Dynein-2: Building and maintaining a functional primary cilium

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Nearly all cells in the human body build a primary cilium, an antenna-like structure that emerges from the surface of nearly all human cells. Defects in the formation and/or function of the cilium lead to a cohort of human diseases known as the ciliopathies. This project does not seek to define the molecular basis of disease but instead is solely directed at a fundamental understanding of cilia biology. Cilia are of great importance for developmental signalling and therefore, dynein-2 underpins the normal function of all cells in the body. Cilia are built around a microtubule rich structure along which molecules are transported by motor proteins. Dynein-2 is a microtubule motor involved in the formation and function of primary cilia. All cells in the body project a primary cilium for their surface and the function of this organelle is essential for normal human development. We were the first to describe the subunit composition of the human dynein-2 complex, the first characterisation of this important motor from any metazoan system. Our more recent work has defined a function for this motor in formation of the axoneme that forms the core of the cilium as well as in building and/or maintaining the ciliary transition zone. This structure acts as a gate to control diffusion of both soluble and membrane proteins into and out of the cilium, and is critical to cilia function to establish and maintain its identity as a signalling hub distinct from the bulk cytoplasm of the cell. Here, we propose to use a combination of in vitro biochemistry, advanced cell imaging, and proteomics to define of the fundamental role of dynein-2 in the formation of cilia, in establishing and maintaining compartment identity, and in ensuring the fidelity of cilia-based signalling. We will also define the location and mechanism of assembly of dynein-2 and explore a new link that we have identified between these processes and the antagonism between ciliogenesis and cell cycle entry.

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. Dynein-2 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 (ref 5 in the proposal) has triggered interest in licensing reagents generated during the project.
The general 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 my own lab a well as the University as a whole is 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.