Journal article
Pervanadate activation of intracellular kinases leads to tyrosine phosphorylation and shedding of syndecan-1
Biochemical journal, Vol.319(1), pp.39-47
10/01/1996
DOI: 10.1042/bj3190039
PMCID: PMC1217733
PMID: 8870647
Abstract
Syndecan-1 is a transmembrane haparan sulphate proteoglycan that binds extracellular matrices and growth factors, making it a candidate to act between these regulatory molecules and intracellular signalling pathways. It has a highly conserved transmembrane/cytoplasmic domain that contains four conserved tyrosines. One of these is in a consensus sequence for tyrosine kinase phosphorylation. As an initial step to investigating whether or not phosphorylation of these tyrosines is part of a signal-transduction pathway, we have monitored the tyrosine phosphorylation of syndecan-1 by cytoplasmic tyrosine kinases in intact cells. Tyrosine phosphorylation of syndecan-1 is observed when NMuMG cells are treated with sodium orthovanadate or pervanadate, which have been shown to activate intracellular tyrosine kinases. Initial studies with sodium orthovanadate demonstrate a slow accumulation of phosphotyrosine on syndecan-1 over the course of several hours. Pervanadate, a more effective inhibitor of phosphatases, allows detection of phosphotyrosine on syndecan-1 within 5 min, with peak phosphorylation seen by 15 min. Concurrently, in a second process activated by pervanadate, syndecan-1 ectodomain is cleaved and released into the culture medium. Two phosphorylated fragments of syndecan-1 of apparent sizes 6 and 8 kDa remain with the cell after shedding of the ectodomain. The 8 kDa size class appears to be a highly phosphorylated form of the 6 kDa product, as it disappears if samples are dephosphorylated. These fragments contain the C-terminus of syndecan-1 and also retain at least a portion of the transmembrane domain, suggesting that they are produced by a cell surface cleavage event. Thus pervanadate treatment of cells results in two effects of syndecan-1: (i) phosphorylation of one or more of its tyrosines via the action of a cytoplasmic kinase(s) and (ii) cleavage and release of the ectodomain into the medium, producing a C-terminal fragment containing the transmembrane/cytoplasmic domain.
Details
- Title: Subtitle
- Pervanadate activation of intracellular kinases leads to tyrosine phosphorylation and shedding of syndecan-1
- Creators
- Jane REILAND - Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison, WI 53706, U.S.AVanessa L OTT - Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison, WI 53706, U.S.A., Graduate Program in Cellular and Molecular Biology, University of Wisconsin, Madison, WI 53706, U.S.AConnie S LEBAKKEN - Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison, WI 53706, U.S.A., Graduate Program in Cellular and Molecular Biology, University of Wisconsin, Madison, WI 53706, U.S.ACharles YEAMAN - Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison, WI 53706, U.S.A., Graduate Program in Cellular and Molecular Biology, University of Wisconsin, Madison, WI 53706, U.S.AJames McCARTHY - Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, U.S.AAlan C RAPRAEGER - Department of Pathology and Laboratory Medicine, University of Wisconsin, Madison, WI 53706, U.S.A., Graduate Program in Cellular and Molecular Biology, University of Wisconsin, Madison, WI 53706, U.S.A
- Resource Type
- Journal article
- Publication Details
- Biochemical journal, Vol.319(1), pp.39-47
- DOI
- 10.1042/bj3190039
- PMID
- 8870647
- PMCID
- PMC1217733
- ISSN
- 0264-6021
- eISSN
- 1470-8728
- Language
- English
- Date published
- 10/01/1996
- Academic Unit
- Anatomy and Cell Biology; Internal Medicine
- Record Identifier
- 9984025698402771
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