Understanding the structural basis of specificity in mitochondrial lipid transport and its role in drug resistance

Mitochondria are the power generators for a cell and play important roles in cell growth and as well as programmed cell death. Diseases such as cancer arise when a series of unwelcome changes occur in these cellular processes. Mitochondrial health requires a highly coordinated supply of proteins and fat-like molecules known as phospholipids that form a membrane that encloses the protein machinery. The PRELI/Ups family of proteins is fundamental to maintaining the correct phospholipid balance. In this proposal we plan to visualise the mechanisms by which specific mitochondrial phospholipids can be discriminated and distributed between distinct membranes. By advanced structure determination methods, such as X-ray crystallography and nuclear magnetic resonance (NMR), the shape, flexibility and interaction of biological molecules will be imaged in solution. Insight from these structural studies will be combined with cellular approaches to understand the features that control lipid transport by the PRELI/Ups system. This will shed new light on the mechanisms that underlie fundamental aspects of mitochondrial regulation, and the aberrant pathways that can lead to disease. In turn, this would lead to a better understanding of how the body responds to drug treatments in cancer as well as new treatments and monitoring their likely effectiveness.

Mitochondrial membrane lipids are either imported from the endoplasmic reticulum (ER) or synthesized at the mitochondrial inner membrane from ER-derived precursor lipids. Recent studies have identified a conserved class of lipid transfer proteins in the intermembrane space, namely the Ups/PRELI family, which ensure intramitochondrial lipid distribution and synthesis by shuttling phospholipids between both mitochondrial membranes. Remarkably, they do this in a highly lipid-specific manner allowing defined alterations in the membrane lipid composition by regulated lipid transfer. Disturbances in the PRELI system play active roles in regulating apoptosis and driving drug resistance in cancer as well as being implicated in other human disease.
The crystal structure of the phosphatidic acid transporter revealed some of the basic features of phospholipid recognition, but the basis for lipid specificity of Ups/PRELI proteins and the transport process remained enigmatic. In this new proposal we will apply interdisciplinary approach to understand fully the mechanism of lipid transport and specificity within mitochondria. Advance structural biology methods together with gain-of-function genetic screens in yeast and biochemical assays will uncover the critical determinants that drive specific lipid transport. This proposal will complete our understanding of the molecular mechanism of lipid transfer between mitochondrial membranes and how the lipid homeostasis of mitochondrial membranes is maintained. Using our insight, we will also discover novel ways of manipulating the process, which will new ideas for treating dysregulation but are of broad relevance for other cellular lipid transport processes.

The outcomes of this research project will transform our insight into the biological function of the TRIAP1/PRELI family of proteins, which play important roles in mitochondrial lipid homeostasis and drug-resistance mechanisms. The first steps will also be taken to identify lead compounds that modulate the activity of the TRIAP1/PRELI and could be applied to alleviate drug tolerance in chemotherapy regimens. The following methods ensure that the impact of this research.
(a) Biotechnology industry
The commercial potential of outcomes from this research project will be realised through the following: the protection of any intellectual property (IP) and the targeting of specific biotechnology companies through industrial networks and with the help of business and translational offices at Imperial. We will also participate in organised networks that bring together academia and industrial personnel to discuss future challenges and opportunities for collaboration. Where appropriate we also will contribute to Industrial liason-days at Imperial. All structural data will be freely available on-line through standard repositories and findings will be published in a timely fashion. Data will be presented at specialised international research conferences where industry will be present, usually prior to publication.
(b) Research networks
The research will contribute to the general area of mitochondrial biology and so where opportunities arise we will engage through professional research networks, which foster contact, interaction and exchange of ideas between scientists in related fields. For example through the Cancer Research UK Imperial Centre in which an extensive and relevant research network is available; including Imperial College-associated hospitals, industry and other Centres of excellence. High-caliber group leaders, young investigators and postdoctoral/PhD research staff are brought together to exchange ideas.
(c) Schools and public engagement
We will also discuss our research findings and overall research area with the wider public. The PI has made school-oriented presentations to explain how the structural biology assists in the drug and vaccine development. He will continue these efforts by approaching several London schools during the grant period. The applicant regularly contributes to school open days on the Imperial Campus also works closely with the press offices at Imperial to disseminate via the popular science press and other media formats. Skills, training and knowledge economy
Dr Miliara (PDRA), part-time Ms Grace Wu (part-time technician) and any undergraduate, postgraduate students that contribute to the project will recievd broad interdisciplinary training, which will be extremely valuable for UK industry and contribute to the knowledge economy and increase the economic competitiveness of the UK.. Imperial College have an active staff development centre, specifically designed around the needs of early stage researchers. Mentoring and specialized courses on career development, fellowship applications and writing publications are available. There will be opportunities for training junior undergraduate and postgraduate students within the scope of the project.
(d) Collaboration
The project will support an extensive and active collaborative network associated with the project, which involves a number of internationally recognised groups working in mitochondrial and cancer biology as well as native mass spectrometry. These contacts will be an invaluable resource in maximising the impact of our discoveries. Methodology/expertise developed in the proposed grant will likely spill over into other projects in the applicants' laboratory and vice-versa.