Heparan sulfate chain valency controls syndecan-4 function in cell adhesion

Sandeep Gopal, Adam Bober, James R Whiteford, Hinke A B Multhaupt, Atsuko Yoneda, John R Couchman

53 Citations (Scopus)

Abstract

Fibroblasts null for the transmembrane proteoglycan, syndecan-4, have an altered actin cytoskeleton, compared with matching wild-type cells. They do not organize α-smooth muscle actin into bundles, but will do so when full-length syndecan-4 is re-expressed. This requires the central V region of the core protein cytoplasmic domain, though not interactions with PDZ proteins. A second key requirement is multiple heparan sulfate chains. Mutant syndecan-4 with no chains, or only one chain, failed to restore the wild-type phenotype, whereas those expressing two or three were competent. However, clustering of one-chain syndecan-4 forms with antibodies overcame the block, indicating that valency of interactions with ligands is a key component of syndecan-4 function. Measurements of focal contact/adhesion size and focal adhesion kinase phosphorylation correlated with syndecan-4 status and α-smooth muscle actin organization, being reduced where syndecan-4 function was compromised by a lack of multiple heparan sulfate chains.

Original languageEnglish
JournalJournal of Biological Chemistry
Volume285
Issue number19
Pages (from-to)14247-58
Number of pages12
ISSN0021-9258
DOIs
Publication statusPublished - 7 May 2010

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