Proper positioning of the cleavage furrow requires α-actinin to regulate the specification of different populations of microtubules

Abstract

Proper positioning of the cleavage furrow is essential for successful cell division. The mitotic spindle consisting of dynamic astral microtubules and stable equatorial microtubules is responsible for this process. However, little is known about how microtubules are regulated in a time and region-dependent manner. Here we show that α-actinin-regulated cortical actin filament integrity is critical to specify different populations of microtubules during cell division in mammalian cells. Depletion of α-actinin caused aberrant recruitment of centralspindlin but neither aurora B nor PRC1 to the tips of astral microtubules, leading to stable association of astral microtubules with the cortex and induced ectopic furrowing. Depletion of α-actinin also caused impaired assembly of midzone microtubules, leading to a failure of relocation of aurora B to midzone. Our findings unveil an unexpected yet critical role for an actin crosslinking protein in the regulation of the localization of the microtubule-associated cytokinetic regulator.