FIGURE 6:

Model for abscission checkpoint regulation by ATR and Chk1. DNA lesions in postmitotic cells (depicted schematically in one nucleus; yellow hatches) trigger activation of a signaling pathway via ATR. This feeds into the abscission checkpoint via the central regulatory node of Chk1 and the downstream kinase Aurora B to delay abscission. Recruitment of 53BP1 (green circles), and likely other factors that protect DNA lesions during genome surveillance, would eventually lead to suppression of this signaling path when these lesions are properly poised for repair. Although the molecular network is not yet defined, other signals (e.g., those triggered by tension forces) feed independently into the Chk1-Aurora B pathway to further control abscission timing.