Dynamic maintenance of asymmetric meiotic spindle position through Arp2/3-complex-driven cytoplasmic streaming in mouse oocytes

Kexi Yi, Jay R. Unruh, Manqi Deng, Brian D. Slaughter, Boris Rubinstein, Rong Li

Research output: Contribution to journalArticlepeer-review

Abstract

Mature mammalian oocytes are poised for completing meiosis II (MII) on fertilization by positioning the spindle close to an actomyosin-rich cortical cap. Here, we show that the Arp2/3 complex localizes to the cortical cap in a Ran-GTPase-dependent manner and nucleates actin filaments in the cortical cap and a cytoplasmic actin network. Inhibition of Arp2/3 activity leads to rapid dissociation of the spindle from the cortex. Live-cell imaging and spatiotemporal image correlation spectroscopy analysis reveal that actin filaments flow continuously away from the Arp2/3-rich cortex, driving a cytoplasmic streaming expected to exert a net pushing force on the spindle towards the cortex. Arp2/3 inhibition not only diminishes this actin flow and cytoplasmic streaming but also enables a reverse streaming driven by myosin-II-based cortical contraction, moving the spindle away from the cortex. Thus, the asymmetric MII spindle position is dynamically maintained as a result of balanced forces governed by the Arp2/3 complex.

Original languageEnglish (US)
Pages (from-to)1252-1258
Number of pages7
JournalNature cell biology
Volume13
Issue number10
DOIs
StatePublished - Oct 2011
Externally publishedYes

ASJC Scopus subject areas

  • Cell Biology

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