High affinity ryanodine binding sites in rat liver endoplasmic reticulum

Shoshan‐Barmatz, Varda

doi:10.1016/0014-5793(90)81403-b

Cited by 38 publications

(24 citation statements)

References 23 publications

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“…2B). These K D values are in agreement with previous data where the K D was estimated to be between 8 and 12 nM in liver microsomes (13,14). The B max value for the hepatic RyR should be compared with the much higher density of RyR1 in terminal cisternae of skeletal muscle SR, where a value of 2.6 pmol/mg protein has been reported (29).…”

Section: Resultssupporting

confidence: 79%

“…The fact that the truncated form of the RyR would still have the capacity to act as a Ca 2ϩ channel is confirmed by functional studies with the C-terminal portion of RyR, which also showed that the pore domain of the channel retains sensitivity to ryanodine and [Ca 2ϩ ] c (38). Ryanodine was used to identify and isolate the RyR (3) and it has been previously shown that liver microsomes have ryanodine binding sites (13,14). We confirmed these observations in liver microsomes and also performed the binding assays in per- meabilized hepatocytes devoid of other cell types, which gave very similar ryanodine binding results.…”

Section: Discussionmentioning

confidence: 93%

“…On one hand there is evidence for [ 3 H]ryanodine binding to microsomal fractions (13,14) and Ca 2ϩ release from internal stores induced by ryanodine treatment (15,16), but on the other failure to detect RyR message (17,18), decrease in frequency of [Ca 2ϩ ] c oscillations after ryanodine challenge (19) and insensitivity to uncaging of cADPR (18) are reported.…”

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confidence: 99%

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Ryanodine Receptors in Liver

Pierobon

Renard-Rooney

Gaspers

et al. 2006

Journal of Biological Chemistry

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The ryanodine receptor has been mainly regarded as the Ca 2؉ release channel from sarcoplasmic reticulum controlling skeletal and cardiac muscle contraction. However, many studies have shown that it is widely expressed, with functions not restricted to muscular contraction. This study examined whether ryanodine receptor plays a role in calcium signaling in the liver. RT-PCR analysis of isolated hepatocytes showed expression of a truncated type 1 ryanodine receptor, but no type 2 or type 3 message was detected. We also detected binding sites for [3 H]ryanodine in the microsomal cellular fraction and in permeabilized hepatocytes. This binding was displaced by caffeine and dantrolene, but not by ruthenium red, heparin or cyclic ADPRibose. Ryanodine, by itself, did not trigger Ca 2؉ oscillations in either primary cultured hepatocytes or hepatocytes within the intact perfused rat liver. In both preparations, however, ryanodine significantly increased the frequency of the cytosolic free [Ca 2؉ ] oscillations evoked by an ␣ 1 adrenergic receptor agonist. Experiments in permeabilized hepatocytes showed that both ryanodine and cyclic ADP-ribose evoked a slow Ca 2؉ leak from intracellular stores and were able to increase the Ca 2؉ -released response to a subthreshold dose of inositol 1,4,5-trisphosphate. Our findings suggest the presence of a novel truncated form of the type 1 ryanodine receptor in rat hepatocytes. Ryanodine modulates the pattern of cytosolic free [Ca 2؉ ] oscillations by increasing oscillation frequency. We propose that the Ca 2؉ released from ryanodine receptors on the endoplasmic reticulum provides an increased pool of Ca 2؉ for positive feedback on inositol 1,4,5-trisphosphate receptors.Two families of channels lead to Ca 2ϩ release from intracellular stores in the endoplasmic reticulum (ER) 2 /sarcoplasmic reticulum (SR). One is the inositol 1,4,5-trisphosphate receptor (IP 3 R) family. Three different isoforms (types I, II, III) have been characterized and there are also a number of splicing variants. Activation of the IP 3 Rs is elicited by IP 3 generated by receptor activation of phosphoinositide-specific phospholipase C (PLC). The IP 3 Rs are predominantly situated in the ER and play a pivotal role in Ca 2ϩ signaling in almost every cell type (1, 2). The second family of intracellular Ca 2ϩ channels has been named ryanodine receptor (RyR) because of its high affinity for the plant alkaloid ryanodine that led to its identification and purification (3). Ryanodine has been utilized as a tool to study Ca 2ϩ release from the ER/SR of, at first, muscle cells, and more recently of a wide variety of nonmuscle cells. As with the IP 3 R family, the RyR family consists of three isoforms: RyR1 is commonly associated with skeletal muscle cells, RyR2 with cardiac muscle cells and RyR3 is widely distributed with low expression and unclear physiological role (4).An interesting feature of both channel families is their regulation by Ca 2ϩ itself. Ca 2ϩ can either stimulate or inhibit the channels depending on...

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Section: Resultssupporting

confidence: 79%

Section: Discussionmentioning

confidence: 93%

mentioning

confidence: 99%

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Ryanodine Receptors in Liver

Pierobon

Renard-Rooney

Gaspers

et al. 2006

Journal of Biological Chemistry

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“…Thus it is unlikely that caffeine is stimulating uterine prostaglandin synthesis by acting on a ryanodine Type 3 receptor. Caffeine-sensitive calcium stores have been reported as being present in adrenal chromaffin cells (Burgoyne et al, 1989), liver (Shoshan-Barmatz, 1990) and pancreas (Schmid et al, 1990). The receptor type involved in the chromaffin cells and liver may be one of the three main ryanodine types.…”

Section: Discussionmentioning

confidence: 99%

The effect of caffeine on prostaglandin output from the guinea‐pig uterus

Naderali

Poyser

1994

British J Pharmacology

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1 Caffeine increased the outputs of prostaglandin F2,. (PGF2.a), PGE2 and 6-keto-PGFI, from the guinea-pig uterus on days 7 and 15 of the oestrous cycle. The effect on PGE2 output depended on the age of the animals and was absent in younger guinea-pigs (<4 months). Theophylline also stimulated the outputs of PGF2,. and 6-keto-PGFI6, but not the output of PGE2, from the day 7 guinea-pig uterus. 2 The stimulatory effects of caffeine on the outputs of PGFu, PGE2 and 6-keto-PGFI. from the guinea-pig uterus were not prevented by lack of extracellular calcium, ryanodine or ruthenium red (both inhibitors of calcium release via the ryanodine receptor), although the increase in PGFu. output tended to be slower when extracellular calcium was absent. Also, ryanodine flattened and broadened the peak of increased PGFu. release.3 The calmodulin antagonists, W-7 and trifluoperazine, had no inhibitory effect on the caffeinestimulated increases in uterine prostaglandin output. In fact, W-7 (but not trifluoperazine) greatly potentiated the action of caffeine on uterine PGF2, output, but had little or no potentiating effect on the action of caffeine on uterine PGE2 and 6-keto-PGFIc outputs.4 TMB-8, an intracellular calcium antagonist, inhibited the increase in PGF2,, output produced by caffeine without preventing the increases in outputs of PGE2 and 6-keto-PGF1I. 5 These studies suggest that caffeine stimulates uterine PGF2, synthesis and release by a mechanism dependent upon intracellular calcium, but this mechanism is not mediated by activation of any of the three well-characterized ryanodine receptors or by calmodulin. Furthermore, the increases in the synthesis and release of PGE2 and 6-keto-PGFI. in the guinea-pig uterus induced by caffeine appear to involve mechanism(s) different from that which stimulates PGF2. production.

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“…Similarly we believe it unlikely that SF is in some way causing Ca2" influx from the extracellular environment because 1) extracellular application has no effect, 2) activity persists when extracellular Ca2" is replaced by Ba2+, and 3) the potentiation of activity by a series of Ca21 currents supports a role for intracellular stores/CICR. It is interesting to note at this point that there is now some evidence pointing to the existence of subtypes of the RyR (Lai et al, 1988;Otsu et al, 1990;Shoshan-Barmatz et al, 1991), which may vary slightly in their CICR mechanism and possible modulatory sites. Similarly there is also evidence for subtypes of the IP3R (Nakagawa et al, 1991).…”

Section: Resultsmentioning

confidence: 99%

Activation of Ca(2+)-dependent currents in cultured rat dorsal root ganglion neurones by a sperm factor and cyclic ADP-ribose.

Currie

Swann

Galione

et al. 1992

MBoC

123

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The effects of intracellular application of two novel Ca2' releasing agents have been studied in cultured rat dorsal root ganglion (DRG) neurones by monitoring Ca2+-dependent currents as a physiological index of raised free cytosolic Ca21 ([Ca21] ). A protein based sperm factor (SF) extracted from mammalian sperm, has been found to trigger Ca21 oscillations and to sensitize unfertilized mammalian eggs to calcium induced calcium release (CICR). In this study intracellular application of SF activated Ca2+-dependent currents in approximately two-thirds of DRG neurones. The SF induced activity was abolished by heat treatment, attenuated by increasing the intracellular Ca2' buffering capacity of the cells and persisted when extracellular Ca2+ was replaced by Ba2 . In addition, activity could be triggered or potentiated by loading the cells with Ca2' by activating a series of voltage-gated Ca21 currents. Ca2+-activated inward current activity was also generated by intracellular application of cyclic ADP-ribose (cADPR), a metabolite of NAD+, which causes Ca21 release in sea urchin eggs. This activity could also be enhanced by loading the cells with Ca2+. The cADPR induced activity, but not the SF induced activity, was abolished by depleting the caffeine sensitive Ca21 store. Ruthenium red markedly attenuated SF induced activity but had little action on cADPR induced activity or caffeine induced activity. Our results indicate that both SF and cADPR release intracellular Ca21 pools in DRG neurones and that they appear to act on subtly distinct stores or distinct intracellular Ca2' release mechanisms, possibly by modulating CICR.

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High affinity ryanodine binding sites in rat liver endoplasmic reticulum

Cited by 38 publications

References 23 publications

Ryanodine Receptors in Liver

Ryanodine Receptors in Liver

The effect of caffeine on prostaglandin output from the guinea‐pig uterus

Activation of Ca(2+)-dependent currents in cultured rat dorsal root ganglion neurones by a sperm factor and cyclic ADP-ribose.

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