Examining the Role of the Endomebrane in Transcription Factor Movement

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INTELLECTUAL MERITIn order for organisms to develop and function properly, cells within the organism must be able to communicate with each other. In plants, communication can occur through specialized intercellular channels called plasmodesmata. Nearly all cells in the plant are connected through plasmodesmata, which allow for the direct exchange of proteins between cells. This means that proteins made by one cell can travel into the neighboring cell and influence the behavior and/or developmental fate of the neighbor. An important question in cell signaling is how this type of protein movement is regulated. Recently the primary investigator identified a protein that she has called SIEL (for SHORT-ROOT INTERACTING EMBRYONIC LETHAL) that promotes the movement of a plant-encoded transcription factor called SHORT-ROOT (SHR) between cells. Movement of SHR is required for the proper formation and growth of the plant root and therefore overall growth of the plant. In addition to SHR, SIEL also interacts with several other mobile transcription factors that are important for plant growth. It is likely that SIEL promotes the movement of other key proteins in plant growth as mutations that cause SIEL not to be produced result in death of the plant early in embryo development. Current data suggest that SIEL acts as an intracellular shuttle that promotes plasmodesmata-dependent movement of proteins through associations with intercellular membranes (specifically endosomes) and the microtubule cytoskeleton. The goal of this project is to determine how SIEL functions in the cell-to-cell transport of proteins during plant development. This research has obvious relevance to plant development and cell biology. In addition, as plant viruses are thought to exploit endogenous plant pathways for intercellular movement, there is relevance to plant disease resistance and agriculture where viral infections can decimate crop yields. BROADER IMPACTSThe primary investigator runs a laboratory in which research participation by students at all levels is highly encouraged. She has hosted students from the local middle schools and high schools and has both high school and undergraduate students actively working in her laboratory on a daily basis. In addition she has actively engaged with local teachers and a Penn education major to develop laboratory exercises that can be performed with materials inexpensively and readily available online or in local grocery or gardening stores. These laboratory exercises meet Pennsylvania standards and benchmarks for science education.