Beller Lectureship (2021): Organizing Principles of Mitochondria, from Fission to RNA Granules

Nearly all eukaryotic cells contain mitochondria, which can change their shape, divide, or fuse with each other. We use super-resolution microscopy and fluorescent sensors of physiological and biophysical states to understand how mitochondrial division and transcription are physically regulated and organized. Where do mitochondria divide along their surface? How is the location of division determined? We find that division occurs spatially in a non-random, regulated manner, giving rise to mitochondria with different fates. How are mitochondrial transcripts organized? Mitochondrial RNA granules are highly enriched in mitochondrial RNA, and we find that they behave as liquid condensates, although they are remarkably stable. Why does one mitochondria constrict and divide where another relaxes? We find that membrane tension plays a key role in deciding the fates of individual fission sites.