Réorganisation des compartiments intracellulaires membranaires pendant la mitose

We discuss the mitotic segregation mechanism of the endoplasmic reticulum, the nuclear envelope and the Golgi apparatus. The results from classical biochemical and morphological studies have suggested that these organites remain distinct during mitosis, although highly fragmented. These fragments were thought to be segregated in a stochatic and passive manner in the two daughter cells where they act as a matrix for the reassembly of the organites. This model has been recently challenged by results obtained using new techniques such as living cells imaging that allow, in real time, studies of the different cell compartments. These results show that the segregation of the mitotic Golgi fragments is an active mechanism involving the spindle microtubules. Furthermore, new results also suggest that the Golgi apparatus and the nuclear envelope lose their identity during mitosis. At the onset of mitosis, they are both absorbed in the endoplasmic reticulum. That is followed by the segregation of this latter organite in the two daughter cells where the two former organites reemerge post-mitotically. Here, we critically analyse these two contradictory models. We also discuss the molecular pathways by which are achieved the disassembly and the reassembly of the nuclear envelope and the Golgi apparatus during mitosis.