Inhibition of the transient receptor potential cation channel TRPM2 by 2-aminoethoxydiphenyl borate (2-APB).
OBJECTIVE
Transient receptor potential melastatin 2 (TRPM2) is a non-selective Ca(2+)-permeable cation channel and is known to be activated by adenosine 5'-diphosphoribose (ADP-ribose) and hydrogen peroxide. TRPM2 current responses are reported to be drastically potentiated by the combination of each of these ligands with heat. Furthermore, the combination of cyclic ADP-ribose with heat also activates TRPM2. Although flufenamic acid, antifungal agents (miconazole and clotrimazole), and a phospholipase A(2) inhibitor (N-(p-amylcinnamoyl)anthranilic acid) inhibit TRPM2, their inhibition was either gradual or irreversible.


METHODS
To facilitate future research on TRPM2, we screened several compounds to investigate their potential to activate or inhibit the TRPM2 channels using the patch-clamp technique in HEK293 cells, transfected with human TRPM2.


RESULTS
2-aminoethoxydiphenyl borate (2-APB) exhibited a rapid and reversible inhibition of TRPM2 channels that had been activated by its ADP-ribose or cADP-ribose and heat in a dose-dependent manner (IC(50) about 1 microM). 2-APB also inhibited heat-evoked insulin release from pancreatic islets, isolated from rats.


CONCLUSIONS
2-APB proved to be a powerful and effective tool for studying the function of TRPM2.
Togashi
K
K
Section of Cell Signaling, Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Okazaki, Aichi, Japan.
Inada
H
H
Tominaga
M
M
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D001896:Boron Compounds / Q000008:administration & dosage / Q000494:pharmacology*; D002460:Cell Line; D002934:Cinnamates / Q000494:pharmacology; D036563:Cyclic ADP-Ribose / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005439:Flufenamic Acid / Q000494:pharmacology; D006358:Hot Temperature; D006801:Humans; D066298:In Vitro Techniques; D020128:Inhibitory Concentration 50; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism; D008297:Male; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D050053:TRPM Cation Channels / Q000037:antagonists & inhibitors*; D014162:Transfection; D062367:ortho-Aminobenzoates / Q000494:pharmacology
D000935:Antifungal Agents; D001896:Boron Compounds; D002934:Cinnamates; D007328:Insulin; D050053:TRPM Cation Channels; C121934:TRPM2 protein, human; D062367:ortho-Aminobenzoates; C085901:4-amylcinnamoylanthranilic acid; D036563:Cyclic ADP-Ribose; D000246:Adenosine Diphosphate Ribose; D005439:Flufenamic Acid; C109986:2-aminoethoxydiphenyl borate