Radboud University Nijmegen

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

The proposed research will develop a novel in vitro model of wound healing within the skin. We will employ state-of-the-art micro-fabrication techniques to create engineered substrates for culturing human keratinocytes. This technology will allow us to precisely control multiple parameters of the wound environment. Specifically, we will determine how the composition, geometry, and stiffness of the wound influence cell behaviour. In addition, we will examine the molecular signalling pathways that regulate the cellular responses to these different environments. This project has the potential to provide significant insights into how human skin cells sense and respond to extrinsic signals during the wound healing process. Moreover, this model system may be a powerful tool for future cell biology studies, drug screening, and other types of translational research.

We propose to characterise the properties of a bacterial enzyme that converts a foul smelling, toxic gaseous organic sulfur compound. Methanethiol oxidase converts methanethiol - a gas smelling of rotten cabbage - which is an important sulfur compound in nature. The products of the methanethiol catalysed reaction are formaldehyde, hydrogen sulfide (smells of rotten eggs) and hydrogen peroxide (a chemical that is used as a bleaching agent in contact lens disinfection fluids). Very little is known of the molecular and catalytic properties of methanethiol oxidases. The work we propose will provide fundamental insights into the biochemistry of methanethiol degradation, a process that on a global scale is responsible for turnover of some 300-500 million tons of sulfur in the oceans alone, where methanethiol occurs as a degradation product of a climate cooling gas (dimethylsulfide) and its precursor molecule (dimethylsulfoniopropionate). Methanethiol plays a role as a flavour compound in foods and beverages, but can also contribute to what we perceive as off-flavours when it occurs at too high concentrations. In an industrial context, methanethiol is also significant as a degradation product of bulk solvents (dimethylsulfoxide) and it is conceivable that methanethiol oxidase could find application as an industrial biocatalyst. Our preliminary data also indicate that this enzyme may work in concert with other enzymes in a complex of proteins inside the cell, which may protect it to some degree from its toxic intermediates and may enhance its function. This enzyme complex will also be studied further. An interesting aspect of methanethiol oxidase that we have just discovered is that this bacterial enzyme is encoded by a gene for which there has not been any information indicating its function previously. It is hence of interest to further investigate the enzyme, in particular as there are similar enzymes encoded by genomes of animals including humans on whose function similarly little is known. Thus, studying this bacterial enzyme in more detail, may shed light on the evolution of a type of protein which is also found in our bodies. The ultimate goal of characterising an enzyme is to elucidate its three dimensional structure. While this is not planned in this project, we aim to make the first step towards achieving that goal by producing crystals of the enzyme that can be characterised by X-ray diffraction analysis. This will require using recombinant DNA technology, which will allow to produce sufficient amounts of the enzyme for crystallisation.

The Paris agreement commits nations to pursuing efforts to limit the global temperature rise to 1.5 degrees. This represents a level of transformation of the socio-economic and energy systems that substantially exceeds the scenarios that have been found using conventional integrated assessment models (IAMs). Such models generally ignore economic disequilibrium effects such as unemployment, which could become important under conditions of radical economic transformation, and neglect key dynamic processes that control the rate of uptake of new technologies. Rapid reductions in greenhouse gas emissions also potentially violate the simple scaling assumptions used to derive environmental impacts in IAMs because of the slow response of some parts of the climate system such as the ocean, as compared to the land. We plan to develop a set of more realistic dynamic pathways to reach the 1.5 degree target using a new, fully dynamic IAM that does not rely on equilibrium or pattern scaling assumptions. The assessment will identify policy options and the degree of negative emissions required and will quantify the resulting spatial patterns of climate change and the associated uncertainty resulting from incomplete knowledge of climate, carbon-cycle and socio-economic parameters.

Molecular imaging is one of the key tools for non-invasive clinical diagnosis and opens up the possibility of personalising patient treatment. Positron Emission Tomography (PET) in particular is expanding rapidly and new PET imaging centres are currently being installed across the UK. Biomedical research provides increasing numbers of active molecules that target disease sites in the body and thus could in principle function as imaging agents by labeling with a positron emitting isotope. However, 18-F-FDG is currently the only routinely used PET tracer in the clinic, despite the wide availability of the 18-F radionuclide. This is mainly due to the complexity of the multistep-procedures requiring specialized equipment to make the 18-F labeled imaging agents. The current labeling methods also can be harmful to sensitive biomolecules and thus a small precursor molecule is often labeled that is then attached to an active biomolecule to create the imaging agent. This project will develop a new 18-F-labeling method for sensitive biomolecules which uses the metal aluminium to bind fluoride, rather than carbon-fluorine bond formation which has been the main approach adopted hitherto. The one step labeling procedure will allow clinicians to add the 18-F-fluoride directly into a prepared kit containing the biomolecule in order to prepare the imaging agent. The use of special polymer beads in the labeling has the potential of achieving a higher ratio of labeled to unlabeled precursor than conventional solution methods. This has the advantage of giving better contrast in-vivo and reducing the problems of patient reaction caused by the presence of unlabelled excess biomolecule. The chemistry involved requires no specialised equipment and the faster, kit-based method helps to minimise the exposure of radiation workers to the radionuclide. To achieve our aim, we are designing metal binding sites for fluoride that will allow radiolabeling under conditions that do not harm sensitive biomolecules and proteins. We also propose to combine this approach with methods to attach biomolecules of interest in a way that preserves their ability to reach the target site in the body. Additionally, the compounds we propose are intrinsically fluorescent, so that the potential imaging agents can also be evaluated in living cells using fluorescence microscopy, since PET imaging on its own does not have the resolution necessary to observe the behaviour of the complexes in something as small as a cell. By offering much improved labeling, our new system will facilitate the discovery of new potent biomolecules and facilitate the adoption of Positron Emission Tomography in the clinic without the need for expensive, specialized equipment. A final benefit of the ligand chemistry involved for aluminium is that it also has the potential to be used with other metallic PET radionuclides.