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Biochem Biophys Res Commun. 1992 Aug 14;186(3):1315-21.

Rapamycin inhibits the phosphorylation of p70 S6 kinase in IL-2 and mitogen-activated human T cells.

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Department of Pediatrics, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206.


Phosphorylation of 40S ribosomal protein S6 is regulated in part by the mitogen-activated p70 S6 kinase (p70s6k). Following the addition of IL-2 to the IL-2 dependent human cell line Kit225, or mitogenic activation of resting human T cells, a rapid phosphorylation of p70s6k was observed by immunoblotting. Rapamycin (RAP), a potent suppressor of T-cell proliferative responses, markedly inhibited the phosphorylation of p70s6k induced by IL-2 in Kit225 cells or by the mitogens added to resting T cells. Other immunosuppressants such as cyclosporin A or an FK506 analogue were without effect. Moreover, the effect of RAP was restricted to p70s6k; it did not inhibit the phosphorylation of p90rsk, another kinase which utilizes the S6 protein as a substrate. These data indicate for the first time that RAP may target the pathway leading to p70s6k phosphorylation during human T-cell proliferation.

[Indexed for MEDLINE]

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