A complex of p190RhoGAP and anillin modulates RhoGTP and the cytokinetic furrow in human cells

Abstract

The cytokinetic furrow (CF) is organized by the RhoA GTPase, which recruits actin and myosin II to the furrow and drives contractility. Here we show a role for the RhoGAP, p190, in cytokinesis and its involvement in regulating Rho GTP levels and contractility. Cells depleted of p190RhoGAP (p190) accumulate high levels of RhoGTP and markers of high Rho activity in the furrow, resulting in failure of the CF to progress to abscission. The loss of p190 can be rescued by a low dose of the myosin II inhibitor blebbistatin, suggesting that cells fail cytokinesis because they have too much myosin activity. p190RhoGAP binds the cytokinetic organizer anillin, and mutants of p190 that are unable to bind anillin or unable to inactivate Rho fail to rescue cytokinesis defects in p190-depleted cells. Together these data demonstrate that a complex of p190RhoGAP and anillin modulates RhoGTP levels in the CF to ensure robust cytokinesis.

The MgcRacGAP SxIP motif tethers Centralspindlin to microtubule plus ends in Xenopus laevis

“…This abnormal accumulation of the key contractile ring components, F-actin and Myosin II, is likely to drive the cytokinesis defects observed when the Mgc SxIP motif is mutated. This is consistent with previous reports demonstrating cytokinesis failure due to an over-robust RhoA activity zone and/or actomyosin contractile ring ( DeWard and Alberts, 2009;Manukyan et al, 2015;Miller and Bement, 2009;Reyes et al, 2014). Collectively, these data provide in vivo evidence that the Mgc SxIP motif plays a functional role in regulating cytokinesis by mediating the precise localization of Centralspindlin in order for proper localized RhoA activation and accumulation of downstream targets.…”

Rho GTPases and actomyosin: Partners in regulating epithelial cell-cell junction structure and function

“…It ensures successful cytokinesis by bundling F-actin, linking F-actin and Myosin II to the membrane, and regulating RhoA activity at the contractile ring (Piekny and Maddox, 2010). The N-terminal domains of Anillin participate in actomyosin binding/assembly, while the C-terminal domains include PH and C2 domains, which anchor it to the membrane, a RhoA binding domain, which allows it to interact with active RhoA, and binding sites for interacting with the GEF Ect2 and the GAPs MgcRacGAP and p190RhoGAP-A (Frenette et al, 2012; Manukyan et al, 2015; Piekny and Maddox, 2010; Sun et al, 2015). Early in cytokinesis, Anillin participates in a positive feedback loop in which its accumulation at the contractile ring is both dependent on and enhances Rho activation (Piekny and Glotzer, 2008).…”

“…Early in cytokinesis, Anillin participates in a positive feedback loop in which its accumulation at the contractile ring is both dependent on and enhances Rho activation (Piekny and Glotzer, 2008). Later in cytokinesis, it interacts with p190RhoGAP-A in a tension-sensitive manner, inactivating RhoA in response to excessive force (Manukyan et al, 2015). Thus, Anillin helps to fine-tune RhoA signaling by coupling GEFs, GAPs, and RhoA with cytoskeletal components like F-actin, Myosin II, and formins.…”

Coupling changes in cell shape to chromosome segregation

“…128), ECT2 degradation 129 , and the loss of PIP 2 (REF. 130), Rho and actin from the midzone 98,131 . Following disassembly of the microtubulebased midbody, which is regulated by centrosomes 132 , mitotic kinases and Spastin 133,134 , ESCRTIII is recruited to the thin membrane tube that connects daughter cells, where it triggers abscission as cells enter G1 (reviewed in REF.…”