Abstract
The cytokinetic furrow is organized by the RhoA GTPase, which recruits actin and myosin II to the furrow and drives contractility. Here, we show that the RhoA GTPase-activting protein (GAP) p190RhoGAP-A (also known as ARHGAP35) has a role in cytokinesis and is involved in regulating levels of RhoA-GTP and contractility. Cells depleted of p190RhoGAP-A accumulate high levels of RhoA-GTP and markers of high RhoA activity in the furrow, resulting in failure of the cytokinetic furrow to progress to abscission. The loss of p190RhoGAP-A 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-A binds the cytokinetic organizer anillin, and mutants of p190RhoGAP-A that are unable to bind anillin or unable to inactivate RhoA fail to rescue cytokinesis defects in p190RhoGAP-A-depleted cells. Taken together, these data demonstrate that a complex of p190RhoGAP-A and anillin modulates RhoA-GTP levels in the cytokinetic furrow to ensure progression of cytokinesis.