G alpha(16) protein expression is up- and down-regulated following T-cell activation: Disruption of this regulation impairs activation-induced cell responses

The role of heterotrimeric G proteins in T-cell activation is poorly understood, Here we show that in normal, mature human T-cells, expression of G alpha(16), the 43 kDa alpha subunit of G(16), varies widely, depending on T-cell activation status, Quiescent blood lymphocytes strongly up-regulate G alpha(16) after Leuco A stimulation: protein expression of G alpha(16) is maximal at day 4, then decreases, Consistently, in human T-cen clones, expression of G alpha(16), is high in the first week following activation and decreases rapidly within the second week. In addition, permanent disruption of regulated G alpha(16) expression in Jurkat T-cells by stable overexpression of 43 kDa G alpha(16), inhibited Leuco A-induced interleukin-2 production, CD69 up-regulation and cell apoptosis (by 58%, 46% and 74%, respectively), suggesting that coordinate regulation of G alpha(16) expression is necessary far optimal activation-induced T-cell responses, and that G alpha(16) proteins may be involved in the negative regulation of TCR signalling. (C) 1997 Federation of European Biochemical Societies.