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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 vinculin and integrin β1 distribution. (A) A375-SM cells were seeded onto 50K (A–C), 50K+H/0 (D–F), or 50K+H/0 in the presence of 10 μg/ml BIM (G–I), and dual-stained for vinculin (A,D, and G) and integrin β1 (B,E, and H). Untreated cells received DMSO as a control. (B) The same experiment was performed for cells seeded onto H/120 without (J–L) or with (M–O) BIM treatment. Bar, 20 μm.
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fig6: Effects of PKCα inhibition on vinculin and integrin β1 distribution. (A) A375-SM cells were seeded onto 50K (A–C), 50K+H/0 (D–F), or 50K+H/0 in the presence of 10 μg/ml BIM (G–I), and dual-stained for vinculin (A,D, and G) and integrin β1 (B,E, and H). Untreated cells received DMSO as a control. (B) The same experiment was performed for cells seeded onto H/120 without (J–L) or with (M–O) BIM treatment. Bar, 20 μm.

Mentions: Consistent with these results, pharmacological inhibition of PKCα with bisindolylmaleimide (BIM) blocked vinculin recruitment to focal adhesions induced by H/0 addition to cells seeded on 50K (Fig. 6 A, panels A, D, and G). By contrast, little change was observed in integrin β1 distribution (Fig. 6 A, panels B, E, and H). Vinculin and β1 integrin recruitment induced by H/120 were not substantially affected by BIM (Fig. 6 B; quantitated in Table II), although focal adhesions were not as well organized.


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 vinculin and integrin β1 distribution. (A) A375-SM cells were seeded onto 50K (A–C), 50K+H/0 (D–F), or 50K+H/0 in the presence of 10 μg/ml BIM (G–I), and dual-stained for vinculin (A,D, and G) and integrin β1 (B,E, and H). Untreated cells received DMSO as a control. (B) The same experiment was performed for cells seeded onto H/120 without (J–L) or with (M–O) BIM treatment. Bar, 20 μm.
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Related In: Results  -  Collection

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

fig6: Effects of PKCα inhibition on vinculin and integrin β1 distribution. (A) A375-SM cells were seeded onto 50K (A–C), 50K+H/0 (D–F), or 50K+H/0 in the presence of 10 μg/ml BIM (G–I), and dual-stained for vinculin (A,D, and G) and integrin β1 (B,E, and H). Untreated cells received DMSO as a control. (B) The same experiment was performed for cells seeded onto H/120 without (J–L) or with (M–O) BIM treatment. Bar, 20 μm.
Mentions: Consistent with these results, pharmacological inhibition of PKCα with bisindolylmaleimide (BIM) blocked vinculin recruitment to focal adhesions induced by H/0 addition to cells seeded on 50K (Fig. 6 A, panels A, D, and G). By contrast, little change was observed in integrin β1 distribution (Fig. 6 A, panels B, E, and H). Vinculin and β1 integrin recruitment induced by H/120 were not substantially affected by BIM (Fig. 6 B; quantitated in Table II), although focal adhesions were not as well organized.

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