Exploring mitochondrial-derived vesicles (MDVs) content, dynamics, and functions during inflammatory response

Abstract:

Mitochondria are complex organelles that house hundreds of biochemical reactions and serve as cellular signaling hubs, thus emerging as key regulators of multiple cellular processes, ranging from the production of energy to the coordination of cell death. Mitochondria communicate with the other intracellular structures by physical association, forming specific inter-organelle contacts that allow the exchange of signals and specific materials. For example, the connection between the endoplasmic reticulum (ER) and mitochondria is instrumental for lipids trafficking and calcium (Ca2+) homeostasis. Importantly, the cross-talk between organelles also relies on vesicular transport that directly involves the mitochondrial compartment. The so-called mitochondrial-derived vesicles (MDVs) incorporate protein cargoes deriving from the outer mitochondrial membrane, as well as from the internal spaces, including mitochondrial inner and matrix proteins. MDVs deliver their contents to lysosomes and peroxisomes for degradation or to multivesicular bodies that fuse with the plasma membrane, leading to the release of their internal content through extracellular vesicles (EVs). Indeed, cells secrete mitochondrial proteins and mtDNA into their environment, which has been proposed to support many functions, including serving as a quality control system, participating in long-range metabolic regulation, or stimulating the immune system. However, the composition, functions, and intracellular dynamics of MDVs, as well as their role in specific inflammatory contexts or disorders are far to be elucidated.

In this project, we propose to elucidate the trafficking of MDVs (from the generation to secretion in the extracellular milieu), their content, and functions by developing innovative methodological approaches. This strategy is based on long-term MDVs monitoring and visualization through a 3D tomographic technology and analysis of mitochondrial cargoes using an optimized protocol for the isolation of EVs. The morphological and biochemical characterization of MDVs will be carried out upon stress conditions elicited by pathogenic infections. Moreover, we will investigate the mitochondrial functions that regulate MDVs homeostasis, by focusing on mitochondrial Ca2+ signaling and ER-mitochondria association. Finally, we will shed light on the role of MDVs in the context of cystic fibrosis (CF), analyzing the contribution of MDVs to the inflammatory response. Therefore, this proposal will apply innovative technologies to provide essential clues on MDVs homeostasis, revealing novel mechanistic insights and indicating their functional contribution to CF disease.