The oligomeric status of syndecan-4 regulates syndecan-4 interaction with α

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• 作者：Youngsil Choi ; Seungin Kim ; Junghyun Lee ; Sung-gun Ko ; Weontae Lee ; Inn-Oc Han ; Anne Woods ; Eok-Soo Oh
• 关键词：Syndecan-4 ; Oligomerization ; α ; -Actinin ; Cytoskeletal organization ; Focal adhesion
• 刊名：European Journal of Cell Biology
• 出版年：2008
• 出版时间：October 2008
• 年：2008
• 卷：87
• 期：10
• 页码：807-815
• 全文大小：575 K

文摘

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 effect of syndecan-4 oligomerization on the cytoskeleton. Glutathione-S-transferase-syndecan-4 proteins were used to show that syndecan-4 interacted specifically with α-actinin, but not paxillin, talin, and vinculin. Interestingly, only dimeric, and not monomeric, recombinant syndecan-4 interacted with α-actinin in the presence of phosphatidylinositol 4,5-bisphosphate (PIP2), and PIP2 potentiated the interaction of both the cytoplasmic domain syndecan-4 peptide and recombinant syndecan-4 proteins with α-actinin, implying that oligomerization of syndecan-4 was important for this interaction. Consistent with this notion, α-actinin interaction was largely absent in syndecan-4 mutants defective in transmembrane domain-induced oligomerization, and α-actinin-associated focal adhesions were decreased in rat embryo fibroblasts expressing mutant syndecan-4. Besides, this interaction was consistently lower with the phosphorylation-mimicking syndecan-4 mutant S183E which is known to destabilize the oligomerization of the syndecan-4 cytoplasmic domain. Taken together, the data suggest that the oligomeric status of syndecan-4 plays a crucial role in regulating the interaction of syndecan-4 with α-actinin.