Shaping Up Mitochondrion in Motion

We previously reported that hair follicle dermal papilla cells (HFDPCs) show two types of mitochondria, which are filamentous (untangled) and rounded (tangled) mitochondria. Platelet- derived growth factor-AA (PDGF-AA) shifts the population balance toward the filamentous type that produces more adenosine triphosphate (ATP) than the other. In addition, the cells show filamentous mitochondria during the process of cellular migration. Furthermore, here we demonstrated that an inner membrane protein, optic atrophy 1 (OPA1), is involved in the filamentous-rounded transition of the organelle. We suggest that OPA1 confers longitudinal rigidity on the filamentous mitochondria. Other cells such as breast cancer cells utilize small fragmented mitochondria, instead of a filamentous form, in the migration process. Regarding the apparent inconsistency with those other reports on the morphological change upon the onset of cellular migration, we discuss communal feature of the regulation of mitochondrial morphol- ogy in different cellular systems: all previous reports showed that the organelle become slender or smaller in the energy-demanding activity.