Gα16protein expression is up- and down-regulated following T-cell activation: disruption of this regulation impairs activation-induced cell responses

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Abstract
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 Gα16, the 43 kDa α subunit of G16, varies widely, depending on T‐cell activation status. Quiescent blood lymphocytes strongly up‐regulate Gα16 after Leuco A stimulation: protein expression of Gα16 is maximal at day 4, then decreases. Consistently, in human T‐cell clones, expression of Gα16 is high in the first week following activation and decreases rapidly within the second week. In addition, permanent disruption of regulated Gα16 expression in Jurkat T‐cells by stable overexpression of 43 kDa Gα16 inhibited Leuco A‐induced interleukin‐2 production, CD69 up‐regulation and cell apoptosis (by 58%, 46% and 74%, respectively), suggesting that coordinate regulation of Gα16 expression is necessary for optimal activation‐induced T‐cell responses, and that Gα16 proteins may be involved in the negative regulation of TCR signalling.