ER-mitochondria contacts couple mtDNA synthesis with mitochondrial division in human cells

How the ER manages mitochondrial division It has been unclear how mitochondrial DNA (mtDNA) replication is spatially controlled in mammalian cells and how the mitochondrial nucleoid—the protein-DNA structure that is the unit of mtDNA inheritance—is distributed at the cellular level. Lewis et al. now show that homeostatic mtDNA synthesis in mitochondrial nucleoids in mammalian cells is spatially linked to a small subset of endoplasmic reticulum (ER)-mitochondria contact sites that are specifically destined for mitochondrial division. Successive events of mtDNA replication, mitochondrial division, and mitochondrial motility function together to ensure the accurate distribution of mtDNA in cells. Furthermore, ER-mitochondria contacts coordinate the licensing of mtDNA replication with division to distribute newly replicated nucleoids to daughter mitochondria. Science , this issue p. 261