Regulation of cell signaling can occur at many different levels. One such signaling mechanism is the interaction between DNA elements and DNA-binding transcription factors (TFs), which can act as a regulatory circuit to turn on or turn off gene expression. Despite the fact that at least 10% of all Arabidopsis genes are sugar responsive, very few regulatory circuits are known to be associated with sugar signaling. Using micro array analysis, this investigator has identified 184 glucose responsive TFs in Arabidopsis. Forty-five of these TFs appear to be glucose responsive without requiring new protein synthesis, i.e. the glucose response cannot be eliminated by the protein synthesis inhibitor cycloheximide (CHX). The hypothesis is that sugar-responsive TFs play key roles in sugar signaling and that CHX-insensitive TFs modulate CHX-sensitive TFs to create an inter-connected regulatory network. To test this hypothesis, the PI will use a CHX-insensitive and sugar-responsive bZIP transcription factor as a model. Reverse genetic analyses will be conducted to unravel the role of this bZIP in plants sugar responses. The downstream target genes of the bZIP will be identified by chromatin immunoprecipitation coupled Gene Chip analysis (ChIP-chip). These studies will also identify the upstream regulators of the bZIP using both computational and wet-lab analyses. This research is expected to shed light on the global regulatory roles of sugar on gene expression in plants.
This project will also provide interdisciplinary training opportunities for undergraduates, graduates, and postdoctoral researchers in the area of molecular genetics, biochemistry, functional genomics, and bioinformatics. The accumulated micro array data and a large portion of the output from this proposal will be integrated into web-based resources available at public depositories.
