A global genetic analysis of nematode spliced leader trans-splicing.

Nematode worms are one of the most successful groups of animals in terms of absolute biomass and the occupation of a diverse range of habitats. The majority of nematodes are free-living, feeding on microorganisms, but a significant number are parasites of animals or plants. Nematode parasites of humans make a substantial contribution to the global burden of disease, with a handful of nematode species annually accounting for some 46 million disability adjusted life years (DALYs), and plant parasites are responsible for global crop losses estimated at $100 billion each year. Although there are some effective treatments for these parasites, increases in the number and distribution of strains that are resistant to these drugs mean that there is a need to develop new therapeutic treatments. Ideal targets for the development of new therapeutics would be molecules and processes that are found only in nematodes, but are absent from the animals and plants that they infect. Ideally the therapeutic target would be one that is found in all nematodes enabling the development of a drug active against a broad range of nematode infections. One such process is spliced leader trans-splicing, which is an essential part of the way that genes are expressed in nematodes. While we have a good understanding of the main events in this process there have been no systematic investigations into the molecules that are involved. We have identified a new experimental approach to investigate this process in the major experimental system used to study nematode biology, C. elegans. Using this system, we have shown for the first time that is possible to visualise, through changes in the expression of a fluorescent protein, alterations in spliced leader trans-splicing in living animals. We will use this breakthrough to better understand sliced leader trans-splicing, and thereby improve the knowledge upon which the development of new anthelmintic drugs depends.

Spliced leader trans-splicing is an essential, but poorly understood process that occurs in many eukaryotes, including those that are major parasites of human, animals and plants. Arguably the organism in which spliced leader trans-splicing is best understood is C. elegans and work in this system underpins much of our current understanding of this process. Despite the fact that the basic steps in spliced leader trans-splicing are known, how these steps are achieved at the molecular level is not understood. To address this we have recently developed a novel, sensitive screening strategy that allows us, for the first time in any experimental system, to visualise loss of spliced leader trans-splicing in vivo. Importantly, we have validated our assay by showing that it is able to detect sub-lethal defects in this process, and have used this assay to show the involvement of three proteins previously implicated in in vitro experiments. The experiments outlined in this proposal build upon this work and aim to carry out the first comprehensive, genome-wide survey of the genes involved in spliced leader trans-splicing. Using our combined expertise in C. elegans genetics and the biochemistry of protein-RNA complexes we will characterise the components we identify and so obtain a better understanding of this process. Given that spliced leader trans-splicing is found in most, if not all, nematodes that affect human and animal health, as well as crop yields, it is likely our findings will ultimately have an impact in these areas of healthcare and food security.

The main beneficiaries of the proposed research would be those individuals and organisations that are focussed upon combating nematodes parasites that affect humans and the animals and plants that are important for human health and well-being. Our research has the potential to identify novel therapeutic targets that would be of interest to pharmaceutical companies, or charitable foundations with an interest in treating neglected tropical diseases. Moreover, the system that we have developed to screen for molecules involved in spliced leader trans-splicing can be readily adapted into an automated, high-throughput screening system to identify chemical inhibitors of spliced leader trans-splicing that could serve as the basis of novel therapeutics, which would have application in the treatment of a broad range of nematode infections of human, animal and plants. Again, there may be commercial interests that would benefit from this knowledge.

The research postholder will also benefit through the training associated with the research position, and through the networking and skills obtained through our collaboration with Professor Blumenthal's laboratory at the University of Colorado.

The wider UK community will potentially benefit from the project, since it is likely to significantly improve our understanding of a fundamental and essential process that is specific to nematode biology. Given the importance of nematodes in terms of global public and animal health, economics and food security, applications of the research offer long-term benefits in terms of new treatments and control measures for nematode diseases.

The wider community (including school children, teachers and the local farming community) will also benefit from initiatives to discuss, and in some cases participate, in the proposed research, and gain an understanding of how the research outcomes could affect them.