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dictyNews Volume 39 Number 01
dictyNews
Electronic Edition
Volume 39, number 1
January 11, 2013
Please submit abstracts of your papers as soon as they have been
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Abstracts
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A dual role model for active Rac1 in cell migration
Jan Faix and Igor Weber
1 Hannover Medical School, Institute for Biophysical Chemistry,
Carl-Neuberg-Str. 1, D-30623 Hannover, Germany
2 Ruder Boskovic Institute, Division of Molecular Biology,
Bijenicka 54, HR-10000 Zagreb, Croatia
Small GTPases, in press
Over time we have come to appreciate that the complex regulation
of Rho GTPases involves additional mechanisms beyond the activating
role of RhoGEFs, the inactivating function of RhoGAPs, and the
sequestering activity of RhoGDIs. One class of regulatory mechanisms
includes direct modifications of Rho proteins such as isoprenylation,
phosphorylation, and SUMOylation. Rho GTPases can also regulate
each other by means of crosstalk signaling, which is again mostly
mediated by GEFs, GAPs, and GDIs. More complex mutual regulation
ensues when and where two or more Rho proteins activate a common
molecular target, i.e. share a common effector. We have recently
unraveled a reciprocal mechanism wherein spatiotemporal dynamics of
Rac1 activity during migration of Dictyostelium cells is apparently
regulated by antagonizing interactions of Rac1-GTP with two distinct
effectors. By monitoring specific fluorescent probes, activated Rac1 is
simultaneously present at the leading edge, where it participates in
Scar/WAVE-mediated actin polymerization, and at the trailing edge,
where it induces formation of a DGAP1/cortexillin actin-bundling complex.
Strikingly, in addition to their opposed localization, the two populations of
activated Rac1 also display opposite kinetics of recruitment to the plasma
membrane upon stimulation by chemoattractants. These findings with
respect to Rac1 in Dictyostelium suggest a novel principle for regulation
of Rho GTPase activity that might also play a role in other cell types and
for other Rho family members.
Submitted by Igor Weber [iweber@irb.hr]
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[End dictyNews, volume 39, number 1]
