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Integrin-specific signaling pathways controlling focal adhesion formation and cell migration.

Mostafavi-Pour Z, Askari JA, Parkinson SJ, Parker PJ, Ng TT, Humphries MJ - J. Cell Biol. (2003)

Bottom Line: After analyses of alpha4+/alpha5+ A375-SM melanoma cell adhesion to fragments of FN that interact selectively with alpha4beta1 and alpha5beta1, we now report two differences in the signals transduced by each receptor that underpin their specific adhesive properties.First, alpha5beta1 and alpha4beta1 have a differential requirement for cell surface proteoglycan engagement for focal adhesion formation and migration; alpha5beta1 requires a proteoglycan coreceptor (syndecan-4), and alpha4beta1 does not.Pharmacological inhibition of PKCalpha and transient expression of dominant-negative PKCalpha, but not dominant-negative PKCdelta or PKCzeta constructs, suppressed focal adhesion formation and cell migration mediated by alpha5beta1, but had no effect on alpha4beta1.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Manchester, Manchester M13 9PT, UK.

ABSTRACT
The fibronectin (FN)-binding integrins alpha4beta1 and alpha5beta1 confer different cell adhesive properties, particularly with respect to focal adhesion formation and migration. After analyses of alpha4+/alpha5+ A375-SM melanoma cell adhesion to fragments of FN that interact selectively with alpha4beta1 and alpha5beta1, we now report two differences in the signals transduced by each receptor that underpin their specific adhesive properties. First, alpha5beta1 and alpha4beta1 have a differential requirement for cell surface proteoglycan engagement for focal adhesion formation and migration; alpha5beta1 requires a proteoglycan coreceptor (syndecan-4), and alpha4beta1 does not. Second, adhesion via alpha5beta1 caused an eightfold increase in protein kinase Calpha (PKCalpha) activation, but only basal PKCalpha activity was observed after adhesion via alpha4beta1. Pharmacological inhibition of PKCalpha and transient expression of dominant-negative PKCalpha, but not dominant-negative PKCdelta or PKCzeta constructs, suppressed focal adhesion formation and cell migration mediated by alpha5beta1, but had no effect on alpha4beta1. These findings demonstrate that different integrins can signal to induce focal adhesion formation and migration by different mechanisms, and they identify PKCalpha signaling as central to the functional differences between alpha4beta1 and alpha5beta1.

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Effects of PKCα inhibition on integrin-mediated migration. The migration of A375-SM cells into scratch wounds on either (A) a 50K substrate in the presence of soluble H/0 or (B) an H/120 substrate was examined without treatment (left panels) or in the presence of 10 μg/ml BIM (right panels). Still images were captured at the indicated times after wounding. The edges of the original wound are marked with dashed lines. Bars, 100 μm.
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fig7: Effects of PKCα inhibition on integrin-mediated migration. The migration of A375-SM cells into scratch wounds on either (A) a 50K substrate in the presence of soluble H/0 or (B) an H/120 substrate was examined without treatment (left panels) or in the presence of 10 μg/ml BIM (right panels). Still images were captured at the indicated times after wounding. The edges of the original wound are marked with dashed lines. Bars, 100 μm.

Mentions: To examine whether the differential dependence of α4β1 and α5β1 on PKC signaling was manifested during cell movement as well as during focal adhesion formation, the sensitivity of A375-SM cell migration to inhibitors of PKC was tested in a wounding assay. For these studies, the early phase of migration between 6 h and 12 h after wounding was examined. Initially, the effects of the broad spectrum PKC inhibitor, BIM, were tested. As shown in Fig. 7 (and Videos 1–4, available at http://www.jcb.org/cgi/content/full/jcb.200210176/DC1), addition of BIM 6 h after wounding prevented wound closure on a 50K + H/0 substrate, but had no discernible effect on H/120-mediated migration. A DMSO vehicle control showed no inhibition. Thus, the substrate-specific inhibition of focal adhesion formation by BIM was also seen for cell migration.


Integrin-specific signaling pathways controlling focal adhesion formation and cell migration.

Mostafavi-Pour Z, Askari JA, Parkinson SJ, Parker PJ, Ng TT, Humphries MJ - J. Cell Biol. (2003)

Effects of PKCα inhibition on integrin-mediated migration. The migration of A375-SM cells into scratch wounds on either (A) a 50K substrate in the presence of soluble H/0 or (B) an H/120 substrate was examined without treatment (left panels) or in the presence of 10 μg/ml BIM (right panels). Still images were captured at the indicated times after wounding. The edges of the original wound are marked with dashed lines. Bars, 100 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172880&req=5

fig7: Effects of PKCα inhibition on integrin-mediated migration. The migration of A375-SM cells into scratch wounds on either (A) a 50K substrate in the presence of soluble H/0 or (B) an H/120 substrate was examined without treatment (left panels) or in the presence of 10 μg/ml BIM (right panels). Still images were captured at the indicated times after wounding. The edges of the original wound are marked with dashed lines. Bars, 100 μm.
Mentions: To examine whether the differential dependence of α4β1 and α5β1 on PKC signaling was manifested during cell movement as well as during focal adhesion formation, the sensitivity of A375-SM cell migration to inhibitors of PKC was tested in a wounding assay. For these studies, the early phase of migration between 6 h and 12 h after wounding was examined. Initially, the effects of the broad spectrum PKC inhibitor, BIM, were tested. As shown in Fig. 7 (and Videos 1–4, available at http://www.jcb.org/cgi/content/full/jcb.200210176/DC1), addition of BIM 6 h after wounding prevented wound closure on a 50K + H/0 substrate, but had no discernible effect on H/120-mediated migration. A DMSO vehicle control showed no inhibition. Thus, the substrate-specific inhibition of focal adhesion formation by BIM was also seen for cell migration.

Bottom Line: After analyses of alpha4+/alpha5+ A375-SM melanoma cell adhesion to fragments of FN that interact selectively with alpha4beta1 and alpha5beta1, we now report two differences in the signals transduced by each receptor that underpin their specific adhesive properties.First, alpha5beta1 and alpha4beta1 have a differential requirement for cell surface proteoglycan engagement for focal adhesion formation and migration; alpha5beta1 requires a proteoglycan coreceptor (syndecan-4), and alpha4beta1 does not.Pharmacological inhibition of PKCalpha and transient expression of dominant-negative PKCalpha, but not dominant-negative PKCdelta or PKCzeta constructs, suppressed focal adhesion formation and cell migration mediated by alpha5beta1, but had no effect on alpha4beta1.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Manchester, Manchester M13 9PT, UK.

ABSTRACT
The fibronectin (FN)-binding integrins alpha4beta1 and alpha5beta1 confer different cell adhesive properties, particularly with respect to focal adhesion formation and migration. After analyses of alpha4+/alpha5+ A375-SM melanoma cell adhesion to fragments of FN that interact selectively with alpha4beta1 and alpha5beta1, we now report two differences in the signals transduced by each receptor that underpin their specific adhesive properties. First, alpha5beta1 and alpha4beta1 have a differential requirement for cell surface proteoglycan engagement for focal adhesion formation and migration; alpha5beta1 requires a proteoglycan coreceptor (syndecan-4), and alpha4beta1 does not. Second, adhesion via alpha5beta1 caused an eightfold increase in protein kinase Calpha (PKCalpha) activation, but only basal PKCalpha activity was observed after adhesion via alpha4beta1. Pharmacological inhibition of PKCalpha and transient expression of dominant-negative PKCalpha, but not dominant-negative PKCdelta or PKCzeta constructs, suppressed focal adhesion formation and cell migration mediated by alpha5beta1, but had no effect on alpha4beta1. These findings demonstrate that different integrins can signal to induce focal adhesion formation and migration by different mechanisms, and they identify PKCalpha signaling as central to the functional differences between alpha4beta1 and alpha5beta1.

Show MeSH
Related in: MedlinePlus