Abstract
BackgroundSyndecans regulate cell migration thus having key roles in scarring and wound healing processes. Our previous results have shown that Thy-1/CD90 can engage both αvβ3 integrin and Syndecan-4 expressed on the surface of astrocytes to induce cell migration. Despite a well-described role of Syndecan-4 during cell movement, information is scarce regarding specific Syndecan-4 partners involved in Thy-1/CD90-stimulated cell migration.MethodsMass spectrometry (MS) analysis of complexes precipitated with the Syndecan-4 cytoplasmic tail peptide was used to identify potential Syndecan-4-binding partners. The interactions found by MS were validated by immunoprecipitation and proximity ligation assays. The conducted research employed an array of genetic, biochemical and pharmacological approaches, including: PAR-3, Syndecan-4 and Tiam1 silencing, active Rac1 GEFs affinity precipitation, and video microscopy.ResultsWe identified PAR-3 as a Syndecan-4-binding protein. Its interaction depended on the carboxy-terminal EFYA sequence present on Syndecan-4. In astrocytes where PAR-3 expression was reduced, Thy-1-induced cell migration and focal adhesion disassembly was impaired. This effect was associated with a sustained Focal Adhesion Kinase activation in the siRNA-PAR-3 treated cells. Our data also show that Thy-1/CD90 activates Tiam1, a PAR-3 effector. Additionally, we found that after Syndecan-4 silencing, Tiam1 activation was decreased and it was no longer recruited to the membrane. Syndecan-4/PAR-3 interaction and the alteration in focal adhesion dynamics were validated in mouse embryonic fibroblast (MEF) cells, thereby identifying this novel Syndecan-4/PAR-3 signaling complex as a general mechanism for mesenchymal cell migration involved in Thy-1/CD90 stimulation.ConclusionsThe newly identified Syndecan-4/PAR-3 signaling complex participates in Thy-1/CD90-induced focal adhesion disassembly in mesenchymal cells. The mechanism involves focal adhesion kinase dephosphorylation and Tiam1 activation downstream of Syndecan-4/PAR-3 signaling complex formation. Additionally, PAR-3 is defined here as a novel adhesome-associated component with an essential role in focal adhesion disassembly during polarized cell migration. These novel findings uncover signaling mechanisms regulating cell migration, thereby opening up new avenues for future research on Syndecan-4/PAR-3 signaling in processes such as wound healing and scarring.Graphical abstract
Highlights
Syndecans regulate cell migration having key roles in scarring and wound healing processes
Our previous studies show that Thymus cell antigen 1 (Thy-1)/Cluster of differentiation 90 (CD90), a protein found in neurons, activated endothelium and some fibroblasts, regulates cell movement through its interaction with two other membrane proteins: integrin and Syndecan-4
We describe the mechanism by which Thy-1/CD90 controls such movement, by unveiling a novel interaction between Syndecan-4 and Partitioning-defective 3 (PAR-3), a protein that has been involved in cell polarity
Summary
Syndecans regulate cell migration having key roles in scarring and wound healing processes. Despite a well-described role of Syndecan-4 during cell movement, information is scarce regarding specific Syndecan-4 partners involved in Thy-1/CD90-stimulated cell migration. The binding of transmembrane proteins (e.g., integrins and Syndecan-4) to extracellular ligands and the cytoskeleton mediates FA formation, promoting cell adhesion. A critical component in the cell-adhesion process is the adhesome –i.e., a complex of > 180 proteins and associated effector partners that connect with receptors such as integrins and Syndecan-4 [2, 3] regulating cell adhesion and other cellular processes, including cell polarization, and migration. Many receptors and proteins are involved in cell movement, ; the key signaling components of the adhesome that regulate FA dynamics remain poorly defined
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
