Induction of protein‐tyrosine phosphatase LC‐PTP by IL‐2 in human T cells

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Abstract
Tyrosine phosphorylation has been implicated in interleukin 2 (IL‐2)‐induced growth signaling and the phosphorylation levels are regulated by the balance of tyrosine kinase and tyrosine phosphatase activities. Here, we demonstrate the rapid activation of a leukocyte tyrosine phosphatase LC‐PTP (HePTP) gene expression by IL‐2 in an IL‐2 dependent human T cell ILT‐Mat. Accumulation of LC‐PTP mRNA appeared at l h and peaked at 6 h after IL‐2 stimulation, simultaneous with the Gl to early S phase, and the induction of LC‐PTP mRNA did not require protein synthesis. LC‐PTP protein increased approximately 6‐fold at 8 h after IL‐2 stimulation. Nuclear run‐on assays showed that the induction of LC‐PTP mRNA expression is mostly due to transcriptional activation. These data suggest that LC‐PTP is an early response gene and its protein seems to be a crucial molecule which regulates the tyrosine phosphorylation level during T cell proliferation.