70 superfamily, to metastasis development will be individually investigated. The role of metastasis-relevant chaperones at the molecular level will be elucidated using mass spectrometry, complemented by next-generation sequencing of metastatic exome. In parallel, a novel proteomics-based method to evaluate aberrant complex formation in tumor cells will be established. Because of the high heterogeneity of cancer, molecularly tailored and combined therapies are needed. To this end, we will capitalize on insights regarding the role of chaperones in metastasis by identifying proteasomal degradation activators able to support or replace the activity of individual chaperones from the HSP70 superfamily. Finally, we will validate the potential of combined, yet specific manipulation of the folding and degradation machineries to suppress metastasis development.

1 366 800 €

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

Motor neurons (MNs) constitute the final common pathway in the generation of behaviors by linking the CNS with the movement apparatus. Herein, MNs diversify into fast, intermediate and slow types whose properties are tuned to the speed, force and endurance of the muscle fiber contractions they elicit. The MN-muscle fiber units display marked plasticity towards chronically altered physical activity, and show strong differences in their vulnerability towards degenerative conditions affecting the neuromuscular system, including amyotrophic lateral sclerosis and aging. Despite their central importance for determining neuromuscular output, plasticity and vulnerability the molecular mechanisms determining the functional MN types remain unknown. My group will use a cross-disciplinary approach by employing molecular genetic, cell biological, electrophysiological and motor behavior assays in mouse and chick to dissect molecular pathways determining MN type status and their contribution to neuromuscular system function and plasticity. Based on our preliminary data, this will focus on the contribution of non-canonical Notch signaling to MN type-specification and neuromuscular function, in addition to four newly identified neural activity modulators as candidate effectors of motor unit output and plasticity. This will be complemented by screening additional pathway components for roles in determining MN type properties through newly developed rapid gene tagging and electrophysiological interrogation in chick, followed by addressing their requirement for motor unit specification and function in mouse. Through an iterative cycle of (i) investigating candidate determinants of motor unit type, (ii) defining their role and mode of action in motor unit specification and function in the context of the neuromuscular system, and (iii) identifying essential downstream components, the proposal will explore molecular pathways operating in motor unit specification, function and plasticity.

1 456 807 €

Start date: 2012-11-01, End date: 2017-10-31

"Multiple Sclerosis (MS) is an inflammatory CNS disease that affects more than 2.5 million individuals worldwide. Damage to axonal connections determines the functional deficits of MS patients. How axons are damaged in MS is only incompletely understood. Using in vivo multiphoton imaging we have discovered a novel axon loss process that underlies axonal damage in experimental and human neuroinflammatory lesions. We have termed this process Focal Axonal Degeneration (FAD). FAD is characterized by a sequence of morphologically defined stages that ultimately result in axonal fragmentation. Notably, intermediate stages of FAD can persist for several days in vivo and still recover spontaneously. In this proposal I want to explore the biological and medical significance of FAD by addressing its: 1. Functional Characteristics I want to analyze two key aspects of axonal function, the ability to transport cargoes and the ability to propagate action potentials, in experimental neuroinflammatory lesions to better understand the in vivo relation between structural and functional deficits during axon damage. 2. Molecular Mechanisms I want to deploy new molecular imaging approaches to directly monitor the redox potential, calcium and ATP levels of axons and their mitochondria in experimental neuroinflammatory lesions. This will allow us to reveal the key effector mechanisms of FAD and the sequence in which they are activated in vivo. 3.Therapeutic Opportunities I plan to make use of advances in automated imaging and microfluidics to develop new in vivo assays for high-throughput screening of therapeutic interventions. This will help us to identify novel strategies for limiting progression and improving recovery of axon damage. The proposed project should provide new insights into the functional and molecular underpinnings of axon damage in vivo, establish new tools and models to study it and guide the development of therapeutic strategies that can prevent or reverse it."

1 487 200 €

Start date: 2012-12-01, End date: 2017-11-30