Inhibition of PTPs by H2O2 regulates the activation of distinct MAPK pathways

It has been shown that endogenous production of reactive oxygen species (ROS) during T cell activation regulates signaling events including MAPK activation. Protein tyrosine phosphatases (PTPs) have been regarded as targets of ROS which modify the catalytic cysteine residues of the enzymes. We have analyzed the interplay between the inhibition of PTPs and the activation of MAPK by H2O2. Stimulation of Jurkat T cells with H2O2 induces the phosphorylation of ERK, p38, and JNK members of MAPK family. H2O2 stimulation of T cells was found to inhibit the PTP activity of CD45, SHP-1, and HePTP. Transfection of cells with wtSHP-1 decreased H2O2-induced ERK and JNK phosphorylation without affecting p38 phosphorylation. Transfection with wtHePTP inhibited H2O2-induced ERK and p38 phosphorylation without inhibiting JNK phosphorylation. The Src-family kinase inhibitor, PP2, inhibited the H2O2-induced phosphorylation of ERK, p38, and JNK. The phospholipase C (PLC) inhibitor, U73122, or the protein kinase C (PKC) inhibitor, Ro-31-8425, blocked H2O2-induced ERK phosphorylation, whereas the same treatment did not inhibit p38 or JNK phosphorylation. Taken together, these results suggest that inhibition of PTPs by H2O2 contributes to the induction of distinct MAPK activation profiles via differential signaling pathways.