Differential G-protein expression during B- 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 range of biological responses including growth, proliferation and differentiation, we have investigated differential expression of G proteins during 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 throughout lymphoid development. Most strikingly, G alpha(i1) and G alpha(11) were very weakly, or not expressed in pre-, immature and mature B cells, thymocytes or mature T cells, but strongly induced in mature B-lymphoblastoid cell lines, some of which have been used as models of germinal 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 progressively 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 and G alpha(11/16)) are differentially regulated in lymphoid cells in a maturation- and lineage-dependent manner.