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Specific SHP-2 partitioning in raft domains triggers integrin-mediated signaling via Rho activation.

Lacalle RA, Mira E, Gomez-Mouton C, Jimenez-Baranda S, Martinez-A C, Manes S - J. Cell Biol. (2002)

Bottom Line: Cell signaling does not occur randomly over the cell surface, but is integrated within cholesterol-enriched membrane domains, termed rafts.By targeting SHP-2 to raft domains or to a non-raft plasma membrane fraction, we studied the functional role of rafts in signaling.Expression of the dominant negative N19Rho abrogates raft-SHP-2-induced signaling, suggesting that Rho activation is a downstream event in SHP-2 signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, UAM Campus de Cantoblanco, E-28049 Madrid, Spain.

ABSTRACT
Cell signaling does not occur randomly over the cell surface, but is integrated within cholesterol-enriched membrane domains, termed rafts. By targeting SHP-2 to raft domains or to a non-raft plasma membrane fraction, we studied the functional role of rafts in signaling. Serum-depleted, nonattached cells expressing the raft SHP-2 form, but not non-raft SHP-2, display signaling events resembling those observed after fibronectin attachment, such as beta1 integrin clustering, 397Y-FAK phosphorylation, and ERK activation, and also increases Rho-GTP levels. Expression of the dominant negative N19Rho abrogates raft-SHP-2-induced signaling, suggesting that Rho activation is a downstream event in SHP-2 signaling. Expression of a catalytic inactive SHP-2 mutant abrogates the adhesion-induced feedback inhibition of Rho activity, suggesting that SHP-2 contributes to adhesion-induced suppression of Rho activity. Because raft recruitment of SHP-2 occurs physiologically after cell attachment, these results provide a mechanism by which SHP-2 may influence cell adhesion and migration by spatially regulating Rho activity.

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Model of SHP-2 function downstream of integrins. Schematic representation of the SHP-2 signaling pathways downstream of integrins. See Discussion for details.
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fig10: Model of SHP-2 function downstream of integrins. Schematic representation of the SHP-2 signaling pathways downstream of integrins. See Discussion for details.

Mentions: We integrate our data in a model for SHP-2–induced ERK activation and cytoskeletal rearrangement downstream of integrins (Fig. 10). The scheme is partial, as integrins trigger distinct signaling pathways simultaneously. Indeed, we observed no more than 50% ERK inhibition by blocking individual signaling pathways (i.e., SHP-2C/S for SHP-2, PP2 for SFK, FRNK for FAK), suggesting that integrins trigger several independent pathways that converge at ERK activation (Barberis et al., 2000). We propose that integrin binding to the ECM substrate promotes SFK activation, which phosphorylates substrates that recruit SHP-2 to rafts. Activated SHP-2 in rafts is essential for regulating Rho activity downstream of integrins, controlling cytoskeletal rearrangements that culminate in integrin clustering and 397Y-FAK phosphorylation. Both SHP-2C/S and N19Rho expression inhibit basal and integrin-induced 397Y-FAK phosphorylation, suggesting that FAK is downstream of these molecules. Activated FAK, alone or in combination with SHP-2 and SFK, participates in turn in adhesion-dependent Rho inhibition, modulating the focal adhesion turnover required for cell spreading (Ren et al., 1999).


Specific SHP-2 partitioning in raft domains triggers integrin-mediated signaling via Rho activation.

Lacalle RA, Mira E, Gomez-Mouton C, Jimenez-Baranda S, Martinez-A C, Manes S - J. Cell Biol. (2002)

Model of SHP-2 function downstream of integrins. Schematic representation of the SHP-2 signaling pathways downstream of integrins. See Discussion for details.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199243&req=5

fig10: Model of SHP-2 function downstream of integrins. Schematic representation of the SHP-2 signaling pathways downstream of integrins. See Discussion for details.
Mentions: We integrate our data in a model for SHP-2–induced ERK activation and cytoskeletal rearrangement downstream of integrins (Fig. 10). The scheme is partial, as integrins trigger distinct signaling pathways simultaneously. Indeed, we observed no more than 50% ERK inhibition by blocking individual signaling pathways (i.e., SHP-2C/S for SHP-2, PP2 for SFK, FRNK for FAK), suggesting that integrins trigger several independent pathways that converge at ERK activation (Barberis et al., 2000). We propose that integrin binding to the ECM substrate promotes SFK activation, which phosphorylates substrates that recruit SHP-2 to rafts. Activated SHP-2 in rafts is essential for regulating Rho activity downstream of integrins, controlling cytoskeletal rearrangements that culminate in integrin clustering and 397Y-FAK phosphorylation. Both SHP-2C/S and N19Rho expression inhibit basal and integrin-induced 397Y-FAK phosphorylation, suggesting that FAK is downstream of these molecules. Activated FAK, alone or in combination with SHP-2 and SFK, participates in turn in adhesion-dependent Rho inhibition, modulating the focal adhesion turnover required for cell spreading (Ren et al., 1999).

Bottom Line: Cell signaling does not occur randomly over the cell surface, but is integrated within cholesterol-enriched membrane domains, termed rafts.By targeting SHP-2 to raft domains or to a non-raft plasma membrane fraction, we studied the functional role of rafts in signaling.Expression of the dominant negative N19Rho abrogates raft-SHP-2-induced signaling, suggesting that Rho activation is a downstream event in SHP-2 signaling.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology and Oncology, Centro Nacional de Biotecnología/CSIC, UAM Campus de Cantoblanco, E-28049 Madrid, Spain.

ABSTRACT
Cell signaling does not occur randomly over the cell surface, but is integrated within cholesterol-enriched membrane domains, termed rafts. By targeting SHP-2 to raft domains or to a non-raft plasma membrane fraction, we studied the functional role of rafts in signaling. Serum-depleted, nonattached cells expressing the raft SHP-2 form, but not non-raft SHP-2, display signaling events resembling those observed after fibronectin attachment, such as beta1 integrin clustering, 397Y-FAK phosphorylation, and ERK activation, and also increases Rho-GTP levels. Expression of the dominant negative N19Rho abrogates raft-SHP-2-induced signaling, suggesting that Rho activation is a downstream event in SHP-2 signaling. Expression of a catalytic inactive SHP-2 mutant abrogates the adhesion-induced feedback inhibition of Rho activity, suggesting that SHP-2 contributes to adhesion-induced suppression of Rho activity. Because raft recruitment of SHP-2 occurs physiologically after cell attachment, these results provide a mechanism by which SHP-2 may influence cell adhesion and migration by spatially regulating Rho activity.

Show MeSH
Related in: MedlinePlus