ERC FUNDED PROJECTS

Despite the discovery of amyloidosis more than a century ago, the molecular and cellular mechanisms of these devastating human disorders remain obscure. In addition to their involvement in disease, amyloid fibrils perform physiological functions, whilst others have potentials as biomaterials. To realise their use in nanotechnology and to enable the development of amyloid therapies, there is an urgent need to understand the molecular pathways of amyloid assembly and to determine how amyloid fibrils interact with cells and cellular components. The challenges lie in the transient nature and low population of aggregating species and the panoply of amyloid fibril structures. This molecular complexity renders identification of the culprits of amyloid disease impossible to achieve using traditional methods. Here I propose a series of exciting experiments that aim to cast new light on the molecular and cellular mechanisms of amyloidosis by exploiting approaches capable of imaging individual protein molecules or single protein fibrils in vitro and in living cells. The proposal builds on new data from our laboratory that have shown that amyloid fibrils (disease-associated, functional and created from de novo designed sequences) kill cells by a mechanism that depends on fibril length and on cellular uptake. Specifically, I will (i) use single molecule fluorescence and non-covalent mass spectrometry and to determine why short fibril samples disrupt biological membranes more than their longer counterparts and electron tomography to determine, for the first time, the structural properties of cytotoxic fibril ends; (ii) develop single molecule force spectroscopy to probe the interactions between amyloid precursors, fibrils and cellular membranes; and (iii) develop cell biological assays to discover the biological mechanism(s) of amyloid-induced cell death and high resolution imaging and electron tomography to visualise amyloid fibrils in the act of killing living cells.

2 498 465 €

Start date: 2013-05-01, End date: 2019-04-30

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

More than 30 million people are living with diabetes in the EU, with a prevalence expected to grow to over 10% of the adult population by the year 2030. Type 2 diabetes is a major cause of cardiovascular disease related death and disability, substantially increasing the risk of myocardial infarction, stroke and peripheral arterial disease. Recent landmark trials, showing that intensive glucose control does not improve cardiovascular outcomes and may increase mortality in some circumstances, provide a compelling rationale for intense research aimed at developing novel therapeutic strategies. Type 2 diabetes is underpinned by resistance to the effects of insulin, which I have shown in endothelial cells causes reduced bioavailability of the anti-atherosclerotic molecule nitric oxide and leads to accelerated atherosclerosis. The cellular effects of insulin are mirrored by insulin-like growth factor factor-1, the bioavailability of which at its receptor is in turn is regulated by a family of high affinity binding proteins (IGFBP). Epidemiological studies demonstrate and inverse association between one of these binding proteins, IGFBP1, and diabetes-related cardiovascular risk. I have recently demonstrated that IGFBP1 when expressed in mice can ameliorate insulin resistance, obesity and atherosclerosis. In endothelial cells, I showed that IGFBP1 upregulates the production of nitric oxide indepenedently of IGF. These findings suggest that IGFBP1 may be a ‘protective’ endogenous protein and that increasing circulating levels may be a therapeutic strategy to prevent development of diabetes and cardiovascular disease. In this proposal I will address this hypothesis by employing state of the art studies in cells and novel gene modified mice to unravel the molecular basis of the protective effects of IGFBP1 and to investigate the possibility of exploiting the IGF-IGFBP axis to prevent cardiovascular disease in the setting of diabetes and obesity.

1 493 543 €

Start date: 2013-01-01, End date: 2017-12-31

Cardiac muscle death, unmatched by muscle cell creation, is the hallmark of acute myocardial infarction and chronic cardiomyopathies. The notion of heart failure as a muscle-cell deficiency disease has driven interest worldwide in ways to increase heart muscle cell number, by over-riding cell cycle constraints, suppressing cell death, or, most directly, cell grafting. Using stem cell antigen-1, we previously identified telomerase-expressing cells in adult mouse myocardium, which have salutary properties for bona fide cardiac regeneration. Here, we seek to address systematically the mechanisms for long-term self-renewal in Sca-1+ adult cardiac progenitor cells and in the smaller side population fraction, which is clonogenic and expresses telomerase at even higher levels. Specifically, we propose to study the roles of telomerase and of the telomere-capping protein, TRF2. Aim 1, Determine the properties of adult cardiac progenitor cells in mice that lack the RNA component of telomerase (TERC). Aim 2, Determine the properties of adult cardiac progenitor cells in mice that lack the catalytic component (TERT). To distinguish between effects of these two gene products themselves versus those that depend on cumulative telomere dysfunction, G2- and G5-null mice will be compared. Aim 3, Determine the properties of adult cardiac muscle and adult cardiac progenitor cells that lack the telomere-capping protein TRF2. Aim 4, Test the prediction that forced expression of TERT and TRF2 can augment cardiac muscle engraftment in vivo and enhance the clonal derivation of adult cardiac progenitor cells in vitro, without adversely affecting the cells differentiation potential. Work proposed in Aims 1-3 would provide indispensable fundamental information about the function of endogenous telomerase in adult cardiac progenitor cells. Conversely, work in Aim 4 would test potential therapeutic implications of telomerase and a telomere-capping protein with this auspicious population.

2 497 576 €

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