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TRPM2 channel opening in response to oxidative stress is dependent on activation of poly(ADP‐ribose) polymerase
Author(s) -
Fonfria Elena,
Marshall Ian C B,
Benham Christopher D,
Boyfield Izzy,
Brown Jason D,
Hill Kerstin,
Hughes Jane P,
Skaper Stephen D,
McNulty Shaun
Publication year - 2004
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0705914
Subject(s) - trpm2 , poly adp ribose polymerase , hek 293 cells , chemistry , oxidative stress , intracellular , transient receptor potential channel , membrane potential , microbiology and biotechnology , biochemistry , polymerase , biology , enzyme , receptor
TRPM2 (melastatin‐like transient receptor potential 2 channel) is a nonselective cation channel that is activated under conditions of oxidative stress leading to an increase in intracellular free Ca 2+ concentration ([Ca 2+ ] i ) and cell death. We investigated the role of the DNA repair enzyme poly(ADP‐ribose) polymerase (PARP) on hydrogen peroxide (H 2 O 2 )‐mediated TRPM2 activation using a tetracycline‐inducible TRPM2‐expressing cell line. In whole‐cell patch‐clamp recordings, intracellular adenine 5′‐diphosphoribose (ADP‐ribose) triggered an inward current in tetracycline‐induced TRPM2‐human embryonic kidney (HEK293) cells, but not in uninduced cells. Similarly, H 2 O 2 stimulated an increase in [Ca 2+ ] i (pEC 50 4.54±0.02) in Fluo‐4‐loaded TRPM2‐expressing HEK293 cells, but not in uninduced cells. Induction of TRPM2 expression caused an increase in susceptibility to plasma membrane damage and mitochondrial dysfunction in response to H 2 O 2 . These data demonstrate functional expression of TRPM2 following tetracycline induction in TRPM2‐HEK293 cells. PARP inhibitors SB750139‐B (patent number DE10039610‐A1 (Lubisch et al ., 2001)), PJ34 ( N ‐(6‐oxo‐5,6‐dihydro‐phenanthridin‐2‐yl)‐ N,N ‐dimethylacetamide) and DPQ (3, 4‐dihydro‐5‐[4‐(1‐piperidinyl)butoxy]‐1(2H)‐isoquinolinone) inhibited H 2 O 2 ‐mediated increases in [Ca 2+ ] i (pIC 50 vs 100 μ M H 2 O 2 : 7.64±0.38; 6.68±0.28; 4.78±0.05, respectively), increases in mitochondrial dysfunction (pIC 50 vs 300 μ M H 2 O 2 : 7.32±0.23; 6.69±0.22; 5.44±0.09, respectively) and decreases in plasma membrane integrity (pIC 50 vs 300 μ M H 2 O 2 : 7.45±0.27; 6.35±0.18; 5.29±0.12, respectively). The order of potency of the PARP inhibitors in these assays (SB750139>PJ34>DPQ) was the same as for inhibition of isolated PARP enzyme. SB750139‐B, PJ34 and DPQ had no effect on inward currents elicited by intracellular ADP‐ribose in tetracycline‐induced TRPM2‐HEK293 cells, suggesting that PARP inhibitors are not interacting directly with the channel. SB750139‐B, PJ34 and DPQ inhibited increases in [Ca 2+ ] i in a rat insulinoma cell line (CRI‐G1 cells) endogenously expressing TRPM2 (pIC 50 vs 100 μ M H 2 O 2 : 7.64±0.38; 6.68±0.28; 4.78±0.05, respectively). These data suggest that oxidative stress causes TRPM2 channel opening in both recombinant and endogenously expressing cell systems via activation of PARP enzymes.British Journal of Pharmacology (2004) 143 , 186–192. doi: 10.1038/sj.bjp.0705914