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 useful information is available at dictyBase - http://dictybase.org. Follow dictyBase on twitter: http://twitter.com/dictybase ========= Abstracts ========= 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] -------------------------------------------------------------------------------------- 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] -------------------------------------------------------------------------------------- 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]] ============================================================== [End dictyNews, volume 38, number 15]