Kim T.-K.,Infectious Disease Medical Research Center |
Nam J.-H.,Dongguk University |
Ahn W.-G.,Infectious Disease Medical Research Center |
Kim N.-H.,Infectious Disease Medical Research Center |
And 8 more authors.
Biochemical Journal | Year: 2013
TRPM2 (transient receptor potential melastatin 2) is a nonselective Ca 2+ -permeable cation channel activated by ADPR (adenosine diphosphoribose) and H2O2. It is widely expressed in mammalian cells and plays an important role in the regulation of various cell functions. However, the mechanisms of TRPM2 channel activation are not fully understood. Previously, we reported that TRPM2 channel activation is induced by high intracellular Cl- concentration. In the present study, we investigated the functional role of Lys1110 in the membraneproximal C-terminal region by site-directed mutagenesis. Replacement of the positively charged amino acid lysine (Lys1110) with the neutrally charged amino acid asparagine (K1110N) or the negatively charged amino acid glutamic acid (K1110E) generated mutants that failed to induce an increase in free cytosolic calcium concentration ([Ca2+ ]i) not only by intracellular injection of Cl- , but also by H2O2 or ADPR. However, a mutant generated by replacing the lysine residue with a positively charged amino acid arginine (K1110R) displayed channel activity similar to wild-type TRPM2. Interestingly, in the K1107N/K1110N doublepoint mutant, the impaired function of the K1110N mutant in response to ADPR andH 2O2, but not to Cl- ,was recovered. There were no changes in protein expression, membrane trafficking and oligomerization of the mutant channels. The extent of [Ca2+ ]i increase by H2O2 in HEK (human embryonic kidney)-293 cells expressing TRPM2 mutants was well correlated with the degree of susceptibility to H 2O2-induced cell death. These results display the crucial role of a positively charged amino acid residue at position 1110 for TRPM2 channel activity. © 2013 Biochemical Society. © 2013 Biochemical Society.