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NAADP mobilizes Ca2+ from a thapsigargin-sensitive store in the nuclear envelope by activating ryanodine receptors.

ABSTRACT: Ca2+ release from the envelope of isolated pancreatic acinar nuclei could be activated by nicotinic acid adenine dinucleotide phosphate (NAADP) as well as by inositol 1,4,5-trisphosphate (IP3) and cyclic ADP-ribose (cADPR). Each of these agents reduced the Ca2+ concentration inside the nuclear envelope, and this was associated with a transient rise in the nucleoplasmic Ca2+ concentration. NAADP released Ca2+ from the same thapsigargin-sensitive pool as IP3. The NAADP action was specific because, for example, nicotineamide adenine dinucleotide phosphate was ineffective. The Ca2+ release was unaffected by procedures interfering with acidic organelles (bafilomycin, brefeldin, and nigericin). Ryanodine blocked the Ca2+-releasing effects of NAADP, cADPR, and caffeine, but not IP3. Ruthenium red also blocked the NAADP-elicited Ca2+ release. IP3 receptor blockade did not inhibit the Ca2+ release elicited by NAADP or cADPR. The nuclear envelope contains ryanodine and IP3 receptors that can be activated separately and independently; the ryanodine receptors by either NAADP or cADPR, and the IP3 receptors by IP3.

SUBMITTER: Gerasimenko JV

PROVIDER: S-EPMC2173522 | biostudies-literature | 2003 Oct

REPOSITORIES: biostudies-literature

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NAADP mobilizes Ca2+ from a thapsigargin-sensitive store in the nuclear envelope by activating ryanodine receptors.

Gerasimenko Julia V JV Maruyama Yoshio Y Yano Kojiro K Dolman Nick J NJ Tepikin Alexei V AV Petersen Ole H OH Gerasimenko Oleg V OV

The Journal of cell biology 20031020 2

Ca2+ release from the envelope of isolated pancreatic acinar nuclei could be activated by nicotinic acid adenine dinucleotide phosphate (NAADP) as well as by inositol 1,4,5-trisphosphate (IP3) and cyclic ADP-ribose (cADPR). Each of these agents reduced the Ca2+ concentration inside the nuclear envelope, and this was associated with a transient rise in the nucleoplasmic Ca2+ concentration. NAADP released Ca2+ from the same thapsigargin-sensitive pool as IP3. The NAADP action was specific because, ...[more]

PMID: 14568993

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Project description:We have investigated the modulation of stimulus-induced changes in intracellular Ca2+ concentration ([Ca2+]i) by a caffeine-and ryanodine-sensitive Ca2+ store in PC12 cells. In populations of fura-2-loaded cells, caffeine cause a concentration-dependent increase in [Ca2+]i that was saturable, reversible and inhibited in a use-dependent fashion by ryanodine. Maximal Ca2+ release occurred with 40 mM caffeine, with an EC50 of 13 mM caffeine and a Hill coefficient (h) of 2.7, indicating that the release mechanism was co-operative. Pretreatment of intact cell populations with increasing concentrations of caffeine in nominally Ca(2+)-free medium inhibited the subsequent Ca2+ response to a maximal concentration of ATP, in a dose-dependent manner. In permeabilized cells, a maximal concentration (40 microM) of InsP3 still released Ca2+ in the presence of a supramaximal concentration (50 mM) of caffeine, whereas caffeine was unable to release Ca2+ after the InsP3-sensitive store had been completely emptied. These data suggest that PC12 cells contain a uniquely InsP3-sensitive Ca2+ store, and a store that is sensitive to both InsP3 and caffeine. Depletion of the caffeine-sensitive Ca2+ store by caffeine and ryanodine pretreatment in intact cells attenuated the Ca2+ response to ATP, but not to 55 mM K+, suggesting that the caffeine-sensitive Ca2+ store acts as a Ca2+ source after ATP stimulation, but not after depolarization with 55 mM K+. Pretreatment of intact cells with ATP and ryanodine resulted in a use-dependent block of both caffeine- and ATP-mediated Ca2+ release, confirming that ATP stimulation of PC12 cells brings about activation of ryanodine receptors. The rate of recovery, but not the magnitude or rate of onset, of the depolarization-induced [Ca2+]i transient was modulated by the state of filling of the caffeine-sensitive Ca2+ store such that recovery was prolonged if the store was either full, or empty and unable to refill. We conclude that the caffeine- and ryanodine-sensitive Ca2+ store can act as a Ca2+ source and a Ca2+ sink in PC12 cells, and that its role may in part be governed by the nature of the stimulating agent.

Dataset Information

NAADP mobilizes Ca2+ from a thapsigargin-sensitive store in the nuclear envelope by activating ryanodine receptors.

Publications

NAADP mobilizes Ca2+ from a thapsigargin-sensitive store in the nuclear envelope by activating ryanodine receptors.

Similar Datasets

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