IL-2 induces transient and specific decrease in cytosolic protein phosphatase PP1 activity in murine T cell lines.

In the IL-2-dependent murine cytotoxic T cell line CTLL-2, IL-2 induced a rapid and transient decrease in Co(2+)-trypsin-treated activity of protein phosphatase PP1. The PP1 activity declined to a minimum level, being 70% of control value, in 20 min after the addition of IL-2 but recovered to the control level within 45 min. The decrease of PP1 activity was dependent on IL-2 concentration and occurred specifically in cytosolic fraction. Similar alteration was observed in IL-2 sensitive murine T-lymphoblasts. Neither activity of protein phosphatase PP2A nor PP2C showed alteration during the IL-2 stimulation. These results suggest that PP1 plays an important role in early events of the intracellular growth signaling from the IL-2 receptor.