Abstract
COP9 signalosome (CSN) is a nuclear complex regulating signal transduction in plants and animals. To dissect the function of CSN, we focused on the function of CSN1 subunit. The N-terminal region of CSN1 (CSN1N) possessed a transcriptional repression activity in mammals, and was essential for survival in plants. To understand this mechanism, we isolated proteins interacting with CSN1N in Arabidopsis, and identified a transcription factor belonging to a plant-specific trihelix family. Through a series of pull-down assays, this transcription factor and the two homologous were shown to directly bind CSN1N in a specific manner. We characterized T-DNA-inserted mutants, RNAi plants, and 35S promoter driven overexpressing plants. Two independent lines with increased mRNA accumulation exhibited slightly shorter hypocotyl compared to wild-type plants. Here, we report the promoter activity, the gene expression pattern of this transcription factor and the phenotype of its mutants. We will further characterize this transcriptional factor and discuss its role in CSN-mediated signal regulation.
