Open mitosis: Nuclear envelope dynamics

Abstract

The nuclear envelope separating the cell nucleus from the cytoplasm is a common feature of all eukaryotic cells, but its origin is still an enigma. Its early evolution appears closely linked with the evolution of the mitotic spindle apparatus. Many regulatory proteins are playing critical dual roles in spindle assembly as well as nuclear envelope and nuclear pore complex formation. During the evolution of higher eukaryotes, open mitosis evolved independently in the plant and animal lineages, leading to a marked diversification of nuclear envelope compositions and roles in mitosis. Unique features of the plant nuclear envelope include its function as mitotic spindle organizing center and the lack of nuclear lamins and associated proteins. Nuclear envelope dynamics observed during mitosis appear to be similar between plants and animals. The nuclear envelope is absorbed into the endoplasmic reticulum after breakdown and reformed from the endoplasmic reticulum membrane pool after mitosis. In addition, nuclear envelope material contributes to the newly forming cell plate in plant cells. Plant and animal cells might use the same underlying molecular signals for nuclear envelope reassembly, but modified as variations of a common theme. © 2008 Springer-Verlag Berlin Heidelberg.