A novel role for Myosin-Va in mitochondrial fission

ABSTRACT In cancer cells metabolic changes and mitochondrial morphology are coupled. It is known that the cytoskeleton and molecular motors are directly involved in regulating mitochondrial morphology. Here we show that myosin-Va, an actin-based molecular motor, is required for the malignant properties of melanoma cells and localizes to mitochondria in these cells. Knockdown of myosin-Va increases cellular respiration rates and ROS production and decreases glucose uptake and lactate secretion. In addition, knockdown of myosin-Va results in reduced mitochondrial fission and correspondingly elongated mitochondria. We show that myosin-Va interacts with the mitochondrial outer membrane protein Spire1C, an actin-regulatory protein implicated in mitochondrial fission, and that Spire1C recruits myosin-Va to mitochondria. Finally, we show that during mitochondrial fission myosin-Va localization to mitochondria increases, and that myosin-Va localizes to mitochondrial fission sites immediately adjacent to Drp1 punctae. We conclude that myosin-Va facilitates mitochondrial fission. These data implicate myosin-Va as a target for the Warburg effect in melanoma cells.