Identification of Rho GTPases implicated in terminal differentiation of muscle cells in ascidia.
BACKGROUND
Members of the Rho GTPase family mediate changes in the actin cytoskeleton and are also implicated in developmental processes, including myogenesis. Nevertheless, a comprehensive analysis of these proteins during myofibrillogenesis has never been performed in any organism.


RESULTS
Using the ascidian model to identify the role of Rho GTPases on myofibrillogenesis, we show that transcripts for all Rho GTPases are detected in muscle cells of the embryo. We find that activation of RhoA, TC10 and Cdc42 (cell division cycle 42) disturbs the polarity of muscle cells, whereas that of other Rho GTPases induced cell positioning defects. Moreover, dominant negative version of five Rho GTPases, RhoA, Rac2, RCL2 (Rac- and Cdc42-like 2), TC10 and WRCH (Wnt-1 responsive Cdc42 homologue), impaired the formation of mature myofibrils.


CONCLUSIONS
Taken together, our results show that several Rho GTPase-dependent pathways are required to control the spatial localization of muscle cells in the embryo and to coordinate myofibril assembly. This stresses the importance of analysing the entire Rho family when studying a new biological process.
Coisy-Quivy
Marjorie
M
CRBM, CNRS-FRE2593, IFR122, 1919 route de Mende, 34293 Montpellier cedex 5, France.
Sanguesa-Ferrer
Juan
J
Weill
Mylène
M
Johnson
David Scott
DS
Donnay
Jean-Marc
JM
Hipskind
Robert
R
Fort
Philippe
P
Philips
Alexandre
A
D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D016764:Cell Polarity; D048430:Cell Shape; D002478:Cells, Cultured; D002938:Ciona intestinalis / Q000033:anatomy & histology / Q000201:enzymology / Q000254:growth & development; D004625:Embryo, Nonmammalian / Q000033:anatomy & histology / Q000201:enzymology / Q000502:physiology; D004789:Enzyme Activation; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology; D006801:Humans; D051379:Mice; D032342:Muscle Cells / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology* / Q000196:embryology / Q000201:enzymology; D009154:Mutation; D010641:Phenotype; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D014018:Tissue Distribution; D019076:Transgenes; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
D011993:Recombinant Fusion Proteins; D020741:rho GTP-Binding Proteins