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dictyNews Volume 38 Number 15
dictyNews
Electronic Edition
Volume 38, number 15
June 22, 2012
Please submit abstracts of your papers as soon as they have been
accepted for publication by sending them to dicty@northwestern.edu
or by using the form at
http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit.
Back issues of dictyNews, the Dicty Reference database and other
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Abstracts
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A matricellular protein and EGF-like repeat signalling in the social
amoebozoan Dictyostelium discoideum
Robert J. Huber and Danton H. OÕDay
Department of Cell and Systems Biology, University of Toronto,
25 Harbord Street, Toronto, ON, Canada M5S 3G5
Department of Biology, University of Toronto Mississauga, 3359
Mississauga Road North, Mississauga, ON, Canada L5L 1C6
Cellular and Molecular Life Sciences, In press
Matricellular proteins interact with the extracellular matrix (ECM) and
modulate cellular processes by binding to cell surface receptors and
initiating intracellular signal transduction. Their association with the
ECM and the ability of some members of this protein family to regulate
cell motility have opened up new avenues of research to investigate
their functions in normal and diseased cells. In this review, we
summarize the research on CyrA, an ECM calmodulin-binding protein
in Dictyostelium. CyrA is proteolytically cleaved into smaller EGF-like
(EGFL) repeat-containing cleavage products during development.
The first EGFL repeat of CyrA binds to the cell surface and activates
a novel signalling pathway that modulates cell motility in this model
organism. The similarity of CyrA to the most well characterized
matricellular proteins in mammals allows it to be designated as
the first matricellular protein identified in Dictyostelium.
Submitted by Robert Huber [robert.huber@utoronto.ca]
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On-Chip Open Microfluidic Devices for Chemotaxis Studies.
Gus A. Wright, Lino Costa, Alexander Terekhov, Dawit Jowhar,
William Hofmeister, and Christopher Janetopoulos.
Microscopy and Microanalysis, in press
Microfluidic devices can provide unique control over both the
chemoattractant gradient and the migration environment of the
cells. Our work incorporates laser-machined micro and nanofluidic
channels into bulk fused silica and cover slip-sized silica wafers.
We have designed ÒopenÓ chemotaxis devices that produce
passive chemoattractant gradients without an external micropipette
system. Since the migration area is unobstructed, cells can be
easily loaded and strategically placed into the devices with a
standard micropipette. The reusable monolithic glass devices have
integral ports that can generate multiple gradients in a single
experiment. We also used cover slip microfluidics for chemotaxis
assays. Passive gradients elicited from these cover slips could be
readily adapted for high throughput chemotaxis assays. We have
also demonstrated for the first time that cells can be recruited into
cover slip ports eliciting passive chemoattractant gradients. This
proves, in principle, that intravital cover slip configurations could
deliver controlled amounts of drugs, chemicals or pathogens as well
as recruit cells for proteomic or histological analysis in living animals
while under microscopic observation. Intravital cover slip fluidics will
create a new paradigm for in vivo observation of biological processes.
Submitted by Gus Wright [gusalanwright@gmail.com]
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SCAR knockouts in Dictyostelium: WASP assumes SCARÕs functions
and upstream regulators.
Douwe M. Veltman, Jason S. King, Laura M. Machesky and
Robert H. Insall*
J. Cell Biology, in press
The Arp2/3 complex activator SCAR/WAVE controls actin polymerization
in pseudopods, while WASP assembles actin at clathrin coated pits.
Unexpectedly, Dictyostelium SCAR knockouts can still spread, migrate
and chemotax using pseudopods driven by the Arp2/3 complex. In the
absence of SCAR, some WASP relocates from the coated pits to the
leading edge, where it behaves with similar dynamics to normal SCAR,
forming split pseudopods and travelling waves. Pseudopods colocalize
with active Rac, whether driven by WASP or SCAR, though Rac is
activated to a higher level in SCAR mutants. Members of the SCAR
regulatory complex like PIR121 are not required for WASP regulation.
We thus show that WASP is unexpectedly able to respond to all core
upstream signals, and regulators that couple through the other members
of SCARÕs regulatory complex are not essential for pseudopod formation.
We conclude that WASP and SCAR can regulate pseudopod actin using
similar mechanisms.
Submitted by Robert Insall [r.insall@beatson.gla.ac.uk]]
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[End dictyNews, volume 38, number 15]
