Control of T lymphocyte morphology by the GTPase Rho
1 Department of Immunology, University of Texas M.D. Anderson Cancer Center, Houston, TX, 77030, USA
2 Present Address: Department of Immunology, Texas Biotechnology Corporation, Houston, TX, USA
3 Present Address: Department of Surgery, Oklahoma City Health Science Center, Oklahoma City, OK, USA
4 Present Address: Children's Hospital, Department of Surgical Research, Enders-10, 300 Longwood Ave., Boston, MA 02115, USA
BMC Cell Biology 2003, 4:2 doi:10.1186/1471-2121-4-2Published: 24 February 2003
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.
Inactivation of the GTPase Rho in the human T lymphocytic cell line HPB-ALL does not inhibit constitutively high adhesion to the integrin β1 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 β1 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.
GTPase Rho is actively involved in the regulation of T lymphocyte morphology and motility.