Induction of T cell receptor gamma chain transcription in murine T cells by trans-complementation.

As an initial approach to understanding the molecular basis of the developmentally regulated expression of T cell receptor (TcR) genes, we constructed hybrids among T cell clones that differ in their expression of CD4 and CD8 antigens as well as in alpha, beta and gamma mRNA levels. Here we report that the TcR gamma gene becomes transcriptionally active in hybrid cells formed between parental clones that lack TcR gamma mRNA. We also observed negative trans-regulation of TcR beta but not of TcR alpha transcription in one of these hybrids. Positive TcR gamma transcription was observed both with (CD4-CD8- X CD4-CD8-) and (CD4-CD8- X CD4+CD8+) hybrids while negative TcR beta gene regulation was only detected in (CD4-CD8- X CD4+CD8+) cells. These data suggest that the regulation of TcR alpha, beta and gamma genes is mediated by the action of specific transacting factors that become asynchronously active in the various stages of T cell development.