rapamycin,drug characterized primarily by its ability to suppress theimmune system, which led to its use in the prevention oftransplantrejection. Rapamycin is produced by the soilbacteriumStreptomyces hygroscopicus. The drug’s name comes from Rapa Nui, theindigenous name ofEaster Island, where thecompound was originally discovered in soil samples in the 1970s.

Rapamycin exerts its immunosuppressive effects byinhibiting the activation and proliferation ofT cells. It acts specifically onFK-binding protein 12 (FKBP12), a substance commonly referred to as an immunophilin because it binds to immunosuppressive drugs. In turn, the rapamycin-FKBP12 complex binds to the mammalian target of rapamycin (mTOR), akinase (anenzyme that adds phosphate groups to other molecules) that plays a fundamental role in regulating the progression of thecell cycle. The rapamycin complexinhibits mTOR and, by doing so, disruptscell division and hence the proliferation of T cells.

Rapamycin is used in combination with other immunosuppressive agents, namely calcineurin inhibitors and glucocorticoids, to prevent transplant rejection. Because aberrant mTOR activity is implicated incancer, rapamycin is being investigated for use in thetreatment of certain malignancies. In addition, studies have indicated that rapamycin-coated stents, which are devices used in the treatment ofcardiovascular disease involving the narrowing of ablood vessel, have been associated with reduced rates of restenosis (recurrence of vessel narrowing). Research conducted in 2009 in mice revealed a potential role for rapamycin as an anti-aging drug. The drug’sinhibition of mTOR is suspected to induce metabolic and stress responses that favour longevity, though exactly how this occurs is not clear.

More From Britannica

aging: Rapamycin

Immune suppression by rapamycin has been associated with potentially serious side effects, including increased risk of infection andlymphoma. Other side effects include fever,diarrhea, joint pain, headache, and vomiting.