Linked Life Data

18922916

Source:http://linkedlifedata.com/resource/pubmed/id/18922916

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
20
pubmed:dateCreated
2008-10-16
pubmed:abstractText
Chemokine-induced activation of alpha4beta1 and alphaLbeta2 integrins (by conformational change and clustering) is required for lymphocyte transendothelial migration (TEM) and entry into lymph nodes. We have previously reported that chemokine-induced TEM is defective in chronic lymphocytic leukemia (CLL) and that this defect is a result of failure of the chemokine to induce polar clustering of alphaLbeta2; engagement of alpha4beta1 and autocrine vascular endothelial growth factor (VEGF) restore clustering and TEM. The aim of the present study was to characterize the nature of this defect in alphaLbeta2 activation and determine how it is corrected. We show here that the alphaLbeta2 of CLL cells is already in variably activated conformations, which are not further altered by chemokine treatment. Importantly, such treatment usually does not cause an increase in the GTP-loading of Rap1, a GTPase central to chemokine-induced activation of integrins. Furthermore, we show that this defect in Rap1 GTP-loading is at the level of the GTPase and is corrected in CLL cells cultured in the absence of exogenous stimuli, suggesting that the defect is the result of in vivo stimulation. Finally, we show that, because Rap1-induced activation of both alpha4beta1 and alphaLbeta2 is defective, autocrine VEGF and chemokine are necessary to activate alpha4beta1 for ligand binding. Subsequently, this binding and both VEGF and chemokine stimulation are all needed for alphaLbeta2 activation for motility and TEM. The present study not only clarifies the nature of the alphaLbeta2 defect of CLL cells but is the first to implicate activation of Rap1 in the pathophysiology of CLL.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
1538-7445
pubmed:author
pubmed:issnType
Electronic
pubmed:day
15
pubmed:volume
68
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
8429-36
pubmed:meshHeading
pubmed:year
2008
pubmed:articleTitle
Cell motility in chronic lymphocytic leukemia: defective Rap1 and alphaLbeta2 activation by chemokine.
pubmed:affiliation
Division of Hematology, School of Cancer Studies, School of Biological Sciences, University of Liverpool, Liverpool, United Kingdom. k.j.till@liv.ac.uk
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't