ERC FUNDED PROJECTS

ATM is the protein kinase that is mutated in the hereditary autosomal recessive disease ataxia telangiectasia (A-T). A-T patients display immune deficiencies, cancer predisposition and radiosensitivity. The molecular role of ATM is to respond to DNA damage by phosphorylating its substrates, thereby promoting repair of damage or arresting the cell cycle. Following the induction of double-strand breaks (DSBs), the NBS1 protein is required for activation of ATM. But ATM can also be activated in the absence of DNA damage. Treatment of cultured cells with hypotonic stress leads to the activation of ATM, presumably due to changes in chromatin structure. We have recently described a second ATM cofactor, ATMIN (ATM INteractor). ATMIN is dispensable for DSBs-induced ATM signalling, but ATM activation following hypotonic stress is mediated by ATMIN. While the biological role of ATM activation by DSBs and NBS1 is well established, the significance, if any, of ATM activation by ATMIN and changes in chromatin was up to now completely enigmatic. ATM is required for class switch recombination (CSR) and the suppression of translocations in B cells. In order to determine whether ATMIN is required for any of the physiological functions of ATM, we generated a conditional knock-out mouse model for ATMIN. ATM signaling was dramatically reduced following osmotic stress in ATMIN-mutant B cells. ATMIN deficiency led to impaired CSR, and consequently ATMIN-mutant mice developed B cell lymphomas. Thus ablation of ATMIN resulted in a severe defect in ATM function. Our data strongly argue for the existence of a second NBS1-independent mode of ATM activation that is physiologically relevant. While a large amount of scientific effort has gone into characterising ATM signaling triggered by DSBs, essentially nothing is known about NBS1-independent ATM signaling. The experiments outlined in this proposal have the aim to identify and understand the molecular pathway of ATMIN-dependent ATM signaling.

1 499 881 €

Start date: 2012-02-01, End date: 2018-01-31

An important question of modern neurobiology is how neurons regulate synaptic function in response to excitation. In particular, the roles of alternative pre-mRNA splicing and mRNA translation regulation in this response are poorly understood. We will study the RNA-binding proteins (RBPs) that control these post-transcriptional changes using a UV crosslinking-based purification method (CLIP) and ultra-high throughput sequencing. Computational analysis of the resulting data will define the sequence and structural features of RNA motifs recognized by each RBP. Splicing microarrays and translation reporter assays will then allow us to examine the regulatory functions of RBPs and RNA motifs. By integrating the biochemical and functional datasets, we will relate the position of RNA motifs to the activity of bound RBPs, and predict the interactions that act as central nodes in the regulatory network. The physiological role of these core RBP-RNA interactions will then be tested using antisense RNAs. Together, these projects will provide insights to the regulatory mechanisms underlying neuronal activity-dependent changes, and provide new opportunities for future treatments of neurodegenerative disorders.

900 000 €

Start date: 2008-09-01, End date: 2013-08-31

Bacterial dehalorespiration is a microbial respiratory process in which halogenated hydrocarbons, from natural or anthropogenic origin, act as terminal electron acceptors. This leads to effective dehalogenation of these compounds, and as such their degradation and detoxification. The bacterial species, their enzymes and other components responsible for this unusual metabolism have only recently been identified. Unlocking the full potential of this process for bioremediation of persistent organohalides, such as polychlorinated biphenyls (PCBs) and tetrachloroethene, requires detailed understanding of the underpinning biochemistry. However, the regulation, mechanism and structure of the reductive dehalogenase (the enzyme responsible for delivering electrons to the halogenated substrates) are poorly understood. This ambitious proposal seeks to study representatives of the distinct reductive dehalogenase classes as well as key elements of the associated regulatory systems. Our group has been at the forefront of studying the biochemistry underpinning transcriptional regulation of dehalorespiration, providing detailed insights in the protein CprK at the atomic level. However, it is now apparent that only a subset of dehalogenases are regulated by CprK homologues with little known about the other regulators. In addition, studies on the reductive dehalogenases have been hampered by the inability to purify sufficient quantities. Using an interdisciplinary, biophysical approach focused around X-ray crystallography, enzymology and molecular biology, combined with novel reductive dehalogenase production methods, we aim to provide a detailed understanding and identification of the structural elements crucial to reductive dehalogenase mechanism and regulation. At the same time, we aim to apply the knowledge gathered and study the feasibility of generating improved dehalorespiratory components for biosensing or bioremediation applications through laboratory assisted evolution.

1 148 522 €

Start date: 2008-09-01, End date: 2013-08-31

Force is ubiquitous in nature and physical stimuli are crucial for cell function. How cells process forces determines key physiological processes such as cell growth and differentiation, in which cells divide or differentiate according to the chemical and physical cues cells receive from the extracellular matrix. Physical stimuli have also been involved in the development of pathological processes, especially those in which cells lose the proper physical communication with the environment, such as cancer and metastasis formation. The major components of the mechanotransduction signaling pathways that transmit and translate these physical messages will most likely to be the molecules that directly sense force from the extracellular matrix. These molecules are integrins and the proteins that link them to the cytoskeleton. Here, I propose a multidisciplinary approach aimed to elucidate how force can modulate cellular behaviour. The project will focus on (i) determining how cells sense, produce and interpret forces and (ii) the cellular outcomes resulting from these processes. First, a nanotechnological suite composed of magnetic tweezers, and siRNA technology will be developed and employed to determine the roles of the molecules involved in these mechanical pathways. Second, the molecular mechanisms that trigger the interaction of proteins under force application will be studied. Several biophysical techniques such as magnetic tweezers, Atomic Force Microscopy (AFM), Total Internal Reflection Fluorescence (TIRF), and Fluorescence Resonance Energy Transfer (FRET) will be used here. Finally, a comparative study of the effect of force in normal and malignant cells will be accomplished. It will be tested whether or not these pathways are involved in the expression of genes in the nucleus, and the ability of normal and malignant cells to respond to external forces and to apply forces on their substrates. Magnetic tweezers, and elastic pillars will be used here.

1 998 331 €

Start date: 2012-03-01, End date: 2018-02-28