Abstract
T cells transduce antigen-recognition signals by T cell receptor (TCR) through the associated CD3 chains. The CD3 complex was composed of two signaling modules : CD3γ δ ε and ζ dimer. We have generated CD3ζ -deficient mice which showed reduced expression of the surface TCR complex and developmental block of T cells. To dissect the function of ζ chain on TCR expression and signaling, ζ -deficient mice were reconstituted by a mutant ζ lacking the cytoplasmic domain. The reconstituted mice expressing the mutant ζ revealed that signals through ζ are important for development of immature thymocytes whereas signals through other CD3 chains are enough to develop mature T cells. The ζ -knockout mice showed a new subset of T cells expressing the FcRy chain instead of ζ . We found that T cells in epithelia such as small intestine, skin, vagina and uterus utilize FcRγ in the TCR complex. To analyze the function of FcRγ, we produced FcRydeficient mice. These mice confirmed the importance of FcRγ for TCR expression and development in T cells present in epithelia. The proportion between ζ and FcRγ determined developmental block of T cells in ζ -or FcRγ -deficient mice.
