Functional interplay of ciliary trafficking complexes and motor proteins.

Lead Research Organisation: University of Bristol
Department Name: Biochemistry

Abstract

Primary cilia project from the surface of nearly all human cells to serve as signalling platforms. They are essential for human and animal development and are also required throughout life to control pathways that relate to the formation and maintenance of bone, kidney function, signalling in the brain and many more body functions. These cilia are built and maintained by a series of large multi-protein complexes. Our two labs in the UK and Japan have made significant contributions to our understanding of the key machines involved. Most recently we have each defined the function of two microtubule motor protein complexes, dynein-2 and kinesin-2 in cilia. They are both required not only to build the cilium but to maintain it and drive transport along this structure. Our work has reached a point where we consider it hugely beneficial to combine our efforts to better understand how these complexes work, not just in isolation, but in the context of the other large multi-protein machines that are required for cilia function. The dynein-2 and kinesin-2 microtubule motors provides a fundamental link between microtubule motor function, protein trafficking, and cilia function because of its function in driving intraflagellar transport (IFT) within cilia. The Stephens lab was the first to define the subunit composition of the dynein-2 motor in humans. The Nakayama lab have made major advances in our understanding of how kinesin-2 integrates with the IFT machinery. This ambitious project seeks to combine our expertise in protein interaction analysis and cell imaging to define how dynein-2 and kinesin-2 interact with, and work in concert with, the other major ciliary machines called IFT-A, IFT-B and the BBSome.

We aim to provide a complete picture of the molecular interactions of the dynein-2 complex with other critical components of the system, the kinesin-2 motor, the BBSome and the IFT particles, IFT-A and IFT-B, using a combination of molecular cell biology approaches including advanced microscopy and proteomics. Our current BBSRC-funded work has developed proteomics approaches that have identified key interacting proteins that seem to direct the assembly and function of dynein-2.

This is a frontier bioscience project that seeks to understand fundamental processes in cell biology. That said, the formation of cilia, tight control of cilia-based signalling pathways, and the control of entry to and exit from the cell cycle are fundamental to normal health as well as having potential long-term impact on human and animal health. Ciliary signals include those that control early human development as well as others that occur throughout life to control metabolism. Key pharmaceuticals targeting common cancers are also directed against ciliary signalling pathway. A full understanding of the structure and function of cilia is key to a diverse array of fields and has relevance from the earliest stages of human development and throughout life.

Planned Impact

There is great interest in the possibility to subvert existing cellular pathways for therapeutic benefit. The dysfunction of these pathways is either a direct or underlying feature of many human diseases. Many human congenital diseases have been determined to be caused by mutations in genes encoding the cilia machinery. These diseases span a range of physiological steps from skeletal development to kidney function. This highlights the importance of a full understanding of these pathways to guide possible future clinical intervention. Through informing our basic understanding of a critical cellular process, it is most likely our work will inform long term projects in other fields including the clinical genetics and the pharmaceutical industry.

Who might benefit and how?
Clinicians - Ciliopathies are a cohort of diseases that affect 1 in 1000 people. Understanding the core biology of their formation and function is central to a good understanding of the role cilia play in development, disease, and ongoing health. Our work present opportunities to engage with clinical colleagues in terms of diagnosis of "orphan" ciliopathies as well as in exploring the potential to modulate cilia function for improved outcomes. Drugs targeting ciliary signalling (notably the hedgehog signalling pathway) are approved for a variety of cancers making our work of interest to oncologists.

Industry - Cilia sit at a nexus between signalling in the context of normal healthy tissue biology and the onset and progression of cancer. As mentioned above, some cilia-specific signalling pathways such as sonic hedgehog have already been targeted successfully for anti-cancer therapies. The IFT machinery plays a direct role in signal transduction within this pathway presenting an opportunity for direct engagement with those targeting cilia-related cancers such as basal cell carcinoma. Furthermore, there is great interest in control of ciliary pathways that have been linked directly through monogenic disorders linked to obesity. In addition, our recent BBSRC-funded work has triggered interest in licensing reagents generated during the project.

The public - In addition to the broad benefits that understanding fundamental bioscience brings in the longer term (32x gross value added per public spend), this work addresses directly key areas of health that have the potential to impact both on acute genetic diseases as well as long term health of the general population. Cilia control key aspects of signalling during embryonic development but also throughout life. Key research into their role in tissue repair and regeneration presents one opportunity here to build on our fundamental discovery science.

Bioscience researchers - This project includes considerable opportunity to train the researchers involved in areas that go beyond the day-to-day research methodology. Examples include our extensive integration with public communication and outreach programmes and the extensive network of University schemes to benefit the training and development of research staff (Bristol is at the forefront of research staff development). I have a good track record in facilitating the placement of staff in areas outside our core research activity including in intellectual property management, clinical trials, and research policy and management. This demonstrates that the environment provided by our own labs a well as our institutions more widely are highly conducive to career development of our staff beyond academic, basic science research alone and thus contributes to the economic development of the nation. Our projects are also very data intensive - notably from imaging work - and the management and analysis of such large (terabyte) datasets is applicable to many areas of professional life.

Publications

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