Biosciences Research Seminar - New roles for Golgi-derived PI(4)P-containing vesicles in mitochondrial division

Mitochondria house hundreds of biochemical reactions involved in processes critical for the survival and homeostatic adaptation of the cell. Beyond their role in energy production, the concept of mitochondria as signaling organelles has recently emerged. Indeed, mitochondria form a dynamic and interconnected network that is constantly remodeled by cycles of membranes fission and fusion. These dynamic transitions are not only required to ensure mitochondrial functions but also to respond to cellular needs by adapting their morphology to the metabolic state of the cell. Defects in mitochondrial morphology have been widely associated to numerous diseases including neurodegenerative disease and cancer, raising the importance of elucidating the molecular mechanisms driving fusion and fission events. Mitochondrial division is a multi-step process mainly regulated by the recruitment and oligomerization of the large GTPase Dynamin-related protein 1 (Drp1) at endoplasmic reticulum (ER) contacts. However, while the initial steps of this process are well characterized, the precise mechanisms of the final scission event are under intense debate. Here, I will present findings highlighting the contribution of TGN vesicles, and in particular the roles of the small GTPase ADP-ribosylation factor 1 (Arf1), and its effector, phosphatidylinositol 4-kinase IIIβ (PI(4)KIIIβ), generating phosphatidyl inositol-4-phosphate (PI(4)P), to the late steps of the mitochondrial division process.