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The syndecan-1 ectodomain regulates alphavbeta3 integrin activity in human mammary carcinoma cells.

Beauvais DM, Burbach BJ, Rapraeger AC - J. Cell Biol. (2004)

Bottom Line: This paper demonstrates that the alpha(v)beta(3) integrin and syndecan-1 (S1) are functionally coupled.Coupling of the syndecan to alpha(v)beta(3) requires the S1 ectodomain (ED), as ectopic expression of glycosylphosphatidylinositol-linked S1ED enhances alpha(v)beta(3) recognition of vitronectin; and treatments that target this domain, including competition with recombinant S1ED protein or anti-S1ED antibodies, mutation of the S1ED, or down-regulation of S1 expression by small-interfering RNAs, disrupt alpha(v)beta(3)-dependent cell spreading and migration.Thus, S1 is likely to be a critical regulator of many cellular behaviors that depend on activated alpha(v)beta(3) integrins.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA.

ABSTRACT
The alpha(v)beta(3) integrin participates in cell morphogenesis, growth factor signaling, and cell survival. Activation of the integrin is central to these processes and is influenced by specific ECM components, which engage both integrins and syndecans. This paper demonstrates that the alpha(v)beta(3) integrin and syndecan-1 (S1) are functionally coupled. The integrin is dependent on the syndecan to become activated and to mediate signals required for MDA-MB-231 and MDA-MB-435 human mammary carcinoma cell spreading on vitronectin or S1-specific antibody. Coupling of the syndecan to alpha(v)beta(3) requires the S1 ectodomain (ED), as ectopic expression of glycosylphosphatidylinositol-linked S1ED enhances alpha(v)beta(3) recognition of vitronectin; and treatments that target this domain, including competition with recombinant S1ED protein or anti-S1ED antibodies, mutation of the S1ED, or down-regulation of S1 expression by small-interfering RNAs, disrupt alpha(v)beta(3)-dependent cell spreading and migration. Thus, S1 is likely to be a critical regulator of many cellular behaviors that depend on activated alpha(v)beta(3) integrins.

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MDA-MB-231 human mammary carcinoma cell spreading on VN, but not FN, is disrupted by soluble, recombinant S1ED. Cells were plated on wells coated with 10 μg/ml VN or FN in plating medium alone or medium containing either 30 μg/ml mAb LM609, 25 μg/ml mAb 13, or 20 μM GST-mS1ED or -mS4ED. Cells were incubated at 37°C for 2 h, fixed, and stained with rhodamine-conjugated phalloidin. Bar, 50 μm.
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fig1: MDA-MB-231 human mammary carcinoma cell spreading on VN, but not FN, is disrupted by soluble, recombinant S1ED. Cells were plated on wells coated with 10 μg/ml VN or FN in plating medium alone or medium containing either 30 μg/ml mAb LM609, 25 μg/ml mAb 13, or 20 μM GST-mS1ED or -mS4ED. Cells were incubated at 37°C for 2 h, fixed, and stained with rhodamine-conjugated phalloidin. Bar, 50 μm.

Mentions: MDA-MB-231 human mammary carcinoma cells, plated in the absence of serum, adhere to and spread (∼15–20 min after plating) on wells coated with either 10 μg/ml VN or FN (Fig. 1). Cells treated with 30 μg/ml LM609 to block αvβ3 integrins fail to spread. LM609 has no effect on spreading in response to FN; instead, the cells rely on α5β1 integrin to respond to FN as spreading is blocked by either 25 μg/ml mAb 13 (Fig. 1; Mould et al., 1996) or mAb 16 (Akiyama et al., 1989; unpublished data). Our previous works have shown that αvβ3 integrins are essential for signaling when these cells are adherent to S1-specific antibody, suggesting a collaboration between these two adhesion receptors even in the absence of an integrin ligand; this collaboration between S1 and αvβ3 integrins is disrupted by the addition of recombinant GST-mS1ED (Beauvais and Rapraeger, 2003). To test whether or not a similar S1/αvβ3 collaboration is at work when cells are bound to matrix, cells were plated on either VN or FN in the presence of 20 μM of recombinant GST-mS1ED. This treatment blocks cell spreading on VN but has no effect on cell spreading on FN (Fig. 1). Treatment with either GST alone (unpublished data) or GST-mS4ED has no effect on spreading on either ligand (Fig. 1, insets).


The syndecan-1 ectodomain regulates alphavbeta3 integrin activity in human mammary carcinoma cells.

Beauvais DM, Burbach BJ, Rapraeger AC - J. Cell Biol. (2004)

MDA-MB-231 human mammary carcinoma cell spreading on VN, but not FN, is disrupted by soluble, recombinant S1ED. Cells were plated on wells coated with 10 μg/ml VN or FN in plating medium alone or medium containing either 30 μg/ml mAb LM609, 25 μg/ml mAb 13, or 20 μM GST-mS1ED or -mS4ED. Cells were incubated at 37°C for 2 h, fixed, and stained with rhodamine-conjugated phalloidin. Bar, 50 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172512&req=5

fig1: MDA-MB-231 human mammary carcinoma cell spreading on VN, but not FN, is disrupted by soluble, recombinant S1ED. Cells were plated on wells coated with 10 μg/ml VN or FN in plating medium alone or medium containing either 30 μg/ml mAb LM609, 25 μg/ml mAb 13, or 20 μM GST-mS1ED or -mS4ED. Cells were incubated at 37°C for 2 h, fixed, and stained with rhodamine-conjugated phalloidin. Bar, 50 μm.
Mentions: MDA-MB-231 human mammary carcinoma cells, plated in the absence of serum, adhere to and spread (∼15–20 min after plating) on wells coated with either 10 μg/ml VN or FN (Fig. 1). Cells treated with 30 μg/ml LM609 to block αvβ3 integrins fail to spread. LM609 has no effect on spreading in response to FN; instead, the cells rely on α5β1 integrin to respond to FN as spreading is blocked by either 25 μg/ml mAb 13 (Fig. 1; Mould et al., 1996) or mAb 16 (Akiyama et al., 1989; unpublished data). Our previous works have shown that αvβ3 integrins are essential for signaling when these cells are adherent to S1-specific antibody, suggesting a collaboration between these two adhesion receptors even in the absence of an integrin ligand; this collaboration between S1 and αvβ3 integrins is disrupted by the addition of recombinant GST-mS1ED (Beauvais and Rapraeger, 2003). To test whether or not a similar S1/αvβ3 collaboration is at work when cells are bound to matrix, cells were plated on either VN or FN in the presence of 20 μM of recombinant GST-mS1ED. This treatment blocks cell spreading on VN but has no effect on cell spreading on FN (Fig. 1). Treatment with either GST alone (unpublished data) or GST-mS4ED has no effect on spreading on either ligand (Fig. 1, insets).

Bottom Line: This paper demonstrates that the alpha(v)beta(3) integrin and syndecan-1 (S1) are functionally coupled.Coupling of the syndecan to alpha(v)beta(3) requires the S1 ectodomain (ED), as ectopic expression of glycosylphosphatidylinositol-linked S1ED enhances alpha(v)beta(3) recognition of vitronectin; and treatments that target this domain, including competition with recombinant S1ED protein or anti-S1ED antibodies, mutation of the S1ED, or down-regulation of S1 expression by small-interfering RNAs, disrupt alpha(v)beta(3)-dependent cell spreading and migration.Thus, S1 is likely to be a critical regulator of many cellular behaviors that depend on activated alpha(v)beta(3) integrins.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA.

ABSTRACT
The alpha(v)beta(3) integrin participates in cell morphogenesis, growth factor signaling, and cell survival. Activation of the integrin is central to these processes and is influenced by specific ECM components, which engage both integrins and syndecans. This paper demonstrates that the alpha(v)beta(3) integrin and syndecan-1 (S1) are functionally coupled. The integrin is dependent on the syndecan to become activated and to mediate signals required for MDA-MB-231 and MDA-MB-435 human mammary carcinoma cell spreading on vitronectin or S1-specific antibody. Coupling of the syndecan to alpha(v)beta(3) requires the S1 ectodomain (ED), as ectopic expression of glycosylphosphatidylinositol-linked S1ED enhances alpha(v)beta(3) recognition of vitronectin; and treatments that target this domain, including competition with recombinant S1ED protein or anti-S1ED antibodies, mutation of the S1ED, or down-regulation of S1 expression by small-interfering RNAs, disrupt alpha(v)beta(3)-dependent cell spreading and migration. Thus, S1 is likely to be a critical regulator of many cellular behaviors that depend on activated alpha(v)beta(3) integrins.

Show MeSH
Related in: MedlinePlus