A role for myosin II in mammalian mitochondrial fission

Farida Korobova, Timothy J. Gauvin, Henry N. Higgs*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

192 Scopus citations

Abstract

Mitochondria are dynamic organelles, undergoing both fission and fusion regularly in interphase cells. Mitochondrial fission is thought to be part of a quality-control mechanism whereby damaged mitochondrial components are segregated from healthy components in an individual mitochondrion, followed by mitochondrial fission and degradation of the damaged daughter mitochondrion [1]. Fission also plays a role in apoptosis [2]. Defects in mitochondrial dynamics can lead to neurodegenerative diseases such as Alzheimer's disease [3]. Mitochondrial fission requires the dynamin GTPase Drp1, which assembles in a ring around the mitochondrion and appears to constrict both outer and inner mitochondrial membranes [4]. However, mechanisms controlling Drp1 assembly on mammalian mitochondria are unclear. Recent results show that actin polymerization, driven by the endoplasmic reticulum-bound formin protein INF2, stimulates Drp1 assembly at fission sites [5]. Here, we show that myosin II also plays a role in fission. Chemical inhibition by blebbistatin or small interfering RNA (siRNA)-mediated suppression of myosin IIA or myosin IIB causes an increase in mitochondrial length in both control cells and cells expressing constitutively active INF2. Active myosin II accumulates in puncta on mitochondria in an actin- and INF2-dependent manner. In addition, myosin II inhibition decreases Drp1 association with mitochondria. Based on these results, we propose a mechanistic model in which INF2-mediated actin polymerization leads to myosin II recruitment and constriction at the fission site, enhancing subsequent Drp1 accumulation and fission.

Original languageEnglish (US)
Pages (from-to)409-414
Number of pages6
JournalCurrent Biology
Volume24
Issue number4
DOIs
StatePublished - Feb 17 2014

Funding

We thank Vinay Ramabhadran for advice and reagent preparation, Rick Horwitz for providing the GFP-MIIA expression plasmid, Tatyana Svitkina for several useful reagents, and Amali Namm for her highly evolved brain. This work was funded by grants from the National Institutes of Health (GM069818 and DK088826).

ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology
  • General Agricultural and Biological Sciences

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