Syndecan-4/PAR-3 signaling regulates focal adhesion dynamics in mesenchymal cells

Abstract

Background: Syndecans 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. Methods: Mass 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. Results: We 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. Conclusions: The 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.

Development of a library of laminin-mimetic peptide hydrogels for control of nucleus pulposus cell behaviors

“…93,95,[97][98][99] Future experimentation would be needed to characterize the kinetics of expression of adhesive proteins, focal adhesion turnover, and intracellular signaling in order to elucidate the relative roles of integrins and syndecans in mediating degenerative NP cells interactions with the extracellular environment. 86,93,95,[99][100][101] While the dual presentation of integrin-binding and syndecan-binding peptides did not elicit a synergistic response in the present study, combinations of other peptides may have the beneficial effects not specifically observed here. 102 For example, combining IKVAV and GD-6 which each promoted the greatest expression of different phenotypic markers may result in an additive or synergistic effect and warrants future study.…”

“…93,95,97–99 Future experimentation would be needed to characterize the kinetics of expression of adhesive proteins, focal adhesion turnover, and intracellular signaling in order to elucidate the relative roles of integrins and syndecans in mediating degenerative NP cells interactions with the extracellular environment. 86,93,95,99–101…”

microRNA‐140‐3p modulates invasiveness, motility, and extracellular matrix adhesion of breast cancer cells by targeting syndecan‐4

“…33 In addition, a recent study demonstrated that the binding of syndecan-4 to PAR-3, involve the Thy-1/CD90-induced FA dynamics in mesenchymal cells by regulating FAK autophosphorylation and Tiam1 activation. 49 While our study demonstrates a clear regulatory impact of both syndecan-4 and miR-140-3p on ECMrelated regulators and mediators of cancer cell adhesion and motility, this regulation partially occurred in a context and cell-type-dependent manner. We ascribe this to the pleiotropic nature of both syndecan and miRNA functions: syndecan-4 acts as a multifunctional coreceptor that impacts on numerous signaling pathways.…”

Thy-1 (CD90), Integrins and Syndecan 4 are Key Regulators of Skin Wound Healing

“…FA turnover is an important event during directional cell migration. Moreover, Thy-1 has been shown to directly interact with integrins and syndecan 4 to form a trimolecular complex that facilitates initial cell adhesion by enhancing FA formation and subsequently, promoting migration by regulating contractility and FA turnover (Avalos et al, 2004;Hermosilla et al, 2008;Avalos et al, 2009;Kong et al, 2013;Fiore et al, 2014;Fiore et al, 2015;Lagos-Cabre et al, 2017;Burgos-Bravo et al, 2020;Valdivia et al, 2020). Although the bidirectional signaling pathways triggered by Thy-1/integrin/ syndecan 4 clustering and activation remain unexplored during skin injury, the biological significance of each of these molecules by themselves has been proven important for an efficient wound healing process.…”

“…Interestingly, Thy-1-mediated migration and focal adhesion dynamics in embryonic fibroblasts depend on the recruitment of Partitioning-defective 3 (PAR3) to the cytoplasmic tail of syndecan 4. Consequently, PAR3 silencing inhibits FA disassembly triggered by Thy-1 stimulation, favoring fibroblast adhesion instead of migration (Valdivia et al, 2020). Further research is necessary to determine if the Thy-1/syndecan 4 interaction can also modulate fibroblast proliferation, differentiation, or ECM secretion.…”