Investigation of the function of the ER/mitochondria contact sites in cell physiology and disease

Lead Research Organisation: MRC Centre Cambridge

Abstract

Mitochondria are highly dynamic organelles essential for the survival of the cell. Mitochondrial dynamics has been linked to different physiological functions, and contacts with other organelles are required for specific metabolic activity and mitochondrial behaviour. Indeed, endoplasmic reticulum and mitochondria work together and their closed juxtaposition is considered as a signalling platform for metabolite flux. Alteration of these contacts has been associated with defects in cellular homeostasis and with human disease. The goal of our group is to characterise the architecture and understand the associated functions of these inter-organelle contacts. Using biochemical, molecular and cell biological approaches, we want to investigate the function of the mitochondria/endoplasmic reticulum contact sites in different cell physiology processes including cell death, lipid and calcium fluxes and cell migration. This work will lead us to obtaining new insights into the importance of mitochondria and mitochondria/ER contacts in cellular signalling pathways, and to better understanding the pathomechanisms underpinning human diseases associated with defects in their regulation and dynamics.

Technical Summary

Mitochondria are complex organelles that provide essentially all of the energy, mainly through ATP synthesis, required for normal physiological function in nearly all cells of the body. They also play a central role in a number of cell signaling pathways, including cell death and regulation of the intracellular calcium homeostasis. Mitochondria are highly dynamic organelles that can adapt their network in response to specific cellular needs. Indeed, they are able to constantly fuse and divide, and these events are intimately related to their metabolic functions and cellular stress signals. Impairment of mitochondrial physiology is linked to human diseases including neurodegenerative and metabolic disorders such as Parkinson’s disease and diabetes, and also in the progression of certain forms of cancer.

It has become clear recently that mitochondria do not function in isolation, but establish direct contact and communication with other cellular organelles to exchange metabolites and signals converging on, or streaming from, mitochondria. For instance, mitochondria are physically coupled to the endoplasmic reticulum through contact sites that act as a signaling platform. These are called mitochondria-associated membranes (MAM), and are essential for a number of processes, including intracellular calcium homeostasis, lipid exchange, mitochondrial dynamics and motility, ROS production and apoptosis. Studies performed in the last decade have identified several proteins which directly tether the two organelles in MAMs and proteins enriched in these contact sites that play highly specialised homeostatic or execution roles. However, the biogenesis, regulation and precise molecular mechanisms associated with these signaling platforms are still poorly understood.

The goal of our lab is to understand the physiological importance of these inter-organelle contacts in specific cellular contexts, including metabolite flux during steady state, and in response to specific triggers, particularly during cell death or cell migration. Using molecular biological and biochemical approaches we will focus on the characterisation of proteins localised at the interface of the mito/ER contacts sites, their potential role in the stability of the MAM structures, and their functions in lipid and calcium fluxes during the execution of the cell death programme. We will couple these techniques with the state-of-the-art advanced microscopic analysis, including spinning disc and scanning confocal systems, super-resolution microscopy, and electron microscopy. To unravel the function of mito/ER contacts sites on cell physiology, live cell imaging will be performed to study organelle movements during cell migration. The precise localisation of target proteins will be studied by the emergent super-resolution microscopy techniques. Finally, we are also interested in understanding the relevance of mitochondrial dynamics and MAMs in the context of mitochondrial disease. We will study the mitochondrial biology, in different cellular models derived from patients, to characterize how mitochondrial morphology and inter-organelle contacts are affected by different gene mutations, and how this contributes to disease progression.

Publications

10 25 50
 
Description Linking mTOR signalling, mitochondrial dynamics and cell survival 
Organisation McGill University
Country Canada 
Sector Academic/University 
PI Contribution In this collaboration, I provided scientific expertise, intellectual input and performed experiments for our publication.
Collaborator Contribution Collaborators designed the project, contributed to scientific expertize and intellectual input, allowed facility access and performed the experiments.
Impact Publication: doi: 10.1016/j.molcel.2017.08.013. PMID: 28918902.
Start Year 2014
 
Description Mitochondrial calcium and cancer cell migration 
Organisation Claude Bernard University Lyon 1 (UCBL)
Country France 
Sector Academic/University 
PI Contribution I contributed to design and start the project, scientific expertize and intelectual input.
Collaborator Contribution They performed all the experiements and contributed to scientific expertize
Impact Publications: doi: 10.1038/srep36570. PMID: 27827394 DOI: 10.5772/intechopen.74494
Start Year 2012
 
Description Mitochondrial dynamics and contact sites 
Organisation McGill University
Department Montreal Neurological Institute and Hospital
Country Canada 
Sector Hospitals 
PI Contribution Scientific expertize, intellectual input, exchange of ideas
Collaborator Contribution Scientific expertize, intellectual input, exchange of ideas
Impact Publication: doi: 10.1016/j.ceb.2017.03.007. PMID: 28391089
Start Year 2013
 
Description Big Biology Day 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Members of the MRC MBU participated in the Big Biology Day 2017 at Hills Road Sixth Form College. Scientists explained the Unit's research with hands-on activities. These included experiments using Drosophila melanogaster - with fluorescent markings and temperature sensitivity, our "Find the mutant fly" game, colouring books and posters. Feedback: Interesting, fun, enjoyable.
2019: Members of the MBU took Mito-gami, "Destroying Mutant Mitochondrial DNA", DNA sequencing puzzles and colouring/activity books. There was much conversation about the science and career options.
Year(s) Of Engagement Activity 2017,2018,2019
URL http://www.hillsroad.ac.uk/college-life/events/2017/10/14/default-calendar/big-biology-day
 
Description Dissemination of scientific achievements via the Unit's website and social media 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact https://www.facebook.com/mrc-mbu
Twitter - @MRC_MBU
http://www.mrc-mbu.cam.ac.uk/people/julien-prudent
http://www.mrc-mbu.cam.ac.uk
Year(s) Of Engagement Activity 2017,2018,2019,2020,2021
URL http://www.mrc-mbu.cam.ac.uk/people/julien-prudent
 
Description The Big Bang Fair London - Newham 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Demonstration of genetic influence on body characteristics in Drosophila, "Find My Mutant Fly" game, posters explaining the science, movies.
Year(s) Of Engagement Activity 2017
URL http://nearme.thebigbangfair.co.uk/london/
 
Description University of Cambridge Science Festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Up close and personal with fluorescent fruit flies. Members of the MBU showcased the Unit's research using fluorescent fruit flies - examined under a microscope. Temperature sensitive fruit flies were also used to demonstrate the effects of Parkinson's disease. Other activities included movies, posters, a game of elimination and an MRC Cambridge colouring book.

2019: Further showcasing of the Unit's research through the use of hands-on games and activities, discussions and explanations.
Year(s) Of Engagement Activity 2017,2018,2019