Linked Life Data

9252391

Source:http://linkedlifedata.com/resource/pubmed/id/9252391

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
33
pubmed:dateCreated
1997-9-4
pubmed:abstractText
Previous work from this laboratory has shown that insulin stimulates the tyrosine phosphorylation of caveolin in 3T3-L1 adipocytes (Mastick, C. C., Brady, M. J., and Saltiel, A. R. (1995) J. Cell Biol. 129, 1523-1531). This phosphorylation is specific for insulin and involves the activation of a tyrosine kinase downstream of the insulin receptor. We report here that tyrosine phosphorylation of caveolin is detected only in fully differentiated adipocytes, not in fibroblasts (preadipocytes), despite the fact that both cell types express caveolin-1 and active insulin receptor. Caveolin copurifies with caveolin tyrosine kinase activity in both preadipocytes and adipocytes. Accumulating evidence indicates that this kinase is the Src family kinase Fyn. Fyn is expressed in the preadipocytes and the adipocytes and is colocalized with caveolin in low density Triton-insoluble complexes in both cell types. In adipocytes, overexpression of wild type Fyn leads to increased basal phosphorylation of caveolin and hyperphosphorylation of caveolin in response to insulin. In vitro kinase assays suggest that Fyn may be activated in response to insulin through the binding of a tyrosine-phosphorylated insulin receptor substrate protein. Previous work suggested that this protein may be c-Cbl (Ribon, V., and Saltiel, A. R. (1997) Biochem. J. 324, 839-846). In 3T3-L1 adipocytes, Cbl binds to Fyn in an insulin-dependent manner, and Cbl phosphorylation is adipocyte-specific. Here we show that phosphorylated Cbl is translocated into caveolin-enriched Triton-insoluble complexes after insulin stimulation. This may lead to the cell type-specific, compartmentalized activation of Fyn and the specific phosphorylation of proteins in the caveolae in response to insulin in adipocytes.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
272
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
20706-14
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Insulin-stimulated tyrosine phosphorylation of caveolin is specific for the differentiated adipocyte phenotype in 3T3-L1 cells.
pubmed:affiliation
Department of Cell Biology, Parke-Davis Pharmaceutical Research Division, Warner-Lambert Co., Ann Arbor, Michigan 48105, USA.
pubmed:publicationType
Journal Article