Control of T lymphocyte morphology by the GTPase Rho.
BACKGROUND
Rho family GTPase regulation of the actin cytoskeleton governs a variety of cell responses. In this report, we have analyzed the role of the GTPase Rho in maintenance of the T lymphocyte actin cytoskeleton.


RESULTS
Inactivation of the GTPase Rho in the human T lymphocytic cell line HPB-ALL does not inhibit constitutively high adhesion to the integrin beta1 substrate fibronectin. It did however result in the aberrant extension of finger-like dendritic processes on the substrates VCAM-1, Fn, and mAb specific to beta1 integrins. Time-lapse video microscopy demonstrated that C3 induced extensions were primarily the result of an altered pseudopod elongation rather than retraction. Once the stellate pseudopodia extended, none retracted, and cells became completely immobile. Filipodial structures were absent and the dendritic-like processes in C3 treated cells were rich in filamentous actin. Immunolocalization of RhoA in untreated HPB-ALL cells spreading on fibronectin demonstrated a diffuse staining pattern within the pseudopodia. In C3 treated cells, clusters of RhoA were pronounced and localized within the altered extensions.


CONCLUSIONS
GTPase Rho is actively involved in the regulation of T lymphocyte morphology and motility.
Woodside
Darren G
DG
Department of Immunology, University of Texas M,D, Anderson Cancer Center, Houston 77030, USA. dwoodside@tbc.com
Wooten
David K
DK
Teague
T Kent
TK
Miyamoto
Yuko J
YJ
Caudell
Eva G
EG
Udagawa
Taturo
T
Andruss
Bernard F
BF
McIntyre
Bradley W
BW
D036002:ADP Ribose Transferases / Q000378:metabolism / Q000494:pharmacology; D000199:Actins / Q000378:metabolism; D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D001905:Botulinum Toxins / Q000378:metabolism / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D022081:Cell Surface Extensions / Q000187:drug effects / Q000378:metabolism; D005353:Fibronectins / Q000494:pharmacology; D006801:Humans; D018715:Microscopy, Video / Q000379:methods; D013601:T-Lymphocytes / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D014407:Tumor Cells, Cultured; D020741:rho GTP-Binding Proteins / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D000199:Actins; D005353:Fibronectins; D000246:Adenosine Diphosphate Ribose; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D001905:Botulinum Toxins; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein