An Epidermal Growth Factor Receptor Promoter Construct Selectively Expresses in the Thymus and Spleen of Transgenic Mice

To determine the range of tissues in which the human epidermal growth factor (EGF) receptor promoter is active, we created 12 independently derived lines of mice expressing a transgene consisting of human EGF receptor promoter and enhancer sequences fused to the bacterial chloramphenicol acetyltransferase (CAT) gene. Analysis for the presence of CAT activity in these transgenic mice revealed that the human EGF receptor promoter construct was consistently active in the thymus and spleen. Thymocytes separated from thymic stromal cells of EGF receptor-CAT mice demonstrated no CAT activity suggesting that expression in the thymus is confined to the thymic stroma, which consists mainly of epithelial cells. Thus, it should be possible to use the EGF receptor promoter construct described in this study to direct expression of a variety of foreign genes to the nonlymphocytic cells of the thymus and spleen so that the effect of these genes on the maturation and proliferation of thymocytes may be addressed.