Document Detail


Identification of direct and indirect effectors of the transient receptor potential melastatin 2 (TRPM2) cation channel.
MedLine Citation:
PMID:  20650899     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Transient receptor potential melastatin 2 (TRPM2) is a Ca(2+)-permeable cation channel involved in physiological and pathophysiological processes linked to oxidative stress. TRPM2 channels are co-activated by intracellular Ca(2+) and ADP-ribose (ADPR) but also modulated in intact cells by several additional factors. Superfusion of TRPM2-expressing cells with H(2)O(2) or intracellular dialysis of cyclic ADPR (cADPR) or nicotinic acid adenine dinucleotide phosphate (NAADP) activates, whereas dialysis of AMP inhibits, TRPM2 whole-cell currents. Additionally, H(2)O(2), cADPR, and NAADP enhance ADPR sensitivity of TRPM2 currents in intact cells. Because in whole-cell recordings the entire cellular machinery for nucleotide and Ca(2+) homeostasis is intact, modulators might affect TRPM2 activity either directly, by binding to TRPM2, or indirectly, by altering the local concentrations of the primary ligands ADPR and Ca(2+). To identify direct modulators of TRPM2, we have studied the effects of H(2)O(2), AMP, cADPR, NAADP, and nicotinic acid adenine dinucleotide in inside-out patches from Xenopus oocytes expressing human TRPM2, by directly exposing the cytosolic faces of the patches to these compounds. H(2)O(2) (1 mM) and enzymatically purified cADPR (10 μM) failed to activate, whereas AMP (200 μM) failed to inhibit TRPM2 currents. NAADP was a partial agonist (maximal efficacy, ∼50%), and nicotinic acid adenine dinucleotide was a full agonist, but both had very low affinities (K(0.5) = 104 and 35 μM). H(2)O(2), cADPR, and NAADP did not enhance activation by ADPR. Considering intracellular concentrations of these compounds, none of them are likely to directly affect the TRPM2 channel protein in a physiological context.
Authors:
Balázs Tóth; László Csanády
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-07-22
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  285     ISSN:  1083-351X     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2010 Sep 
Date Detail:
Created Date:  2010-09-20     Completed Date:  2010-10-21     Revised Date:  2012-04-27    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  30091-102     Citation Subset:  IM    
Affiliation:
Department of Medical Biochemistry, Semmelweis University, Budapest H-1094, Hungary.
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MeSH Terms
Descriptor/Qualifier:
Adenosine Diphosphate Ribose / pharmacology
Animals
Calcium / metabolism
Cyclic ADP-Ribose / pharmacology
Humans
Hydrogen Peroxide / pharmacology
NAD / analogs & derivatives*,  pharmacology
NADP / analogs & derivatives,  pharmacology
Oxidants / pharmacology
Oxidative Stress / drug effects*,  physiology
TRPM Cation Channels / agonists*,  genetics,  metabolism*
Xenopus laevis
Chemical
Reg. No./Substance:
0/Oxidants; 0/TRPM Cation Channels; 0/TRPM2 protein, human; 119340-53-3/Cyclic ADP-Ribose; 20762-30-5/Adenosine Diphosphate Ribose; 53-59-8/NADP; 53-84-9/NAD; 5502-96-5/NAADP; 6450-77-7/nicotinic acid adenine dinucleotide; 7440-70-2/Calcium; 7722-84-1/Hydrogen Peroxide
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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