Anillin-mediated Targeting of Peanut to Pseudocleavage Furrows Is Regulated by the GTPase Ran

Abstract

During early development in Drosophila, pseudocleavage furrows in the syncytial embryo prevent contact between neighboring spindles, thereby ensuring proper chromosome segregation. Here we demonstrate that the GTPase Ran regulates pseudocleavage furrow organization. Ran can exert control on pseudocleavage furrows independently of its role in regulating the microtubule cytoskeleton. Disruption of the Ran pathway prevented pseudocleavage furrow formation and restricted the depth and duration of furrow ingression of those pseudocleavage furrows that did form. We found that Ran was required for the localization of the septin Peanut to the pseudocleavage furrow, but not anillin or actin. Biochemical assays revealed that the direct binding of the nuclear transport receptors importin alpha and beta to anillin prevented the binding of Peanut to anillin. Furthermore, RanGTP reversed the inhibitory action of importin alpha and beta. On expression of a mutant form of anillin that lacked an importin alpha and beta binding site, inhibition of Ran no longer restricted the depth and duration of furrow ingression in those pseudocleavage furrows that formed. These data suggest that anillin and Peanut are involved in pseudocleavage furrow ingression in syncytial embryos and that this process is regulated by Ran.

Importin β2 Mediates the Spatio-temporal Regulation of Anillin through a Noncanonical Nuclear Localization Signal

“…Further suggestion that anillin's importin ␤2 interaction may be actively regulated comes from observations that Drosophila anillin is not always in the nucleus during interphase. In syncytial nuclear cycles of Drosophila embryos, anillin does not enter the nucleus, rather it is either cytosolic or targeted to the pseudocleavage furrow (32,38). However, anillin enters the nucleus promptly after cellularization, on a time scale of minutes.…”

The evolution, complex structures and function of septin proteins

“…Mutations that result in amino acid changes in the C-terminal PH domain of anillin cause defects in septin recruitment to the furrow canal and contractile ring and also alter the timing and rate of furrow ingression [104]. Direct binding of the nuclear transport receptors importin a and b to anillin was found to prevent the binding of Peanut to anillin, and the GTPase Ran was required for the localization of the septin Peanut to the pseudocleavage furrow [105].…”

Characterization of Mid1 domains for targeting and scaffolding in fission yeast cytokinesis

“…During mitosis, anillins interact with GTPase RhoA (Piekny and Glotzer, 2008) and RacGAP50C (D'Avino et al, 2008;Gregory et al, 2008) and are recruited to the cleavage furrow, where they organize the cytokinetic machinery by interacting with actin filaments, formins, myosin-II, septins and other proteins (D'Avino et al, 2008;Field and Alberts, 1995;Goldbach et al, 2010;Gregory et al, 2008;Haglund et al, 2010;Kinoshita et al, 2002;Maddox et al, 2005;Oegema et al, 2000;Piekny and Maddox, 2010;Silverman-Gavrila et al, 2008;Straight et al, 2005;Watanabe et al, 2010). The domains interacting with actin filaments (Field and Alberts, 1995;Kinoshita et al, 2002;Oegema et al, 2000), myosin-II (Straight et al, 2005) and the formin mDia2 (Watanabe et al, 2010) reside in the N-termini of anillins, whereas the C-terminal PH domain interacts with and recruits septins (Kinoshita et al, 2002;Oegema et al, 2000;Silverman-Gavrila et al, 2008).…”