The characterization of the induction of lipocortin I by administration of dexamethasone and thyroid hormone in a thymic epithelial cell lne

dc.contributor.author Riley, Henry Drinker en_US
dc.date.accessioned 2009-07-15T17:16:34Z
dc.date.available 2009-07-15T17:16:34Z
dc.date.issued 1990 en_US
dc.description Thesis (Ph. D.)--University of Hawaii at Manoa, 1990. en_US
dc.description Includes bibliographical references (leaves 68-76) en_US
dc.description Microfiche. en_US
dc.description xi, 76 leaves, bound ill. 29 cm en_US
dc.description.abstract Lipocortin I, a putative phospholipase A2 inhibitor, has been previously reported to be either unresponsive or induced at the level of transcription or translation by glucocorticoid administration depending on which cell line or model system was under investigation. using a thymic epithelial cell line I show in this dissertation the rapid induction in serum free conditions of lipocortin I mRNA by dexamethasone. Using a lipocortin I cDNA probe, hybridization to Northern blots of RNA shows that induction occurs within 30 minutes of treatment with nanomolar amounts of dexamethasone, and continues to rise for at least three hours. It is demonstrated that this induction is dose dependent. Immunoblots employing a polyclonal antibody to lipocortin I establishes that there is also an increase in lipocortin I protein following dexamethasone treatment. I also discovered that lipocortin I mRNA is induced by the picomolar administration of thyroid hormone (T3) in serum free conditions. Northern blot analysis using lipocortin I cDNA indicates an increase in mRNA within 30 minutes which continues to increase for up to four hours. This induction is also shown to be dose dependent. Immunoblots show an increase of lipocortin I protein following T3 administration. Through the use of nuclear run-off experiments I demonstrate that the induction of lipocortin I mRNA by both hormones is the result of an increase in the transcriptional activity of the gene and not stabilization of the message. Under continuous culture conditions both hormones attenuate the response to the other. This result is discussed in relationship to the ambiguity surrounding the inducibility of lipocortin I mRNA and protein found in the current literature. Finally the thymic epithelial cell line is transfected with inducible constructs containing the complete coding region of the cDNA for lipocortin I in either sense or antisense orientations. The cells containing the sense orientation show a greatly increased number and size of Hassall's corpuscles. These structures are found in the thymic medulla in vivo and are thought to be sites of thymic hormone production and secretion. en_US
dc.identifier.uri http://hdl.handle.net/10125/9372
dc.language.iso en-US en_US
dc.relation Theses for the degree of Doctor of Philosophy (University of Hawaii at Manoa). Biomedical Sciences (Biochemistry); no. 2563 en_US
dc.rights All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner. en_US
dc.subject Lipocortins en_US
dc.subject Dexamethasone -- Physiological effect en_US
dc.subject Epithelial cells en_US
dc.subject Serum-free culture media en_US
dc.title The characterization of the induction of lipocortin I by administration of dexamethasone and thyroid hormone in a thymic epithelial cell lne en_US
dc.type Thesis en_US
dc.type.dcmi Text en_US
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