Delay of HeLa cell cleavage into interphase using XXXX : retention of a postmitotic spindle and telophase disc correlates with synchronous cleavage recovery.

@entity1 @entity12086 @entity10610 @entity5242
The molecular signals that determine the position and timing of the cleavage furrow during @entity1 cell cytokinesis are presently unknown. We have studied in detail the effect of @entity12086 ( @entity5242 ), a drug that interferes with actin assembly, on specific late mitotic events in synchronous HeLa cells. When cleavage furrow formation is blocked at 10 microM @entity5242 , cells return to interphase by the criteria of reformation of nuclei with lamin borders, degradation of the cyclin B component of @entity10610 kinase, and loss of mitosis specific MPM-2 antigens. However, the machinery for cell cleavage is retained for up to one hour into G1 when cleavage cannot proceed. The components retained consist prominently of a "postmitotic" spindle and a telophase disc, a structure templated by the mitotic spindle in anaphase that may determine the position and timing of the cleavage furrow. Upon release from @entity5242 block, G1 cells proceed through a rapid and synchronous cleavage. We conclude that the mitotic spindle is not inevitably destroyed at the end of mitosis, but persists as an integral structure with the telophase disc in the absence of cleavage. We also conclude that cell cleavage can occur in G1, and is therefore an event metabolically independent of mitosis. The retained telophase disc may indeed signal the position of furrow formation, as G1 cleavage occurs only in the position where the retained disc underlies the cell cortex. The protocol we describe should now enable development of a model system for the study of @entity1 cell cleavage as a synchronous event independent of mitosis.
