title: 8-Bromo-cyclic inosine diphosphoribose: towards a selective cyclic ADP-ribose agonist.
abstract: cADPR (cyclic ADP-ribose) is a universal Ca(2+) mobilizing second messenger. In T-cells cADPR is involved in sustained Ca(2+) release and also in Ca(2+) entry. Potential mechanisms for the latter include either capacitative Ca(2+) entry, secondary to store depletion by cADPR, or direct activation of the non-selective cation channel TRPM2 (transient receptor potential cation channel, subfamily melastatin, member 2). Here we characterize the molecular target of the newly-described membrane-permeant cADPR agonist 8-Br-N(1)-cIDPR (8-bromo-cyclic IDP-ribose). 8-Br-N(1)-cIDPR evoked Ca(2+) signalling in the human T-lymphoma cell line Jurkat and in primary rat T-lymphocytes. Ca(2+) signalling induced by 8-Br-N(1)-cIDPR consisted of Ca(2+) release and Ca(2+) entry. Whereas Ca(2+) release was sensitive to both the RyR (ryanodine receptor) blocker RuRed (Ruthenium Red) and the cADPR antagonist 8-Br-cADPR (8-bromo-cyclic ADP-ribose), Ca(2+) entry was inhibited by the Ca(2+) entry blockers Gd(3+) (gadolinium ion) and SKF-96365, as well as by 8-Br-cADPR. To unravel a potential role for TRPM2 in sustained Ca(2+) entry evoked by 8-Br-N(1)-cIDPR, TRPM2 was overexpressed in HEK (human embryonic kidney)-293 cells. However, though activation by H(2)O(2) was enhanced dramatically in those cells, Ca(2+) signalling induced by 8-Br-N(1)-cIDPR was almost unaffected. Similarly, direct analysis of TRPM2 currents did not reveal activation or co-activation of TRPM2 by 8-Br-N(1)-cIDPR. In summary, the sensitivity to the Ca(2+) entry blockers Gd(3+) and SKF-96365 is in favour of the concept of capacitative Ca(2+) entry, secondary to store depletion by 8-Br-N(1)-cIDPR. Taken together, 8-Br-N(1)-cIDPR appears to be the first cADPR agonist affecting Ca(2+) release and secondary Ca(2+) entry, but without effect on TRPM2.
authors.affiliation: The Calcium Signalling Group, University Medical Center Hamburg-Eppendorf, Center of Experimental Medicine, Institute of Biochemistry and Molecular Biology I: Cellular Signal Transduction, Hamburg, Germany.
authors.forename: Tanja
authors.initials: T
authors.lastname: Kirchberger
authors.forename: Christelle
authors.initials: C
authors.lastname: Moreau
authors.forename: Gerd K
authors.initials: GK
authors.lastname: Wagner
authors.forename: Ralf
authors.initials: R
authors.lastname: Fliegert
authors.forename: Cornelia C
authors.initials: CC
authors.lastname: Siebrands
authors.forename: Merle
authors.initials: M
authors.lastname: Nebel
authors.forename: Frederike
authors.initials: F
authors.lastname: Schmid
authors.forename: Angelika
authors.initials: A
authors.lastname: Harneit
authors.forename: Francesca
authors.initials: F
authors.lastname: Odoardi
authors.forename: Alexander
authors.initials: A
authors.lastname: Flügel
authors.forename: Barry V L
authors.initials: BV
authors.lastname: Potter
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Guse
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects; D036563:Cyclic ADP-Ribose / Q000031:analogs & derivatives*; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D005682:Gadolinium / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007292:Inosine Nucleotides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D015640:Ion Channel Gating / Q000187:drug effects; D019169:Jurkat Cells; D008845:Microinjections; D051381:Rats; D012430:Ruthenium Red / Q000494:pharmacology; D050053:TRPM Cation Channels / Q000378:metabolism
chemical_list: C543311:8-bromo-cyclic inosine diphosphoribose; D007093:Imidazoles; D007292:Inosine Nucleotides; D050053:TRPM Cation Channels; C121934:TRPM2 protein, human; D012430:Ruthenium Red; D036563:Cyclic ADP-Ribose; D005682:Gadolinium; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole