Regulation of TRP channel TRPM2 by the tyrosine phosphatase PTPL1

TRPM2, a member of the transient receptor potential (TRP) superfamily, is a Ca2+-permeable channel, which mediates susceptibility to cell death following activation by oxidative stress, TNFα, or β-amyloid peptide. We determined that TRPM2 is rapidly tyrosine phosphorylated after stimulation with H2O2 or TNFα. Inhibition of tyrosine phosphorylation with the tyrosine kinase inhibitors genistein or PP2 significantly reduced the increase in [Ca2+]i observed after H2O2 or TNFα treatment in TRPM2-expressing cells, suggesting that phosphorylation is important in TRPM2 activation. Utilizing a TransSignal PDZ domain array blot to identify proteins which interact with TRPM2, we identified PTPL1 as a potential binding protein. PTPL1 is a widely expressed tyrosine phosphatase, which has a role in cell survival and tumorigenesis. Immunoprecipitation and glutathione-S-transferase pull-down assays confirmed that TRPM2 and PTPL1 interact. To examine the ability of PTPL1 to modulate phosphorylation or activation of TRPM2,...