The long-term objective of this project is to gain further understanding of the modulation of T-cell functions. Two systems will be investigated: (1) The effects of glucocorticoids on gene expression in murine T-lymphomas; (2) The structure of the genes encoding the alpha and beta subunits of the human fibronectin receptor and their regulation in human T-cell lines and other cell types. The multiple effects of glucocorticoids on the immune system, in both animals and man, are the basis for their extensive clinical use. T-cell lines established from lymphomas or leukemias have been to study glucocorticoid-induced T-cell lysis, in particular the murine thymoma cell line W7. The mechanism of this response is obscure, and no lymphoid-specific gene regulated by glucocorticoids has as yet been identified.
The first aim of this project is to isolate and characterize cDNA clones corresponding to genes regulated by glucocorticoids (alone or in combination with cAMP) in W7 cells. In preliminary experiments, we have successfully used a subtractive hybridization procedure to isolate such cDNA clones. These other clones will be further characterized by Southern and Northern blot analyses. The expression of the corresponding genes will be examined in T-lymphoma variants and in different cell types. The inserts will be sequenced and genomic clones will be isolated to analyze the mechanisms of regulation of those genes by glucocorticoids. The cell surface fibronectin receptor is expressed on a subset of T-lymphocytes. This receptor mediates the various effects of fibronectin, and cell adhesion in particular. Several hormones and factors have been shown to modulate the expression of this receptor on various cell types. Such stimuli could direct the traffic of circulating T-lymphocytes through connective tissue to lymphoid organs or sites of inflammation, or their migration during development. Therefore, those receptors could play a major role in the immune response.
The second aim of this project is to analyze the genes encoding the alpha and beta subunits of this receptor and their regulation. Genomic clones will be isolated and characterize and the regulation of these genes by several hormones and factors will be examined. Human T-cell lines will be used as model systems to investigate whether the expression of this receptor is modulated by antigenic activation and during T-cell maturation.
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