earticle

영어

Syndecan-4, a cell surface heparan sulfate proteoglycan, is known to regulate the organization of the cytoskeleton and oligomerization is crucial for syndecan-4 function. We therefore explored a possible regulatory role of syndecan-4 oligomerization on the syndecan-4 link to cytoskeleton. Glutathione-S-transferase-syndecan-4 proteins were used to show that syndecan-4 interacted specifically with a-actinin, but not paxillin, talin, and vinculin. Interestingly, only dimeric, and not monomeric, recombinant syndecan-4 interacted with a-actinin in the presence of phosphatidylinositol 4,5-bisphosphate (PIP2), and PIP2 potentiated the interaction of both the cytopasmic domain syndecan-4 peptide and recombinant syndecan-4 proteins with a-actinin, implying that oligomerization of syndecan-4 was importance for this interaction. Consistent with this notion, a-actinin interaction was largely absent in syndecan-4 mutants defective in transmembrane domain-induced oligomerization and a-actinin-associated focal adhesions were decreased in REFs expressing syndecan-4 mutant, compared to that of wild type syndecan-4. Besides, this interaction was consistently lower with the phosphorylation-mimicking syndecan-4 mutant S183E which is known to destabilize the oligomerization of syndecan-4 cytoplasmic domain. Taken together, the data suggest that the oligomeric status of the syndecan-4 plays a crucial role in regulating the interaction of syndecan-4 with a-actinin.