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71.67 T lymphocyte activation is accompanied by the down-regulation of three G alpha genes
B Rock1, L Xin, J E Niederhuber
1Department of Dermatology, Emory University, Atlanta, Georgia 30322, USA.
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 G alpha genes from a lymphocyte cell line by amplifying areas of divergent sequence between conserved primer sites. These murine cDNAs are homologous with previously reported G alpha s, G alpha i2, and G alpha i3 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 G alpha 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 G alpha mRNA steady-state levels.
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 G alpha genes from a lymphocyte cell line by amplifying areas of divergent sequence between conserved primer sites. These murine cDNAs are homologous with previously reported G alpha s, G alpha i2, and G alpha i3 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 G alpha 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 G alpha mRNA steady-state levels.