Interactions between mitochondria and the endoplasmic reticulum in cell physiology and disease
Mitochondria play a central role in a number of cell signalling pathways, including cell death and regulation of intracellular calcium homoeostasis. 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 signalling platform. These are called mitochondria-associated membranes (MAM), and are essential for a number of processes, including intracellular calcium homoeostasis, 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 homoeostatic or execution roles. However, the biogenesis, regulation and precise molecular mechanisms associated with these signalling 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.