Linked Life Data

1979585

Source:http://linkedlifedata.com/resource/pubmed/id/1979585

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
1991-1-28
pubmed:abstractText
Both cellular activation signals and exposure to glucocorticoids such as dexamethasone (Dex) cause programmed cell death in T cell hybridomas. When cells were activated in the presence of Dex, however, the degree of killing that was achieved by either stimulus alone was markedly reduced. Dex-induced programmed cell death of normal T cell clones was also prevented by cellular activation. Cyclosporin A (CsA) completely blocked the activation-induced death of T cell hybridomas, but actually enhanced the killing caused by Dex. The addition of CsA to activated T cell hybridomas in the presence of Dex allowed killing to proceed, consistent with ability of CsA to block activation-induced nuclear gene transcription. A number of independent approaches were used to explore the effect of activation on the glucocorticoid signaling/effector pathway. First, RU-486, which binds the glucocorticoid receptor and is a potent competitive antagonist of Dex, did not inhibit activation-induced cell killing. Second, activation of T cell hybridomas did not cause the translocation of the glucocorticoid receptor from the cytoplasm to the nucleus, nor did it prevent the receptor translocation induced by treatment with Dex. Finally, T cell hybridomas were transfected with a plasmid containing the chloramphenicol acetyltransferase (CAT) gene under the control of two tandemly arranged glucocorticoid-responsive elements. Activation of these cells did not induce CAT activity, and did not inhibit the CAT activity induced by Dex. In fact, there was a paradoxical increase in CAT activity when cells were treated with both stimuli. We conclude that cellular activation does not directly utilize the glucocorticoid receptor nor the glucocorticoid pathway when inducing programmed cell death. Furthermore, the ability of activation to inhibit Dex-mediated killing is not due to interference with the classical glucocorticoid signaling pathway, up to and including the initiation of gene transcription. Alternative mechanisms of antagonism, as well as the possible relevance of this phenomenon to the positive selection of self-recognizing thymocytes, are discussed.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
AIM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0022-1767
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
145
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4037-45
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:1979585-Animals, pubmed-meshheading:1979585-Antigens, Surface, pubmed-meshheading:1979585-Antigens, Thy-1, pubmed-meshheading:1979585-Cell Compartmentation, pubmed-meshheading:1979585-Cell Nucleus, pubmed-meshheading:1979585-Cell Survival, pubmed-meshheading:1979585-Cells, Cultured, pubmed-meshheading:1979585-Cyclosporins, pubmed-meshheading:1979585-Cytosol, pubmed-meshheading:1979585-DNA Damage, pubmed-meshheading:1979585-Dexamethasone, pubmed-meshheading:1979585-Gene Expression Regulation, pubmed-meshheading:1979585-Hybridomas, pubmed-meshheading:1979585-Lymphocyte Activation, pubmed-meshheading:1979585-Mice, pubmed-meshheading:1979585-Mifepristone, pubmed-meshheading:1979585-Receptors, Antigen, T-Cell, pubmed-meshheading:1979585-Receptors, Glucocorticoid, pubmed-meshheading:1979585-Regulatory Sequences, Nucleic Acid, pubmed-meshheading:1979585-T-Lymphocytes
pubmed:year
1990
pubmed:articleTitle
Programmed T lymphocyte death. Cell activation- and steroid-induced pathways are mutually antagonistic.
pubmed:affiliation
Division of Cancer Treatment, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
pubmed:publicationType
Journal Article, In Vitro