Involvement of the nuclear pore complex in morphology of the plant nucleus.

Trafficking between the nucleoplasm and the cytoplasm occurs through the nuclear pore complex (NPC), which consists of large multiprotein complexes. Over the last several years, major progress has been made in both structural determination of the entire assembly of the NPC in yeast and animal cells. By contrast, the plant NPC has long been neglected. Components of the NPC in Arabidopsis thaliana have been identified recently using an interactive proteomic approach. The Arabidopsis nucleoporins are homologous to human nucleoporins, except for a single protein called Nup136. Nup136 is involved in flowering and pollen development, suggesting that Nup136 plays a physiological role in plant reproduction. Nup136 also regulates morphology of the nucleus. Overexpression of Nup136-GFP was found to induce elongation of nuclei in various tissues, whereas deficiency of Nup136 caused a reduction in the size of nuclei. Nup136 is thought to be a functional homolog to animal Nup153, although they have no sequence homology. The mechanism underlying the regulation of nuclear morphology by Nup136, which is thought to be unique to higher plants, is discussed.