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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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Related in: MedlinePlus

Focal adhesion and actin stress fiber formation in A375-SM melanoma cells seeded on H/120 or H/120-GAG-ABC. Cells were incubated for 2 h on H/120 (A–C) or H/120-GAG-ABC (D–F), fixed and dual-stained for vinculin (A and D) and actin (B and E). Arrows in the merged images (C and F) indicate localization of vinculin at the ends of actin bundles. Bar, 20 μm.
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fig4: Focal adhesion and actin stress fiber formation in A375-SM melanoma cells seeded on H/120 or H/120-GAG-ABC. Cells were incubated for 2 h on H/120 (A–C) or H/120-GAG-ABC (D–F), fixed and dual-stained for vinculin (A and D) and actin (B and E). Arrows in the merged images (C and F) indicate localization of vinculin at the ends of actin bundles. Bar, 20 μm.

Mentions: The ability of H/120-GAG-ABC to support focal adhesion formation and microfilament polymerization was then assessed by double immunofluorescence microscopy using anti-vinculin antibody and rhodamine-conjugated phalloidin. As shown in Fig. 4 and quantitated in Table I, cells seeded on either H/120 or H/120-GAG-ABC were of a similar shape, and both the number and location of focal adhesions was indistinguishable. Identical results were obtained when A375-SM cells were plated onto either CS1 peptide (as an IgG conjugate) or recombinant VCAM-1-Fc (unpublished data; CS1 is a synthetic peptide containing the major α4β1 binding site within H/120, and VCAM-1 is an alternative α4β1 ligand; neither protein binds heparin). Together, these results indicate that focal adhesion formation mediated by α4β1 does not require simultaneous engagement of a syndecan coreceptor.


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)

Focal adhesion and actin stress fiber formation in A375-SM melanoma cells seeded on H/120 or H/120-GAG-ABC. Cells were incubated for 2 h on H/120 (A–C) or H/120-GAG-ABC (D–F), fixed and dual-stained for vinculin (A and D) and actin (B and E). Arrows in the merged images (C and F) indicate localization of vinculin at the ends of actin bundles. Bar, 20 μm.
© Copyright Policy
Related In: Results  -  Collection

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

fig4: Focal adhesion and actin stress fiber formation in A375-SM melanoma cells seeded on H/120 or H/120-GAG-ABC. Cells were incubated for 2 h on H/120 (A–C) or H/120-GAG-ABC (D–F), fixed and dual-stained for vinculin (A and D) and actin (B and E). Arrows in the merged images (C and F) indicate localization of vinculin at the ends of actin bundles. Bar, 20 μm.
Mentions: The ability of H/120-GAG-ABC to support focal adhesion formation and microfilament polymerization was then assessed by double immunofluorescence microscopy using anti-vinculin antibody and rhodamine-conjugated phalloidin. As shown in Fig. 4 and quantitated in Table I, cells seeded on either H/120 or H/120-GAG-ABC were of a similar shape, and both the number and location of focal adhesions was indistinguishable. Identical results were obtained when A375-SM cells were plated onto either CS1 peptide (as an IgG conjugate) or recombinant VCAM-1-Fc (unpublished data; CS1 is a synthetic peptide containing the major α4β1 binding site within H/120, and VCAM-1 is an alternative α4β1 ligand; neither protein binds heparin). Together, these results indicate that focal adhesion formation mediated by α4β1 does not require simultaneous engagement of a syndecan coreceptor.

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