Subtype‐specific increase in G‐protein α‐subunit mRNA by interleukin 1β

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Abstract
The guanine nucleotide regulatory proteins (G‐proteins) which are substrates for ADP‐ribosylation by pertussis toxin (αi−1, αi−2, αi−3 and α0) transduce a variety of hormonal signals. Endothelial cells express mRNA for three αi subtypes although the level of αi−1 mRNA is very low. Interleukin 1β (IL1β), a pleiotropic inflammatory mediator which stimulates a complex series of responses in human endothelial cells leading to increased coagulation and platelet adhesion, increases expression of one subtype of αi (αi−2) mRNA in human endothelial cells as determined by Northern blot analysis without affecting the level of mRNA for other α‐subunits. These studies show that mRNA levels for αi subtypes are independently regulated, suggesting that there may be subtype specificity in the cell's requirements for the Gi class of signal‐transducing proteins.