Interactions between intracellular Ca2+ stores: Ca2+ released from the NAADP pool potentiates cADPR-induced Ca2+ release.
Cells possess multiple intracellular Ca2+-releasing systems. Sea urchin egg homogenates are a well-established model to study intracellular Ca2+ release. In the present study the mechanism of interaction between three intracellular Ca2+ pools, namely the nicotinic acid adenine dinucleotide phosphate (NAADP), the cyclic ADP-ribose (cADPR) and the inositol 1',4',5'-trisphosphate (IP3)-regulated Ca2+ stores, is explored. The data indicate that the NAADP Ca2+ pool could be used to sensitize the cADPR system. In contrast, the IP3 pool was not affected by the Ca2+ released by NAADP. The mechanism of potentiation of the cADPR-induced Ca2+ release, promoted by Ca2+ released from the NAADP pool, is mediated by the mechanism of Ca2+-induced Ca2+ release. These data raise the possibility that the NAADP Ca2+ store may have a role as a regulator of the cellular sensitivity to cADPR.
Chini
Eduardo N
EN
Department of Anesthesia, Mayo Clinic and Foundation, 200 First Street, Rochester, MN 55905, USA. chini.eduardo@mayo.edu
D000246:Adenosine Diphosphate Ribose / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D036563:Cyclic ADP-Ribose; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D009249:NADP / Q000031:analogs & derivatives* / Q000494:pharmacology* / Q000502:physiology; D010063:Ovum / Q000187:drug effects* / Q000378:metabolism; D012617:Sea Urchins
D036563:Cyclic ADP-Ribose; D000246:Adenosine Diphosphate Ribose; D009249:NADP; C024376:NAADP; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium