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Syndecan-4 regulates localization, activity and stability of protein kinase C-α

Title
Syndecan-4 regulates localization, activity and stability of protein kinase C-α
Authors
Keum E.Kim Y.Kim J.Kwon S.Lim Y.Han I.Oh E.-S.
Ewha Authors
오억수
SCOPUS Author ID
오억수scopus
Issue Date
2004
Journal Title
Biochemical Journal
ISSN
0264-6021JCR Link
Citation
vol. 378, no. 3, pp. 1007 - 1014
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
During cell-matrix adhesion, syndecan-4 transmembrane heparan sulphate proteoglycan plays a critical role in the formation of focal adhesions and stress fibres. We have shown previously that the syndecan-4 cytoplasmic domain directly binds to and activates PKC-α (protein kinase C-α) in vitro [Oh, Woods and Couchman (1997) J. Biol. Chem. 272, 8133-8136]. However, whether syndecan-4 has the same activity in vivo needs to be addressed. Using mammalian two-hybrid assays, we showed that syndecan-4 interacted with PKC-α in vivo and that this interaction was mediated through syndecan-4 cytoplasmic domain. Furthermore, the activation of PKC increased the extent of interaction between syndecan-4 and PKC-α. Overexpression of syndecan-4, but not a mutant lacking its cytoplasmic domain, specifically increased the level of endogenous PKC-α and enhanced the translocation of PKC-α into both detergent-insoluble and membrane fractions. In addition, rat embryo fibroblasts overexpressing syndecan-4 exhibited a slowed down-regulation of PKC-α in response either to a prolonged treatment with PMA or to maintaining cells in suspension culture. PKC-α immunocomplex kinase assays also showed that syndecan-4 overexpression increased the activity of membrane PKC-α. Taken together, these results suggest that syndecan-4 interacts with PKC-α in vivo and regulates its locali-zation, activity and stability.
DOI
10.1042/BJ20031734
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자연과학대학 > 생명과학전공 > Journal papers
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