Chromatin attachment to the nuclear matrix represses hypocotyl elongation inArabidopsis thaliana

Abstract

AbstractThe nuclear matrix is a nuclear compartment that has diverse functions in chromatin regulation and transcription. However, how this structure influences epigenetic modifications and gene expression in plants is largely unknown. In this study, we showed that a nuclear matrix binding protein, AHL22, together with the two transcriptional repressors FRS7 and FRS12, regulates hypocotyl elongation by suppressing the expression of a group of genes known asSMALL AUXIN UP RNAs(SAURs) inArabidopsis thaliana. The transcriptional repression ofSAURsdepends on their attachment to the nuclear matrix. The AHL22 complex not only brings these SAURs, which contained matrix attachment regions (MARs), to the nuclear matrix, but it also recruits the histone deacetylase HDA15 to theSAURloci. This leads to the removal of H3 acetylation at theSAURloci and the suppression of hypocotyl elongation. Taken together, our results indicate that MAR-binding proteins act as a hub for chromatin and epigenetic regulators. Moreover, we present a novel mechanism by which nuclear matrix attachment to chromatin regulates histone modifications, transcription, and hypocotyl elongation.