71.67 T Lymphocyte Activation Is Accompanied by the Down-Regulation of Three Gα Genes

A direct role for heterotrimeric G proteins in signal transduction through the T cell receptor complex has been hypothesized, but never definitively demonstrated, Nonetheless, several lines of evidence support the importance of G proteins in lymphocyte activation and differentiation events. In this study, PCR was used to generate cDNA segments of murine Gα genes from a lymphocyte cell line by amplifying areas of divergent sequence between conserved primer sites. These murine cDNAs are homologous with previously reported Gαs, Gαi2, and Gαi3 genes from other tissues and were used as probes to determine their levels of mRNA expression in a mitogen- and antigen-stimulated T lymphocyte line, 71.67, which provides a model for T cell activation. mRNA levels for all three Gα genes were found to be differentially down-regulated with 71.67 activation, but not with stimulation of three more immature lymphocyte cell lines. These findings suggest that an important element in signal transduction through these G proteins in lymphocytes may include regulation of Gα mRNA steady-state levels.