Aggregation of integrins and RhoA activation are required for Thy-1-induced morphological changes in astrocytes.

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Serval ID
serval:BIB_A20521842F96
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Aggregation of integrins and RhoA activation are required for Thy-1-induced morphological changes in astrocytes.
Journal
Journal of Biological Chemistry
Author(s)
Avalos A.M., Arthur W.T., Schneider P., Quest A.F., Burridge K., Leyton L.
ISSN
0021-9258 (Print)
ISSN-L
0021-9258
Publication state
Published
Issued date
2004
Volume
279
Number
37
Pages
39139-39145
Language
english
Abstract
Thy-1, a cell adhesion molecule abundantly expressed in mammalian neurons, binds to a beta(3)-containing integrin on astrocytes and thereby stimulates the assembly of focal adhesions and stress fibers. Such events lead to morphological changes in astrocytes that resemble those occurring upon injury in the brain. Extracellular matrix proteins, typical integrin ligands, bind to integrins and promote receptor clustering as well as signal transduction events that involve small G proteins and cytoskeletal changes. Here we investigated the possibility that the cell surface protein Thy-1, when interacting with a beta(3)-containing integrin on astrocytes, could trigger signaling events similar to those generated by extracellular matrix proteins. DI-TNC(1) astrocytes were stimulated with Thy-1-Fc immobilized on beads, and increased RhoA activity was confirmed using an affinity precipitation assay. The effect of various inhibitors on the cellular response was also studied. The presence of Y-27632, an inhibitor of Rho kinase (p160ROCK), a key downstream effector of RhoA, significantly reduced focal adhesion and stress fiber formation induced by Thy-1. Similar effects were obtained when astrocytes were treated with C3 transferase, an inhibitor of RhoA. Alternatively, astrocytes were transfected with an expression vector encoding fusion proteins of enhanced green fluorescent protein with either the Rho-binding domain of Rhotekin, which blocks RhoA function, or the dominant-negative N19RhoA mutant. In both cases, Thy-1-induced focal adhesion formation was inhibited. Furthermore, we observed that RhoA activity after stimulation with soluble Thy-1-Fc molecule was augmented upon further cross-linking using protein A-Sepharose beads. The same was shown by cross-linking beta(3)-containing integrin with anti-beta(3) antibodies. Together, these results indicate that Thy-1-mediated astrocyte stimulation depended on beta(3) integrin clustering and the resulting increase in RhoA activity.
Keywords
Amides/pharmacology, Animals, Antigens, Thy-1/metabolism, Astrocytes/metabolism, Cell Adhesion, Cell Line, Extracellular Matrix/metabolism, Fluorescent Antibody Technique, Indirect, Focal Adhesions, Genes, Dominant, Integrins/chemistry, Integrins/metabolism, Ligands, Microscopy, Fluorescence, Protein Binding, Pyridines/pharmacology, Rats, Recombinant Proteins/chemistry, Time Factors, rhoA GTP-Binding Protein/chemistry
Pubmed
Web of science
Open Access
Yes
Create date
19/01/2008 18:30
Last modification date
18/01/2020 7:17
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