The role of calcineurin in lymphocyte activation

Lymphokine gene transcription involves numerous signal transduction molecul es and second messengers. The serine/threonine phosphatase calcineurin has been demonstrated to play a central role in. the immediate, early activatio n of numerous lymphokines (such as interleukin [IL]-2) and in the regulatio n of cell surface receptors such as CD40L, CD95, and recently CD25 alpha (t he a chain of the IL-2 receptor). In addition to lymphocyte activation, cal cineurin functions include control of neuronal signaling; muscle contractio n, muscle hypertrophy and cellular death. Therefore, calcineurin not only p lays a vital role in the regulation of T lymphocyte function, but also func tions in cellular environments outside the immune system.