At the end of mitosis the Mitotic Exit Network (MEN) pathway triggers complex tasks which mainly include the spindle disassembly and the nuclear envelopes assembly. In the course of telophase, which often lasts less than an hour and corresponds to only about 2% of the entire cell cycle’s duration,spatial and temporal cues are integrated to ensure that cytokinesis occurs after the genome has partitioned between mother and daughter cells. From the end of anaphase through telophase, sequential components of a Ras-like GTPase signaling pathway are controlled by a set of different spatial and temporal signals. Successful propagation of these signals through multi-step transduction requires a remarkably complex coordination. By considering that cells lacking proper MEN function fail to exit from mitosis, I argue that in a hybrid genome impaired coordination between two diverged MENs is prone to result in critical mitotic defects, from late anaphase through telophase. The so-called HyMEN model of hybrid incompatibility depicted here can be regarded as an extension of the Bateson-Dobzhansky-Muller model of speciation, centered on the MEN.
Author(s): Pierre Hutter