Transient assembly of F-actin on the outer mitochondrial membrane contributes to mitochondrial fission

S Li, S Xu, BA Roelofs, L Boyman, WJ Lederer… - Journal of Cell …, 2015 - rupress.org
Journal of Cell Biology, 2015rupress.org
In addition to established membrane remodeling roles in various cellular locations, actin has
recently emerged as a participant in mitochondrial fission. However, the underlying
mechanisms of its participation remain largely unknown. We report that transient de novo F-
actin assembly on the mitochondria occurs upon induction of mitochondrial fission and F-
actin accumulates on the mitochondria without forming detectable submitochondrial foci.
Impairing mitochondrial division through Drp1 knockout or inhibition prolonged the time of …
In addition to established membrane remodeling roles in various cellular locations, actin has recently emerged as a participant in mitochondrial fission. However, the underlying mechanisms of its participation remain largely unknown. We report that transient de novo F-actin assembly on the mitochondria occurs upon induction of mitochondrial fission and F-actin accumulates on the mitochondria without forming detectable submitochondrial foci. Impairing mitochondrial division through Drp1 knockout or inhibition prolonged the time of mitochondrial accumulation of F-actin and also led to abnormal mitochondrial accumulation of the actin regulatory factors cortactin, cofilin, and Arp2/3 complexes, suggesting that disassembly of mitochondrial F-actin depends on Drp1 activity. Furthermore, down-regulation of actin regulatory proteins led to elongation of mitochondria, associated with mitochondrial accumulation of Drp1. In addition, depletion of cortactin inhibited Mfn2 down-regulation– or FCCP-induced mitochondrial fragmentation. These data indicate that the dynamic assembly and disassembly of F-actin on the mitochondria participates in Drp1-mediated mitochondrial fission.
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