NET1 mRNA localization to the midbody is required for Arp2/3-dependent initiation of mitotic abscission.

The recruitment and activation of abscission machinery following mitosis is tightly spatiotemporally regulated, yet the mechanisms underlying this remain poorly understood. We find that RNA localization and local translation at the midbody governs when and where abscission-regulating proteins are expressed. The 3' UTR of NET1 mRNA contains an element that is necessary and sufficient for RNA targeting to the midbody. Mislocalization of NET1 mRNA results in a loss of NET1 protein, a Rho family GEF, throughout the intercellular bridge, delaying abscission and slowing cell proliferation. Arp2/3-mediated branched actin accumulation at the midbody, which is necessary for abscission, requires localized NET1 protein that is competent for binding Rho family GTPases. These findings establish midbody RNA localization and local translation as a key regulatory layer over abscission timing and identify a role for NET1 as a regulator of Arp2/3-mediated branched actin accumulation at the abscission site.