Linked Life Data

9351403

Source:http://linkedlifedata.com/resource/pubmed/id/9351403

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
1997-11-20
pubmed:abstractText
In a previous study, we have demonstrated that the platelet adhesive glycoprotein thrombospondin-1 (TSP-1) interacts specifically with the cytoskeletal protein alpha-actinin in a solid-phase binding assay. Stored in the alpha-granules of platelets, TSP-1 is secreted during cell activation and binds to the plasma membrane promoting the platelet macroaggregate formation. However, the molecular mechanism by which TSP-1 reaches and binds to the platelet surface is to date unelucidated. alpha-Actinin is an actin-binding and actinin-cross-linking protein that is present in most cells and may act as a link between the bundles of F-actin and the plasma membrane. In this study, we have investigated a possible interaction of alpha-actinin with TSP-1 in platelets by examining their respective subcellular location during the platelet activation process. By indirect immunofluorescence. alpha-actinin was found to display a granular staining in resting platelets similar to that of TSP-1. Performing postembedding immunogold labeling for electron microscopy, we detected the presence of alpha-actinin throughout the cytoplasm, but the strongest gold staining was found in organelles identified as alpha-granules on the basis of their ultrastructure and TSP-1 content. With the use of double immunogold labeling on platelets at different stages of activation by thrombin, both alpha-actinin and TSP-1 were seen redistributing from the alpha-granules to the platelet surface via the open canalicular system (OCS). At the same time, the cytoplasmic alpha-actinin concentrated toward the plasma membrane, but no colocalization with the F-actin bundles was evidenced. Finally, preembedding immunogold labeling and immunoprecipitation of 125I-surface-labeled, thrombin-activated platelets further demonstrated that alpha-actinin was expressed on the plasma membrane in the absence of any detectable expression of actin and that it could from molecular complexes with TSP-1 on activated platelets. These results suggest that alpha-actinin found to be present on the platelet surface together with TSP-1 originates in the alpha-granules by fusion of the alpha-granules with the plasma membrane during platelet exocytosis.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
1079-5642
pubmed:author
pubmed:issnType
Print
pubmed:volume
17
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2293-305
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Evidence for an alpha-granular pool of the cytoskeletal protein alpha-actinin in human platelets that redistributes with the adhesive glycoprotein thrombospondin-1 during the exocytotic process.
pubmed:affiliation
Unité INSERM 353, Hôpital Saint-Louis, Paris, France.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't