Talk abstracts

Talk on Friday 04:30-04:45pm submitted by Shawn Foley

A global view of RNA-protein interactions reveals novel root hair cell fate regulators

Shawn W. Foley (Department of Biology, Cell and Molecular Biology Graduate Group, University of Pennsylvania, Philadelphia, PA USA), Sager J. Gosai, Nur Selamoglu, Amelia C. Solitti, Fevzi Daldal (Department of Biology, University of Pennsylvania, Philadelphia, PA USA), Dorothee Staiger (Department of Molecular Cell Physiology, Bielefeld University, Bielefeld, Germany), Dongxue Wang, Roger B. Deal (Department of Biology, Emory University, Atlanta, GA USA ), Brian D. Gregory (Department of Biology, Cell and Molecular Biology Graduate Group, University of Pennsylvania, Philadelphia, PA USA)

The Arabidopsis root epidermis is comprised of two cell types: hair cells and nonhair cells, which differentiate from the same precursor cell. This cell fate decision is partially dependent on environmental cues, as root hair cells uptake both water and nutrients from the surrounding soil. Previous studies have focused on understanding the transcriptional regulators that differ between these cell types, identifying transcription factors that are necessary for hair or nonhair cell fate. Despite these advances, little is known about cell type specific post-transcriptional regulation. RNA-binding proteins (RBPs) tightly regulate all post-transcriptional regulatory processes, such as splicing, polyadenylation, stability, and microRNA biogenesis and targeting. RBPs bind to interaction sites on target RNAs via sequence and secondary structure specific interactions, thereby functioning to promote or inhibit splicing events in a cell-type specific manner. Therefore, identifying both the RBPs and RBP interaction sites that distinguish these two cell types will deepen our understanding of the post-transcriptional programs that determine root epidermal cell fate.

To address this question, we utilized our protein interaction profile sequencing (PIP-seq) technique to globally probe the RNA-protein interaction sites in root hair and nonhair cell nuclei. Using these nuclear data, we identify enriched protein-bound RNA sequences. These sequences allowed us to identified two RBPs, one that promotes and one that inhibits root hair cell fate. Follow up experiments reveal that overexpressing the root hair cell promoting RBP in plants results in an abundance of phosphate stress response genes, indicating that this protein activates the phosphate stress response pathway thereby leading to an increase in root hair cell number. In total, these data identify novel functions of two known RBPs, and illuminate an understudied aspect of plant root development.

Keywords: RNA-protein interactions, post-transcriptional regulation, Plant development