[Matzke, Antonius; Lin, Wen-Dar; Matzke, Marjori] Evidence that ion-based signaling initiating at the cell surface can potentially influence chromatin dynamics and chromatin-bound proteins in the nucleus


Legend: Confocal image of a homozygous fluorescence-tagged genomic site used in this study of chromatin dynamics and chromatin-bound proteins in response to pH changes in roots of living Arabidopsis plants. Boxed nuclei were used for analysis.

We have developed tools and performed pilot experiments to test the hypothesis that an intracellular ion-based signaling pathway, provoked by an extracellular stimulus acting at the cell surface, can influence interphase chromosome dynamics and chromatin-bound proteins in the nucleus. The experimental system employs chromosome-specific fluorescent tags and the genome-encoded fluorescent pH sensor SEpHluorinA227D, which has been targeted to various intracellular membranes and soluble compartments in root cells of Arabidopsis thaliana. We are using this system and three-dimensional live cell imaging to visualize whether fluorescent-tagged interphase chromosome sites undergo changes in constrained motion concurrently with reductions in membrane-associated pH elicited by extracellular ATP, which is known to trigger a cascade of events in plant cells including changes in calcium ion concentrations, pH, and membrane potential. To examine possible effects of the proposed ion-based signaling pathway directly at the chromatin level, we generated a pH-sensitive fluorescent DNA binding protein that allows pH changes to be monitored at specific genomic sites. Results obtained using these tools support the existence of a rapid, ion-based signaling pathway that initiates at the cell surface and reaches the nucleus to induce alterations in interphase chromatin movement and the surrounding pH of chromatin-bound proteins. Such a pathway could conceivably act under natural circumstances to allow external stimuli to swiftly influence gene expression by affecting interphase chromosome mobility and the structures and/or activities of chromatin-associated proteins.


doi: https://doi.org/10.3389/fpls.2019.01267