Molecular mechanisms regulating the shape of plant cell nuclei

Abstract

Most animal cells harbor spherical and oval nuclei, whereas the nuclei in terrestrial plants do not only show spherical and oval shapes but also show various morphologies such as spindle-shaped and rod-shaped. The morphology of animal nuclei is regulated by lamin proteins, which form the nuclear lamina. In contrast, lamin orthologs are not conserved in plants; therefore, nuclear lamina proteins that regulate nuclear morphology in plants have not been identified. In my research, I detected CROWDED NUCLEI (CRWN) proteins in crude nuclear lamina fraction prepared from Arabidopsis thaliana. Phenotype analysis of crwn disruptants and the subcellular localization analysis of CRWNs demonstrated that CRWNs are plant-specific nuclear lamina proteins and play essential roles in regulating nuclear morphology. In addition, I found that CRWNs govern the transcriptional control of many environmental stress-responsive genes. Particularly, I revealed that CRWNs alter the position of the CA gene cluster in the nucleus affecting CA gene expression, contributing to tolerance to excess copper.