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Integrins control motile strategy through a Rho-cofilin pathway.

Danen EH, van Rheenen J, Franken W, Huveneers S, Sonneveld P, Jalink K, Sonnenberg A - J. Cell Biol. (2005)

Bottom Line: During wound healing, angiogenesis, and tumor invasion, cells often change their expression profiles of fibronectin-binding integrins.The activity of the small GTPase RhoA is particularly high in cells adhering by alpha5beta1, and inhibition of Rho signaling causes a switch from a beta1- to a beta3-associated mode of migration, whereas increased Rho activity has the opposite effect.Thus, alterations in integrin expression profiles allow cells to modulate several critical aspects of the motile machinery through Rho GTPases.

View Article: PubMed Central - PubMed

Affiliation: Division of Cell Biology, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands. e.danen@nki.nl

ABSTRACT
During wound healing, angiogenesis, and tumor invasion, cells often change their expression profiles of fibronectin-binding integrins. Here, we show that beta1 integrins promote random migration, whereas beta3 integrins promote persistent migration in the same epithelial cell background. Adhesion to fibronectin by alpha(v)beta3 supports extensive actin cytoskeletal reorganization through the actin-severing protein cofilin, resulting in a single broad lamellipod with static cell-matrix adhesions at the leading edge. Adhesion by alpha5beta1 instead leads to the phosphorylation/inactivation of cofilin, and these cells fail to polarize their cytoskeleton but extend thin protrusions containing highly dynamic cell-matrix adhesions in multiple directions. The activity of the small GTPase RhoA is particularly high in cells adhering by alpha5beta1, and inhibition of Rho signaling causes a switch from a beta1- to a beta3-associated mode of migration, whereas increased Rho activity has the opposite effect. Thus, alterations in integrin expression profiles allow cells to modulate several critical aspects of the motile machinery through Rho GTPases.

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β1 and β3 integrins differentially regulate actin cytoskeletal reorganization. (A) GEβ1 or GEβ3 cells, stably expressing GFP-paxillin, were plated overnight on FN-coated coverslips, confluent monolayers were wounded with a micropipette tip, and preparations were fixed and permeabilized after 5 h. Organization of the actin cytoskeleton and localization of paxillin is shown as indicated. Arrowheads indicate protrusions of cells moving into the wounded area. Bar, 10 μm. (B) GEβ1 and GEβ3 cells were plated on FN-coated coverslips for 4 h and fixed and permeabilized either immediately (control) or after stimulation with PMA for 1 h as indicated. Single staining for F-actin, double staining for F-actin (red) and paxillin (green), or single staining for α-tubulin are shown as indicated with details of membrane protrusions shown at higher magnification at the far right. Dotted line separates two different protrusions. Bars, 5 μm.
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fig2: β1 and β3 integrins differentially regulate actin cytoskeletal reorganization. (A) GEβ1 or GEβ3 cells, stably expressing GFP-paxillin, were plated overnight on FN-coated coverslips, confluent monolayers were wounded with a micropipette tip, and preparations were fixed and permeabilized after 5 h. Organization of the actin cytoskeleton and localization of paxillin is shown as indicated. Arrowheads indicate protrusions of cells moving into the wounded area. Bar, 10 μm. (B) GEβ1 and GEβ3 cells were plated on FN-coated coverslips for 4 h and fixed and permeabilized either immediately (control) or after stimulation with PMA for 1 h as indicated. Single staining for F-actin, double staining for F-actin (red) and paxillin (green), or single staining for α-tubulin are shown as indicated with details of membrane protrusions shown at higher magnification at the far right. Dotted line separates two different protrusions. Bars, 5 μm.

Mentions: We next tested if differences in actin cytoskeletal polarization could explain the maintenance of directionality in GEβ3 versus its loss in GEβ1 cells. Indeed, GEβ3 cells formed broad lamellipodia at the leading edge that were devoid of stress fibers and contained numerous small cell–matrix adhesions, whereas no such remodeling of the actin cytoskeleton was observed in GEβ1 cells: these cells extended long, thin membrane protrusions with actin stress fibers ending at elongated cell–matrix adhesions (Fig. 2 A). To analyze whether GEβ1 cells intrinsically lacked the ability to undergo extensive actin cytoskeletal remodeling, we treated the GEβ1 and GEβ3 cells with EGF, HGF, and the phorbol ester PMA, which is known to cause a reorganization of the actin cytoskeleton (Schliwa et al., 1984). Although EGF did not noticeably affect the morphology of either cell type, HGF induced ruffling in GEβ3 cells but not in GEβ1 cells (unpublished data). Moreover, although GEβ3 cells responded to PMA treatment with a dramatic reorganization of the actin cytoskeleton and formation of a large lamellipod that was devoid of actin stress fibers, PMA hardly affected the actin cytoskeleton in GEβ1 cells (Fig. 2 B). It has been reported that the distribution of microtubules is changed to conform to the altered cellular shape upon PMA stimulation, but that the microtubule cytoskeleton is not functionally implicated in the morphological response to PMA (Schliwa et al., 1984). Indeed, GEβ3 (but not GEβ1) cells also underwent a dramatic reorganization of their microtubule cytoskeleton in response to PMA (Fig. 2 B).


Integrins control motile strategy through a Rho-cofilin pathway.

Danen EH, van Rheenen J, Franken W, Huveneers S, Sonneveld P, Jalink K, Sonnenberg A - J. Cell Biol. (2005)

β1 and β3 integrins differentially regulate actin cytoskeletal reorganization. (A) GEβ1 or GEβ3 cells, stably expressing GFP-paxillin, were plated overnight on FN-coated coverslips, confluent monolayers were wounded with a micropipette tip, and preparations were fixed and permeabilized after 5 h. Organization of the actin cytoskeleton and localization of paxillin is shown as indicated. Arrowheads indicate protrusions of cells moving into the wounded area. Bar, 10 μm. (B) GEβ1 and GEβ3 cells were plated on FN-coated coverslips for 4 h and fixed and permeabilized either immediately (control) or after stimulation with PMA for 1 h as indicated. Single staining for F-actin, double staining for F-actin (red) and paxillin (green), or single staining for α-tubulin are shown as indicated with details of membrane protrusions shown at higher magnification at the far right. Dotted line separates two different protrusions. Bars, 5 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2171933&req=5

fig2: β1 and β3 integrins differentially regulate actin cytoskeletal reorganization. (A) GEβ1 or GEβ3 cells, stably expressing GFP-paxillin, were plated overnight on FN-coated coverslips, confluent monolayers were wounded with a micropipette tip, and preparations were fixed and permeabilized after 5 h. Organization of the actin cytoskeleton and localization of paxillin is shown as indicated. Arrowheads indicate protrusions of cells moving into the wounded area. Bar, 10 μm. (B) GEβ1 and GEβ3 cells were plated on FN-coated coverslips for 4 h and fixed and permeabilized either immediately (control) or after stimulation with PMA for 1 h as indicated. Single staining for F-actin, double staining for F-actin (red) and paxillin (green), or single staining for α-tubulin are shown as indicated with details of membrane protrusions shown at higher magnification at the far right. Dotted line separates two different protrusions. Bars, 5 μm.
Mentions: We next tested if differences in actin cytoskeletal polarization could explain the maintenance of directionality in GEβ3 versus its loss in GEβ1 cells. Indeed, GEβ3 cells formed broad lamellipodia at the leading edge that were devoid of stress fibers and contained numerous small cell–matrix adhesions, whereas no such remodeling of the actin cytoskeleton was observed in GEβ1 cells: these cells extended long, thin membrane protrusions with actin stress fibers ending at elongated cell–matrix adhesions (Fig. 2 A). To analyze whether GEβ1 cells intrinsically lacked the ability to undergo extensive actin cytoskeletal remodeling, we treated the GEβ1 and GEβ3 cells with EGF, HGF, and the phorbol ester PMA, which is known to cause a reorganization of the actin cytoskeleton (Schliwa et al., 1984). Although EGF did not noticeably affect the morphology of either cell type, HGF induced ruffling in GEβ3 cells but not in GEβ1 cells (unpublished data). Moreover, although GEβ3 cells responded to PMA treatment with a dramatic reorganization of the actin cytoskeleton and formation of a large lamellipod that was devoid of actin stress fibers, PMA hardly affected the actin cytoskeleton in GEβ1 cells (Fig. 2 B). It has been reported that the distribution of microtubules is changed to conform to the altered cellular shape upon PMA stimulation, but that the microtubule cytoskeleton is not functionally implicated in the morphological response to PMA (Schliwa et al., 1984). Indeed, GEβ3 (but not GEβ1) cells also underwent a dramatic reorganization of their microtubule cytoskeleton in response to PMA (Fig. 2 B).

Bottom Line: During wound healing, angiogenesis, and tumor invasion, cells often change their expression profiles of fibronectin-binding integrins.The activity of the small GTPase RhoA is particularly high in cells adhering by alpha5beta1, and inhibition of Rho signaling causes a switch from a beta1- to a beta3-associated mode of migration, whereas increased Rho activity has the opposite effect.Thus, alterations in integrin expression profiles allow cells to modulate several critical aspects of the motile machinery through Rho GTPases.

View Article: PubMed Central - PubMed

Affiliation: Division of Cell Biology, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands. e.danen@nki.nl

ABSTRACT
During wound healing, angiogenesis, and tumor invasion, cells often change their expression profiles of fibronectin-binding integrins. Here, we show that beta1 integrins promote random migration, whereas beta3 integrins promote persistent migration in the same epithelial cell background. Adhesion to fibronectin by alpha(v)beta3 supports extensive actin cytoskeletal reorganization through the actin-severing protein cofilin, resulting in a single broad lamellipod with static cell-matrix adhesions at the leading edge. Adhesion by alpha5beta1 instead leads to the phosphorylation/inactivation of cofilin, and these cells fail to polarize their cytoskeleton but extend thin protrusions containing highly dynamic cell-matrix adhesions in multiple directions. The activity of the small GTPase RhoA is particularly high in cells adhering by alpha5beta1, and inhibition of Rho signaling causes a switch from a beta1- to a beta3-associated mode of migration, whereas increased Rho activity has the opposite effect. Thus, alterations in integrin expression profiles allow cells to modulate several critical aspects of the motile machinery through Rho GTPases.

Show MeSH
Related in: MedlinePlus