Inhibition of inositol trisphosphate-induced calcium release by cyclic ADP-ribose in A7r5 smooth-muscle cells and in 16HBE14o- bronchial mucosal cells.
Ca2+ release from intracellular stores occurs via two families of intracellular channels, each with their own specific agonist: Ins(1, 4,5)P3 for the Ins(1,4,5)P3 receptor and cyclic ADP-ribose (cADPR) for the ryanodine receptor. We now report that cADPR inhibited Ins(1, 4,5)P3-induced Ca2+ release in permeabilized A7r5 cells with an IC50 of 20 microM, and in permeabilized 16HBE14o- bronchial mucosal cells with an IC50 of 35 microM. This inhibition was accompanied by an increase in specific [3H]Ins(1,4,5)P3 binding. 8-Amino-cADPR, but not 8-bromo-cADPR, antagonized this effect of cADPR. The inhibition was prevented by a whole series of inositol phosphates (10 microM) that did not affect Ins(1,4,5)P3-induced Ca2+ release, and by micromolar concentrations of PPi and various nucleotide di- or triphosphates. We propose that cADPR must interact with a novel regulatory site on the Ins(1,4,5)P3 receptor or on an associated protein. This site is neither the Ins(1,4,5)P3-binding domain, which prefers Ins(1,4,5)P3 and only binds nucleotides and PPi in the millimolar range, nor the stimulatory adenine nucleotide binding site.
Missiaen
L
L
Laboratorium voor Fysiologie, K.U. Leuven Campus Gasthuisberg, Belgium.
Parys
J B
JB
De Smedt
H
H
Sienaert
I
I
Sipma
H
H
Vanlingen
S
S
Maes
K
K
Kunzelmann
K
K
Casteels
R
R
D000227:Adenine Nucleotides / Q000378:metabolism; D000246:Adenosine Diphosphate Ribose / Q000031:analogs & derivatives* / Q000378:metabolism / Q000502:physiology; D000818:Animals; D001011:Aorta; D001665:Binding Sites; D001980:Bronchi / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D002110:Caffeine / Q000378:metabolism; D002118:Calcium / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism; D002460:Cell Line; D036563:Cyclic ADP-Ribose; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism / Q000494:pharmacology*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D009092:Mucous Membrane / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism
D000227:Adenine Nucleotides; D015220:Calcium Channels; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D019837:Ryanodine Receptor Calcium Release Channel; D036563:Cyclic ADP-Ribose; D000246:Adenosine Diphosphate Ribose; D002110:Caffeine; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium