EXPRESSION OF ZAP-70 GENE IN THE DEVELOPING THYMUS AND VARIOUS NONLYMPHOID TISSUES OF EMBRYONIC AND ADULT MICE

The full length of cDNA encoding murine ZAP-70 was obtained from a cDN A library of embryonic mouse thymus. Northern blot analysis indicated that the expression of ZAP-70 mRNA was most pronounced in the thymus a nd spleen and also slightly in the brain. Analysis by in situ hybridiz ation revealed that the mRNA was expressed not only in T cells in the thymus and spleen, but also in nerve cells of the brain. In the thymus , the distribution of positive cells was different between newborn and young adult mice. In the newborn thymus, positive signal in thymocyte s was localized in the subcapsular layer as well as in the medulla, wh ile in the young adult thymus, it was localized exclusively in the med ulla. Furthermore, the in situ hybridization revealed that positive si gnal was also seen in the liver, intestine, and lung of embryonic mice . These findings have suggested that ZAP-70 plays an important role in growth, differentiation, and function of not only T cells but also ne rve cells and several embryonic tissues, (C) 1995 Academic Press, Inc.