title: H2O2-induced Ca2+ influx and its inhibition by N-(p-amylcinnamoyl) anthranilic acid in the beta-cells: involvement of TRPM2 channels.
abstract: Type 2 melastatin-related transient receptor potential channel (TRPM2), a member of the melastatin-related TRP (transient receptor potential) subfamily is a Ca(2+)-permeable channel activated by hydrogen peroxide (H(2)O(2)). We have investigated the role of TRPM2 channels in mediating the H(2)O(2)-induced increase in the cytoplasmic free Ca(2+) concentration ([Ca(2+)](i)) in insulin-secreting cells. In fura-2 loaded INS-1E cells, a widely used model of beta-cells, and in human beta-cells, H(2)O(2) increased [Ca(2+)](i), in the presence of 3 mM glucose, by inducing Ca(2+) influx across the plasma membrane. H(2)O(2)-induced Ca(2+) influx was not blocked by nimodipine, a blocker of the L-type voltage-gated Ca(2+) channels nor by 2-aminoethoxydiphenyl borate, a blocker of several TRP channels and store-operated channels, but it was completely blocked by N-(p-amylcinnamoyl)anthranilic acid (ACA), a potent inhibitor of TRPM2. Adenosine diphosphate phosphate ribose, a specific activator of TRPM2 channel and H(2)O(2), induced inward cation currents that were blocked by ACA. Western blot using antibodies directed to the epitopes on the N-terminal and on the C-terminal parts of TRPM2 identified the full length TRPM2 (TRPM2-L), and the C-terminally truncated TRPM2 (TRPM2-S) in human islets. We conclude that functional TRPM2 channels mediate H(2)O(2)-induced Ca(2+) entry in beta-cells, a process potently inhibited by ACA.
authors.affiliation: Department of Clinical Sciences and Education, Karolinska Institutet, Research Centre, Stockholm South Hospital, Stockholm, Sweden.
authors.forename: Muhammad R
authors.initials: MR
authors.lastname: Bari
authors.forename: Sanian
authors.initials: S
authors.lastname: Akbar
authors.forename: Mohamed
authors.initials: M
authors.lastname: Eweida
authors.forename: Frank J P
authors.initials: FJ
authors.lastname: Kühn
authors.forename: Amanda Jabin
authors.initials: AJ
authors.lastname: Gustafsson
authors.forename: Andreas
authors.initials: A
authors.lastname: Lückhoff
authors.forename: Md Shahidul
authors.initials: MS
authors.lastname: Islam
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002934:Cinnamates / Q000378:metabolism*; D051152:Clusterin / Q000378:metabolism*; D000939:Epitopes / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D007340:Insulinoma / Q000378:metabolism; D009553:Nimodipine / Q000494:pharmacology; D051381:Rats; D062367:ortho-Aminobenzoates / Q000378:metabolism*
chemical_list: D015220:Calcium Channels; D002934:Cinnamates; D051152:Clusterin; D000939:Epitopes; D062367:ortho-Aminobenzoates; C085901:4-amylcinnamoylanthranilic acid; D009553:Nimodipine; D006861:Hydrogen Peroxide; D002118:Calcium