Does brassinosteroid function require chromatin remodeling?

The phytohormone brassinosteroid (BR) is crucial for plant growth and development. Although genetic and molecular approaches have improved understanding of the cellular BR signaling pathway, we still do not have sufficient knowledge about the function of BR. Therefore, proteomic analysis was used to elucidate BR signaling and gene expression in the nuclei of suspended Arabidopsis cells treated with brassinolide, a bioactive BR, or brassinazole, a BR biosynthesis inhibitor. Interestingly, chromatin remodeling-related proteins, the abundance of which was altered in response to cellular BR levels, were identified. This suggested that BR-induced gene expression is regulated not only by transcription factors directly binding to cis-elements, but also by chromatin remodeling in response to BR signaling. In this addendum, we summarize the functions of our identified nuclear proteins in chromatin remodeling and discuss the need for chromatin remodeling regulated by BR signal transduction for expression of BR-induced genes.