User:Benjamin R Harrison

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Benjamin R Harrison

Hi, my name is Benjamin R Harrison, and I'm currently a postdoctoral researcher at the University of Alaska. You can email me through OpenWetWare.

Current Research

I am currently studying the regulation of antisense transcription and chromatin function in the budding yeast Saccharomyces cerevisiae [1] in the lab of Dr Jocelyn Krebs [2].

Previous Research

As a graduate student I studied gravity signal transduction in plant roots (Perrin et al., 2005) in the lab of Dr Patrick Masson [3] at the University of Wisconsin-Madison. In particular we focused our studies on the model plant Arabidopisis thaliana [4]. I spent most of my time studying the functions of two related proteins named ARG1 and ARL2. Work of previous members of the Masson lab had shown that ARG1 and ARL2 are required for Arabidopsis roots to respond to gravity and likely function early in the response to gravity stimulation (Sedbrook et al., 1999; Guan et al., 2003; Boonsirichai et al., 2003). Our work has further demonstrated that ARG1 and ARL2 function in specialized gravity-sensing cells in the root tip, called statocytes.

ARG1 and ARL2 are members of the HSP40 family. HSP40 proteins are defined by the presence of a J-domain, a well characterized domain known to facilitate physical interaction with, and stimulation of, HSP70 chaperones. HSP40-HSP70 co-chaperone systems function in many signal transduction pathways and general cell functions by modulating the activity, folding, modification or stability of other protein substrates. Outside of the J-domain, HSP40 proteins show significant architectural divergence and these regions are thought to provide substrate specificity to HSP70 chaperone systems. ARG1 and ARL2 both posses regions predicted to form coiled-coil motifs similar to those found in actin-binding proteins, and we have shown that ARG1 likely interacts with actin in vivo (Boonsirichai et al., 2003; Harrison and Masson, 2008b). These results suggest that ARG1 and ARL2 may function to alter actin dynamics, a process thought to be intimately associated with gravity sensing in roots (Perbal and Driss-Ecole 2003 ; Hou et al., 2004 ; Perrin et al., 2005).

ARG1 and ARL2 functionally link the direction of the gravity vector to regulation of the flow of the hormone auxin away from the root cap toward the region of the root responsible for growth (Harrison and Masson 2008a). This appears to occur, in part, through the localization of the auxin efflux protein PIN3 to the plasma membrane along particular sides of the statocytes, a process that also requires adenosine kinase (Young et al., 2006). Current work on genetic modifiers of ARG1 and ARL2, and proteins that associate with ARG1 in vivo by John Stanga and others in the Masson lab is turning up some very interesting insights into gravity signaling. Please stay tuned.