DIFFERENTIAL G-PROTEIN EXPRESSION DURING B-CELL AND T-CELL DEVELOPMENT

The molecular mechanisms underlying B- and T-cell development are, as yet, poorly understood. However, as G proteins regulate a diverse rang e of biological responses including growth, proliferation and differen tiation, we have investigated differential expression of G proteins du ring B- and T-cell development with the aim of identifying key signals involved in lymphocyte maturation. Differential expression of beta(1/ 2) and alpha-subunits of the Gs-, i- and q-families was found througho ut lymphoid development. Most strikingly, G alpha(i1) and G alpha(11) were very weakly, or not expressed in pre-, immature and mature B cell s, thymocytes or mature T cells, but strongly induced in mature B-lymp hoblastoid cell lines, some of which have been used as models of germi nal centre B cells, suggesting that expression of these G proteins may correlate with the later stages of B-cell development. In contrast, G alpha(16) expression was highest in T cells and pre-B cells and progr essively declined with B-cell maturation. These findings suggest that G proteins, and the signals they regulate, such as ion channels and/or adenylate cyclase (G alpha(s/i)) and phospholipase C (G beta gamma an d G alpha(11/16)) are differentially regulated in lymphoid cells in a maturation- and lineage-dependent manner.