My lab is interested in the mechanisms by which cells are able
to send signals and share information with each other. Patterning
of organs and specification of cell types requires intercellular
signaling to communicate positional information and coordinate
devlopment. The signaling molecules involved in these developmental
events include small molecules, polypeptide ligands, and small
RNAs. Surprisingly, in plants, transcription factors can also
traffic from cell to cell and serve as signaling molecules [1].
My research has concentrated on determining the mechanism by
which the transcription factor, SHORT-ROOT (SHR), moves between
specific cells in the Arabidopsis root (Figure 1) [2]. We have
shown that SHR movement is regulated and dynamic and uncovered
an unexpected correlation between the ability of SHR to nuclear
localize and to move [3]. This correlation suggests a mechanistic
requirement for nuclear localization in cell-to-cell transport,
which may be similar to what has been demonstrated in mammalian
systems for specific classes of proteins that traffic by unconventional
secretion (ie do not use the usual ER to golgi route for export)
[4-7]. Abnormal regulation of these proteins in mammals is associated
with developmental abnormalities and cancer.
Using both cell biological
and novel genomic techniques, including small molecule screens
and inducible RNAi, we plan to identify and further characterize
the
mechanisms of intercellular protein movement in the Arabidopsis root. As tractable
entry points into understanding the mechanisms of cell-to-cell signaling, we
will use SHR and six recently characterized non-cell autonomous transcription
factors. This research has the potential to elucidate protein movement not
only between plant cells, but also the mechanisms of intercellular
protein movement
between animal cells, as there is emerging evidence that at least some of the
trafficking machinery is conserved between these two kingdoms [4-7].
selected
publications
Gallagher, K.L., Examination of the mechanisms
of SHR movement. submitted.
Gallagher, K.L. and P.N. Benfey, Not just another hole in
the wall: understanding intercellular protein trafficking. Genes
Dev, 2005. 19(2): p. 189-95.
Tassetto, M., et al., Plant and animal homeodomains use convergent
mechanisms for intercellular transfer. EMBO Rep, 2005. 6(9):
p. 885-90.
Nickel, W., Unconventional secretory routes: direct protein
export across the plasma membrane of mammalian cells. Traffic,
2005. 6(8): p. 607-14.
Gallagher, K.L., Paquette, A.J.,
Nakajima, K. and Benfey, P. N., Mechanisms Regulating SHORT-ROOT
Intercellular Movement.
Current Biology, 2004. 14(20): p. 1847-51.
Nickel, W., The mystery of nonclassical
protein secretion. A current view on cargo proteins and potential
export routes.
Eur J Biochem, 2003. 270(10): p. 2109-19.
Prochiantz, A. and A. Joliot, Can
transcription factors function as cell-cell signalling molecules?
Nat Rev Mol
Cell Biol, 2003.
4(10): p. 814-9.
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