Limits...
Rac mediates cytoskeletal rearrangements and increased cell motility induced by urokinase-type plasminogen activator receptor binding to vitronectin.

Kjøller L, Hall A - J. Cell Biol. (2001)

Bottom Line: In addition, a fourfold increase in the level of activated Rac is induced by uPAR expression.We conclude that uPAR interacts with VN both to initiate a p130Cas/Rac-dependent signaling pathway leading to actin reorganization and increased cell motility and to act as an adhesion receptor required for these responses.This mechanism may play a role in uPAR-mediated regulation of cell motility at sites where VN and uPAR are co-expressed, such as malignant tumors.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Council Laboratory for Molecular Cell Biology, Cancer Research Campaign Oncogene and Signal Transduction Group, University College London, United Kingdom.

ABSTRACT
The urokinase-type plasminogen activator receptor (uPAR) is involved in the regulation of cell motility in a variety of cell types. We show here that expression of human uPAR in growing murine fibroblasts leads to a dramatic reorganization of the actin cytoskeleton. uPAR expression induces multiple rapidly advancing protrusions that resemble the leading edge of migrating cells. The cytoskeletal changes are independent of uPA and activation of the RGD-binding activity of integrins but require uPAR binding to vitronectin (VN). The actin reorganization is blocked by coexpression of dominant negative versions of either Rac (N17Rac) or p130Cas, but not by inhibitors of Cdc42 or Rho, and is accompanied by a Rac-dependent increase in cell motility. In addition, a fourfold increase in the level of activated Rac is induced by uPAR expression. We conclude that uPAR interacts with VN both to initiate a p130Cas/Rac-dependent signaling pathway leading to actin reorganization and increased cell motility and to act as an adhesion receptor required for these responses. This mechanism may play a role in uPAR-mediated regulation of cell motility at sites where VN and uPAR are co-expressed, such as malignant tumors.

Show MeSH

Related in: MedlinePlus

Effect of uPAR expression on cell motility. Swiss 3T3 cells in growth medium were injected with pRc/CMV-uPAR (100 μg/ml) and/or pRK5–myc-N17Rac (20 mg/ml), and the average distance migrated in 3 h was calculated. The effects of uPAR expression and the effect of N17Rac expression on the uPAR-induced increase in migration were found to be statistically significant by Student's t test (P < 0.0001). Results are mean ± SD from examination of at least 12 individual cells.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2199201&req=5

Figure 10: Effect of uPAR expression on cell motility. Swiss 3T3 cells in growth medium were injected with pRc/CMV-uPAR (100 μg/ml) and/or pRK5–myc-N17Rac (20 mg/ml), and the average distance migrated in 3 h was calculated. The effects of uPAR expression and the effect of N17Rac expression on the uPAR-induced increase in migration were found to be statistically significant by Student's t test (P < 0.0001). Results are mean ± SD from examination of at least 12 individual cells.

Mentions: The effect of uPAR on cell motility was analyzed by time-lapse videomicroscopy. Cells were injected with expression plasmids as indicated in the legend to Fig. 10. 3 h after injection, cells were filmed for 3 h, fixed, and protein expression in the observed cells was confirmed by immunofluorescence. For quantification of motility, the position of the center of the cell nucleus was manually tracked at 2-min intervals throughout the 3-h period and the distance of its movement was calculated. uPAR expression induced a threefold increase in cell migration which was completely inhibited by coexpression of N17Rac. Examination of the migration paths revealed that both basal and uPAR-induced cell migration occurred in a nondirectional “random” manner with cells changing their course several times during the assay (data not shown). We conclude that the cytoskeletal changes induced by uPAR-mediated Rac activation are associated with an increase in cell motility.


Rac mediates cytoskeletal rearrangements and increased cell motility induced by urokinase-type plasminogen activator receptor binding to vitronectin.

Kjøller L, Hall A - J. Cell Biol. (2001)

Effect of uPAR expression on cell motility. Swiss 3T3 cells in growth medium were injected with pRc/CMV-uPAR (100 μg/ml) and/or pRK5–myc-N17Rac (20 mg/ml), and the average distance migrated in 3 h was calculated. The effects of uPAR expression and the effect of N17Rac expression on the uPAR-induced increase in migration were found to be statistically significant by Student's t test (P < 0.0001). Results are mean ± SD from examination of at least 12 individual cells.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199201&req=5

Figure 10: Effect of uPAR expression on cell motility. Swiss 3T3 cells in growth medium were injected with pRc/CMV-uPAR (100 μg/ml) and/or pRK5–myc-N17Rac (20 mg/ml), and the average distance migrated in 3 h was calculated. The effects of uPAR expression and the effect of N17Rac expression on the uPAR-induced increase in migration were found to be statistically significant by Student's t test (P < 0.0001). Results are mean ± SD from examination of at least 12 individual cells.
Mentions: The effect of uPAR on cell motility was analyzed by time-lapse videomicroscopy. Cells were injected with expression plasmids as indicated in the legend to Fig. 10. 3 h after injection, cells were filmed for 3 h, fixed, and protein expression in the observed cells was confirmed by immunofluorescence. For quantification of motility, the position of the center of the cell nucleus was manually tracked at 2-min intervals throughout the 3-h period and the distance of its movement was calculated. uPAR expression induced a threefold increase in cell migration which was completely inhibited by coexpression of N17Rac. Examination of the migration paths revealed that both basal and uPAR-induced cell migration occurred in a nondirectional “random” manner with cells changing their course several times during the assay (data not shown). We conclude that the cytoskeletal changes induced by uPAR-mediated Rac activation are associated with an increase in cell motility.

Bottom Line: In addition, a fourfold increase in the level of activated Rac is induced by uPAR expression.We conclude that uPAR interacts with VN both to initiate a p130Cas/Rac-dependent signaling pathway leading to actin reorganization and increased cell motility and to act as an adhesion receptor required for these responses.This mechanism may play a role in uPAR-mediated regulation of cell motility at sites where VN and uPAR are co-expressed, such as malignant tumors.

View Article: PubMed Central - PubMed

Affiliation: Medical Research Council Laboratory for Molecular Cell Biology, Cancer Research Campaign Oncogene and Signal Transduction Group, University College London, United Kingdom.

ABSTRACT
The urokinase-type plasminogen activator receptor (uPAR) is involved in the regulation of cell motility in a variety of cell types. We show here that expression of human uPAR in growing murine fibroblasts leads to a dramatic reorganization of the actin cytoskeleton. uPAR expression induces multiple rapidly advancing protrusions that resemble the leading edge of migrating cells. The cytoskeletal changes are independent of uPA and activation of the RGD-binding activity of integrins but require uPAR binding to vitronectin (VN). The actin reorganization is blocked by coexpression of dominant negative versions of either Rac (N17Rac) or p130Cas, but not by inhibitors of Cdc42 or Rho, and is accompanied by a Rac-dependent increase in cell motility. In addition, a fourfold increase in the level of activated Rac is induced by uPAR expression. We conclude that uPAR interacts with VN both to initiate a p130Cas/Rac-dependent signaling pathway leading to actin reorganization and increased cell motility and to act as an adhesion receptor required for these responses. This mechanism may play a role in uPAR-mediated regulation of cell motility at sites where VN and uPAR are co-expressed, such as malignant tumors.

Show MeSH
Related in: MedlinePlus